| dc.description.abstract | With the continuous advancement of technology, silicon photonics is undergoing constant development and evolution. One of the key advantages of this technology lies in the high integration of both photonic and electronic components within the traditional CMOS semiconductor fabrication process. Group velocity dispersion plays a crucial role in high-speed optical communication, data transmission, and nonlinear optics. Therefore, in this thesis, we first conducted dispersion simulations using finite element method on the required waveguide structures. In the first part, we observed the pros and cons of geometric modulation of dispersion under different heights and widths. In the second part, after confirming the geometry of the silicon nitride waveguide, we simulated the variation in deposited dispersion modulation by using different coating materials and gradually increasing the thickness of the coating layer.
Next, we introduced the fabrication steps of the micro-ring resonator and verified that atomic layer deposition does not cause additional losses or affect the quality factor of the waveguide. For dispersion measurement, we used two materials, Hafnium Dioxide (HfO2) and Aluminum Oxide (Al2O3), coated on the silicon nitride micro-ring resonator.
Through atomic layer deposition, we could precisely control the deposition thickness and accurately modulate the dispersion. With the deposition of Hafnium Dioxide coating, we were able to modulate the dispersion of the silicon nitride waveguide from -274 ps/nmkm to -205 ps/nm-km. Furthermore, with the deposition of Aluminum Oxide coating, we could modulate the waveguide dispersion from -213 ps/nm-km to 46 ps/nm-km. The experimental results showed that using Aluminum Oxide coating could tune the waveguide dispersion to near-zero dispersion. Additionally, increasing the coating thickness could further transform normal dispersion into anomalous dispersion, indicating greater flexibility in dispersion tuning.
Finally, we investigated methods to enhance the quality of the micro-ring resonator. Through femtosecond laser annealing, we conducted localized annealing on the microring resonator. Raman spectroscopy and Atomic Force Microscope were utilized to identify the annealing power most beneficial to the silicon nitride film. We found that
specific power levels contributed to a 1.3-fold improvement in the quality factor of the micro-ring resonator.
This thesis demonstrates the enhancement of micro-ring resonator quality through laser annealing, providing a means of precise and flexible dispersion modulation without
introducing additional losses to the waveguide. | en_US |