This study presents a comparison between resonant and non-resonant electro-optical modulator configurations. The focus lies on finding the configuration with the highest modulation amplitude at the lowest drive voltage while achieving a large electro-optical bandwidth. It is found that the ring-assisted Mach-Zehnder modulator (RaMZM) offers chirp-free and resonantly enhanced modulation without bandwidth limitations imposed by the ring. In contrast, a racetrack modulator (RTM) offers resonant enhancement at the cost of a chirped modulated signal and with a bandwidth limitation. The traditional non-resonant Mach-Zehnder modulator (MZM) configuration requires higher modulation voltages while offering chirp-free operation with a flat frequency response. The RaMZM, therefore, looks like an ideal candidate for encoding information in backbone networks where small modulation voltages and perfect control over the phase of a signal are needed. The results are supported by experiments that show driverless plasmonic modulation at 220 GBaud 2PAM, 160 GBaud 4PAM and 100 GBaud 8PAM with record low peak voltages of 0.5 V.

We report the first power performance of Type-II GaInAsSb/InP UTC-PDs. The UTCPDs attain a zero-bias output power of -14 dBm at 100 GHz, one of the highest reported for any zero-bias photodiodes.

The Pockels coefficients in thin-film barium titanate (BTO) and lithium niobate (LN) have been measured for modulating frequencies up to 300 GHz. BTO’s effective nonlinearity is ~10 times larger than LN’s with a small frequency dependence.

Resonant modulators encode electrical data onto wavelength-multiplexed optical carriers. Today, silicon microring modulators are perceived as promising to implement such links; however, they provide limited bandwidth and need thermal stabilization systems. Here we present plasmonic micro-racetrack modulators as a potential successor of silicon microrings: they are equally compact and compatible with complementary-metal–oxide–semiconductor-level driving voltages, but offer electro-optical bandwidths of 176 GHz, a 28 times improved stability against operating temperature changes and no self-heating effects. The temperature-resistant organic electro-optic material enables operation at 85 °C device temperature. We show intensity-modulated transmission of up to 408 Gbps at 12.3 femtojoules per bit with a single resonant modulator. Plasmonic micro-racetrack modulators offer a solution to encode high data rates (for example, the 1.6 Tbps envisioned by next-generation communications links) at a small footprint, with low power consumption and marginal, if no, temperature control.

Plasmonics is increasingly emerging as an alternative to photonics. It has the potential to revolutionize the field of communications and radio science as it gives the user access to devices with highest bandwidths, on a most compact footprint and at lowest power consumption. And while the potentials are many, the technology also has its challenges. So, for instance, plasmonic fabrication requires a technology that can handle features with a 10 nanometer precision and better. Another aspect relates to plasmonic losses. Losses are inherent to the technology that is why device sizes need to be kept small and RF-to-light interaction must be maximized. In this review, we summarize the state in the field and comment on potentials and challenges of plasmonics in view of communications and radio science applications.

A method for reducing the training time of a deep learning based digital backpropagation (DL-DBP) is presented.The method is based on dividing a link into smaller sections.A smaller section is then compensated by the DL-DBP algorithm and the same trained model is then reapplied to the subsequent sections.We show in a 32 GBd 16QAM 2400 km 5-channel wavelength division multiplexing transmission link experiment that the proposed stacked DL-DBPs provides a 0.41 dB gain with respect to linear compensation scheme.This needs to be compared with a 0.56 dB gain achieved by a non-stacked DL-DBPs compensated scheme for the price of a 203% increase in total training time.Furthermore, it is shown that by only training the last section of the stacked DL-DBP, one can increase the compensation performance to 0.48 dB.

A novel vertical incidence metamaterial enhanced graphene photodetector featuring a 200 nm spectral window and a setup limited bandwidth of 500 GHz is demonstrated. The photodetector has been tested for data transmission in an all plasmonic EOE-link offering unprecedented 250 GHz bandwidth.

A high-speed and compact plasmonic organic racetrack modulator is shown to be orders of magnitude more robust against operating condition changes compared to resonant modulators based on the plasma dispersion effect while maintaining thermal tunability. Stable operation at 80°C is shown with no degradation. © 2022 Optica

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.

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.

