Published Date: October 1, 2023

First demonstration of a silicon-organic hybrid (SOH) modulator based on a long-term-stable crosslinked electro-optic material

Abstract: We demonstrate the first silicon-organic hybrid electro-optic modulator relying on a long-term-stable thermally crosslinked organic electro-optic material. After more than 2200 hours of high-temper-ature storage at 120°C, the device still operates at line rates of 200 Gbit/s PAM4 and 100 Gbit/s OOK.

Citations:

• A. Schwarzenberger; A. Mertens; H. Kholeif; A. Kotz; C. Eschenbaum; L. E. Johnson; D. L. Elder; S. R. Hammond; K. O’Malley; L. Dalton; S. Randel; W. Freude; and C. Koos. 49th European Conference on Optical Communications (ECOC 2023). 2023, , 859-862. Doi: https://ieeexplore.ieee.org/document/10484589

Published Date: May 4, 2023

Perspective: Nanophotonic electro-optics enabling THz bandwidths, exceptional modulation and energy efficiencies, and compact device footprints

Abstract: The growth of integrated photonics has driven the need for efficient, high-bandwidth electrical-to-optical (EO) signal conversion over a broad range of frequencies (MHz–THz), together with efficient, high bandwidth photodetection. Efficient signal conversion is needed for applications including fiber/wireless telecom, data centers, sensing/imaging, metrology/spectroscopy, autonomous vehicle platforms, etc., as well as cryogenic supercomputing/quantum computing. Diverse applications require the ability to function over a wide range of environmental conditions (e.g., temperatures from <4 to >400 K). Active photonic device footprints are being scaled toward nanoscopic dimensions for size compatibility with electronic elements. Nanophotonic devices increase optical and RF field confinement via small feature sizes, increasing field intensities by many orders of magnitude, enabling high-performance Pockels effect materials to be ultimately utilized to their maximum potential (e.g., in-device voltage-length performance ≤0.005 V mm). Organic materials have recently exhibited significant improvements in performance driven by theory-guided design, with realized macroscopic electro-optic activity (r₃₃) exceeding 1000 pm/V at telecom wavelengths. Hybrid organic/semiconductor nanophotonic integration has propelled the development of new organic synthesis, processing, and design methodologies to capture this high performance and has improved understanding of the spatial distribution of the order of poled materials under confinement and the effects of metal/semiconductor-organic interfaces on device performance. Covalent coupling, whether from in situ crosslinking or sequential synthesis, also provides a thermally and photochemically stable alternative to thermoplastic EO polymers. The alternative processing techniques will reduce the attenuation of r₃₃ values observed in silicon organic hybrid and plasmonic organic hybrid devices arising from chromophore-electrode electrostatic interactions and material conductance at poling temperatures. The focus of this perspective is on materials, with an emphasis on the need to consider the interrelationship between hybrid device architectures and materials.

Citations:

• Larry R. Dalton; Juerg Leuthold; Bruce H. Robinson; Christian Haffner; Delwin L. Elder; Lewis E. Johnson; Scott R. Hammond; Wolfgang Heni; Claudia Hosessbacher; Benedikt Baeuerle; Eva De Leo; Ueli Koch; Patrick Habegger; Yuriy Fedoryshyn; David Moor; and Ping Ma. APL Mater. 2023, 11 (5) , . Doi: https://doi.org/10.1063/5.0145212

Published Date: September 18, 2022

Cryogenic Operation of a Silicon-Organic Hybrid (SOH) Modulator at 50 Gbit/s and 4 K Ambient Temperature

Abstract: We demonstrate cryogenic operation of a silicon-organic hybrid (SOH) Mach-Zehnder modulator. The device is based on a dedicated material formulation and allows for 50 Gbit/s on-off-keying (OOK) at 4 K – a record-high line rate generated by an MZM at this temperature.

Citations:

• A. Schwarzenberger; A. Kuzmin; C. Eschenbaum; C. Füllner; A. Mertens; L.E. Johnson; D. L. Elder; S. R. Hammond; L. Dalton; S. Randel; W. Freude; and C. Koos. 2022 European Conference on Optical Communication (ECOC). 2022, , 1-6 pp. Doi: https://ieeexplore.ieee.org/document/9979191

Published Date: June 6, 2022

Gigahertz free-space electro-optic modulators based on Mie resonances

Abstract: Electro-optic modulators are essential for sensing, metrology and telecommunications. Most target fiber applications. Instead, metasurface-based architectures that modulate free-space light at gigahertz (GHz) speeds can boost flat optics technology by microwave electronics for active optics, diffractive computing or optoelectronic control. Current realizations are bulky or have low modulation efficiencies. Here, we demonstrate a hybrid silicon-organic metasurface platform that leverages Mie resonances for efficient electro-optic modulation at GHz speeds.

Citations:

• Ileana-Cristina Benea-Chelmus; Sydney Mason; Maryna L. Meretska; Delwin L. Elder; Dmitry Kazakov; Amirhassan Shams-Ansari; Larry R. Dalton; and Federico Capasso. Nature Communications. 2022, (13) , . Doi: https://doi.org/10.1038/s41467-022-30451-z

Published Date: March 7, 2022

Organic electro-optic materials combining extraordinary nonlinearity with exceptional stability to enable commercial applications

Abstract: Hybrid organic electro-optic (OEO) modulators consist of a layer of ordered organic chromophores confined between layers of metals or semiconductors, enabling optical fields to be tightly confined within the OEO material. The combination of tight confinement with the high electro-optic (EO) performance of state-of-the-art OEO materials enables extraordinary EO modulation performance in silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) device architectures. Recent records in POH devices include bandwidths >500 GHz and energy efficiency <100 aJ/bit. To enable commercial applications of these materials and devices, however, they must withstand demanding thermal and environmental conditions, both during manufacture and operation. To address these concerns, we examined the long-term thermal and environmental shelf storage stability of state-of-the-art commercial and developmental OEO materials under a variety of conditions relevant to Telecordia GR-468-CORE standards. We examined the shelf storage of poled OEO materials under a nitrogen atmosphere at a range of temperatures from 85 ˚C up to 150 ˚C to understand the kinetics of the thermally activated de-poling of the OEO materials. We also examined the shelf storage of OEO materials under a variety of atmospheres, including the aggressive 85 ˚C and 85% relative humidity damp heat condition, to understand the relative sensitivities of the materials to water and oxygen at different temperatures. We analyze the results of these studies and discuss their implications for commercial application of these materials and devices, including manufacturing, encapsulation requirements, and expected operational lifetimes.

