Highly-Permissible Alignment Tolerance of Back-Illuminated Photo-Diode Array Attached with a Self-Aligned Micro Ball Lens

Kazuhiro NISHIDE  Kenji IKEDA  Xueliang SONG  Shurong WANG  Yoshiaki NAKANO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.9   pp.1472-1479
Publication Date: 2008/09/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.9.1472
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Lasers, Quantum Electronics
Keyword: 
photodiode,  photodiode array,  ball lens,  fiber optical alignment,  

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Summary: 
Simulation and fabrication results on back-illuminated 4-channel photodiode (PD) array with a self-aligned micro ball lens are described. The channel pitch and diameter of each photosensitive area are 250 µm and 40 µm, respectively. Measured photocurrent is 1.92 times larger than that without a lens. Alignment tolerance between the single mode fiber (SMF) optical axis and the photodiode is improved from 21.2 µm to 42.7 µm. Moreover, the separation tolerance between the fiber and the lens is 210.5 µm. These large tolerances agree with simulation results, demonstrating that the device configuration is suitable for receivers for multi-channel inter-connection. Frequency response and inter-channel cross talk are also discussed.