Coherence radius and mode size of a broad-area vertical-cavity surface-emitting laser in the incoherent emission regime

Gordon Craggs, Guy Verschaffelt, I. Fischer, Michael Peeters, S.k. Mandre

Research output: Chapter in Book/Report/Conference proceedingConference paperResearch

Abstract

We present experiments measuring the complex degree of coherence of a Broad-Area Vertical-Cavity Surface-Emitting Laser (BA-VCSEL) when it is driven into a regime of spatially incoherent emission. This high-power, spatially incoherent emission regime is quite uncommon for semiconductor lasers but; call be useful in e.g. illumination and projection systems, as the low degree, of spatial coherence may help to reduce speckle. The near-field coherence properties are measured for different positions in the VCSEL's aperture using a 180 degrees reversing-wavefront Michelson interferometer. We give evidence that the coherence area is much smaller than the VCSEL's aperture and that, the intensity fluctuations across the coherence area are small, therefore allowing the BA-VCSEL to be considered a quasi-homogeneous source. We explain the reason for the relatively small coherence radius of about 1.4 mu m based on the mode size in a planar cavity together with the thermal gradient within the VCSEL aperture.
Original languageEnglish
Title of host publicationProc. SPIE, 2008
PublisherSPIE
Volume6997
ISBN (Print)978-0-8194-7195-6
Publication statusPublished - 2008
EventFinds and Results from the Swedish Cyprus Expedition: A Gender Perspective at the Medelhavsmuseet - Stockholm, Sweden
Duration: 21 Sep 200925 Sep 2009

Publication series

NameProc. SPIE, 2008
Number699738

Conference

ConferenceFinds and Results from the Swedish Cyprus Expedition: A Gender Perspective at the Medelhavsmuseet
CountrySweden
CityStockholm
Period21/09/0925/09/09

Keywords

  • MICROCAVITY LASERS; SPATIAL COHERENCE
  • TRANSVERSE; VCSELS

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