All-fiber mode-locked pulse fiber laser and super-continuum generation

Abstract

Super-continuum(SC) is widely used in coherent photography technology, optical spectroscopy analysis, interferometry, etc because of its flat and broad high spatial coherence and high power. Super-continuum generation could be realized on theory by ultra-short pulse laser getting through the high nonlinear medium, accompany with self-phase modulation (SPM), stimulated Raman scattering (SRS), four-wave mixing (FWM). With the development of fiber technology, Yb-doped ultra-short pulse fiber laser, which has high peak power, high optic-to-optic efficiency, compact structure and small volume was elected as the pump source, and high nonlinear photonic crystal fiber (PCF) as the nonlinear medium for SC. In this paper, steady and self-starting mode-locked pulse ring cavity fiber laser based on the nonlinear polarization rotated effect as seed source is obtained. Taking Yb-doped double-cladding fiber as the gain medium, through MOPA structure, the 80mW signal was amplified to 3.1W, with 1064nm wavelength, 41.3MHz repetition frequency and 50ps impulse duration; the amplified mode-locked pulse was coupled into a 10m PCF, with 1040nm zero dispersion point, to generate 1.5W super-continuum by fusing method, during which the key parameters like discharge time, discharge interval, loss are seriously optimized to keep the fusing quality well. The whole system is all fiber structure, which is much higher than conventional free-space coupling way in both conversion efficiency and stability.