The control of polarization of laser diodes

The mode-competition phenomena are studied through three experiments. At first, in double-heterostructure laser diodes with thick active layers, TE and TM modes tend to coexist and the mode competition between these two modes is observed from the correlation of the light outputs of these two modes where the increase of light output of one mode tends to decrease the light output of other mode. In a laser diode operating with an external reflector, the increase of light output for the TE mode leads to the decrease of light output for the TM mode. In case the external reflector is set to deviate from the parallel plane to the cleaved surface of the laser diode, the TM-mode component tends to its magnitude, even if the inherent mode of this diode is TE. In the experiment of external light-beam irradiation onto a laser diode, the light intensity of one mode is decreased by an incidence of light beam having another mode from the other laser diode. In this experiment, the significance of a gap distance between the two laser diodes is confirmed clearly, where the two laser diodes interact with each other through the light beam.