Development of a Widely lkinable MidNInfrared Coherent Optical Source Based on a Difference Frequency Generation in a Periodically Poled LiNb03

The development ofa widely tunable coherent mid'infrared optical source, which can be used for various types of trace'gas sensing, is reported. This source utilizes difiference frequency generation (DFG) in a periodically poled LiNb03 (PPLN) crystal pumped by two single-frequency diode lasers. Wide range tunable output in the range 3.7 to 4.8 pm is achieved by tuning one of the diode laser and altering the temperature of the single'period PPLN. Development of a fiber'coupled, tunable Cr3':LiSrAIF6 laser, which can be used for the DFG process is also described. In addition, preliminary studies regarding an application of the gas sensor for absorption measurements of ambient C02 gas is reported.