Tunable single- and double-frequency diode-pumped Nd:YAG lasers

An Nd:YAG 1-cm-long crystal has been used as the active medium for tunable single- and double-frequency lasers with a metallic absorbing thin-film selector. Cobalt and chromium thin films (210-nm thickness) were used for mode number and frequency control. The laser with a short cavity (25 mm) provided slow smooth tuning up to 6 GHz, the frequency chirp up to 4 GHz with repetition rate about 0.5 kHz and hop tuning over 150 GHz at a maximum pump power of 1.8 W. 520 mW of single-frequency output power was achieved. Double-frequency operation with a space of 1.5-2.5 GHz was realized in a laser with cavity length up to 100 mm.