Citations:

• Scott R. Hammond; Kevin M. O’Malley; Huajun Xu; Delwin L. Elder; and Lewis E. Johnson. Organic Photonic Materials and Devices XXIV. 2022, Proc. SPIE 11998 (119980C) , . Doi: https://doi.org/10.1117/12.2622099

Published Date: January 14, 2022

Organic Electro-Optics and Optical Rectification: From Mesoscale to Nanoscale Hybrid Devices and Chip-Scale Integration of Electronics and Photonics

Abstract: The performance of electro-optic devices based on organic second order NLO materials has been improved by orders of magnitude through theory-guided improvement in the electro-optic activity and other relevant properties of organic materials and by field compression of radio frequency (RF) and optical fields associated with the transition from microscale/mesoscale devices to silicon–organic hybrid (SOH) and plasmonic–organic hybrid (POH) devices with nanoscopic dimensions. This paradigm shift in organic electro-optic R&D has led to many performance improvements, including record performance for voltage-length performance of less than 50 V-μm, energy consumption of less than 70 attojoules/bit, bandwidths of greater than 500 gigahertz (GHz), and device footprints of less than 20 μm². Another consequence of improving electro-optic performance is the corresponding improvement of the converse second order nonlinear optical property of optical rectification (transparent photodetection). Theory has permitted identification of optimum optical nonlinearity/transparency values and dipole moments for newly developed chromophores, which have led, in turn, to state-of-the-art materials and device performance.

Citations:

• Elder, D.L. and Dalton, L.R.. Industrial & Engineering Chemistry Research. 2022, , . Doi: https://doi.org/10.1021/acs.iecr.1c03836

Published Date: September 23, 2021

Design and synthesis of chromophores with enhanced electro-optic activities in both bulk and plasmonic–organic hybrid devices

Abstract: This study demonstrates enhancement of in-device electro-optic activity via a series of theory-inspired organic electro-optic (OEO) chromophores based on strong (diarylamino)phenyl electron donating moieties. These chromophores are tuned to minimize trade-offs between molecular hyperpolarizability and optical loss. Hyper-Rayleigh scattering (HRS) measurements demonstrate that these chromophores, herein described as BAH, show >2-fold improvement in β versus standard chromophores such as JRD1, and approach that of the recent BTP and BAY chromophore families. Electric field poled bulk devices of neat and binary BAH chromophores exhibited significantly enhanced EO coefficients (r₃₃) and poling efficiencies (r₃₃/E_p) compared with state-of-the-art chromophores such as JRD1. The neat BAH13 devices with charge blocking layers produced very large poling efficiencies of 11.6 ± 0.7 nm² V⁻² and maximum r₃₃ value of 1100 ± 100 pm V⁻¹ at 1310 nm on hafnium dioxide (HfO₂). These results were comparable to that of our recently reported BAY1 but with much lower loss (extinction coefficient, k), and greatly exceeding that of other previously reported OEO compounds. 3 : 1 BAH-FD : BAH13 blends showed a poling efficiency of 6.7 ± 0.3 nm² V⁻² and an even greater reduction in k. 1 : 1 BAH-BB : BAH13 showed a higher poling efficiency of 8.4 ± 0.3 nm² V⁻², which is approximately a 2.5-fold enhancement in poling efficiency vs. JRD1. Neat BAH13 was evaluated in plasmonic–organic hybrid (POH) Mach–Zehnder modulators with a phase shifter length of 10 μm and slot widths of 80 and 105 nm. In-device BAH13 achieved a maximum r₃₃ of 208 pm V⁻¹ at 1550 nm, which is ∼1.7 times higher than JRD1 under equivalent conditions.

Citations:

• Xu, H.; Elder, D.L.; Johnson, L.E.; Heni, H.; de Coene, Y; De Leo, E.; Destraz, M.; Meier, N.; Ghinst, W.V.; Hammond, S.R.; Clays, K.; Leuthold, J; Dalton, L.R.; and Robinson, B.H.. Materials Horizons. 2021, , . Doi: https://doi.org/10.1039/D1MH01206A

Published Date: September 20, 2021

Electro-Optic Activity in Excess of 1000 pm V⁻¹ Achieved via Theory-Guided Organic Chromophore Design

Abstract: High performance organic electro-optic (OEO) materials enable ultrahigh bandwidth, small footprint, and extremely low drive voltage in silicon-organic hybrid and plasmonic-organic hybrid photonic devices. However, practical OEO materials under device-relevant conditions are generally limited to performance of ≈300 pm V⁻¹ (10× the EO response of lithium niobate). By means of theory-guided design, a new series of OEO chromophores is demonstrated, based on strong bis(4-dialkylaminophenyl)phenylamino electron donating groups, capable of EO coefficients (r₃₃) in excess of 1000 pm V⁻¹. Density functional theory modeling and hyper-Rayleigh scattering measurements are performed and confirm the large improvement in hyperpolarizability due to the stronger donor. The EO performance of the exemplar chromophore in the series, BAY1, is evaluated neat and at various concentrations in polymer host and shows a nearly linear increase in r₃₃ and poling efficiency (r₃₃/E_p, E_p is poling field) with increasing chromophore concentration. 25 wt% BAY1/polymer composite shows a higher poling efficiency (3.9 ± 0.1 nm² V⁻²) than state-of-the-art neat chromophores. Using a high-ε charge blocking layer with BAY1, a record-high r₃₃ (1100 ± 100 pm V⁻¹) and poling efficiency (17.8 ± 0.8 nm² V⁻²) at 1310 nm are achieved. This is the first reported OEO material with electro-optic response larger than thin-film barium titanate.

Citations:

• Xu, H.; Elder, D.L.; Johnson, L.E.; de Coene, Y.; Hammond, S.R.; Ghinst, W.V.; Clays, K.; Dalton, L.R.; and Robinson, B.H.. Advanced Materials. 2021, (33) , . Doi: https://doi.org/10.1002/adma.202104174

Published Date: August 26, 2021

Birefringence, dimensionality, and surface influences on organic hybrid electro-optic performance

Abstract: Hybrid organic electro-optic (OEO) devices consist of a layer of ordered organic chromophores confined between layers of metals or semiconductors, enabling optical fields to be tightly confined within the OEO material. The combination of tight confinement with the high electro-optic (EO) performance of state-of-the art OEO materials enables exceptional electro-optic switching performance in silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) device architectures. Recent records in POH devices include bandwidths < 500 GHz and energy efficiency < 100 aJ/bit. However, optimization of device performance requires both understanding and improving the degree to which chromophores can be acentrically ordered near a metal or semiconductor interface. Applying bulk and/or isotropic models of OEO materials to nanophotonic device architectures often lead to overly optimistic translation of materials performance to device performance. Prior work has identified influences of high centrosymmetric order (birefringence), altered relations between acentric and centrosymmetric order (dimensionality), and surface electrostatics on chromophore ordering. We combine these models into a representation that can be used to understand the influences of these phenomena on device performance, how some prior OEO materials exhibited unusually high performance under confinement, how ordering close to surfaces may be improved, and implications for future electro-optic device design.

