Widely Tunable Narrow-Linewidth Intracavity Optical Parametric Oscillators Based on an Yb: KYW Laser

We report the generation of widely-tunable, narrow-linewidth midinfrared laser emission from an Yb: KYW-based intracavity singly-resonant optical parametric oscillator (ICSRO). The wavelength-tuning scheme is based on exploiting the wide emission-bandwidth of Yb: KYW crystals. Birefringent filters were used in the ICSRO cavity for linewidth narrowing and wavelength tuning. The benefit of this tuning scheme is that it does not rely on the temperature-tuning mechanism or the usage of customized fanout PPLN crystals. By using 6 different poling-periods of a 25 mm-long PPLN crystal, and synchronizing the tuning of the pump and signal waves, we obtained midinfrared idler light with a tuning range over 2600–4030 nm, having an estimated linewidth of less than 0.8 cm ⁻¹ .