A micromachined silicon-submount package for vertical emission of edge emitting laser diodes

Abstract

A silicon-submount package structured with vertical emission of edge emitting laser diodes (LDs) is addressed. Utilizing the micromachining technique, a (100) silicon wafer can be engraved into a batch of submount structures having 45 degrees-slant mirrors for light deflection, and mesas for precise die dwelling. The mirrors are fabricated by deep V-groove etching with the etching window aligned to [100] crystal direction, and by multiple cycles of oxidation-and-isotropic etching processes. The initial ridged surface can thus be polished to a final roughness below 30 nm, with 100-mu m depth, sufficient to accommodate the vertically extended angle of a laser beam. Gold plating on the surface is patterned to form reflective mirrors on the slopes individually, and to provide the bases, which are connected to common electrode, for electroplating of thick indium pads selectively on the mesa areas. Self-alignment of LD bars or dice soldered right on the mesas can be achieved by the surface-tension mechanism that existed between the LD gold electrodes and the indium pads during melting. With simple TO-5 package, a vertically emitted beam has been observed on a stacked LD-submount device, as expected. (C) 2000 Elsevier Science S.A. All rights reserved.