Citations:

• Lewis E. Johnson; Delwin L. Elder; Stephanie J. Benight; Andreas F. Tillack; Scott R. Hammond; Wolfgang Heni; Larry R. Dalton; and Bruce H. Robinson. Physical Chemistry of Semiconductor Materials and Interfaces XX. 2021, Proc. SPIE 11799 (1179917) , . Doi: https://doi.org/10.1117/12.2594939

Published Date: August 4, 2021

New paradigms in materials and devices for hybrid electro-optics and optical rectification

Abstract: We review recent transformative advances in materials design, synthesis, and processing as well as device engineering for the utilization of organic materials in hybrid electro-optic (EO) and optical rectification (OR) technologies relevant to telecommunications, sensing, and computing. End-to-end (from molecules to systems) modeling methods utilizing multi-scale computation and theory permit prediction of the performance of novel materials in nanoscale device architectures including those involving plasmonic phenomena and architectures in which interfacial effects play a dominant role. Both EO and OR phenomenon require acentric organization of constituent active molecules. The incumbent methodology for achieving such organization is electric field poling, where chromophore shape, dipole moment, and conformational flexibility play dominant roles. Optimized chromophore design and control of the poling process has already led to record-setting advances in electro-optic performance, e.g., voltage-length performance of < 50 volt-micrometer, bandwidths < 500 GHz, and energy efficiency < 70 attojoule/bit. They have also led to increased thermal stability, low insertion loss and high signal quality (BER and SFDR). However, the limits of poling in the smallest nanophotonic devices—in which extraordinary optical field densities can be achieved—has stimulated development of alternatives based on covalent coupling of modern high-performance chromophores into ordered nanostructures. Covalent coupling enables higher performance, greater scalability, and greater stability and is especially suited for the latest nanoscale architectures. Recent developments in materials also facilitate a new technology—transparent photodetection based on optical rectification. OR does not involve electronic excitation, as is the case with conventional photodiodes, and as such represents a novel detection mechanism with a greatly reduced noise floor. OR already dominates at THz frequencies and recent advances will enable superior performance at GHz frequencies as well.

Citations:

• Johnson, L. E.; Elder, D. L.; Xu, H.; Hammond, S. R.; Benight, S. J.; O’Malley, K.; Robinson, B. H.; and Dalton, L. R.. Proc. SPIE 11812. 2021, Molecular and Nano Machines IV (1181202) , . Doi: https://doi.org/10.1117/12.2595638

Published Date: February 8, 2021

Bis(4-dialkylaminophenyl) heteroarylamino donor chromophores exhibiting exceptional hyperpolarizabilities

Abstract: Organic electro-optic (EO) materials incorporated into silicon-organic hybrid and plasmonic-organic hybrid devices have enabled new records in EO modulation performance. We report a new series of nonlinear optical chromophores engineered by theory-guided design, utilizing bis(4-dialkylaminophenyl)heteroarylamino donor moieties to greatly enhance molecular hyperpolarizabilities. Hyperpolarizabilities predicted using density functional theory were validated by hyper-Rayleigh scattering measurements, showing strong prediction/experiment agreement and >2-fold advancement in static hyperpolarizability over the best prior chromophores. Electric field poled thin films of these chromophores showed significantly enhanced EO coefficients (r₃₃) and poling efficiencies (r₃₃/E_p) at low chromophore concentrations compared with state-of-the-art chromophores such as JRD1. The highest performing blend, containing just 10 wt% of the novel chromophore BTP7, showed a 12-fold enhancement in poling efficiency per unit concentration vs. JRD1. Our results suggest that further improvement in chromophore hyperpolarizability is feasible without unacceptable tradeoffs with optical loss or stability.

Published Date: August 7, 2020

Silicon-organic hybrid (SOH) Mach-Zehnder modulators for 100 GBd PAM4 signaling with sub-1 dB phase-shifter loss

Abstract: We report on compact and efficient silicon-organic hybrid (SOH) Mach-Zehnder modulators (MZM) with low phase-shifter insertion loss of 0.7 dB. The 280 µm-long phase shifters feature a π
-voltage-length product of 0.41 Vmm and a loss-efficiency product as small as aUπL = 1.0 VdB. The device performance is demonstrated in a data transmission experiment, where we generate on-off-keying (OOK) and four-level pulse-amplitude modulation (PAM4) signals at symbol rates of 100 GBd, resulting in line rates of up to 200 Gbit/s. Bit error ratios are below the threshold for hard-decision forward error correction (HD-FEC) with 7% coding overhead, leading to net data rates of 187 Gbit/s. This is the highest PAM4 data rate ever achieved for a sub-1 mm silicon photonic MZM.

Citations:

• Clemens Kieninger, Christoph Füllner, Heiner Zwickel, Yasar Kutuvantavida, Juned N. Kemal, Carsten Eschenbaum, Delwin L. Elder, Larry R. Dalton, Wolfgang Freude, Sebastian Randel, and Christian Koos. Optics Express. 2020, (28) , . Doi: https://doi.org/10.1364/oe.390315

Published Date: June 1, 2020

A monolithic bipolar CMOS electronic–plasmonic high-speed transmitter

Abstract: To address the challenge of increasing data rates, next-generation optical communication networks will require the co-integration of electronics and photonics. Heterogeneous integration of these technologies has shown promise, but will eventually become bandwidth-limited. Faster monolithic approaches will therefore be needed, but monolithic approaches using complementary metal–oxide–semiconductor (CMOS) electronics and silicon photonics are typically limited by their underlying electronic or photonic technologies. Here, we report a monolithically integrated electro-optical transmitter that can achieve symbol rates beyond 100 GBd. Our approach combines advanced bipolar CMOS with silicon plasmonics, and addresses key challenges in monolithic integration through co-design of the electronic and plasmonic layers, including thermal design, packaging and a nonlinear organic electro-optic material. To illustrate the potential of our technology, we develop two modulator concepts—an ultra-compact plasmonic modulator and a silicon-plasmonic modulator with photonic routing—both directly processed onto the bipolar CMOS electronics.

