Guy Verschaffelt

Polarisation switching in proton-implanted VCSELs

Presents a comprehensive experimental study of the polarisation behaviour of proton-implanted GaAs/AlGaAs VCSELs operating around 850 nm. Whereas until now only switching from the shorter to the longer wavelength (higher to lower photon energy) has been reported experimentally (henceforth referred to as type I switching), we have also observed PS in the opposite direction, occurring at higher injection levels and corresponding to a switching from lower to higher photon energy (type II switching). Secondly, in order to explain some of these experimental results, we propose to take into account not only the temperature and wavelength dependence of the gain, but also the same dependence of the free carrier absorption in the highly p-doped DBR mirror, which is known to be particularly important in VCSELs.

Deep proton lithographic CAD-CAM for the fabrication of monolithic micro-optical elements

The technology of deep proton lithography in PMMA (poly methyl methacrylate) is a fabrication method for monolithic integrated refractive micro-optical elements and micro-mechanical holder structures, which allows structural depths in the order of several hundred microns. Different optical functions can be fabricated in one block and form monolithic integrated optical systems. In addition mechanical support structures and alignment features can be integrated with these optical systems. This paper will focus on the technological requirements of the irradiation, the development and diffusion procedures, and of the computer aided design-computer aided manufacturing (CAD-CAM) approach, which are necessary to achieve reproducible micro-optical components.

Realization of polarization-reconfigurable optical interconnections using VCSELs and polarization selective diffractive optical elements

We show how the polarization properties of VCSELs can be exploited usefully in order to realize reconfigurable optical interconnects. We present three set-ups in which the VCSEL light output falls on a polarization-selective diffractive optical element (PSDOE): polarization switching by current modulation, polarization switching by optical injection, and the use of two independent orthogonally polarized VCSELs. A PS-DOE was designed to generate a different spot array for each of the two orthogonal linear polarization states.

CW operation of fabricated semiconductor ring lasers based on retro-reflector cavities with parabolic mirrors

CW operation is achieved in novel semiconductor ring lasers based on retro-reflector cavities with parabolic mirrors downsized to equivalent ring radius of 16mum at room temperature. L-I curves and optical spectra are observed.

The effect of in-plane uniaxial strain on polarization switching in vertical-cavity surface-emitting lasers

Summary form only given. Because of their cylindrical symmetry and surface emission, the material gain and waveguiding anisotropies in VCSELs are small. As a result, polarisation switching (PS) between two orthogonal linearly polarised states is often observed. We study experimentally the effect of in-plane uniaxial strain, resulting from an external stress applied to the VCSEL package.