| Abstract [eng] |
Optical parametric generation converts laser light into new wavelengths through the nonlinear interaction of intense laser pulses in specially engineered crystals. This thesis explores such phenomena in the sub-nanosecond pulse regime, developing and studying compact, wavelength-tunable parametric light sources pumped by modern Q-switched Nd:YAG microlasers. The research focuses on co- and counter-propagating three-wave interactions in periodically poled crystals. Developed optical parametric generators (OPGs) based on multigrating and fan-out MgO:PPLN crystals achieved wavelength tuning from 1.4 to 4.4 µm with up to 45% conversion efficiency, while also revealing device limitations imposed by optical damage and non-collinear interactions. Seeding these parametric systems with a narrowband diode laser and a fiber-generated supercontinuum significantly enhanced the output's energy, spectral, and stability characteristics. A green-pumped MgO:PPLN OPG revealed the complex interplay between parametric gain and nonlinear absorption, while off-axis pumping exploited the grating edge effect to tailor the OPG output properties. This OPG was used to seed a parametric amplifier, generating visible-tunable pulses. The first microlaser-pumped backward-wave optical parametric oscillators (BWOPOs) were demonstrated, generating counter-propagating signal and idler waves that delivered tunable sub-nanosecond pulses with pm-level bandwidth, high beam quality, and 50% conversion efficiency. Finally, parametric light generation was employed as a diagnostic tool to assess the homogeneity and thermal stability of the QPM crystals, offering valuable feedback for optimizing ferroelectric domain-engineered nonlinear media. |
