GaN-based VCSELs
Paper i proceeding, 2015

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, bio-medical 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 have shown to be challenging, and so far only a handful research groups have demonstrated lasing from such electrically pumped devices [1-6]. The presented performance is typically orders of magnitudes lower compared to that from electrically driven GaAs-based VCSELs. Some of the challenges are to achieve efficient transverse current spreading, transverse optical mode confinement, high-reflectivity mirrors and resonator length control. This talk will summarize the 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 [7]. We will also present an alternative to the use of distributed Bragg reflectors as high-reflectivity mirrors, namely a TiO2/air high contrast gratings (HCGs). Fabricated HCGs of this type show a high reflectivity (>95%) over a 25 nm wavelength span, which is in excellent agreement to the reflectivity spectrum predicted by numerical simulations assuming an ideal HCG geometry [8]. References [1] T.-C. Lu, et al., Applied Physics Letters, 92, 14, (2008). [2] Y. Higuchi, et al., Applied physics express, 1, 12, 121102, (2008). [3] G. Cosendey, et al., Applied Physics Letters, 101, 15, (2012). [4] C. Holder, et al., Applied Physics Express, 5, 092104, (2012). [5] T. Onishi, et al., IEEE J. of Quantum Electronics, 48, 9,1107–1112, (2012). [6] W.-J. Liu, et al., Applied Physics Letters, 104, 251116 (2014). [7] E. Hashemi, et al., Optics Express, vol. 22 1, p. 411-426, (2014). [8] E. Hashemi, et al., Proceedings of SPIE, (0277-786X), vol. 9372 (2015).

GaN VCSEL laser


Åsa Haglund

Chalmers, Mikroteknologi och nanovetenskap, Fotonik

Seyed Ehsan Hashemi

Chalmers, Mikroteknologi och nanovetenskap, Fotonik

Jörgen Bengtsson

Chalmers, Mikroteknologi och nanovetenskap, Fotonik


Johan Gustavsson

Chalmers, Mikroteknologi och nanovetenskap

Gatien Cosendey

Marlene Glauser

Georg Rossbach

Nicolas Grandjean

Marco Calciati

Michele Goano

VI Workshop on Physics and Technology of Semiconductor Lasers


Nanovetenskap och nanoteknik



Annan elektroteknik och elektronik

Den kondenserade materiens fysik



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