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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.

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A beam steering type 1:4 optical switch with phase shifters in a silica arrayed-waveguide is proposed. It consists of collimating waveguide mirrors, an arrayed-waveguide which has deep trenches with polymer materials, and input/output waveguides. It can switch the output port of the incident light at high extinction ratio. The incident light is guided to the front mirror, collimated, and input to the arrayed-waveguide. Each waveguide in the arrayed-waveguide has the same length. The number of narrow trenches filled with polymer linearly increases in order. The refractive index of the polymer is set to the effective index of the single mode silica waveguide at certain temperature. The propagation direction of the output light from the arrayed-waveguide can be controlled by changing the temperature of the device because of the large thermo-optic coefficient of the polymer. The second mirror converges the light into one of the output waveguide.We designed two types of the switch which had 9 or 15 waveguides in the arrayed waveguide and they are under fabrication. The chip sizes are about 2.5 mm x 8.0 mm and 2.5 mm x 9.0 mm, respectively. The required temperature shift for the switching from one output port to the adjacent output port is 20 [K] when we use the polymer with a TO coefficient of -1.8x10 -4 [1/K].