<title>Lens-coupled laser-diode module integrated on silicon platform</title>

Abstract

We have realized a highly efficient optical-coupling scheme and simple fabrication structure for laser-diode module by using a new assembly technique. In our module, laser-diode, GRIN rod lens, and single-mode fiber were hybridly integrated on a silicon platform by a passive alignment method. Accurate positioning of the laser in a lateral direction was achieved through the use of a center and side fiducial markers etched onto silicon dioxide film on the silicon platform. Lens and single-mode fibers were set into a V-groove in front of the center marker formed by an anisotropic etching process. The relative height in vertical direction between the lens and the fiber was determined by widths of the V-groove taking account of layer thickness of solder and the laser. Finally, axial positioning of the lens and the fiber were determined using markers on both sides of the V-groove, and the V-grooved lid was used to fix the lens and the fiber using PbSn solder. We attained a highly efficient coupling (coupling loss less than 3 dB) and simple assembly process using GRIN rod lens by a novel passive alignment, leading to low cost and excellent productivity.