Abstract

Tunable Fourier-transform-limited picosecond pulses are of high interest for applications such as time-resolved spectroscopy. In the mid-infrared, tunable emissions can be conveniently provided by synchronously pumped optical parametric oscillators (SPOPOs). In this context, the use of a diffraction grating as an intracavity frequency-selective reflector is a well-established approach [1,2]. Here, we investigate the use of an aperiodic, or chirped, quasi phase matched crystal [3] to broaden the parametric gain bandwidth and thus enable fast tuning over a wide spectral range without changing the crystal temperature or the nonlinear grating. We report a new OPO approach that is to combine a fast tunable intracavity spectral filter with such a broad gain bandwidth nonlinear material based on an aperiodically poled lithium niobate (APPLN) crystal.

© 2015 IEEE