CLEO 2020 Koshiro Wada

Comprehensive presentation on the stabilization of solitons in ring resonators made of III-V alloys (Al0.2Ga0.8). Group III-V alloys have attracted attention as a new platform for soliton generation because their nonlinear refractive index is larger (35~260) than that of conventional ring resonators (0.3~2.4) and nonlinear absorption is less likely to occur. However, the Q-value is not sufficient for soliton generation, and the thermo-optic coefficient is high, etc. With the improvement of fabrication techniques, the highest Q-value of more than 1.5×106 has been produced, and soliton stepping has been observed, but stabilization has not been achieved yet. In this presentation, after theoretically verifying that a decrease in the thermo-optic coefficient leads to an increase in the length of the soliton step, we confirmed that the thermo-optic coefficient decreases linearly with decreasing temperature in silicon nitride and that there is no change in resonator characteristics (Q value, Pth, FSR, Dint) at very low temperatures ( 7~60 K), and that the soliton step length increases at ultra-low temperatures (7~60 K). This is in good agreement with LLE simulations performed at T=0 K. We then performed similar experiments for III-V alloys (AlGaAs) and confirmed that the thermo-optic coefficient decreases dramatically below 30 K. The soliton generation at such low temperatures was also confirmed experimentally.