Abstract

Coherent single frequency mid-infrared sources are important for applications in pollutant detection. Up to now, mainly three types are available: semiconductor interband or intersubband (quantum cascade) lasers with about 1 W output peak power and rather small tunability (few 10’s of nm), difference frequency generation with low output powers (typically few μW) and cw optical parametric oscillators (OPOs). None of these sources are fit for lidar operation where nanosecond high power (100’s W) pulses are needed. Conversely, nanosecond OPOs operating with periodically poled materials (like PPLN) display low threshold and allow thus new compact high repetition rate sources to be used.^1,2 However, the multi-frequency behavior of pulsed OPOs is detrimental for most of applications that require a typical line width of 100 MHz. To fulfill the spectral need, dual-cavity Doubly Resonant Optical Parametric Oscillators (DROPOs) are well suitable since they provide a low threshold of oscillation in combination with compactness. We report here a novel compact nanosecond OPO leading to single-longitudinal-mode output from a semi-monolithic linear dual-cavity DROPO operating at several kHz in the mid-infrared domain.

© 2002 Optical Society of America