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An impact of the electrical pumping scheme on some VCSEL performance characteristics

Morawiec S., Kowalczewski P., Sarzała R. P.

Optica Applicata

2009

Vol. 39, nr 4

691-699

A comprehensive theoretical model of an operation of vertical-cavity surface-emitting diode lasers (VCSELs) is used to compare anticipated room-temperature (RT) continuous-wave (CW) performance of three modern VCSEL designs: the MESA VCSEL with the upper ring contact on the upper p-side DBR structure and the bottom broad-area contact as well as the single and the double intra-cavity contacted VCSELs. The MESA VCSEL has been found to demonstrate the best mode selectivity because its desired single fundamental mode operation is expected even for the largest 20-žm diameter devices. However its RT CW lasing thresholds are by about 30% higher than those for both intra-cavity contacted VCSELs because of increasing free-carrier absorption and heat generation. Therefore large-size MESA VCSELs cannot operate at higher temperatures and/or for higher operation currents. On the contrary, although both intra-cavity contacted VCSELs ensure single-fundamental-mode operation for smaller devices only, they seem to operate properly also at higher temperatures and operation currents. Therefore, with an exception of some special applications, intra-cavity contacted VCSELs currently seem to be the best VCSEL designs.

Simplified modelling of photonic-crystal-confined vertical-cavity surface-emitting diode lasers

Nakwaski W.

Optica Applicata

2005

Vol. 35, nr 3

579-589

In standard GaAs-based oxide-confined vertical-cavity surface-emitting diode lasers (VCSELs), their transverse single-fundamental-mode operation is limited to relatively low outputs. It is a direct consequence of small radial sizes of their active regions and strong real waveguiding effects induced by their oxide apertures. Photonic crystals applied in VCSEL designing in a way shown in the present paper enable a subtle waveguiding modification leading to a considerable increase in an output of the VCSEL single-mode operation. Unfortunately, the structure of aphotonic crystal damages inside a VCSEL volume its axial symmetry, which makes rigorous simulation of its operation much more difficult. In the present paper, a simplified approach to physical (optical, electrical and thermal) phenomena taking place within VCSEL volumes equipped with photonic crystals is presented. Designing guidelines to obtain single-mode-operating photonic-crystal-confined VCSELs have been proposed. Various possible distributed-Bragg-reflector (DBR) output mirrors designed for various wavelengths have been analysed. From among them, GaN-based DBRs have been found to enable higher single-mode VCSEL outputs, especially for longer wavelengths.