We demonstrate a monolithically integrated O-band silicon photonics five-segment Mach-Zehnder modulator with a distributed driver in a 45-nm CMOS process, packaged with wirebonds on a PCB. Each segment includes a cascode driver and 0.7 mm traveling-wave electrode with a termination. Open eyes and BERs below the KP-4 and KR-4 FEC threshold are measured up to 40 Gbaud with 3.09 pJ/bit energy efficiency, without feedforward equalization (FFE). Open eyes and BER below the KP-4 FEC threshold are also measured at 50 Gbaud with 2.47 pJ/bit energy efficiency using an analog 5-tap finite impulse response (FIR) equalizer. The design approach enabled a low power consumption of 116.5 mW.

We demonstrate an O-band silicon photonics 2x2x2λ wavelength selective switch (WSS) based on Coupled Ring Resonators (CRR). The optical switch achieves a record-low average polarization dependent loss (PDL) of 0.41dB.

Presented is an O-band silicon photonics dual-polarization coherent/IMDD modulator integrated with semiconductor optical amplifiers and tunable laser to enhance the short-reach link budget. The laser demonstrated output power >6 dBm and a <250 kHz linewidth over a 14 nm tuning range. Modulators paired with custom 64 Gbaud QPSK drivers exhibited improved analog link sensitivity compared to similar devices without integrated gain sections. They also demonstrated 53 Gbaud dual-polarization PAM4 operation when characterized with a linear driver and MaxLinear 100G/lane DSP board. Both optical links achieved BERs at the KP4-FEC threshold and overall transmitter assembly energy consumption <6.9 pJ/bit without any thermal control when at steady room temperatures.

A fully packaged O-band coherent transmitter, comprising a fiber-attached MRM -based silicon photonic transmitter and a co-designed electronic integrated circuit on a custom PCB, achieved 100 Gbps QPSK modulation below the HD-FEC bit error rate threshold. © 2024 The Author(s)

We report a 0.91 pJ/bit, differential dual-channel TIA with variable gain reaching 64 dBΩ in 90-nm SiGe measured in a reconfigurable PAM4/QPSK O-band receiver at 53.125 Gbaud with BERs below the KP4-FEC threshold of 2.2e-4.

We report what is believed to be the first unamplified analog coherent link using heterogeneously integrated lasers in both the TX and RX. The link achieves a 10 dB fiber-to-fiber link budget while operating with BER below the KP-4 FEC threshold, and a 7 dB fiber-to-fiber link budget with BER below the KR-4 FEC threshold, both while transporting 100 Gbps QPSK over a single polarization. The facet-to-facet link budgets are 23 dB and 20 dB respectively. QPSK transmission is measured through an O-band silicon photonics integrated wavelength-selective switch with a BER below the Staircase FEC threshold.

Here we report a dual-polarization, O-band optical phase-locked loop packaged in a footprint compatible with pluggable optics. Custom-designed analog Costas loop electronics and silicon photonic circuits, including a hybrid-integrated tunable laser serving as the local oscillator, were integrated into a functional receiver subsystem that was characterized as part of a full coherent link. The receiver frequency and phase locked loop had a bandwidth of 450 MHz and was capable of locking to frequency offsets < 8 GHz and tracking the local oscillator's +/- 1.5 GHz frequency drift, enabling DSP-free carrier-recovery. The entire homodyne coherent link achieved a maximum QPSK transmission rate of 112 Gb/s (56 Gbaud) for single polarization and 30 Gb/s (15 Gbaud) for dual-polarization operation. Bit error rates below hard decision forward error correction thresholds of 3.8. 10(-3) were achieved with 4.8 pJ/bit of transmitter and 8.8 pJ/bit of receiver power consumption, demonstrating the potential for a DSP-free solution for coherent links below 10km as an alternative to current IMDD schemes.

We report the first net 400 Gbps/λ O-band coherent, dual-polarization, 60 Gbaud 16QAM link using SiP TX/RX PICs with heterogeneously integrated lasers, operating below the 15% overhead SD-FEC limit over 2 km without external amplifiers.

We demonstrate the first 200-G O-band coherent PON using a heterogeneously-integrated SiP PIC transmitter as an OLT and PIC/EIC receivers as ONUs. A joint DSCM and NOMA scheme is presented for flexibly dense access scenarios.

We report a net 400 Gbps/ $\lambda$ O-band, dual-polarization, intradyne coherent link using silicon photonic (SiP) transmitter and receiver photonic integrated circuits (PIC) with heterogeneously integrated lasers and semiconductor optical amplifiers (SOA). Operation below the 15.3% overhead 2×10 -2 open forward error correction (O-FEC) threshold was achieved for 60 Gbaud 16QAM over 2 km and 100 Gbaud QPSK over 10 km without external optical amplification. These results demonstrate the potential for implementing SiP PICs with integrated lasers and SOAs in future short-reach coherent links.

We report the first O-band link with electrically reconfigurable intensity-modulation direct-detection (IMDD) and coherent operation using custom silicon photonic chips packaged with commercial electronic chips. Transmission below the KP4-FEC threshold is shown using commercial 53 Gbaud PAM4 digital signal processing (DSP) for 16QAM (200 Gbps/λ) and PAM4 (100 Gbps/λ). Efficient operation of the packaged full link at 12 and 11.2 pJ/bit is achieved for the PAM4 and 16QAM modes, respectively.

