Gallium arsenide laser-array-on-silicon package

Abstract

A monolithic array of AlGaAs lasers has been packaged together with an array of fiber lightguides on a substrate of silicon. The components have been optimized for maximum lightguide output radiance consistent with reliable cw laser operation. Coupling efficiencies up to 80% have been achieved between laser and lightguide. Output powers up to 70 mW cw have been observed from a 50-microm core diameter lightguide of 0.15 numerical aperture. Eight-device array multispot packages have been fabricated with 10 mW/spot, limited by laser quality and thermoelectric cooler capacity. Fabrication tolerances and device electrical and optical crosstalk are discussed.

Semiconductor Optical Sensors

“…Rather than restricting the alignment process to that between only two components, the optical bench provides a mechanical and, often, electrical substrate on which any number of components may be mounted and aligned; the schematic structure in Figure 1.4 represents a simple example. The idea behind such an opto-hybrid is not new [51], but recent years have seen an explosion of interest in the approach.…”

(GaAl)As Laser Requirements for Local Attached Data Link Applications

“…Coupling efficiencies of 20-35% have been reported for fibers butted to lasers [18,19]. This efficiency can be increased to 55% [19] by melting the fiber end to form a hemispherical lens, while coupling efficiencies up to 80% are obtained [20] by using a piece of fiber as a cylindrical lens to compensate for both laser beam asymmetry and large perpendicular beam divergence.…”

“…Current approaches involve mounting the laser on a heat sink very close to an edge and then mounting the optical system just beyond the edge. The optical system may be the fiber itself [18], the fiber with a melted tip [19], or a miniature cylindrical lens followed by the fiber [20]. Typical coupling efficiencies into low-NA, multimode, doped silica fibers using the above approaches are 25, 50, and 70%, respectively.…”

“…A transverse displacement between the cleaved end of a fiber and the emission facet of the laser of a distance equal to the core radius (e.g., = ±25 /Am) results in a 50% reduction in coupling efflciency. With lensed surfaces, this tolerance drops to typically one-fifth the core radius (e.g., = ±6ju,m) [20]. Therefore, if high laser-to-fiber coupling eflRciency is desired, the package must provide accurate alignment of the optical components to the laser.…”

“…This technique lends itself to less expensive assembly and should yield greater alignment reliability, but it presumes that the grooves and optical components can be made with sufficient precision to allow self-alignment techniques to work. With etched grooves in single-crystal Si, alignment accuracies better than ±3 ^m have been demonstrated [20].…”