Resonant and non-resonant modulator configurations are compared for operation with the lowest drive voltage. The ring-assisted Mach-Zehnder modulator is shown to offer a steep slope in the transfer function while delivering an open eye diagram. This enables 220GBd 2PAM plasmonic modulation with record low 0.5V p .

The electro-optical frequency response of thin-film barium titanate (BTO) has been characterized in hybrid plasmonic-photonic phase shifters across the spectral range from 20 to 270 GHz. A flat frequency response was found.

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.

We introduce efficient polarization-insensitive SiN O-band grating coupler relying on a simple fabrication procedure. It's an essential but missing building block in photonics and needed, for example, to realize detectors for light with unknown polarization.

A computationally efficient deep learning based digital backpropagation (DL-DBP) algorithm providing a 1.9 dB SNR over a conventional linear compensation (chromatic dispersion compensation algorithm) and a 1 dB gain over a conventional back-propagation algorithm of the same complexity is presented. The algorithm has been tested in a 1200km transmission experiment. Also, if the algorithm is tested against a conventional digital backpropagation algorithm with the gain, then the new algorithm requires a factor 6 lower complexity. We discuss its training procedure and its principle. We discuss its training procedure and its principle.

OOK line rates of 220 Gbit/s and 408 Gbit/s 8PAM and transmission over 100 m are demonstrated with a resonant plasmonic racetrack modulator. The device requires low 0.6 Vp driver voltages, offers a bandwidth >110 GHz and on-chip losses of 1.0 dB.

Data centers require optical interconnect solutions that are highly scalable with respect to the channel count, the bit rates and the power consumption. Plasmonics offers smallest footprints, operates up to highest speed, requires little driver circuitry and thus meets many of the DCI requirements.

We present a plasmonic platform featuring efficient, broadband metallic fiber-to-chip couplers that directly interface plasmonic slot waveguides, such as compact and high-speed electro-optic modulators. The metallic gratings exhibit an experimental fiber-to-slot coupling efficiency of -2.7 dB with -1.4 dB in simulations with the same coupling principle. Further, they offer a huge spectral window with a 3 dB passband of 350 nm. The technology relies on a vertically arranged layer stack, metal-insulator-metal waveguides, and fiber-to-slot couplers and is formed in only one lithography step with a minimum feature size of 250 nm. As an application example, we fabricate new modulator devices with an electro-optic organic material in the slot waveguide and reach 50 and 100 Gbit/s data modulation in the O- and C-bands within the same device. The devices' broad spectral bandwidth and their relaxed fabrication may render them suitable for experiments and applications in the scope of sensing, nonlinear optics, or telecommunications.

Metallic grating couplers can be extremely broadband and efficient. In this work, we investigate an all-plasmonic fiber-to-chip coupler with a coupling efficiency of -2.7 dB and an optical 3-dB passband of 300 nm.

As the reach of optical communications continues to shrink, photonics is moving from rack-to-rack datacom links to centimeter-scale in-computer applications (computercom) where different architectures are needed. Integrated optical microring resonators (MRRs) are emerging as an attractive choice for fulfilling the more stringent area and efficiency requirements: They offer scaling by wavelength division multiplexing (WDM) and high bandwidth densities. In this paper we present compact electro-optical transmit (TX) and receive (RX) macros for computercom monolithically integrated in 45 nm CMOS. They operate with MRR modulators and photodetectors and include all necessary electronics and optics to enable optical links between on-chip data sources and sinks. A most compact implementation for thermal stabilization was enabled by sensing the optical device's bias currents in the driving electronics instead of using external operating point sensing optics. Using a field-effect transistor as heating element — as is possible in monolithic integration platforms — further reduces area and power necessary for thermal control. The TX macro is shown to work for data rates up to 16 Gb/s with a 5.5 dB extinction ratio (ER) and 2.4 dB insertion loss (IL). The RX macro demonstrates a sensitivity of 71 µApp at 12 Gb/s for a BER ≤ 10−10. An intra-chip link built with the macros achieves ≤2.35 pJ/b electrical efficiency and a BER ≤10−10 at 10 Gb/s. Both macros are realized within 0.0073 mm2 which amounts to 1.4 Tb/s/mm2 bandwidth density per macro.