Self-pulsation in the output intensity and spectrum of GaAs-AlGaAs cw diode lasers coupled to a frequency-selective external optical cavity

Abstract

The laser emission of a cw diode laser coupled to an external cavity is self-pulsing at a frequency of 3–30 MHz, that is, two orders of magnitude lower than the resonance frequencies of the external cavity (typically 0.5 m long). The low-frequency self-pulsation is also present with a wavelength-selective external cavity using a grating as a reflector that narrows the laser emission to a single longitudinal mode. This paper describes some of the characteristics of the self-pulsation such as the pulse shape, the frequency dependence, the shift of the wavelength of the lasing mode during a pulse, and their dependence on the wavelength selection by the grating.