Analysis of structurally sensitive loss in GaN-based VCSEL cavities and its effect on modal discrimination
Journal article, 2014

Lateral loss causes optical energy to leave the laser cavity in the transverse, lateral, direction, and is sometimes neglected to simplify the numerical simulations. However, in contrast to outcoupling and absorption losses, we show that the lateral loss can change drastically with only nanometer-sized changes of the cavity structure, from being virtually zero to becoming the major source of cavity loss, since the cavity becomes antiguiding. This can be explained as the opening of a channel of efficient resonant lateral leakage of optical power at a certain oblique propagation angle. A number of different realizations of current apertures and top mirror designs in GaN-based VCSEL cavities, which have been suggested for realization of microcavity lasers emitting in the blue wavelength range, are simulated. Many of these are shown to lead to unintentional antiguiding, which can more than double the threshold gain for lasing. Notably, for strong enough antiguiding the resonant lateral leakage decreases so that the threshold gain values might again be tolerable. This regime has been suggested for robust single-mode operation since earlier predictions, building on analogies with slab waveguides, hinted at a very strong suppression of higher order modes. However, our simulations indicate that for the VCSEL cavities the derived formulas grossly overestimate the modal discrimination.

Author

Seyed Ehsan Hashemi

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Jörgen Bengtsson

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Johan Gustavsson

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Martin Stattin

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Gatien Cosendey

Ecole Polytechnique Federale De Lausanne

Nicolas Grandjean

Ecole Polytechnique Federale De Lausanne

Åsa Haglund

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Optics Express

1094-4087 (ISSN)

Vol. 22 1 411-426

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Subject Categories

Telecommunications

Nano Technology

Infrastructure

Nanofabrication Laboratory

DOI

10.1364/OE.22.000411

More information

Latest update

5/3/2018 1