Citations:

• Koch, U.; Uhl, C.; Hettrich, H.; Fedoryshyn, Y.; Hoessbacher, C.; Heni, W.; Baeuerle, B.; Bitachon, B. I.; Josten, A.; Ayata, M.; Xu, H.; Elder, D. L.; Dalton, L. R.; Mentovich, E.; Bakopoulos, P.; Lischke, S.; Krüger, A.; Zimmermann, L.; Tsiokos, D.; Pleros, N.; Möller, M.; Leuthold, J.. Nature Electronics. 2020, 3, 338–345. Doi: https://doi.org/10.1038/s41928-020-0417-9

Published Date: February 12, 2020

Ultra-High-Speed 2:1 Digital Selector and Plasmonic Modulator IM/DD Transmitter Operating at 222 GBaud for Intra-Datacenter Applications

Abstract: We demonstrate a 222 GBd on-off-keying transmitter in a short-reach intra-datacenter scenario with direct detection after 120 m of standard single mode fiber. The system operates at net-data rates of >200 Gb/s OOK for transmission distances of a few meters, and >177 Gb/s over 120 m, limited by chromatic dispersion in the standard single mode fiber. The high symbol rate transmitter is enabled by a high-bandwidth plasmonic-organic hybrid Mach-Zehnder modulator on the silicon photonic platform that is ribbon-bonded to an InP DHBT 2:1 digital multiplexing selector. Requiring no driving RF amplifiers, the selector directly drives the modulator with a differential output voltage of 622 mVpp measured across a 50 Ω resistor. The transmitter assembly occupies a footprint of less than 1.5 mm × 2.1 mm.

Citations:

• Heni, W.; Baeuerle, B.; Mardoyan, H.; Jorge, F.; Estaran, J. M.; Konczykowska, A.; Riet, M.; Duval, B.; Nodjiadjim, V.; Goix, M.; Dupuy, J.-Y.; Destraz, M.; Hoessbacher, C.; Fedoryshyn, Y.; Xu, H.; Elder, D. L.; Dalton, L.; Renaudier, J.; Leuthold, J.. Journal of Lightwave Technology. 2020, 9 (1) , 2734-2739. Doi: https://doi.org/10.1109/JLT.2020.2972637

Published Date: January 13, 2020

Ultrahigh Electro-Optic Coefficients, High Index of Refraction, and Long-Term Stability from Diels–Alder Cross-Linkable Binary Molecular Glasses

Abstract: The development of organic electro-optic (EO) materials that concurrently possess a high electro-optic coefficient (r₃₃), high index of refraction, and long-term or high-temperature stability of chromophore alignment has been a crucial goal. To address this challenge, we developed a crosslinkable EO system consisting of two chromophores, HLD1 and HLD2, which can be electric field poled and then thermally crosslinked in situ to form a stable EO material. This approach avoids the necessity for nonlinear optically inactive materials such as polymers or small molecule cross-linkers, thus resulting in high chromophore density (>5 × 10²⁰ molecules/cm³) and high index of refraction (n = 1.89 at 1310 nm) for HLD1/HLD2. Different ratios of HLD1 and HLD2 were evaluated to optimize poling efficiency and thermal stability of the poling-induced order. With 2:1 HLD1/HLD2 (wt/wt), a maximum r₃₃ of 290 ± 30 pm/V was achieved in a cross-linked film. Thermal stability tests showed that after heating to 85 °C for 500 h, greater than 99% of the initial r₃₃ value was maintained. This combination of large EO activity, high index of refraction, and long-term alignment stability is an important breakthrough in EO materials. HLD1/HLD2 can also be poled without the subsequent cross-linking step, and even larger maximum r₃₃ (460 ± 30 pm/V) and n³r₃₃ figure of merit (3100 ± 200 pm/V) were achieved. Hyperpolarizabilities of HLD and control molecules were analyzed by hyper-Rayleigh scattering and computational modeling with good agreement, and they help explain the high acentric order achieved during poling.

Citations:

• Xu, H.; Liu, F.; Elder, D. L.; Johnson, L. E.; de Coene, Y.; Clays, K.; Robinson, B. H.; Dalton, L. R.. Chemistry of Materials. 2020, 32, 1408-1421. Doi: https://doi.org/10.1021/acs.chemmater.9b03725

Published Date: December 5, 2019

Compact and ultra-efficient broadband plasmonic terahertz field detector

Abstract: Terahertz sources and detectors have enabled numerous new applications from medical to communications. Yet, most efficient terahertz detection schemes rely on complex free-space optics and typically require high-power lasers as local oscillators. Here, we demonstrate a fiber-coupled, monolithic plasmonic terahertz field detector on a silicon-photonics platform featuring a detection bandwidth of 2.5 THz with a 65 dB dynamical range. The terahertz wave is measured through its nonlinear mixing with an optical probe pulse with an average power of only 63 nW. The high efficiency of the scheme relies on the extreme confinement of the terahertz field to a small volume of 10⁻⁸(λ_THz/2)³. Additionally, on-chip guided plasmonic probe beams sample the terahertz signal efficiently in this volume. The approach results in an extremely short interaction length of only 5 μm, which eliminates the need for phase matching and shows the highest conversion efficiency per unit length up to date.

Citations:

• Salamin, Y.; Benea-Chelmus, I. C.; Fedoryshyn, Y.; Heni, W.; Elder, D. L.; Dalton, L. R.; Faist, J.; Leuthold, J.. Nature Communications. 2019, 10, 5550. Doi: https://doi.org/10.1038/s41467-019-13490-x

Published Date: October 29, 2018

Microwave plasmonic mixer in a transparent fibre–wireless link

Abstract: To cope with the high bandwidth requirements of wireless applications1, carrier frequencies are shifting towards the millimetre-wave and terahertz bands. Conversely, data is normally transported to remote wireless antennas by optical fibres. Therefore, full transparency and flexibility to switch between optical and wireless domains would be desirable. Here, we demonstrate a direct wireless-to-optical receiver in a transparent optical link. We successfully transmit 20 and 10 Gbit s⁻¹ over wireless distances of 1 and 5 m, respectively, at a carrier frequency of 60 GHz. Key to the breakthrough is a plasmonic mixer directly mapping the wireless information onto optical signals. The plasmonic scheme with its subwavelength feature and pronounced field confinement provides a built-in field enhancement of up to 90,000 over the incident field in an ultra-compact and complementary metal-oxide–semiconductor compatible structure. The plasmonic mixer is not limited by electronic speed and thus compatible with future terahertz technologies.

Citations:

• Salamin, Y.; Baeuerle, B.; Heni, W.; Abrecht, F. C.; Josten, A.; Fedoryshyn, Y.; Haffner, C.; Bonjour, R.; Watanabe, T.; Burla, M.; Elder, D. L.; Dalton, L. R.; Leuthold, J.. Nature Photonics. 2018, 12, 749-753. Doi: https://doi.org/10.1038/s41566-018-0281-6

Published Date: May 30, 2019

500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics

Abstract: Broadband electro-optic intensity modulators are essential to convert electrical signals to the optical domain. The growing interest in terahertz wireless applications demands modulators with frequency responses to the sub-terahertz range, high power handling, and very low nonlinear distortions, simultaneously. However, a modulator with all those characteristics has not been demonstrated to date. Here, we experimentally demonstrate that plasmonic modulators do not trade-off any performance parameter, featuring—at the same time—a short length of tens of micrometers, record-high flat frequency response beyond 500 GHz, high power handling, and high linearity, and we use them to create a sub-terahertz radio-over-fiber analog optical link. These devices have the potential to become a new tool in the general field of microwave photonics, making the sub-terahertz range accessible to, e.g., 5G wireless communications, antenna remoting, Internet of Things, sensing, and more.

