Circular polarization emission from an external cavity diode laser

Abstract

An external cavity diode laser (ECDL) containing a chiral sculptured-thin-film (STF) mirror for very pure circularly polarized (CP) emission was fabricated and its single-mode, left-handed CP lasing performance was observed. The extinction ratio of the CP output was found to increase rapidly near the threshold of the injection current for the laser diode. The Jones-matrix representation of a chiral STF mirror was used to calculate the eigenstates in the external cavity of the ECDL with the transfer matrix method, the results suggesting that the only resonant mode in the external cavity of the laser is CP with the same handedness as the structural handedness of the chiral STF mirror.