Volume 93, Issue 5, 01 March 2003
Index of content:
- LASERS, OPTICS, AND OPTOELECTRONICS (PACS 42)
93(2003); http://dx.doi.org/10.1063/1.1539917View Description Hide Description
A simple theoretical model is proposed for a description of light propagation in ion-implanted leaky waveguides. It permits interpretation of existing published experimental results. A single parameter, the imaginary component of the refractive index, is sufficient to describe losses in the barrier. Simple analytical expressions are obtained for both the lateral resonance condition and the confinement coefficient. For each quasiguided mode, we calculate an optimal barrier thickness which gives the lowest attenuation coefficient. Interestingly, for thick barriers, high-order modes give the best confinement coefficient. Our approach can also describe prism-loaded slab type waveguides.
93(2003); http://dx.doi.org/10.1063/1.1540724View Description Hide Description
A technique for the fabrication of small (2–10 μm in diameter) microlenses on the surface of glass with embedded silvernanoclusters in a subsurface diffusion layer is demonstrated. The dependence of the microlens size on the exposure time and the laser power of a focused continuous wave (cw) laser beam is discussed. It is shown that the optical transmission of the lenses increases with increasing laser power used for the exposure. The temperature distribution in the glass around the focal spot is calculated taking into account the temperature dependence of heat conductivity, shape of the beam, and decrease of absorption coefficient with depth through the diffusion layer containing Ag clusters. The measured microlens sizes are in good agreement with the calculations.
93(2003); http://dx.doi.org/10.1063/1.1543645View Description Hide Description
We propose cascade structures based on type-II heterostructures with graded barriers separating electron and hole layers. The electron–hole separation is controlled by an external bias due to modification of the barrier shape. This principle can be used for fabrication of a class of devices. In particular, bipolar interband cascade lasers are considered in which an external bias changes the rate of electron–hole radiative recombination by several orders of magnitude. Theoretical calculations predict the feasibility of these lasers.
Polarization-dependent intersubband absorption saturation and its effect on polarization selection in vertical cavity surface-emitting lasers93(2003); http://dx.doi.org/10.1063/1.1540745View Description Hide Description
A mechanism of nonlinear dichroism of net gain in vertical-cavity surface-emitting lasers based on polarization-dependent saturation of intersubband absorption in p-contact layers is proposed and analyzed. Microscopic perturbative calculations are used to obtain approximate analytical expressions for the magnitude of the effect. It is shown that the proposed mechanism can play a significant part in polarization switching and bistability in vertical-cavity lasers.