ABSTRACT
Optical parametric oscillators (OPOs) have become popular for generating tunable MWIR radiation for many of the previously mentioned applications [1]. e maturing diode-pumped solid-state laser technology combined with continued improvements of IR transmitting nonlinear crystals, especially with respect to reduced bulk absorption at the pump wavelength (typically between 1-3 µm) and the higher damage threshold, have contributed to the development of MWIR OPOs. Much e›ort has been spent on designing tandem OPO-based systems using a 1064 nm laser as the pump source [2]. While these systems use the most mature laser as a pump source (i.e., Nd:YAG laser), the tandem OPO con„guration adds considerable complexity to the design and operation of the overall system and often results in signi„cant penalty in terms of the e›ective electrical-to-optical conversion e¢ciency, when compared to a single-stage OPO system with the pump laser emitting between 2.1-3 µm. e advances in nonlinear material, IR coating, and OPO systems level design have resulted in operation over a broad range of pulse durations (femtosecond pulses and continuous wave [CW]), spectral region coverage, power scaling, and more importantly overall system robustness. However, such lasers are still a specialty item primarily due to the high cost and limited commercial availability of high-quality MWIR nonlinear crystals.
