FREQUENCY STABILIZATION OF A DIODE-LASER AT 1540 NM BY LOCKING TO SUB-DOPPLER LINES OF POTASSIUM AT 770 NM

An external cavity 1540-nm diode laser was frequency doubled in a 3-cm -long periodically poled LiNbO3 waveguide doubler with 150% W-1 conver sion efficiency, thereby generating more than 3 mu W at 770 nm. Second -harmonic light was used to detect and lock to sub-Doppler lines of th e K-39 D-1 transition. (C) 1998 Optical Society of America.