Measurement of Temperature-Dependent Polarization Parameters in Long-Wavelength VCSELs

Measurements of the polarization-resolved characteristics of a 1550-nm vertical-cavity surface-emitting laser (VCSEL) as a function of the temperature are presented. Type I (from the high-frequency to the low-frequency polarization mode) and Type II (from the low-frequency to the high-frequency polarization mode) polarization switchings (PS) are found in our device. Double PS (Type II followed by Type I and vice versa) are found when increasing the bias current for different device temperatures. Type II polarization switching to the gain disfavored mode is obtained. PS current, nonlinear dichroism, differential gain, and threshold current are measured as a function of the temperature. An expression relating these quantities to the spin-flip rate is derived. Using this expression, we have found large values of the spin-flip rate and its temperature dependence. The spin-flip rate increases with temperature except in a narrow temperature region in which a local minimum is observed. This behavior is mainly determined by the dependence of the inverse of the nonlinear dichroism on the temperature.