| Summary: | We describe low-loss SiN/SiON waveguides for wavelength-division-multiplexing filters on a Si platform. The key technology is a low-temperature deposition of refractiveindex-controllable SiN/SiON films by using a hydrogen-free gas source (SiD4), which avoids the strong optical absorption due to N-H bond. Using this technology, we demonstrate a low-loss ring resonator with a SiN waveguide, whose loss is 0.47 dB/cm at 1550 nm. It shows excess loss of 2.7 dB, a 3-dB bandwidth of 0.13 nm, and an extinction ratio of 27 dB in the entire C band. In addition, we also demonstrate a polarization-insensitive arrayedwaveguide grating with a SiON waveguide, whose loss is 0.29 dB/cm at 1550 nm. It shows insertion loss of 5.3 dB, crosstalk of less than -27 dB, and polarization insensitivity in the entire C band.
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