Optical parametric oscillator pumped by a coiled multi-mode fiber amplifier

摘要

We have demonstrated operation of an optical parametric oscillator (OPO) pumped by a coiled multi-mode fiber amplifier. Coiling of multi-mode fiber amplifiers is a simple technique that allows the output from diode-pumped fibers to be substantially increased relative to that from a standard single-mode fiber, while maintaining the diffraction-limited beam quality. Pulse energies from such fiber amplifiers are high enough to drive nonlinear optical processes. Here we report efficient frequency down-shifting of such a device using an OPO. A diode-pumped Yb-doped fiber was used to amplify 1 microjoule, 20 nanosecond pulses from a 1.064 μm Nd:YVO_4 laser to a level of up to 107 microjoules in a single transverse mode, polarized beam. The 6m-length fiber had a 200 micron diameter cladding and a 25 micron core. An unpolarized output of 5.6 Watts was measured for 13 Watts of 976nm diode pump input. Oscillation of a periodically-poled lithium niobate (PPLN) OPO was observed with an oscillation threshold pump pulse energy of 31 microjoules. Up to 0.63 Watts of 1.5 μm OPO signal output was measured with 2.6 Watts of incident pump, at a repetition rate of 24kHz. Tuning of the OPO signal wavelength was performed between 1.5 and 1.6μm.