Sequential TE/TM polarization emission from a tunable external cavity diode laser

A tunable external cavity diode laser that emits in a closely spaced sequence of alternating TE and TM wavelength intervals in the range between 1256 and 1282 nm is reported. In each interval, stable single longitudinal mode TE and then TM emission occurs that can be tuned in wavelength. Two consecutive intervals are separated by a wavelength region where emission instabilities are observed. The wavelength spacing between two successive intervals belonging to the same polarization state corresponds to the mode spacing of the solitary diode laser. As the laser is tuned beyond 1282 nm and up to 1316 nm, the emitted radiation is only TM polarized. The above-mentioned phenomena are based on the composite cavity gain modulation with the wavelength, and on the comparable losses of the system for the TE and TM polarization.<
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