Citations:

• Burla, M.; Hoessbacher, C.; Heni, W.; Haffner, C.; Fedoryshyn, Y.; Werner, D.; Watanabe, T.; Massler, H.; Elder, D. L.; Dalton, L. R.; Leuthold, J.. APL Photonics. 2019, 4, . Doi: https://doi.org/10.1063/1.5086868

Published Date: May 22, 2019

Molecular Engineering of Structurally Diverse Dendrimers with Large Electro-Optic Activities

Abstract: To boost electro-optic (EO) performance, a series of multichromophore dendrimers have been developed based on higher hyperpolarizability (CLD-type) chromophore cores that have been used previously (FTC-type dendrimers). The multichromophore dendrimers were molecularly engineered to have either three arms, two arms, or one arm; long or short linkers; and a fluorinated dendron (FD) or tert-butyldiphenylsilyl (TBDPS) shell. The EO performance obtained by FDSD (poling efficiency = 1.60 nm² V^–2), based on succinic diester linkers, was higher than the analogue with longer adipic diester linkers and higher than the analogs with fewer chromophore moieties. Due to the shorter succinic diester linker and improved site isolation, the dendrimer chromophore with TBDPS groups exhibited enhanced glass-transition temperature (T_g = 108 °C) and comparable poling efficiency (1.62 nm² V^–2) to the FD-containing version. These neat EO dendrimers have a higher index of refraction (n = 1.75–1.84 at 1310 nm) than guest–host polymeric EO materials (n ≈ 1.6, 1310 nm) and FTC-type EO dendrimers (n = 1.73, 1310 nm), which is important, because a key metric for Mach–Zehnder modulators is proportional to n³. In addition, binary chromophore organic glasses (BCOGs) were prepared by doping a secondary EO chromophore at 25 wt % into neat dendrimers. Enhancements of EO performance were found in all BCOG materials compared with neat dendrimers due to the effect of blending. As a result of increased chromophore density, the n values of the BCOGs improved to 1.81–1.92. One BOCG, in particular, displayed the highest poling efficiency (2.35 nm² V^–2) and largest EO coefficient (r₃₃) value of 275 pm V^–1 at 1310 nm, which represents a high n³r₃₃ figure-of-merit of 1946 pm V^–1. The high poling efficiencies and n³r₃₃ figure-of-merit combined with excellent film forming confirm these neat dendrimers and BCOGs based on them as promising candidates for incorporation into photonic devices.

Citations:

• Xu, H.; Elder, D. L.; Johnson, L. E.; Robinson, B. H.; Dalton, L. R.. ACS Applied Materials & Interfaces. 2019, 11, 21058-21068. Doi: https://doi.org/10.1021/acsami.9b05306

Published Date: April 12, 2019

Plasmonic IQ modulators with attojoule per bit electrical energy consumption

Abstract: Coherent optical communications provides the largest data transmission capacity with the highest spectral efficiency and therefore has a remarkable potential to satisfy today’s ever-growing bandwidth demands. It relies on so-called in-phase/quadrature (IQ) electro-optic modulators that encode information on both the amplitude and the phase of light. Ideally, such IQ modulators should offer energy-efficient operation and a most compact footprint, which would allow high-density integration and high spatial parallelism. Here, we present compact IQ modulators with an active section occupying a footprint of 4 × 25 µm × 3 µm, fabricated on the silicon platform and operated with sub-1-V driving electronics. The devices exhibit low electrical energy consumptions of only 0.07 fJ bit⁻¹ at 50 Gbit s⁻¹, 0.3 fJ bit⁻¹ at 200 Gbit s⁻¹, and 2 fJ bit⁻¹ at 400 Gbit s⁻¹. Such IQ modulators may pave the way for application of IQ modulators in long-haul and short-haul communications alike.

Citations:

• Heni, W.; Fedoryshyn, Y.; Baeuerle, B.; Josten, A.; Hoessbacher, C. B.; Messner, A.; Haffner, C.; Watanabe, T.; Salamin, Y.; Koch, U.; Elder, D. L.; Dalton, L. R.; Leuthold, J.. Nature Communications. 2019, 10, 1694. Doi: https://doi.org/10.1038/s41467-019-09724-7

Published Date: February 27, 2019

Unraveling Excitonic Effects for the First Hyperpolarizabilities of Chromophore Aggregates

Abstract: Excitonic interactions often significantly affect the optoelectronic properties of molecular materials. However, their role in determining the nonlinear optical response of organic electro-optic materials remains poorly understood. In this paper, we explore the effects of excitonic interactions on the first hyperpolarizability for aggregates of donor–acceptor chromophores. We show that calculations of the first hyperpolarizabilty of chromophore aggregates based on a two-state model agree well with the more rigorous coupled perturbed Hartree–Fock method. We then use both time-dependent density functional theory calculations and the molecular exciton approximation to parametrize the two-state model. Use of the molecular exciton approximation to the two-state model (i) is appropriate for disordered aggregates (unlike band theory), (ii) is computationally efficient enough for calculating the first hyperpolarizability of materials that consist of thousands of interacting chromophores, and (iii) allows the unraveling of the effects of both excitonic interactions and electrostatic polarization of the chromophore electron density by its environment on the first hyperpolarizability of molecular materials. We find that use of the molecular exciton approximation to the two-state model does not introduce significant additional errors compared to those introduced by applying the two-state model alone. We determine that the absolute change to the first hyperpolarizability of chromophore aggregates due to excitonic interactions increases with the size of the aggregate. For all sizes of disordered aggregates of chromophores considered in this paper, the inclusion of excitonic interactions on average decreases the magnitude of the first hyperpolarizability by 12–14% compared to the case of non-interacting chromophores. Finally, we present a method for analytically calculating the first hyperpolarizability of a one-dimensional periodic array of chromophores within the molecular exciton approximation to the two-state model. This technique can be used to include an approximate correction for excitonic effects when simulating the electro-optic response of disordered and ordered organic materials.

