Hybrid Amplification Approach Towards Wideband Optical Communications

Abstract

Optical amplification techniques using fiber nonlinearities have the potential to cover new bands beyond the C and L-bands. Among nonlinear amplifiers, the phase-sensitive amplifier has a noise figure that can ideally be 0 dB, and it can compensate for the additional noise resulting from the higher losses of new bands compared to C and L-bands in transmission fibers. In this paper, a hybrid amplifier that combines three nonlinear phenomena in highly nonlinear fibers, namely parametric wavelength conversion, Raman amplification, and phase-sensitive amplification, is proposed as a discrete amplifier to achieve sufficient gain in the new band while simultaneously minimizing amplified spontaneous emission (ASE). The combination of these phenomena helped to simplify the overall amplifier by eliminating the need for electrical phased lock loop and aligning the powers of the signal and idler and maximizing the pump power without signal/pump path separation. In addition, the fiber Bragg grating-based phase shifter reduced the total phase of the signals, idlers, and pump close to zero by temperature tuning. The prototype of the hybrid amplifier achieved >25 nm gain bandwidth, approximately 20 dB net gain, and the ASE level was suppressed. The proposed amplifier is suitable for applications in large-scale high-capacity networks, such as metro and long-haul networks.