Novel distributed-feedback surface-emitting laser design

Abstract

Surface-emitting semiconductor lasers are attractive for applications in optical computing, coherent communications, high-power two-dimensional arrays, and integrated opto-electronics. Vertical-cavity surface-emitting structures are especially promising because of their simplicity compared with other surface-emitting lasers, which use gratings or inclined mirrors to deflect the output from horizontal (in-plane) active region. Recently, the advantages of the resonant-periodic-gain (RPG) medium have been demonstrated in vertical-cavity structures.1,2 Here we describe a new concept for a vertical-cavity distributed-feedback (DFB) surface-emitting laser that incorporates an RPG active region. In this design, a vertical resonator with highly reflective mirrors is created by a stack of alternating high- and low-refractive-index quarter-wave layers that form a DFB medium. An RPG active region is interspersed within this medium. Each element of the RPG active region consists of a single or multiple quantum well whose position coincides with the antinodes of a standing wave at a design wavelength. The elements of the embedding DFB medium form spacers between active regions. This design eliminates the need for the end reflectors in previous RPG structures by interlacing the quarter-wave multilayer high reflectors with the gain medium, thus reducing the total thickness of the device. In the same instance, the characteristic features of the RPG medium (enhancement of gain in vertical direction, wavelength selectivity, and suppression of amplified spontaneous emission) are retained. Examples of cavity calculations for the novel structure will be given, and various configurations will be discussed.