Tunable difference-frequency oscillator in the 3.8–6 μ range with a high pulse repetition frequency

A pulse-periodic (with a pulse repetition frequency of 7.6 kHz) coherent source of infrared radiation tunable between 3.8 and 6 μ, having a line width of 0.6 cm^–1 and an average power of 10–100 μW was developed. Infrared radiation was obtained by difference frequency generation involving mixing, in an LiIO₃ crystal, radiation from a copper vapor laser and radiation from a rhodamine 6G dye laser pumped by this copper vapor laser.