1994 Fiscal Year Final Research Report Summary
Study on simplified schems for coupling between laser diodes and single-mode fibers
| Project/Area Number |
05452202
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
情報通信工学
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| Research Institution | Utsunomiya university |
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Principal Investigator |
SHIRAISHI Kazuo Utsunomiya Univ., Eng.Fac., Assoc.Prof., 工学部, 助教授 (90134056)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMURA Kazuhito Utsunomiya Univ., Eng.Fac., Prof., 工学部, 教授 (70005297)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Optical fiber / Expanded core fiber / Laser diode / Lensed fiber / Coreless fiber / Optical coupling / Coupling loss / Aspheric lens |
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| Research Abstract |
The intergrated light coupling scheme from laser diode arrays to single-mode fiber arrays shown is one of important technologies in constructing practical fiber networks. Hemispherical end fibers for this use have desirable features, such as simple, stable, and the potential for attaining high coupling efficiency.For the purpose, a reasonable working distance (an air gap between diodes and fibers) longer than -100 mum is required not to make contact between them during an automatic as sembling process. Conventional lensed fibers, however, need very short (less than 10 mum) working distances. We proposed a new lensed-fiber configuration which enables a long working distance with a high coupling losses.
The new configuration consists of a coreless fiber chip spliced onto an expanded core fiber. In contrast to the conventional one, we can make use of the cladding as a part of the lens. The working distance could been increased to roughly the size of the cladding diameter. Analyzes developped in the research and experiments show that a large core diameter rather than high NA (namely, expanded core fiber) is preferable to attain a high coupling efficiency. The fabrication process is as follows. A coreless fiber tip with 125-mum diameter and 980-mum length was spliced onto the expanded core fiber whose modal field diameter at the wavelength 1.49mum is expanded to 45 mm from the original size, 10mum. The other side of the tip was melted into a hemispherical profile with the radius R=75 mum by use of an arc-discharge fiber splicer.
The minimum coupling loss obtained was 4.3 dB at the working distance 160 mum. The long working-distance operation with a long working distance has been published. We have successfully performed the research.
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