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We report on experimental and theoretical studies of widely tunable high-efficiency subnanosecond optical parametric generator (OPG) and amplifier (OPA) based on a 2 cm long multigrating MgO-doped periodically-poled lithium niobate (MgO:PPLN) crystal pumped by a passively Q-switched Nd:YAG micro-laser. Our OPG can be continuously tuned from 1442 nm to 4040 nm with signal wave energies ranging from 33 μ J to 265 μ J and total OPG conversion efficiency up to 46 % that depended on the pump focusing conditions. Characterization of spatial properties of the OPG determine Lorentzian spatial profile of the signal beam with M 2 ≈ 2 that was also dependent on the pump focusing conditions. High OPG gain and subsequent pump depletion led to the adjustment of the output signal pulse duration in the range of 242 – 405 ps by varying the incident pump power. By using a distributed feedback (DFB) continuous-wave (CW) 1550 nm wavelength seed laser for the OPA operation we reduced the generation threshold up to 1.6 times, increased maximum conversion efficiency by 4 – 20%, and achieved nearly transform-limited output signal pulses. Experimentally measured characteristics were supplemented by numerical simulations based on the quantum mechanical model for the OPG, and classical three-wave interaction model for the OPA operation.

We demonstrate single-pass and double-pass pre-chip managed (PCMA) rod-type fiber amplifier systems, in which pulse pre-chirping and compression is realized using Gires–Tournois interferometric (GTI) mirror pairs. Such a combination of GTI mirrors and PCMA allowed to achieve compact, easy to adjust, high slope (up to 65%) and optical (up to 73%) efficiency amplifiers that produce broadband pedestal-free nearly transform-limited (TL) 75 fs–85 fs pulses with average power of ∼ 20 W at 76 MHz repetition rate. These nearly TL pulses can only be obtained at optimal pre-chirping group delay dispersion values. Laser sources with the aforementioned parameters can be used as a high power and pulse quality laser systems for nonlinear optics experiments.

A detailed investigation of piezoelectric ringing and resonance effects in beta barium borate (BBO)-crystal-based Pockels cells in a pulse picker device is presented. Measurements mapping piezoelectric oscillation amplitude distribution in the aperture of BBO crystal are also performed. It is determined that in BBO Pockels cells, due to piezoelectric ringing and related effects, the optical contrast ratio is reduced by six to 70 times at certain (resonance) frequencies. Moreover, we demonstrate that in our pulse picker device, which uses a special sequence of control pulses (regeneration method) for the Pockels cell, at certain high-voltage control signal durations, piezoelectric oscillations can be suppressed, which significantly improves performance of the Pockels-cell-based laser pulse picker device at resonance frequencies: in such cases, the optical contrast ratio is stable and higher than 1000:1. Numerical simulation results support the experimental data.

The piezoelectric ringing phenomenon for the Pockels cell with DKDP crystal is analyzed. The dependencies of contrast ratio of Pockels cell with the DKDP crystal on high-voltage pulse duration in the range from 100 ns up to 5 μs and on the pulse frequency in range from 50 Hz to 250 kHz are obtained and analyzed. Measurements that map the piezoelectric ringing amplitude distribution in the aperture of the DKDP crystal of the Pockels cell are performed as well.