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Polarisation switching in vertical-cavity surface-emitting lasers: from experimental observations to applications

Verschaffelt G., Panajotov K., Albert J., Nagler B., Peeters M., Danckaert J., Veretennicoff I., Thienpont H.

Opto-Electronics Review

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2001

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Vol. 9, No. 3

257-268

EN

Touted as promising components for present and future data-communication and sources for photonic switching fabrics, vertical-cavity surface-emitting lasers (VCSELs) have been studied in detail during the past years, with a focus on their static light-current and dynamic intensity modulation characteristics. Their superior beam quality, low power consumption, Gigahertz modulation bandwidth and the possibility of manufacturing these devices in 2D arrays are often cited as substantial advantages compared to traditional edge-emitting semiconductor lasers or light emitting diodes. A disadvantage of VCSELs is that the polarisation of the emitted light is not defined a priori due to the VCSEL’s quasi-cylindrical symmetry and its direction of lasing perpendicular to the active region. However, real VCSELs do emit linearly polarised light and often polarisation switching from one state to the orthogonal one is observed as the current is changed. In this contribution we will discuss the experimental characteristics of this intriguing polarisation switching phenomenon. We will give an overview of various physical mechanism proposed to explain the polarisation behaviour of these devices and we will illustrate the use of this polarisation switching in the implementation of reconfigurable optical interconnects.

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Selectivity properties of circular grating DFB/DBR lasers with phase shift.

Szczepański P., Tarasiuk S.

Optica Applicata

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2001

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Vol. 31, nr 2

351-371

EN

A threshold analysis is presented for circular grating distributed feedback (CG-DFB) and circular grating distributed Bragg reflector (CG-DBR) lasers with additional phase shift introduced in the grating region. It is found that the proper value and position of the additional phase shift reduces the threshold gain of the laser structure and also improves its mode selectivity

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Modelling of radial steam oxidation of AlAs layers in cylindrically symmetric mesa structures of vertical-cavity surface-emitting lasers

Nakwaski W., Maćkowiak P.

Optica Applicata

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2001

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Vol. 31, nr 2

289-299

EN

During the last several years selective steam oxidation process has evolved into a key technology in fabrication of high-performance vertical-cavity surface-emitting lasers (VCSELs). In the paper, kinetics of AlAs steam oxidation process in cylindrically symmetric VCSEL mesa structures is investigated theoretically. Compact analytical formulae describing the oxidation process are derived and discussed. The process parameters are extracted from existing experimental data. The parameters are found to be strongly dependent on the AlAs layer thickness and temperature. It is shown that significant differences exist between the predictions of the cylindrical model and those of widely used one-dimensional Cartesian model. Our detailed model can therefore be very important for achieving a good control of the oxidation process in fabrication of modern VCSELs

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Crucial structure elements of possible nitride vertical-cavity surface-emitting lasers

Nakwaski W., Maćkowiak P.

Optica Applicata

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2001

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Vol. 31, nr 2

337-349

EN

Problems connected with designing possible nitride vertical-cavity surface-emitting lasers (VCSELs) for their efficient room-temperature (RT) operation are discussed and analyzed. Crucial elements of the VCSEL geometry, i.e. active regions, spacers, DBR mirrors, current and heat-flux paths, substrates as well as contacts, are examined in detail taking into account the latest achievements of the currently available technology. An impact of various structure configurations on threshold properties of the possible RT CW nitride VCSELs is discussed and the most recommended structure details are chosen. A possibility to manufacture efficient nitride VCSELs in a close future is considered and discussed.