Thermo-optic effects in on-chip lithium niobate microdisk resonators

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• High-quality factor (high-Q) on-chip microdisks are crucial for photonic integrated circuits.
• Thermo-optic effects in lithium-niobate (LN) can significantly influence microdisk performance.
• Understanding these effects is key to designing stable and efficient photonic devices.

Purpose of the Study:

• To experimentally observe and theoretically analyze thermo-optic effects in high-Q LN microdisks.
• To investigate the influence of laser wavelength sweeping speed on microdisk resonance.
• To develop a theoretical model explaining the observed spectral behaviors.

Main Methods:

• Experimental measurement of resonance transmission dips in LN microdisks.
• Systematic variation of laser wavelength sweeping speeds (slow: 4.8 pm/s, fast: 4.8 nm/s).
• Theoretical modeling incorporating fast thermo-optic effects and slow heat dissipation in LN.

Main Results:

• Resonance dip broadening/compression observed with slow wavelength tuning (4.8 pm/s).
• Reversal of dip shape change tendencies at fast sweeping rates (4.8 nm/s).
• Oscillatory transmission spectra observed during slow blue-shifting wavelength sweeps.
• Experimental results successfully explained by the theoretical model.

Conclusions:

• The thermo-optic effect in LN microdisks is highly dependent on the laser wavelength sweeping speed.
• A model combining fast thermo-optic response and slow heat dissipation accurately predicts experimental observations.
• Microdisk deformation due to heat dissipation leads to resonance wavelength reduction.