High Optical Coupling Scheme in LD Modules with Silicon Platform Technology

Kazuhiro TANAKA  Seimi SASAKI  Gohji NAKAGAWA  Tsuyoshi YAMAMOTO  Kazunori MIURA  Shouichi OGITA  Mitsuhiro YANO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E80-C   No.1   pp.107-111
Publication Date: 1997/01/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Devices, Packaging Technology, and Subsystems for the Optical Access Network)
Category: 
Keyword: 
silicon platform,  optical coupling,  passive alignment,  marker,  laser diode,  spot size transformer,  

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Summary: 
Laser module fabricated with silicon platform technology is very attractive for low-cost modules. The technology enables passive optical alignment of an LD to an optical fiber. Our marker design for passive alignment allows positioning accuracy within 1 µm of LD. However, coupling efficiency is a key issue because that by conventional butt coupling scheme is low with about 10 dB coupling loss. We investigated optical coupling characteristics in various types of coupling scheme: conventional flat end fibers, cone fibers, integrated GRIN rod lenses on the platform and the coupling with new-type LDs integrated with spot size transformer. Improvement of coupling efficiency with 3 dB and 7.5 dB compared to flat-end fiber is achieved by using the cone fiber and the GRIN rod lens, respectively, although 1-dB coupling tolerances for alignment deteriorated with these schemes. We obtained high efficient coupling with 3.5 dB coupling loss and wide alignment tolerance of 2.3 µm simultaneously with a new-type LD integrated with spot size transformer owing to its expanded spot size characteristics.