Application of Difference Frequency Laser in Trace Gas Measurement System

Abstract

Based on Nd:YAG laser, tunable diode laser, electro-optic amplitude modulator and the difference frequency generator, a servo scanning laser source is designed, and the principle of trace gas concentration measurement model is introduced as well, which can realize the gas concentration measurement in the band of mid-infrared and far-infrared. Based on the theory of electromagnetic field, mutual coupling equation about laser transmission in nonlinear crystal and the optical frequency conversion characteristics are analyzed theoretically. As a result, in the range of far-field, electric field intensity of coupled wave increases approximatively exponentially,then tends to be stable.