Optical polarization bistability in TM wave injected semiconductor lasers

Detailed experimental results of optical polarization bistability in InGaAsP semiconductor lasers are reported. Then, the causes of polarization switching and nonlinear response in this bistability are discussed. The light input signal consisted of the transverse magnetic (TM) wave, while the semiconductor lasers operated in a fundamental transverse electric (TE) mode when the light input was not injected. The light output versus light input characteristics were dependent on the input wavelength. Switching times of up to a few hundred picoseconds were achieved for both switch-up and switch-down. The authors found that the TE and TM outputs originate from the TE oscillation and the TM amplification, respectively. The calculation using the rate equations showed that the TM input induces the nonlinearity of the carrier density. These results support that this bistability is a type of dispersive bistability