Pulse Amplitude Equalization of Amplified Dispersive Wave Radiation Emitting Around 1 μm

We demonstrate, for the first time to our knowledge, pulse amplitude equalization for a 1 μm ultrashort pulse laser source generated by shifting the spectrum of a 1.55 μm mode-locked Er-doped fiber laser in a highly nonlinear fiber via dispersive wave radiation. Three optimized nonlinear optical loop mirror (NOLM)-based pulse amplitude equalizers (PAEs) were designed to reduce the severe pulse amplitude fluctuation of 1 μm source, which was caused by the long pulse duration of 1550 nm pump laser. As a result, the clock amplitude jitter of the pulse train efficiently decreased from 40.2 % to 12.1 % by employing a reflection-type PAE composed of a fiber circulator and a NOLM. This scheme provides a new way to meet the requirement for an equalized pulse amplitude operation in many fields.