Femtosecond-laser pumped CdSiP₂ optical parametric oscillator producing 100 MHz pulses centered at 6.2 μm

摘要

We report the first, to the best of our knowledge, femtosecond-laser-pumped optical parametric oscillator (OPO) based on the newly developed nonlinear crystal, CdSiP2. The OPO was synchronously pumped by a mode-locked Yb:KYW/Yb:fiber master-oscillator power amplifier, providing 1.053xA0;x3BC;m pump pulses with durations of 130xA0;fs at a repetition rate of 100xA0;MHz. The 0.5-mm-thick CdSiP2 crystal was cut for a type-I noncritical interaction, providing a broad phase-matching bandwidth and ensuring excellent temporal overlap among the pump, signal, and idler pulses. The OPO generated signal pulses with a spectral coverage over 1260x2013;1310xA0;nm and mid-infrared idler pulses with a broad spectral coverage at 5.8x2013;6.6xA0;x3BC;m (6.2xA0;THz). With a 2% output coupler (OC), the threshold pump power was 600xA0;mW. At the maximum pump power of 1.6xA0;W, 0.55xA0;W was absorbed due to two-photon absorption and residual linear absorption in the CdSiP2 crystal, 0.75xA0;W was transmitted, and 53xA0;mW signal power was extracted through the OC. We estimate that the generated idler power was 24xA0;mW.