Achieving both high thermal stability and high electro-optical (EO) activity has traditionally been challenging in organic EO (OEO) materials. The highest combination of thermal stability and EO performance has previously been obtained with HLD1/HLD2, which is a cross-linkable, polymer-free binary OEO material capable of achieving an EO coefficient (r(33)) of up to 450 pm/V when not cross-linked and >250 pm/V (n(3)r(33) > 2000 pm/V) at 1310 nm when cross-linked to a glass transition temperature (T-g) similar to 175 degrees C. Herein, we report the design, synthesis, and evaluation of a cross-linkable chromophore system based on two higher hyperpolarizability chromophores BAH-X1 and BAH-X2, with complementary cross-linkable side chains. BAHX has similar to 2 times the hyperpolarizability of HLD & horbar;based on hyper-Rayleigh scattering measurements & horbar;and similar to 2 times the EO performance (maximum r(33) up to 1100 pm/V when not cross-linked and >650 pm/V, n(3)r(33) > 4500 pm/V, when cross-linked to T-g similar to 150 degrees C). Long-term (>2000 h) thermal stability of EO activity has been demonstrated at 85 degrees C under nitrogen. This high EO activity has been translated to excellent device performance in a plasmonic-organic hybrid phase modulator utilizing 2:1 BAHX, demonstrating a push-pull Mach-Zehnder modulator equivalent V pi L = 38 V mu m at 1550 nm.

We demonstrate open-eye 224G PAM4 transmission in a 1.6T-DR8 PIC implementing low-Vπ silicon-organic hybrid modulators (VπL < 0.5 V-mm) with >80 3 dB GHz bandwidth and a variant capable of 400G/λ (> 110 GHz) for 3.2T-DR8. Both PIC variants use commercial crosslinkable organic electro- optic materials.

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.

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.

We performed the design and fabrication of polymer waveguide circuits, aiming for applications as electro-optic devices. Uniform waveguides with over one centimeter of length were fabricated by soft nanoimprint lithography. These multimode waveguides present a height of 3 µm and low surface roughness (2 nm), with a thin residual layer of 600 nm. Propagation losses at 1550 nm are estimated to be around 7 dB/cm.

Hybrid organic electro-optic (OEO) modulators consist of aligned OEO chromophores confined in a metal or semiconductor slot waveguide, 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, the materials integration processes must be finely tuned to afford excellent EO activity and long-term stability under demanding conditions, both during manufacture and operation. The conceptually simple design of POH devices affords a useful platform for process optimization, while the intense optical confinement provides an ideal environment to examine the photochemical stability of OEO materials in hybrid modulators. We have performed process optimization to obtain good EO performance with commercial and developmental OEO materials in POH devices, and examined the long-term operational and shelf storage stability of such devices under a variety of conditions relevant to Telecordia GR-468-CORE standards. We analyze the results of these studies and discuss their implications for commercial applications, including manufacturing, encapsulation requirements, and expected operational lifetimes.

THz frequencies offer enormous amounts of bandwidth, which could solve the current speed bottleneck for next-generation wireless communications. Recent reports show sub-THz links offering capacities of hundreds of Gbit/s, finally approaching those of state-of-the-art optical transmission channels. Non-etheless, generation, transport, detection and processing of signals in the THz range is far from being a trivial task. Even though the recent evolution of integrated technology is starting to indicate that chip-scale THz technology could gradually close the so-called “THz gap,” much work still needs to be done to enable functional systems, in particular in terms of efficiency. Photonics can be of help, thanks to its extremely low loss and broad bandwidth. Yet, a particularly critical aspect hindering the deployment of THz technology is that state-of-the-art photonics devices generally do not offer sufficient electro-optical bandwidth to process THz signals. Plasmonics, by focusing electromagnetic surface waves at sub-wavelength scales, can play a key role in this quest, as it finally enables the realization of electro-optical devices such as modulators and detectors displaying sufficient compactness and speeds to reach the THz range. This paper overviews recent achievements on plasmonic-based modulators displaying characteristics of speed, efficiency and linearity that enable high-performance access to this much desired frequency range.

Above 3 dB modulation enhancement is demonstrated by cointegrating a resonant microwave circuit with a lumped-element plasmonic modulator. The resonant circuit can compensate electronic driver roll-offs and enable increased transmitter bandwidths. Furthermore, the circuit is complemented by an integrated bias-Tee to tune the modulator.

