Optimizing optical pulse breakup for efficient supercontinuum generation in an all-fiber system

Abstract

Ultra-broadband supercontinuum (SC) is generated by an all-fiber system with well-defined pulses (WDPs) as a seed laser. Through properly adjusting the lengths of the fiber segments in the system, sub-pulses with high peak powers are generated through the process of optical pulse breakup. Then, the broken optical pulses are launched into a hybrid nonlinear, which consists of a highly nonlinear optical fiber and a photonic crystal fiber, generating a SC of 1.8 W covering a spectral range from 554 nm to 2.17 µm. In this study, it is demonstrated through experimental observation that optical pulse breakup is an essential process for WDPs before the pulses are launched into a nonlinear optical fiber to generate SC. However, pulse breakup must not happen before the amplification of the WDPs; otherwise, the amplification efficiency is decreased, leading to a subsequent low efficiency of SC generation. The proper breakup of the WDPs after they are efficiently amplified is accomplished by sending these pulses through an optimum length of regular optical fiber, which depends on the peak power of the amplified WDPs. An optical fiber of an insufficient length leads to insufficient pulse breakup, which does not significantly increase the peak power of the pulses, resulting in little enhancement of SC generation. An excessively long fiber leads to excessive pulse breakup, which stretches the pulsewidth and splits the pulse energy, resulting in decreasing the efficiency of SC generation.