Wavelength-Tunable Rectangular Pulses Generated from All-Fiber Mode-Locked Laser Based on Semiconductor Saturable Absorber Mirror**Supported by the National High-Technology Research and Development Program of China under Grant No 2014AA041901, the NSAF Foundation of National Natural Science Foundation of China under Grant No U1330134, the Opening Project of Shanghai Key Laboratory of All Solid-State Laser and Applied Techniques under Grant No 2012ADL02,

Abstract

The wavelength-tunable rectangular mode-locking operation is demonstrated in an all-fiber laser based on semiconductor saturable absorber mirror. As the dissipative soliton resonance signature, the pulse duration varies from 580 ps to 2.1 ns as a function of the increasing pump power. Correspondingly, the maximum pulse energy is 9.11 nJ. Moreover, it is found that the wavelength tunable operation with a range of approximately 10 nm could be obtained by properly adjusting the polarization controllers. The characteristics of the rectangular pulses at different wavelengths are similar to each other. The demonstration of the wavelength tunable rectangular pulses would be beneficial to some applications for many fields such as spectroscopy and sensing research.