Optical tuning of Si₃N₄ring resonators using an external short visible wavelength laser source

The use of integrated silicon photonic devices has been critical in the advancement of data communication technologies. However, the fabrication and operation of active photonic devices for these applications is often complicated and costly. By using an external 478nm laser source, we have demonstrated the ability to opto-thermally tune passive photonic devices. We have demonstrated various methods of thermal tuning using an external laser source with tuning capabilities up to 24.4 pm/mW for a passive Si3N4 chip with SiO2 cladding material. By etching the cladding layer using standard reactive ion etching techniques to better thermally isolate the individual resonators, we increased the tuning capability to 44.4 pm/mW. In this way, we have successfully tuned the resonance of a passive photonic chip without the use of electrical contacts or thermal electric devices. This poses potential alternatives to conventional thermal tuning techniques.