Progress and challenges in electrically pumped GaN-based VCSELs
Paper i proceeding, 2016

The Vertical-Cavity Surface-Emitting Laser (VCSEL) is an established optical source in short-distance optical communication links, computer mice and tailored infrared power heating systems. Its low power consumption, easy integration into two-dimensional arrays, and low-cost manufacturing also make this type of semiconductor laser suitable for application in areas such as high-resolution printing, medical applications, and general lighting. However, these applications require emission wavelengths in the blue-UV instead of the established infrared regime, which can be achieved by using GaN-based instead of GaAs-based materials. The development of GaN-based VCSELs is challenging, but during recent years several groups have managed to demonstrate electrically pumped GaN-based VCSELs with close to 1 mW of optical output power and threshold current densities between 3-16 kA/cm2. The performance is limited by challenges such as achieving high-reflectivity mirrors, vertical and lateral carrier confinement, efficient lateral current spreading, accurate cavity length control and lateral optical mode confinement. This paper summarizes different strategies to solve these issues in electrically pumped GaN-VCSELs together with state-of-the-art results. We will highlight our work on combined transverse current and optical mode confinement, where we show that many structures used for current confinement result in unintentionally optically anti-guided resonators. Such resonators can have a very high optical loss, which easily doubles the threshold gain for lasing. We will also present an alternative to the use of distributed Bragg reflectors as high-reflectivity mirrors, namely TiO2/air high contrast gratings (HCGs). Fabricated HCGs of this type show a high reflectivity (>95%) over a 25 nm wavelength span.

optical guiding

HCG

VCSEL

Vertical-cavity surface-emitting laser

GaN

Gallium Nitride

anti-guiding

Författare

Åsa Haglund

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

Seyed Ehsan Hashemi

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

Jörgen Bengtsson

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

Johan Gustavsson

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

Martin Stattin

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

M. Calciati

Politecnico di Torino

M. Goano

Politecnico di Torino

Proceedings of SPIE - The International Society for Optical Engineering

0277786X (ISSN) 1996756X (eISSN)

Vol. 9892 98920Y

Ämneskategorier

Elektroteknik och elektronik

DOI

10.1117/12.2229428

ISBN

9781510601376

Mer information

Senast uppdaterat

2018-08-28