ACCURATE FREQUENCY CONTROL OF EXTERNAL-CAVITY LASER-DIODE BY SIDE-BAND LOCKING TECHNIQUE

We developed a new, simple laser diode (LD) system in which the laser frequency can be tuned continuously and stabilized at a desired value. The frequency of the 780 M1 LD which had no additional antireflection coating on the output facet was varied continuously over a range of 2 2 GHz by scanning the grating angle and the drive current simultaneous ly. The LD frequency was offset locked by locking of the frequency of one of the sidebands to a Fabry-Perot interferometer which was locked to a frequency-stabilized He-Ne laser. The, sidebands were generated b y passing the laser beam through a traveling-wave EO-modulator. By var ying the modulation frequency of the EO-modulator; the laser frequency was varied smoothly in a range of 200 MHz, and was stabilized at a fr equency which differed by 500 MHz from the resonance frequency of the Fabry-Perot interferometer.