[Show abstract][Hide abstract] ABSTRACT: The spatial coherence and the optical phase distribution across a two-dimensional (2D) photonic crystal implemented with coupled arrays of vertical cavity surface emitting lasers (VCSELs) are experimentally characterized. This is achieved by performing Young’s interference experiments between pairs of array elements using a spatial light modulator arrangement. In contrast to far-field measurements that provide information only on the global spatial coherence, this approach can yield full mapping of the complex degree of spatial coherence. Examples of such analysis are presented for nominally uniform one-dimensional and 2D arrays of coupled VCSELs and possible mechanisms of the observed coherence degradation are discussed.
Full-text · Article · Jan 2007 · Applied Physics Letters
[Show abstract][Hide abstract] ABSTRACT: Mapping of the degree of spatial coherence among the elements of VCSEL-based photonic crystal homo- and hetero-structures reveals details of the phase locking not available from conventional far-field diffraction patterns.
[Show abstract][Hide abstract] ABSTRACT: We present a two-dimensional (2D) spatial lock-in amplifier that provides a contrast ratio of more than 10,000:1 for transmitted and blocked intensity patterns using a conventional liquid-crystal spatial light modulator. The device is based on spatial-domain modulation-demodulation of intensity patterns under coherent imaging conditions. The operation of the 2D lock-in amplifier is illustrated by implementing Young's double-slit arrangement for measurements of the mutual coherence between individual emitters of a 2D phase-coupled array of vertical cavity surface emitting lasers.
[Show abstract][Hide abstract] ABSTRACT: Phase-coupled arrays of vertical cavity surface emitting lasers (VCSELs) constitute a particular class of two-dimensional photonic crystal (PhC) structures in which the refractive index varies periodically in the plan normal to the beam propagation direction. The relatively simple implementation of these structures via lithography techniques permits the exploration of novel PhC configurations and the realization of novel spatial-mode-controlled VCSEL array structures. We review here the properties of VCSEL-based PhC structures realized using Bragg mirror patterning. Design and control of the photonic envelope functions in these devices using a variety of PhC homostructures and heterostructures are demonstrated and discussed. Potential applications of these structures in high power VCSELs, dynamic beam switching and optical image processing are mentioned.