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Proceedings Paper

Broad area lasers with folded-resonator geometry for integrated transverse mode selection
Author(s): Dirk Hoffmann; Klaus Huthmacher; Christoph Doering; Henning Fouckhardt
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Paper Abstract

AlGaInAsSb-based broad area lasers (BALs) with a monolithically integrated Fourier-optical 4f set-up in a folded-resonator geometry are realized. The two resonator branches - each one d = 0.825 mm long - are connected through a dry-etched cylindrical total-internal-reflection (TIR) mirror acting as a Fourier-transform element. Transverse mode selection (TMS) is achieved by monolithically integrated spatial-frequency filters positioned in the back focal plane of the mirror (i.e. in the Fourier-transform plane). The whole resonator is gain section (active medium) as well as part of the TMS 4f set-up at the same time. The integration of TMS within the active BAL chip is shown to be successful. All employed BAL/TMS type-II heterostructure lasers are MBE-grown on GaSb substrates, designed for an emission wavelength in the mid-infrared around 2 μm. Different laser samples without any filter elements (no-TMS) and with filters for the selection of the fundamental transverse mode (#0; TMS0) are prepared and characterized. Just for a proof of principle also samples for the selection of higher order transverse modes, here exemplarily mode #6 (TMS6) and #8 (TMS8), have been processed and investigated. The free spectral range between the longitudinal modes is found to be around 0.33 nm corresponding to the BAL's total-resonator length 2d = 1.65 mm (with an effective refractive index neff ≈ 3.8). This result strongly emphasizes that both resonator branches act together as one entity.

Paper Details

Date Published: 17 February 2011
PDF: 7 pages
Proc. SPIE 7953, Novel In-Plane Semiconductor Lasers X, 79531R (17 February 2011); doi: 10.1117/12.873378
Show Author Affiliations
Dirk Hoffmann, Kaiserslautern Univ. of Technology (Germany)
Klaus Huthmacher, Kaiserslautern Univ. of Technology (Germany)
Christoph Doering, Kaiserslautern Univ. of Technology (Germany)
Henning Fouckhardt, Kaiserslautern Univ. of Technology (Germany)


Published in SPIE Proceedings Vol. 7953:
Novel In-Plane Semiconductor Lasers X
Alexey A. Belyanin; Peter M. Smowton, Editor(s)

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