Si Photonic Wire Waveguide Devices

Hirohito YAMADA  Tao CHU  Satomi ISHIDA  Yasuhiko ARAKAWA  

IEICE TRANSACTIONS on Electronics   Vol.E90-C   No.1   pp.59-64
Publication Date: 2007/01/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.1.59
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Section on Microoptomechatronics)
optical device,  optical waveguide,  Si wire,  lightwave circuit,  integrated optics,  

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We fabricated various microscopic optical devices with Si photonic wire waveguides and demonstrated their fundamental characteristics. The bending loss of the waveguide was practically negligible when the bending radius of the waveguide exceeded 5 µm. Therefore, we can fabricate very compact optical devices with the waveguide. We demonstrated an optical directional coupler with the waveguide. The coupling length of the directional coupler was extremely small, several micrometers, because of strong optical coupling between the waveguide cores. We also demonstrated ultrasmall optical add/drop multiplexers (OADMs) with Bragg grating reflectors constructed from the waveguides. The dropping wavelength bandwidth of the OADM device was less than 2 nm and the dropping center wavelength could be tuned using thermooptic control with a microheater formed on the Bragg reflector. Using the Si photonic wire waveguide, we also demonstrated thermooptic switches by forming a microheater on a branch of a Mach-Zehnder interferometer made up of the waveguides. In this switching operation, we observed an extinction ratio exceeding 30 dB, a switching power less than 90 mW, and a switching response speed less than 100 µs using a 12 optical switch with an 8530 µm2 footprint.