Issue Eur. Phys. J. Appl. Phys. Volume 46, Number 3, June 2009 Metamaterials Article Number 30701 Number of page(s) 9 Section Photonics DOI 10.1051/epjap/2009068 Published online 22 April 2009

Eur. Phys. J. Appl. Phys. 46, 30701 (2009)
DOI: 10.1051/epjap/2009068

Optimisation of an asymmetric three phase-shift distributed feedback semiconductor laser

Structure concerning the above-threshold stability

C.A.F. Fernandes¹, J.A.P. Morgado^{1, 2} and J.B.M. Boavida<sup>1

1</sup>  Optical Communications Group, Instituto de Telecomunicações, Av. Rovisco Pais, 1049–001 Lisboa, Portugal
²  Portuguese Air Force Academy, Grânja do Marquês, 2715-021 Sintra, Portugal

japmorgado@gmail.com

Received: 10 January 2009 / Received in final form: 11 February 2009 / Accepted: 5 March 2009 / Published online: 22 April 2009

Abstract
This paper shows that accurately optimised asymmetric three phase-shift (3PS)-distributed feedback (DFB) laser structures can strongly improve the stability of the single-longitudinal mode (SLM) operation, described by the mode selectivity and the flatness of the photon density profile, through an extended range of current injection, when compared to optimised symmetric 3PS-DFB structures reported elsewhere. This study reveals its importance in modern high bit-rate optical communication systems, by enhancing the possibility of attaining high performance DFB lasers, in easily fabricated structures. The procedure, based on matrix techniques, aims at the description of the optimal design of the laser structure and it is described step-by-step. Above-threshold calculations have been accomplished to evaluate the performance of the optimised asymmetric 3PS-DFB structure, namely: the mode selectivity (G), the flatness, the lasing wavelength, the optical power, and the side-mode suppression ratio (SMSR) evolutions with the current injection. For a current injection five times bigger than the threshold current, substantially improvements in G (five times bigger) and in the SMSR (about 9 dB higher) are achieved when compared to similar, but symmetric, DFB structures.

PACS
42.55.Px - Semiconductor lasers; laser diodes.
85.60.-q - Optoelectronic devices.
42.82.-m - Integrated optics.
75.40.Mg - Numerical simulation studies.

© EDP Sciences 2009

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