High-power picosecond fiber-based laser operating at 515 nm

We have developed a fiber-based laser source operating at 515 nm. The experimental setup is composed of a 1030 nm picosecond fiber laser, a Volume Bragg Grating (VBG) based compressor, and a Second Harmonic Generation (SHG) module. The 1030 nm picosecond fiber laser is made with an ANDi mode-lock all-fiber oscillator using a tilted Fiber Bragg Grating (FBG) for spectral filtering. A bandpass filter centered at 1030 nm permits to reduce the bandwidth of the laser to 1.5 nm. A Chirped Fiber Bragg Grating (C-FBG) based stretcher increases the pulse duration to about 90 ps for avoiding nonlinear effects during amplification. A fiber pre-amplifier followed by a double-clad 15 µm core LMA fiber amplifier pumped with a 27 W multimode diode are subsequently used. The total available power at 1030 nm is 14 Watts. SHG is achieved with a type I non-critical phase-matching (NCPM), 15 mm long, Lithium Triborate (LBO) crystal. The 515 nm signal is near diffraction limit (M² < 1.2). The emitted average output power is 5.8 W, the pulse duration is 2.1 ps and the repetition rate is 89 MHz (SHG efficiency is 45%)