A monolithically integrated plasmonic SiGe-BiCMOS electronic transmitter operating at 180 GBd is demonstrated. Such compact high-speed electronic-photonic integrated circuit (EPIC) transmitters are key components for future high-performance computing (HPC) and data center interconnects (DCI). © 2021 OCIS Codes: 130.4110, 130.3120

The development of silicon-organic hybrid (SOH) and plasmonic-organic hybrid (POH) electro-optic modulators in the 2010s has enabled the large electro-optic (EO) performance of organic chromophores to be leveraged for high-performance photonic components capable of integration with CMOS electronics. Recent improvements in theory-aided design and materials performance have enabled large increases in both electro-optic performance and materials stability. We report on the implications of these developments for hybrid device performance, manufacturability, processing, and packaging, as well as potential new directions for increasingly scalable fabrication of hybrid electro-optic devices for classical and quantum communications and computing applications.

The first transparent Optical-subTHz-Optical link providing record-high line-rates of 240 and 190 Gbit/s over distances from 5 to 115 m was recently demonstrated. The link has been based on a direct data-conversion from optical to subTHz using a > 500 GHz plasmonic Mach-Zehnder modulator. We discuss the potential of plasmonic devices in subTHz wireless links to efficiently bridge optical fiber networks.

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.

Electro-optic modulators from non-linear χ (2) materials are essential for sensing, metrology and telecommunications because they link the optical domain with the microwave domain. At present, most geometries are suited for fiber applications. In contrast, architectures that modulate directly free-space light at gigahertz (GHz) speeds have remained very challenging, despite their dire need for active free-space optics, in diffractive computing or for optoelectronic feedback to free-space emitters. They are typically bulky or suffer from much reduced interaction lengths. Here, we employ an ultrathin array of sub-wavelength Mie resonators that support quasi bound states in the continuum (BIC) as a key mechanism to demonstrate electro-optic modulation of free-space light with high efficiency at GHz speeds. Our geometry relies on hybrid silicon-organic nanostructures that feature low loss ( Q = 550 at λ res = 1594 nm) while being integrated with GHz-compatible coplanar waveguides. We maximize the electro-optic effect by using high-performance electro-optic molecules (whose electro-optic tensor we engineer in-device to exploit r 33 = 100 pm/V) and by nanoscale optimization of the optical modes. We demonstrate both DC tuning and high speed modulation up to 5 GHz ( f EO,-3 dB = 3 GHz) and shift the resonant frequency of the quasi-BIC by Δλ res =11 nm, surpassing its linewidth. We contrast the properties of quasi-BIC modulators by studying also guided mode resonances that we tune by Δλ res =20 nm. Our approach showcases the potential for ultrathin GHz-speed free-space electro-optic modulators.

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.

A transparent Optical-subTHz-Optical link providing record-high single line rates of 240 Gbit/s and 192 Gbit/s on a single optical carrier over distances from 5 to 115 m is demonstrated.Besides a direct mapping of the optical to a 230 GHz subTHz-carrier frequency by means of a uni-traveling carrier (UTC) photodiode, we demonstrate direct conversion of data from the subTHz domain back to the optical domain by a plasmonic modulator.It is shown that the subTHz-to-optical upconversion can even be performed at good quality without any electrical amplifiers.Finally, at the receiver, the local oscillator is employed to directly map the optical signal back to the electrical baseband within a coherent receiver.

Ultra-short, low-loss graphene-organic hybrid phase modulators are introduced. 20 Gbit/s PAM-2 and PAM-4 data modulation are demonstrated with devices of 25 μm length and on-chip losses of 0.86 dB.

We design and fabricate an electro optical spatial light modulator based on a Fabry Perot resonator utilizing a fast switchable integrated organic polymer layer, where the phase response can be tuned on a subwavelength scale.

A plasmonically enhanced graphene organic hybrid electro-optic phase modulator of 10 μm length with low plasmonic losses of 2.5 dB and a bandwidth of 270 GHz and beyond is demonstrated. The device is verified for high-speed on-off-keying data modulation at a line rate of 140 Gbit/s.

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-mu m, energy consumption of less than 70 attojoules/bit, bandwidths of greater than 500 gigahertz (GHz), and device footprints of less than 20 mu m(2). 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.