V-shaped external cavity diode pump for 100 nm continuous tuning of a difference-frequency generation

Abstract

We report the generation of a mid-infrared (MIR) difference-frequency radiation between 4.76 μm and 4.86 μm rang inside AgGaS2 nonlinear crystal using a V-shaped external cavity configuration fabricated around pump source. The effect of using such V-shaped scheme on tuning characteristics of a commercial diode laser have been studied and experimentally presented. More than ~11 nm continuous tuning is obtained for the emerging original beam through rotating a blazed grating over a certain angular range with a measured accuracy of 1.4 μm/degree. Such characterized V-shaped external cavity is used as pump source in a DFG experimental setup. An appreciable extension in generated MIR-DFG bandwidth is observed when the intracavity grating is rotated over ~600 μm in opposite directions. The performance of such extended V-shaped external cavity base MIR-DFG radiation is demonstrated as trace detection of P(16) and P(18) rovibrational lines of 1-0 fundamental band of carbon monoxide (12C16O) molecule with and without using V-shaped cavity. © 2013 Elsevier Ltd.