Optical Vernier Effect Enabled Narrow Linewidth All-Fiber SBS-FWM-Based Tunable Optical Frequency Comb Generation

In this paper, we experimentally demonstrate a lowpower, broadband, and narrow linewidth SBS-FWM OFC with tunable line spacing of 50 to 600 GHz. The SBS-FWMOFC spans a bandwidth of approximate to 100 nm over the C+L-band region using approximate to 15 dBm pump power. The OFC is obtained by cascaded FWM process in highly nonlinear fiber (HNLF), seeded by SBS pumps in an all-fiber ring cavity setup. The linewidth of the SBS-FWM comb lines is measured to be approximate to 20 MHz which is largely determined by the SBS pump properties. By using the optical Vernier effect, the linewidth of comb lines is reduced by a factor of more than 2000 to below 20 kHz. We utilize the SBS-FWM OFC to study the performance of binary and 4-PAM transmission at 1 and 10 Gbps in a back-to-back (B2B) setup. The side-modes caused by the FP-cavity, formed by the HNLF modules in the ring cavity in our setup, affects the performance of the B2B transmission of PAM system.

Automated summary

This paper demonstrates an experimental study on a low-power, broadband, and narrow linewidth SBS-FWM OFC with tunable line spacing of 50 to 600 GHz. The linewidth of the comb lines is reduced to below 20 kHz using the optical Vernier effect. The OFC is utilized to investigate the performance of binary and 4-PAM transmission at different data rates.