[8a-PB2-1~11] 4 JSAP-OSA Joint Symposia 2017 (poster)

▲ [8a-PB2-9] Measurements of Thermo-Optic Coefficients in Ta₂O₅ based micro-ring cavity

〇(M1)Chao-Wei Liu¹, Chung-Lun Wu¹, Ding-Shin Ou¹, Jen-Yang Huang¹, Yi-Jen Chiu¹, Min-Hsiung Shih^1,3,4, Ann-Kuo Chu¹, Chao-Kuei Lee^1,2 (1.Dep. of Photonics for NSYSU, 2.Dep. of Physics for NSYSU, 3.RCAS for Academia Sinica, 4.Dep. of Photonics for NCTU)

Keywords:Ta2O5, Si photonics

Tantalum pentoxide (Ta₂O₅) of a large bandgap material has recently utilized to demonstrate nonlinear optical waveguide applications due to its superior linear and nonlinear optical properties [1][2], including low absorption loss coefficient in visible to infrared regions, high Kerr coefficients, and free of nonlinear absorption. In this work, the thermal-optical coefficient of tantalum pentoxide has been investigated experimentally by using a micro-ring resonator structure. Taking the advantage of index-sensitively property of ring resonator, the material with ultralow thermal-optical coefficient is easily to be measured and analyzed by using a ring waveguide structure. The cross-section of Ta₂O₅ based micro-ring resonator is set as 1.5μm*0.7μm, and the diameter of ring resonator is set as 100μm. By increasing the substrate temperature of micro-ring resonator, the variation of resonant wavelength of micro-ring resonator is recorded accordingly. The central wavelength of micro-ring resonator is red-shifted from 1543.430 nm to 1543.586 nm when the substrate temperature increases from 20 to 40^ºC. By considering the thermal-optical and thermal expansion effect of micro-ring resonator, the thermal-optical coefficient of Ta₂O₅ is estimated to be 6.8x10^-6/K at ~1550 nm. The thermal-optical coefficient of Ta₂O₅ is ten times of magnitude less than those of conventional III-V semiconductors, indicating that Ta₂O₅ supports the development of thermal-insensitive devices, such as sub-multiplexer and filter element.