Frequency stabilization of an extended-cavity violet diode laser by resonant optical feedback

Frequency-stable operation of an extended-cavity GaN diode laser was achieved by resonant optical feedback from a confocal cavity. The observed frequency fluctuations were smaller than 300 kHz peak-to-peak in one second. and the upper limit of the linewidth was measured to be 880 kHz. A continuous frequency scan up to 5 GHz was realized by simultaneous servo control on the optical feedback phase and on the extended-cavity diode laser frequency. The violet laser was used to perform saturation spectroscopy on the 5(2)S(1) (2-)6(2)P(3) (2) transition of rubidium at 420 nm in a gas cell, and resulted in spectra with a linewidth of 2.3 MHz. (C) 2002 Elsevier Science B.V. All rights reserved.