Tunable high-average-power optical parametric oscillators near 2  μm

Abstract

We report on the development of high-average-power nanosecond and picosecond laser sources tunable near 2 m based on optical parametric oscillators (OPOs) pumped by solid-state Nd:YAG and Yb-fiber lasers at 1.064 m. By exploiting a 50-mm-long MgO-doped lithium niobate (MgO:PPLN) as the nonlinear crystal and operating the OPO in near-degenerate doubly-resonant configuration with intracavity wavelength selection elements, we have generated tunable high-average-power radiation across 1880-2451 nm in high spectral and spatial beam quality with excellent output stability. In nanosecond operation, pumping with a Q-switched Nd:YAG laser and using an intracavity prism for spectral control, we have generated more than 2 W of average power in pulses of 10 ns duration at 80 kHz repetition rate in narrow linewidth (<3 nm), with M 2 <2.8, and a passive power stability better than 2.2% rms over 1 hour. In picosecond operation, pumping with a mode-locked Yb-fiber laser and using a diffraction grating as the wavelength selection element, we have generated more than 5 W of average power in pulses of 20 ps at 80 MHz repetition rate in narrow bandwidth (~2.5 nm), with M 2 <1.8 and a passive power stability better than 1.3% rms over 2 hours. The demonstrated sources represent viable alternatives to Tm 3+ /Ho 3+ -doped solid-state and fiber lasers for the generation of high-power radiation in the ~2 m spectral range.

Ultrashort pulsed laser amplifier: simultaneous optimization of thermally induced diffraction loss and energy transfer upconversion

“…The importance of pulsed lasers particularly with picosecond (ps) time duration corresponds to their high peak power and cost-effectiveness. When these features are accompanied with high-repetition-rate pulses, they attract broad interest in many applications such as precision processing [1], blue and IR spectral extension of super continuum generation [2,3]. Recently, Q-switched microchip (MC) lasers are used as reliable sources for KHz repetition-rate pulses [4,5].…”

“…Recently, Q-switched microchip (MC) lasers are used as reliable sources for KHz repetition-rate pulses [4,5]. Microchip lasers are low-cost and close-packed, however, they deliver nanojoules output energy that are not suitable for applications like micromachining and photon echo spectroscopy [1,6] and should be amplified to microjoules energy levels [1,2,7]. In this respect, few-pass laser amplifiers have been proposed without affecting their original repetition-rates [7,8].…”