POLARIZATION BISTABILITY IN TUNED, EXTERNAL-GRATING DIODE-LASERS

Spectral domains showing polarization-wavelength hysteresis regions up to 0.3 nm wide were observed when the emission frequency of a diode l aser having a nearly polarization-independent confinement factor was t uned in a simple external cavity with grating. In these regions the la ser emits in a stable single mode with either TE or TM polarization, d epending on whether the region was entered from lower or higher wavele ngths. We explain the observed phenomenon on the basis of nonlinear ga in saturation between TE and TM polarization.