LONGITUDINAL MODE CONTROL IN LASER-DIODES

A method is described for selecting the longitudinal mode of a diode laser, using either a thin plate or graded index (GRIN) rod mounted almost-equal-to 50-mu-m from the diode. Although this method has already been reported in a number of experiments, a detailed study has received little attention in the literature to date. The method requires no modification of the diode laser itself and may be combined with the method of resonant optical feedback for reducing the laser linewidth. This dual feedback system can provide both mode selectable and narrow linewidth operation and this paper presents results and practical comments on this method.