Numerical investigation of nonlinear broadened OFC based on the CS-DSB modulation frequency shift recirculation loop

Since the growing needs of broadband optical frequency combs (OFCs) in many applications, in this paper, a carrier suppressed dual-sideband modulation recirculating frequency shift loop (RFSL) with an additional piece of highly nonlinear fiber (HNLF) is numerically investigated. The numerical results indicate that, thanking to the RFSL scheme, the frequency spacing of OFC can be both widely and precisely tuned over the range of 0.5 - 40 GHz. Moreover, the comb lines generated from RFSL can be then efficiently increased, using four wave mixing effect of HNLF in the simulation, thus the spectrum is further broadened. This work contributes to an effective and compact RFSL scheme for a frequency tunable OFC generation with broadband spectrum.