Engineering the transverse optical guiding in GaN-based VCSELs to avoid detrimental optical loss
Conference poster, 2012

In order to improve the current injection in GaN-based blue vertical cavity surface emitting lasers (VCSELs) a dielectric aperture is generally used in combination with an indium-tin-oxide (ITO) layer on the top intracavity p-contact layer. The most straightforward way to realize this introduces a depression of the structure near the optical axis and we show, by using a 2D effective index method and a 3D coupled-cavity beam propagation method, that this typically results in optically anti-guided structures with associated high optical losses and thus very high threshold gains. Remarkably, the threshold gain reduces with increased negative guiding, which is due to improved lateral confinement and reduction of lateral leakage. Still, moderately positively guided designs should be preferred to avoid the detrimental effect of lateral leakage and high diffraction loss. To ensure positive index guiding, we propose to planarize the structure or introduce an elevation near the optical axis by additional processing, with an associated reduction in threshold material gain from 6000 cm-1 to 2000 cm-1 for the studied structures.

Gallium Nitride based lasers

Blue VCSEL

Blue Microcavity lasers

Author

Seyed Ehsan Hashemi

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Johan Gustavsson

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Jörgen Bengtsson

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Martin Stattin

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Anders Larsson

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Gatien Cosendey

Nicolas Grandjean

Åsa Haglund

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

International Workshop on Nitride Semiconductors 2012, October 14-19, 2012, Sapporo, Japan, p. ThP-OD-33

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Subject Categories

Nano Technology

Other Electrical Engineering, Electronic Engineering, Information Engineering

Infrastructure

Nanofabrication Laboratory

More information

Created

10/7/2017