High quality Tantalum pentoxide thin film growth and its application for low loss nonlinear waveguide*

Tantalum pentoxide (Ta₂O₅) of a large bandgap material has shown its potential for Si photonics due to its low absorption loss coefficient in visible to infrared regions, high Kerr coefficients, and nonlinear absorption(TPA/FCA) free. Development of large scale high optical quality thin film for integrated photonics is therefore desired. In this work, by using e-gun evaporation, large scale Ta₂O₅ thin film growth was performed. Beside the measurement of x-ray and Ramen pattern for identifying the structure, the AFM and SEM results all show the grown thin film with high quality. In addition, a low-loss and high-Q Ta₂O₅ based micro-ring resonator was fabricated and characterized. The propagating loss of 0.3 dB/cm was obtained and unloaded quality as high as 300000 was accordingly estimated. This is, in our knowledge, the largest unloaded quality for Ta₂O₅ waveguide. This all show that electron beam thermal evaporation (E-gun) grown Ta₂O₅ film is with great potential for photonic integrated circuit.