Origin of UV Sensitivity of SiON Film and Bidirectional UV Trimming of SiON Microring Resonator

We discovered a photoluminescence phenomenon of SiON waveguide by the UV irradiation and investigated the luminescence spectrum by a conventional microscope and diffraction grating spectroscopy. It was shown from these measurements that the defect created by UV irradiation causes the UV sensitivity of SiON film after thermal annealing. Next, we measured the spectrum change of a microring resonator with SiON core via single point long time UV irradiation and multi point UV irradiation. As a result, we demonstrated a selective UV trimming of microring resonator combining thermal annealing and multi point UV irradiation.