Silicon traveling-wave Mach-Zehnder modulators are monolithically integrated with tunable inductive terminations for low-power, variable equalization circuits. Equalizing subthreshold forward-biased modulators doubled EO bandwidth for 56 Gbit/s transmission below KP4-FEC thresholds while consuming 360 fJ/bit.

We present the first >200 Gbps/lambda, 0 -band optical link with integrated transmitter and receiver photonic and electronic ICs. 224 Gbps/lambda, DP-QPSK transmission is demonstrated below the 3.8.10(-3) HD-FEC threshold with 6.8 pJ/bit power consumption. (c) 2022 The Author(s)

We present a 64 Gb/s O-band Quadrature Phase Shift Keying (QPSK) coherent transmitter, consisting of a silicon photonic transmitter (TX) integrated with micro-transfer printed (MTP) InP electro-absorption modulator (EAM) and a differential driver. We also show a co-designed flip-chip compatible electronic integrated circuit (EIC) and the photonic integrated circuit (PIC) based on the previous design.

Scaling data centers to 200 Gbps/lane with direct detection may not provide sufficient link budget for optical switches. Analog coherent detection leverages phase and polarization of optical signals to scale efficiently without requiring digital signal processing and employs integrated lasers to maximize link budgets for optical switches. We report the first O-band silicon photonics coherent transmitter integrated with hybrid semiconductor optical amplifiers and tunable lasers. The laser demonstrated <6 dBm output power with ∼700 kHz linewidths across its 14 nm tuning spectrum. 64 Gbaud QPSK transmission was demonstrated with BER ∼4e-4 and ∼6.6 pJ/bit energy-efficiency when utilizing SiGe BiCMOS drivers.

Coherent optical links are becoming increasingly attractive for intra-data center applications as data rates scale. Realizing the era of high-volume short-reach coherent links will require substantial improvements in transceiver cost and power efficiency, necessitating a reassessment of conventional architectures best-suited for longer-reach links and a review of assumptions for shorter-reach implementations. In this work, we analyze the impact of integrated semiconductor optical amplifiers (SOAs) on link performance and power consumption, and describe the optimal design spaces for low-cost and energy-efficient coherent links. Placing SOAs after the modulator provide the most energy-efficient link budget improvement, up to 6 pJ/bit for large link budgets, despite any penalties from nonlinear impairments. Increased robustness to SOA nonlinearities makes QPSK-based coherent links especially attractive, and larger supported link budgets enable the inclusion of optical switches, which could revolutionize data center networks and improve overall energy efficiency.

Multi-wavelength analog coherent links using mode-locked laser (MLL) frequency combs as transmitter and local oscillator (LO) sources are proposed. Carrier recovery (CR) in all wavelength channels is achieved using only two optical phase-locked loops (PLLs), while polarization demultiplexing and static phase offset removal are performed using cascaded optical phase shifters. A three-section Fabry-Perot semiconductor laser structure is proposed for the comb sources. Phase-error performance in a 2.6 Tb/s system using 56-Gbaud dual-polarization quadrature phase-shift keying on 13 channels is studied. For optical and microwave beat linewidths of 2 MHz and 1 kHz, respectively, achieving phase-error penalties below 1.5 dB requires PLL delays below 400 ps. A symmetric CR scheme is shown to achieve better phase-error performance than an asymmetric CR scheme. In 13-channel analog coherent links, the MLL comb-based design is projected to consume 38 $\%$ less power than a resonator-enhanced electro-optic comb-based design and 20 $\%$ less power than a design using arrays of single-wavelength lasers as transmitter and LO sources, excluding modulator driver power, which is identical for the three designs.

We report the first demonstration of a full O-band coherent link for intra-data center applications, including custom photonic and electronic integrated circuits for the transmitter and receiver. Full-link 112 Gbps (56 Gbaud QPSK) transmission is shown with $2.1\cdot 10^{-4}$ measured BER, and record baud rate 128 Gbps (64 Gbaud QPSK) transmission is shown for the stand-alone coherent transmitter. The link architecture is based on analog coherent detection (ACD), which improves power consumption substantially by performing functions in the analog domain that are normally implemented with power-hungry digital signal processing (DSP). Energy efficiency of 9.5 pJ/bit is demonstrated for the O-band coherent link, with 12.5 pJ/bit expected with next-generation circuits that include integrated optical gain. These results show the potential for next-generation data center networks based on low-power O-band coherent links.

A fully-functional photonic integrated circuit (PIC) platform with supporting active and passive components in the extended short- and mid-wave infrared spectral regime is of significant research interest for next-generation optical systems. Here we design offset quantum well-based photonic integrated circuits which primarily consist of four section-based widely tunable single-mode lasers emitting at 2560 nm. The platform requires the selective removal of InGaAsSb multi-quantum wells located above a GaSb-based optical waveguide layer and then subsequent single blanket GaSb regrowth. Encouraging preliminary experimental results on regrowth are also reported to confirm the feasibility of the proposed PICs. The simulation result for the tunable laser design shows that a tuning range as wide as ~120 nm is possible. The quasi-theoretical work performed here is an initial step towards demonstrating complex non-telecommunication PICs which could offer a comprehensive range of photonic functionalities.

We present the first >200 Gbps/λ O-band optical link with integrated transmitter and receiver photonic and electronic ICs. 224 Gbps/λ DP-QPSK transmission is demonstrated below the 3.8 • 10 −3 HD-FEC threshold with 6.8 pJ/bit power consumption.