Abstract

A method of coherently summing the outputs of two diode-pumped ring lasers has been tested. The output of one such Nd:YAG laser (the master laser) at 1064 nm was mode-matched into a similar laser (the slave laser). The frequency of the slave laser was tuned toward that of the master laser by adjusting the crystal temperature (and thus the optical path length). The difference frequency was detected until the locking range was reached, when the free-running oscillation of the slave laser was completely injection-locked by the injected signal. With the master laser power of 15 mW and the slave laser power of 5 mW, the locking frequency occurred at ~23 MHz. The combined output power during locking ranged from ~20 to 21 mW with the maximum representing a 5% increase over the summation of the unlocked free-running lasers. Locking was held for periods >15 min. These results indicate the possibility of chaining together this type of laser to obtain coherent single-mode outputs with higher powers than currently possible.

© 1988 Optical Society of America