Relaxation oscillations in single-frequency InAsSb narrow band-gap lasers

Relaxation oscillations have been investigated in A3B5 narrow band-gap semiconductor lasers. Based on wideband intensity noise measurements, the relaxation oscillation frequency has been observed up to 2 GHz for a 2 mW cw single-frequency InAsSb laser at a 3.4 μm wavelength. Laser parameters that influence the bandwidth, including the photon lifetime τp, the differential gain A and the spontaneous recombination lifetime τs were calculated from experimental data obtained at 95 K. We found τp in the range 0.7–1.9 ps, A was estimated to be (4.7–7.3)×10−6 cm−3 s−1 and τs=2.5–6.9 ns. Relaxation oscillations occurred beyond the modulation bandwidth required for typical applications of antimonide lasers in spectroscopy.