Citations:

• Kocherzhenko, A. A.; Shedge, S. V.; Sosa Vazquez, X.; Maat, J.; Wilmer, J.; Tillack, A. F.; Johnson, L. E.; Isborn, C. M.. The Journal of Physical Chemistry C. 2019, 123 (22) , 13818-13836. Doi: https://doi.org/10.1021/acs.jpcc.8b12445

Published Date: August 17, 2018

Optimization of Plasmonic-Organic Hybrid Electro-Optics

Abstract: Plasmonic-organic hybrid technology affords the potential for exceptional bandwidth, extremely small footprint, and very low drive voltages resulting in substantially improved energy efficiency for devices. Optical loss is a well-recognized problem for plasmonic technologies but is currently addressed with some notable success. Thereby, the optimization of electrically poled organic electro-optic (OEO) materials is most critical since a large electro-optical coefficient allows implementation of short active device structures that result in lower insertion losses and lower voltage-length products. Most importantly, short structures also guarantee largest bandwidths and best energy efficiencies. Yet, an efficient optimization of in-device performance of OEO materials requires the development of novel computational simulation methods, especially as waveguide width dimensions reach tens of nanometers in plasmonic waveguides and as electrode surface/material interfacial effects become more and more dominant. The focus of this communication is on novel multi-scale modeling methods, including coarse-grained Monte Carlo statistical mechanical simulations combined with quantum mechanical methods to simulate and analyze the linear and nonlinear optical properties for high chromophore number density solid-state OEO materials. New chromophores are developed with the assistance of theory and may lead to an order of magnitude improvement in device performance.

Citations:

• Robinson, B. H.; Johnson, L. E.; Elder, D. L.; Kocherzhenko, A. A.; Isborn, C. M.; Haffner, C.; Heni, W.; Hoessbacher, C.; Fedoryshyn, Y.; Salamin, Y.; Baeuerle, B.; Josten, A.; Ayata, M.; Koch, U.; Leuthold, J.; Dalton, L. R.. Journal of Lightwave Technology. 2018, 36, 5036-5047. Doi: https://doi.org/10.1109/JLT.2018.2865882

Published Date: April 25, 2018

Low-loss plasmon-assisted electro-optic modulator

Abstract: For nearly two decades, researchers in the field of plasmonics—which studies the coupling of electromagnetic waves to the motion of free electrons near the surface of a metal—have sought to realize subwavelength optical devices for information technology, sensing, nonlinear optics, optical nanotweezers and biomedical applications. However, the electron motion generates heat through ohmic losses. Although this heat is desirable for some applications such as photo-thermal therapy, it is a disadvantage in plasmonic devices for sensing and information technology and has led to a widespread view that plasmonics is too lossy to be practical. Here we demonstrate that the ohmic losses can be bypassed by using ‘resonant switching’. In the proposed approach, light is coupled to the lossy surface plasmon polaritons only in the device’s off state (in resonance) in which attenuation is desired, to ensure large extinction ratios between the on and off states and allow subpicosecond switching. In the on state (out of resonance), destructive interference prevents the light from coupling to the lossy plasmonic section of a device. To validate the approach, we fabricated a plasmonic electro-optic ring modulator. The experiments confirm that low on-chip optical losses, operation at over 100 gigahertz, good energy efficiency, low thermal drift and a compact footprint can be combined in a single device. Our result illustrates that plasmonics has the potential to enable fast, compact on-chip sensing and communications technologies.

Citations:

• Haffner, C.; Chelladurai, D.; Fedoryshyn, Y.; Josten, A.; Baeuerle, B.; Heni, W.; Watanabe, T.; Cui, T.; Cheng, B.; Saha, S.; Elder, D. L.; Dalton, L. R.; Boltasseva, A.; Shalaev, V. M.; Kinsey, N.; Leuthold, J.. Nature. 2018, 556, 483-486. Doi: https://doi.org/10.1038/s41586-018-0031-4

Published Date: February 21, 2018

Three-Dimensional Phase Modulator at Telecom Wavelength Acting as a Terahertz Detector with an Electro-Optic Bandwidth of 1.25 Terahertz

Abstract: We report a thin film phase modulator employing organic nonlinear optical molecules, with an electro-optic bandwidth of 1.25 THz. The device acts as a polarization sensitive broadband Pockels medium for coherent electric field detection in a dual wavelength terahertz time-domain spectroscopy setup in the telecom band at 1550 nm. To increase the sensitivity, we combine a three-dimensional bow-tie antenna structure with strongly electro-optically active molecules JRD1 in poly(methyl methacrylate) supporting polymer. The antenna provides subwavelength field confinement of the terahertz wave with its waveguide gap with lateral dimensions of 2.2 μm × 5 μm × 4 μm. In the gap, the electric field is up to 150× stronger than in a diffraction limited space-time volume, such that an interaction length of only 4 μm suffices for the detection of fields below 10 V/m. This device is promising in the growing field of quantum optics in the terahertz, single photon terahertz detection, nonlinear imaging, and on-chip telecommunication.

Citations:

• Benea-Chelmus, I.-C.; Zhu, T.; Settembrini, F. F.; Bonzon, C.; Mavrona, E.; Elder, D. L.; Heni, W.; Leuthold, J.; Dalton, L. R.; Faist, J.. ACS Photonics. 2018, 5 (4) , 1398-1403. Doi: https://doi.org/10.1021/acsphotonics.7b01407

Published Date: November 3, 2017

Complete High-speed Plasmonic Modulator in a Single Metal Layer. Science

Abstract: Plasmonics provides a possible route to overcome both the speed limitations of electronics and the critical dimensions of photonics. We present an all-plasmonic 116–gigabits per second electro-optical modulator in which all the elements—the vertical grating couplers, splitters, polarization rotators, and active section with phase shifters—are included in a single metal layer. The device can be realized on any smooth substrate surface and operates with low energy consumption. Our results show that plasmonics is indeed a viable path to an ultracompact, highest-speed, and low-cost technology that might find many applications in a wide range of fields of sensing and communications because it is compatible with and can be placed on a wide variety of materials.

Citations:

• Ayata, M.; Fedoryshyn, Y.; Heni, W.; Baeuerle, B.; Josten, A.; Elder, D. L.; Dalton, L. R.; Leuthold, J.. Science. 2017, 358 (6363) , 630-632. Doi: https://doi.org/10.1126/science.aan5953

Published Date: July 7, 2017

Effect of Rigid Bridge-Protection Units, Quadrupolar Interactions, and Blending in Organic Electro-Optic Chromophores

