Yb:YAG master oscillator power amplifier and PPLN optical parametric amplifiers for remote wind sensing

A coherent Doppler lidar (light detection and ranging) system can be used to measure tropospheric wind velocities from space and provide much needed data for atmospheric modeling of climate and weather prediction. To achieve a precision of 1 m/s in velocity with a 400 km altitude lidar system, the laser transmitter should output greater than 133 mJ pulses at 40 Hz, at an eye-safe wavelength (lambda > 1.4 mum), and a single frequency linewidth of 1.3 MHz. To meet these requirements, we model and demonstrate a 1.03 mum Yb:YAG master oscillator power amplifier (MOPA) and a nonlinear frequency conversion module based on optical parametric amplification (OPA) of a 1.55 mum laser.; Efficient energy storage and extraction are the key challenges to power scaling in a solid state laser amplifier at 1.03 mum. We choose to engineer end-pumped zig-zag slab amplifiers to achieve high gain. Parasitic oscillations and amplified spontaneous emission (ASE) limit the gain and stored energy. We overcome this limitation by confining and absorbing the pump light while simultaneously suppressing parasitic oscillations by reducing the effective reflectivity of the surfaces for ASE. Claddings on the slab's TIR and edge surfaces confine the pump and signal light by total internal reflection (TIR) and allow leakage of ASE rays that don't meet the TIR condition. This enables a record e3, e5, and e8 single-pass, double-pass and quadruple-pass small-signal amplifier gain respectively. The development of methods for parasitic suppression is accompanied and enabled by an advance in slab fabrication. We present a new batch fabrication technique that yields slabs of high optical quality at low cost.; We also present experimental results of PPLN optical parametric amplifiers at 1.55 mum to generate the required eye-safe radiation. We demonstrate a PPLN waveguide OPA with 45 dB gain at 1.55 mum with 10 muJ/mus output pulses. In a separate single-stage bulk PPLN OPA, we amplify 1 nJ/mus pulses to the 2 mJ level. In the future, the waveguide and bulk PPLN OPAs can be cascaded to yield > 133 mJ/mus pulses at 1.55 mum for global wind velocity measurements from a space platform.