Polarization- and Modal-Control in a Vertical-Cavity Surface-Emitting Laser With an External-Cavity Formed by a Liquid Crystal Overlay

Abstract

By utilizing a fully-vectorial three-dimensional coldcavity optical simulation, we analyze the spectral, polarization, and modal-losses behavior of a vertical-cavity surface-emitting laser with a nematic liquid-crystal (LC) overlay. We identify phenomena responsible for mode and polarization selectivities and show how they can be controlled by varying design geometry parameters, such as LC thickness and oxide aperture diameter, or by electrooptically tuning the LC director. We present possibility of achieving voltage-controlled polarization switching of a fundamental mode or transverse mode switching within the same polarization. Furthermore, we show that it is theoretically possible to obtain improved single-mode operation by means of increased higher order transverse mode discrimination. Finally, we point out a way to destabilize the diode by equalizing the modal losses of all the analyzed modes.

Liquid-Crystal Spin-VCSEL with Electro-Optically Controllable Birefringence

“…The strongest impact of the LC on the LC-VCSEL properties is achieved when the middle DBR is completely omitted (c.f. [25][26][27] for the optimization of wavelength tuning region of intracavity LC-VCSELs). In our case, however, such an intracavity LC-VCSEL is very sensitive to LC voltage change.…”

“…LC embedded in a second cavity, coupled with the active VCSEL cavity, has been shown to provide polarization control [19][20][21], emission of circularly polarized light [22,23] and high contrast modulation [21,24]. Utilizing nematic LC for wavelength tuning has also been considered both theoretically [25][26][27][28] and experimentally [29,30].…”