High UV sensitivity of SiON film and its application to center wavelength trimming of microring resonator filter

We demonstrated a vertically coupled microring resonator (VCMRR) filter as an Add/Drop wavelength filter. However, the accuracy of center wavelength was not sufficiently high for dense wavelength division multiplexing (DWDM) systems. Thus, a UV trimming technique using a Sin (n=2.01 at λ=1.55μm) ring core was previously developed. Although a wide center wavelength trimming range of -12.1 nm and the long-term stability of center wavelength were realized, the core size required for single-mode propagation was too small for fabrication using a photolithography process. Therefore in this study, we introduced SiON as the microring core to relax the single-mode condition of core size. We discovered a large UV sensitivity of SiON film formed by a PECVD method, and a wide range UV trimming of microring resonator of -10.5 nm was demonstrated using this phenomenon