REFLECTION NOISE IN VERTICAL-CAVITY SURFACE-EMITTING LASERS

We describe the effect of back reflections on the relaxation-oscillati on peaks of low threshold (< 6 mA), high intrinsic bandwidth (31 GHz) vertical cavity surface emitting lasers. With the largest feedback pos sible with our experimental arrangement, x = -5.8 dB, the relaxation-o scillation peak breaks up into a series of sharp resonances with the s pacing corresponding to the round tip frequency of the external cavity . In contrast to edge emitting lasers, no effect of reflections is obs erved for feedback levels x < -12.9 dB. This relative immunity of vert ical cavity lasers to reflection noise is expected to be of interest f or their applications to fiber communications.