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Proceedings Paper

Mode beating in tapered high-power lasers
Author(s): B. M. Azizur Rahman; Riyadh A. Abdallah; Muttukrishnan Rajarajan; Anu Parameswaran; Kenneth T. V. Grattan
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Paper Abstract

Compact and low-cost semiconductor laser sources have significant potential for use in applications which are currently dominated by expensive solid state lasers. In such high power lasers, the optical mode size of the laser source has to be expanded in order to reduce the junction temperature, and the nonlinear effects and the optical power density at the laser facets. Broad-area tapered devices have been proposed to achieve high output power, together with achieving better quantum efficiency and higher beam quality [1]. To study the evolution of the optical beam in an axially non-uniform structure a beam propagation method (BPM) is essential as part of the design process. Thus a full-vectorial FEM-based BPM [2] is used to obtain the transformation of optical beam profile in the tapered region of the device. In this work a deeply-etched semiconductor tapered structure is considered and an expansion of the beam shape has been observed. This characteristic, together with the optical power loss for various taper designs has been studied will be presented. Mode beating also generates beam filamentation in the transverse direction and can deteriorate the overall beam quality. Our subsequent analysis by the use of overlap integral approach has showed the generation of higher order odd modes and their interference with the fundamental mode. The axial variation of the spot-size has also been correlated with the beat lengths between these modes. REFERENCES [1] E S Kintzer et al., IEEE Photonics Technology Letter, 5, pp.605, 1993. [2] S S A Obayya et al., J Lightwave Technol., 18, pp.409-415, 2000.

Paper Details

Date Published: 20 December 2004
PDF: 12 pages
Proc. SPIE 5577, Photonics North 2004: Optical Components and Devices, (20 December 2004); doi: 10.1117/12.567444
Show Author Affiliations
B. M. Azizur Rahman, City Univ. London (United Kingdom)
Riyadh A. Abdallah, City Univ. London (United Kingdom)
Muttukrishnan Rajarajan, City Univ. London (United Kingdom)
Anu Parameswaran, City Univ. London (United Kingdom)
Kenneth T. V. Grattan, City Univ. London (United Kingdom)

Published in SPIE Proceedings Vol. 5577:
Photonics North 2004: Optical Components and Devices
John C. Armitage; Simon Fafard; Roger A. Lessard; George A. Lampropoulos, Editor(s)

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