Vertical-Cavity Surface-Emitting Lasers with coupled cavities and with liquid crystal overlay

We perform a theoretical linear study of the spectral and polarization threshold characteristics of coupled-cavity Vertical-Surface-Emitting Lasers (CC-VCSEL) and VCSELs with with Liquid Crystal overlay (LC-VCSEL). We show that strong wavelength discrimination can be achieved in CC-VCSELs by slightly detuning the cavities. We also consider the case of reverse-biasing one of the cavities, i.e. using it as a modulator via linear and/or quadratic electrooptic effect. Such a CC-VCSEL can act as a voltage-controlled polarization or wavelength switching device that is decoupled from the laser design. LC-VCSELs provide the possibility of selecting between two orthogonal directions of linear polarization (LP) of the fundamental mode (x or y LP) by electro-optically tuning the LC director. Finally, we numerically demonstrate that LC-VCSEL would be capable of efficient wavelength tuning.