INJECTION-SEEDED OPTICAL PARAMETRIC OSCILLATOR FOR RANGE-RESOLVED DIAL MEASUREMENTS OF ATMOSPHERIC METHANE

A pulsed injection-seeded optical parametric oscillator (OPO) has been studied and its suitability for applications requiring dual-wavelengt h operation has been demonstrated. Single-mode operation was achieved by injection seeding the OPO with radiation from a tunable diode laser . The OPO was tuned over a range of 90 nm (1490.6-1580.3 nm) with an a verage output energy of 5 mJ (7% conversion efficiency) and a linewidt h of 140 MHz. The inherent stability of the travelling-wave cavity des ign has enabled stable operation to be achieved without active stabili sation of the cavity. Dual-wavelength operation has been achieved by i njecting two seed frequencies simultaneously. The suitability of the O PO for infrared Differential Absorption Lidar (DIAL) measurements has been demonstrated by making a range-resolved measurement of atmospheri c methane. (C) 1997 Elsevier Science B.V.