180-Degree-Bend Structures Using Light Reflection at Double Elliptic Mirror in Slab Waveguide
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We have proposed a small 180°-bend structure employing a double elliptic mirror where the light changes its propagating direction by reflecting at the two mirrors. There are three other types of bend structure: (1) a Ag mirror bend structure, (2) a total internal reflection (TIR) mirror bend structure, and (3) a TIR mirror bend structure employing tapered waveguides. In the Ag mirror bend structure, Ag functions as the mirror, while in a TIR mirror bend structure, an air gap functions as the mirror. The size of the proposed structure is considerably smaller than that of a conventional bend waveguide; additionally, a large tolerance to mirror position misalignment and a low wavelength-dependent loss (WDL) can be attained. The insertion losses at 1550 nm are 4.28 dB for an Ag mirror bend structure, 8.69 dB for a TIR mirror bend structure, and 4.78 dB for a TIR mirror bend structure with tapered waveguides. Further loss reduction is expected by taking into consideration the phase shift due to reflection.
- Jpn J Appl Phys
Jpn J Appl Phys 46(1), 168-174, 2007-01-15
INSTITUTE OF PURE AND APPLIED PHYSICS