Abstract: A new organic electro-optic (EO) molecule was designed with two modifications aimed at increasing acentric order. The molecule is based on the well-known CLD donor-π bridge-acceptor template. The first structural modification introduces rigid aromatic fluorenyl and naphthyl site-isolation units (sterically bulky functional groups) to reduce aggregation. Site isolation units have been used in the past, but this is the first time that both the “front” and “back” of the CLD tetraene bridge have been modified with site-isolation units, and we had to introduce new synthetic methodology to do so. The second design element was the inclusion of cooperatively interacting aromatic dendron (HD) and fluoroaromatic dendron (FD) side groups to increase the acentric order. HD/FD units have previously been successfully used to increase EO performance, but we changed their location on the chromophore: they are attached to the donor and acceptor ends of the molecule to better match side chain ordering with the dipole moment of the molecule. Comparison chromophores were synthesized with alkyl (-MOM), hydroxyl (-OH), or HD units on the acceptor end of the molecule and either the traditional CLD bridge (T-bridge) or modified bridge (BB-bridge) for a family of eight chromophores. The HD/FD units increased glass transition temperature, T_g, by 4–21 °C, and the bulky bridge modification increased T_g by 27–44 °C, which is very beneficial as that results in extra thermal stability of the poling-induced acentric order. UV/vis absorbance spectroscopy shows that the site-isolation units reduce aggregation. Unfortunately, poor film formation of the neat materials precluded full chromophore evaluation in poling and r₃₃ experiments. The EO performance obtained for HD-BB-FD and HD-BB-OH was lower than expected, with r₃₃/E_p ≈ 1 nm² V^–2 at 1310 nm. We found that blending in 25 wt % YLD124 improved film-forming and poling efficiency. Due to the effect of blending and improved site isolation, r₃₃/E_p improved to 2.1–2.3 nm² V^–2 for 3:1 HD-BB-FD:YLD124, HD-BB-OH:YLD124, and HD-BB-MOM:YLD124, and r₃₃ as high as 351 pm V^–1 was obtained with 3:1 HD-BB-MOM:YLD124. Chromophore blends were also evaluated in plasmonic organic hybrid (POH) phase modulators with slot lengths of 5–20 μm. In POH devices, r₃₃ was as high as 325 pm V^–1 at 1260 nm and 220 pm V^–1 at 1520 nm. Overall, the increase in acentric order afforded by the HD/FD interactions was found to be small and resulted in no increase in r₃₃ due to the reduced number density. Ultimately, the increase in r₃₃/E_p afforded by the site isolation and blending resulted in a modest increase in r₃₃/E_p relative to YLD124, but combined with the increased T_g, the chromophore system is a significant improvement and points to an important design strategy.

Citations:

• Elder, D. L.; Haffner, C.; Heni, W.; Fedoryshyn, Y.; Garrett, K. E.; Johnson, L. E.; Campbell, R. A.; Avila, J. D.; Robinson, B. H.; Leuthold, J.; Dalton, L. R.. Chemistry of Materials. 2017, 29, 6457-6471. Doi: https://doi.org/10.1021/acs.chemmater.7b02020

Published Date: June 12, 2017

Silicon–Organic and Plasmonic–Organic Hybrid Photonics

Abstract: Chip-scale integration of electronics and photonics is recognized as important to the future of information technology, as is the exploitation of the best properties of electronics, photonics, and plasmonics to achieve this objective. However, significant challenges exist including matching the sizes of electronic and photonic circuits; achieving low-loss transition between electronics, photonics, and plasmonics; and developing and integrating new materials. This review focuses on a hybrid material approach illustrating the importance of both chemical and engineering concepts. Silicon–organic hybrid (SOH) and plasmonic–organic hybrid (POH) technologies have permitted dramatic improvements in electro-optic (EO) performance relevant to both digital and analog signal processing. For example, the voltage–length product of devices has been reduced to less than 40 Vμm, facilitating device footprints of <20 μm2 operating with digital voltage levels to frequencies above 170 GHz. Energy efficiency has been improved to around a femtojoule/bit. This improvement has been realized through exploitation of field enhancements permitted by new device architectures and through theory-guided improvements in organic electro-optic (OEO) materials. Multiscale theory efforts have permitted quantitative simulation of the dependence of OEO activity on chromophore structure and associated intermolecular interactions. This has led to new classes of OEO materials, including materials of reduced dimensionality and neat (pure) chromophore materials that can be electrically poled. Theoretical simulations have helped elucidate the observed dependence of device performance on nanoscopic waveguide dimensions, reflecting the importance of material interfaces. The demonstration and explanation of the dependence of in-device electro-optic activity, voltage–length product, and optical insertion loss on device architecture (e.g., slot width) suggest new paradigms for further dramatic improvement of performance.

Citations:

• Heni, W.; Kutuvantavida, Y.; Haffner, C.; Zwickel, H.; Kieninger, C.; Wolf, S.; Lauermann, M.; Fedoryshyn, Y.; Tillack, A. F.; Johnson, L. E.; Elder, D. L.; Robinson, B. H.; Freude, W.; Koos, C.; Leuthold, J.; Dalton, L. R.. ACS Photonics. 2017, 4, 1576-1590. Doi: https://doi.org/10.1021/acsphotonics.7b00224

Published Date: February 1, 2017

Nonlinearities of organic electro-optic materials in nanoscale slots and implications for the optimum modulator design

Abstract: The performance of highly nonlinear organic electro-optic (EO) materials incorporated into nanoscale slots is examined. It is shown that EO coefficients as large as 190 pm/V can be obtained in 150 nm wide plasmonic slot waveguides but that the coefficients decrease for narrower slots. Possible mechanism that lead to such a decrease are discussed. Monte-Carlo computer simulations are performed, confirming that chromophore-surface interactions are one important factor influencing the EO coefficient in narrow plasmonic slots. These highly nonlinear materials are of particular interest for applications in optical modulators. However, in modulators the key parameters are the voltage-length product U^πL and the insertion loss rather than the linear EO coefficients. We show record-low voltage-length products of 70 Vµm and 50 Vµm for slot widths in the order of 50 nm for the materials JRD1 and DLD164, respectively. This is because the nonlinear interaction is enhanced in narrow slot and thereby compensates for the reduced EO coefficient. Likewise, it is found that lowest insertion losses are observed for slot widths in the range 60 to 100 nm.

