2 January 1998 Alternative shape for tapered geometry semiconductor optical sources
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Proceedings Volume 3211, International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '96; (1998) https://doi.org/10.1117/12.345523
Event: International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '96, 1996, Madras, India
Abstract
Recently a high level of in-plane emission in VCSELs has been reported [1]. Existence of the problem for vertical cavities has been previously demonstrated in connection with electron beam pumped lasers [2] and LED [3]. The effect results in increasing threshold and a reduction of efficiency of the devices [2]. Prili- menary estimation shows importance of the problem for large diameter VCSEL as well [4]. Thus, suppression of the in-plane emission gives a way of improvement of VCSEL operational characteristics. Features of the spontaneous emission (SE) pattern is a basis for simulation and modelling of the effect. In this paper the SE is considered for both A— and A/2— cavities in the framework of a planar multilayer structure model taking into account the QW optical spectrum. The model is suitable for large diameter VCSELs with weak radial boundaries and allows the consideration of both in-plane and vertical propagating modes. Results of calculation show that, for a A/2— cavity, all in-plane propagating modes have weak coupling to a dipole of the active region (QW), unlike the A— cavity case where there is a mode having a field maximum in the position of QW and thus strong dipole coupling. This leads to a 2 - 4 times reduction of spontaneous emission in the in-plane direction for the A/2— cavity. However, this is still comparable with the SE in ”vertical” modes and therefore can not be neglected, as is usually assumed. The ” vertical” modes in general propagate at different angles to the 55 pure vertical direction” and hence have an in-plane component of the propagation constant. Analysis shows the ’’pure” vertical part of the SE to be extremely small compared to the total. Thus, the in-plane component of the SE should be taken into account to improve VCSEL desig
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Alexander I. Onischenko, Alexander I. Onischenko, Jayanta Sarma, Jayanta Sarma, } "Alternative shape for tapered geometry semiconductor optical sources", Proc. SPIE 3211, International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '96, (2 January 1998); doi: 10.1117/12.345523; https://doi.org/10.1117/12.345523
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