Polarization control in vertical-cavity surface-emitting lasers (VCSELs) has attracted a lot of interest and different techniques have been proposed to achieve it. Among them, one of the most attractive relies on slight modifications of existing and well-behaving devices, i.e., by introducing a noncircular transverse section layer somewhere in the device. Even though experimental verifications of this principle have already been carried out, a theoretical framework to better understand and possibly optimize such devices is still missing. This mainly originates from the need of a fully vectorial and three-dimensional approach. In this paper we will undertake a joint experimental and theoretical effort: first, we give experimental evidence of polarization control by applying elliptical surface etching. Then, after having validated the vectorial electromagnetic model by comparing numerical and experimental results, we are able for the first time to explain and compare the polarization selection mechanisms and, consequently, to provide guidelines for optimized structures.

Polarization control in vertical-cavity surface-emitting lasers (VCSELs) has attracted a lot of interest and different techniques have been proposed to achieve it. Among them, one of the most attractive relies on slight modifications of existing and well behaving devices, i.e. by introducing a non-circular transverse layer section somewhere in the device. Even though experimental verifications. of this principle have already been carried out, a theoretical framework to better understand and possibly optimize such devices is still missing. This mainly originates from the need of a fully vectorial and three-dimensional approach. In this paper we will undertake a joint experimental and theoretical effort: first we give experimental evidence of polarization control by applying elliptical surface etching. Then, after having validated the vectorial electromagnetic model by comparing numerical and experimental results, we are able to better explain the polarization selection mechanisms and consequently to provide suggestions for optimized structures.

The theoretical aspect of single transversal mode operation in a photonic crystal surface emitting laser (PCSEL) is presented. First generalized VB diagrams for the holey waveguiding laser structure based on the effective refractive index of the photonic crystal cladding region are presented and discussed. In this paper, we also discuss advantages and drawbacks of mode stabilization due to light localization with photonic crystal defect.

Summary form only given. The present paper focuses on the theoretical background of single-mode operation in VCSELs with incorporated photonic crystals - Photonic Crystal Surface-Emitting Lasers (PCSELs). This work provides direct identification of the waveguiding mode by computation of the normalized propagation constant B which shows the fraction of the optical mode guided by the core region. We present a design rule for hole diameter and pitch values where true single-mode oscillations of PCSELs should be found.

Selected results of a numerical analysis of the spatial part of the optical mode in Photonic Crystal Surface-Emitting Lasers (PCSELs) is introduced. It is shown that such a structure provides different propagation constants for different spatial modes which can result in larger optical feedback for LP01 optical mode in comparison with other modes guided by the photonic crystal defect.

Optically controllable gates are of increasing interest in prospective optical data processing, in optical transmission systems for external modulation, and, arranged in parallel, for all-optical interconnects. In optical data processing besides logical switching elements memory devices are of decisive importance for buffered input and output and for clocked processing cycles. In this contribution we investigate dynamic memory characteristics of InGaAsP photonic switching devices. We achieve a hold time greater than 10 ns which enables clocked signal processing.

Optical modulators in A1GaAs or GaInAsP are of particular interest since they allow for optoelectronic integration with transistors, semiconductor lasers and photodetectors. Potential applications are, for instance, in space or time division multiplexing for high-speed signal processing in optical communication networks.

Under reverse bias a phase shift per unit length of up to 500 degrees /mm is observed in a GaInAsP/InP inverted rib waveguide embedded in a double-heterostructure pin diode. The waveguides were fabricated by wet chemical etching and subsequent liquid phase epitaxy. Diodes were formed by selective Zn diffusion in the InP cladding layer. The planar structure is favourable for integration with other ...