Citations:

• Heni, W.; Haffner, C.; Elder, D. L.; Tillack, A. F.; Fedoryshyn, Y.; Cottier, R.; Salamin, Y.; Hoessbacher, C.; Koch, U.; Cheng, B.; Robinson, B.; Dalton, L. R.; Leuthold, J.. Optics Express. 2017, 25 (3) , 2627-2653. Doi: https://doi.org/10.1364/OE.25.002627

Published Date: July 19, 2016

Systematic Generation of Anisotropic Coarse-Grained Lennard-Jones Potentials and Their Application to Ordered Soft Matter

Abstract: We have developed an approach to coarse-grained (CG) modeling of the van der Waals (vdW) type of interactions among molecules by representing groups of atoms within those molecules in terms of ellipsoids (rather than spheres). Our approach systematically translates an arbitrary underlying all-atom (AA) representation of a molecular system to a multisite ellipsoidal potential within the family of Gay–Berne type potentials. As the method enables arbitrary levels of coarse-graining, or even multiple levels of coarse-graining within a single simulation, we describe the method as a Level of Detail (LoD) model. The LoD model, as integrated into our group’s Metropolis Monte Carlo computational package, is also capable of reducing the complexity of the molecular electrostatics by means of a multipole expansion of charges obtained from an AA force field (or directly from electronic structure calculations) of the charges within each ellipsoid. Electronic polarizability may additionally be included. The present CG representation does not include transformation of bonded interactions; ellipsoids are connected at the fully atomistic bond sites by freely rotating links that are constrained to maintain a constant distance. The accuracy of the method is demonstrated for three distinct types of self-assembling or self-organizing molecular systems: (1) the interaction between benzene and perfluorobenzene (dispersion interactions), (2) linear hydrocarbon chains (a system with large conformational flexibility), and (3) the self-organization of ethylene carbonate (a highly polar liquid). Lastly, the method is applied to the interaction of large (∼100 atom) molecules, which are typical of organic nonlinear optical chromophores, to demonstrate the effect of different CG models on molecular assembly.

Citations:

• Tillack, A. F.; Johnson, L. E.; Eichinger, B. E.; Robinson, B. H.. Journal of Chemical Theory and Computation. 2016, 12 (9) , 4362-4374. Doi: https://doi.org/10.1021/acs.jctc.6b00219

Published Date: March 18, 2016

Structure–function relationship exploration for enhanced thermal stability and electro-optic activity in monolithic organic NLO chromophores

Abstract: We have developed a series of novel monolithic materials based on molecules previously explored as dopants in guest–host systems to study intrinsic structure–function relationships in organic electro-optic (EO) materials. In a library of EO molecules with varied bridge segments, molecular modification of the donor with bis(tert-butyldiphenylsilyl) groups led to improvement in formation of amorphous films and led to enhanced poling efficiency. Further modification to include a carbazole site-isolation group on the bridge effectively reduced intermolecular dipole–dipole interactions, led to a material with poling efficiency of approximately 3 (nm V₋₁)₂, and an increased glass transition temperature to 20–40 °C higher than similar reported monolithic materials. This level of thermal stability is comparable to common guest/host systems, which incorporated poly(methyl methacrylate) (PMMA) as the host. Our research showed that π-bridge length and type impacted first molecular hyperpolarizability β of a chromophore, which is accordingly reflected in the EO response. These findings further promote the utility of monolithic materials for their increased EO behavior and improved thermal stability, making this material system a competitor of guest–host systems in commercial applications.

Citations:

• Jin, W.; Johnston, P. V.; Elder, D. L.; Manner, K. T.; Garrett, K. E.; Kaminsky, W.; Xu, R.; Robinson, B. H.; Dalton, L. R.. Journal of Materials Chemistry C. 2016, 4, 3119-3124. Doi: https://doi.org/10.1039/C6TC00358C

Published Date: November 16, 2015

Direct Conversion of Free Space Millimeter Waves to Optical Domain by Plasmonic Modulator Antenna

Abstract: A scheme for the direct conversion of millimeter and THz waves to optical signals is introduced. The compact device consists of a plasmonic phase modulator that is seamlessly cointegrated with an antenna. Neither high-speed electronics nor electronic amplification is required to drive the modulator. A built-in enhancement of the electric field by a factor of 35 000 enables the direct conversion of millimeter-wave signals to the optical domain. This high enhancement is obtained via a resonant antenna that is directly coupled to an optical field by means of a plasmonic modulator. The suggested concept provides a simple and cost-efficient alternative solution to conventional schemes where millimeter-wave signals are first converted to the electrical domain before being up-converted to the optical domain.

Citations:

• Salamin, Y.; Heni, W.; Haffner, C.; Fedoryshyn, Y.; Hoessbacher, C.; Bonjour, R.; Zahner, M.; Hillerkuss, D.; Leuchtmann, P.; Elder, D. L.; Dalton, L. R.; Hafner, C.; Leuthold, J.. Nano Lett. 2015, 15 (12) , 8342–8346. Doi: https://doi.org/10.1021/acs.nanolett.5b04025

Published Date: November 11, 2015

Silicon-Organic Hybrid (SOH) and Plasmonic-Organic Hybrid (POH) Integration

Abstract: Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, reducing device footprint by more than an order of magnitude. However, neither silicon nor metals exhibit appreciable second-order optical nonlinearities, thereby making efficient electro-optic modulators challenging to realize. These deficiencies can be overcome by the concepts of silicon-organic hybrid (SOH) and plasmonic-organic hybrid integration, which combine SOI waveguides and plasmonic nanostructures with organic electro-optic cladding materials.

Citations:

• Koos, C.; Leuthold, J.; Freude, W.; Kohl, M.; Dalton, L.; Bogaerts, W.; Giesecke, A. L.; Lauermann, M.; Melikyan, A.; Koeber, S.; Wolf, S.; Weimann, C.; Muehlbrandt, S.; Koehnle, K.; Pfeifle, J.; Hartmann, W.; Kutuvantavida, Y.; Ummethala, S.; Palmer, R.; Korn, D.; Alloatti, L.; Schindler, P. C.; Elder, D. L.; Wahlbrink, T.; Bolten, J.. Journal of Lightwave Technology. 2016, 34, 256-268. Doi: https://doi.org/10.1109/JLT.2015.2499763

Published Date: July 27, 2015

All-plasmonic Mach–Zehnder modulator enabling optical high-speed communication at the microscale

Abstract: Optical modulators encode electrical signals to the optical domain and thus constitute a key element in high-capacity communication links. Ideally, they should feature operation at the highest speed with the least power consumption on the smallest footprint, and at low cost. Unfortunately, current technologies fall short of these criteria. Recently, plasmonics has emerged as a solution offering compact and fast devices. Yet, practical implementations have turned out to be rather elusive. Here, we introduce a 70 GHz all-plasmonic Mach–Zehnder modulator that fits into a silicon waveguide of 10 μm length. This dramatic reduction in size by more than two orders of magnitude compared with photonic Mach–Zehnder modulators results in a low energy consumption of 25 fJ per bit up to the highest speeds. The technology suggests a cheap co-integration with electronics.

Citations:

• Haffner, C.; Heni, W.; Fedoryshyn, Y.; Niegemann, J.; Melikyan, A.; Elder, D. L.; Baeuerle, B.; Salamin, Y.; Josten, A.; Koch, U.; Hoessbacher, C.; Ducry, F.; Juchli, L.; Emboras, A.; Hillerkuss, D.; Kohl, M.; Dalton, L. R.; Hafner, C.; Leuthold, J.. Nature Photonics. 2015, 9, 525-528. Doi: https://doi.org/10.1038/nphoton.2015.127