Fig. 4: Direct thermo-optic tuning of a silicon microresonator.

a Schematic of the setup employed for direct thermo-optic tuning. b The resonance frequency is shifted while adjusting the optical power of the laser diode that serves as the pump to drive the thermo-optic effect. Bottom-left inset: the transmission signal at different optical powers, showing the resonance shift. Top-right inset: schematic of the device. c For a focused beam with dimensions of w_x ~ 40 μm and w_y ~ 13 μm, the temperature profile along the angular position is plotted for three different beam positions. d The normalized response of the resonator as a function of the modulation frequency. Inset: the phase difference between the laser power and the detected mid-IR signal and the modulation depth of the mid-IR signal⁹⁹. Reprinted with permission from ref. ⁹⁹ [OSA The Optical Society]