Optical PAM-4 signal generation using a silicon Mach-Zehnder optical modulator

An analytic model is proposed to study the linearity performance of the silicon Mach-Zehnder optical modulator. According to the simulation results, we optimize the width of the silicon rib waveguide and the location of the PN junction to improve the linearity performance. The fabricated silicon Mach- Zehnder optical modulator has a spurious free dynamic range of 113.3 dB.Hz(2/3) and 88.9 dB.Hz(1/2) for the third-order intermodulation distortion and the second-order harmonic distortion. We also demonstrate the optical fourlevel pulse-amplitude-modulation (PAM-4) signal generation through the device. The generated optical PAM-4 signal is characterized at the rates up to 35 Gbaud. The BERs of the optical PAM-4 signals can reach 5.2x10(-6) at 20 Gbaud and 6.6x10(-5) at 32 Gbaud, which are much lower than the threshold of hard decision forward error correction (3.8x10(-3)). (C) 2017 Optical Society of AmericaProgram 863 [2015AA015503, 2015AA017001]; National Key R&D Program of China [2017YFA0206402, 2016YFB0402501]; National Natural Science Foundation of China (NSFC) [61535002, 61505198, 61235001, 61575187, 61377067]SCI(E)ARTICLE1923003-230132

WDM-compatible multimode optical switching system-on-chip

The development of optical interconnect techniques greatly expands the communication bandwidth and decreases the power consumption at the same time. It provides a prospective solution for both intra-chip and inter-chip links. Herein reported is an integrated wavelength-division multiplexing (WDM)-compatible multimode optical switching system-on-chip (SoC) for large-capacity optical switching among processors. The interfaces for the input and output of the processor signals are electrical, and the on-chip data transmission and switching process are optical. It includes silicon-based microring optical modulator arrays, mode multiplexers/de-multiplexers, optical switches, microring wavelength de-multiplexers and germanium-silicon high-speed photodetectors. By introducing external multi-wavelength laser sources, the SoC achieved the function of on-chip WDM and mode-division multiplexing (MDM) hybrid-signal data transmission and switching on a standard silicon photonics platform. As a proof of concept, signals with a 25 Gbps data rate are implemented on each microring modulator of the fabricated SoC. We illustrated 25 × 3 × 2 Gbps on-chip data throughput with two-by-two multimode switching functionality through implementing three wavelength-channels and two mode-channel hybrid-multiplexed signals for each multimode transmission waveguide. The architecture of the SoC is flexible to scale, both for the number of supported processors and the data throughput. The demonstration paves the way to a large-capacity multimode optical switching SoC