SOA-Integrated Silicon Photonics Switch and Its Lossless Multistage Transmission of High-Capacity WDM Signals

Abstract

We experimentally demonstrate the lossless transmission of wavelength division multiplexing (WDM) signals through a silicon-photonics 4 × 4 switch with a flip-chip bonded 4-channel semiconductor optical amplifier (SOA). We first optimized the input power and gain of the SOA-integrated switch to obtain the optimum operation point in terms of the transmitted signal quality. We then performed simultaneous transmission of 8-ch, 32-Gbaud, SP 16-QAM WDM (800 Gb/s) signals through all the four paths of the switch. The effect of crosstalk on the switch was very small, and thus could not be observed. We also examined multistage (up to four stages) transmission of the signals with circulating configurations. We show that even for a 4-stage transmission, the bit error rate of the transmitted signal is below the 20% forward-error-correction limit. Finally, we discuss approaches to improve the optical signalto-noise ratio of the transmitted signals to enlarge the signal quality margin and increase the possible number of the cascading stages and/or WDM channels for wide applications.

Lossless Operation of an 8 × 8 SiPh/InP Hybrid Optical Switch

“…A minimum N F G B of 17.56 dB is achieved at 80 mA bias current. The N F G B is comparable but slightly higher than the NF of 16.6 dB recently reported for 4 × 4 SOA integrated SiPh switch [6]. This higher than expected NF is mainly due to the extra coupling loss at the input of gain block.…”

“…Simplifying eq. (2) one obtains: [6]. We showed in this study that in spite of the 25 dB of gain provided by the SOAs, the OSNR remains large enough even at large values of SOA bias current (Fig.…”

“…Alternatively, the SiPh chip is accounted by replacing it with a loss component. The InP semiconductor optical amplifier (SOA) provided gain exceeds 25 dB, 10 dB more than in earlier reported 4 × 4 SiPh/InP hybrid integrated optical switch [6]. Further to [8], this paper presents an evaluation of the noise figure (NF), the optical signal-to-noise ratio (OSNR) degradation in the gain block, and the switch energy consumption.…”

“…However, optical switches in SiPh incur substantial insertion loss, while not providing any practical mechanism for its compensation, by virtue of an indirect bandgap semiconductor inherently incapable of inter-band gain. The required gain could be provided off chip by hybrid integration to an external gain block, e.g., in Indium Phosphide (InP)-a direct bandgap semiconductor featuring strong inter-band gain in the spectral range of interest for most optical switch applications [6]- [8]. In a SiPh/InP hybrid optical switch, routing the optical signal from an input port to the desired output port is on the SiPh chip, while the InP gain block provides amplification required for compensation of the insertion loss.…”

Scalable SiPh-InP Hybrid Switch Based on Low-Loss Building Blocks for Lossless Operation

“…We find the NF for two different scenarios: when the inter-chip coupling is budgeted 1.7 dB and 5 dB; and the filter loss is 0.5 dB and 3.5 dB, respectively. The NF of 4 × 4 and 8 × 8 switches are for the single stage gain hybrid switches presented in [14], [7]. Employing the distributed gain design, one can achieve lossless operation of 64 × 64 switch with NF below 30 dB.…”