Independent tuning of free spectral range in thin-film lithium niobate microring resonators

Area of Science:

• Integrated photonics
• Materials science
• Waveguide optics

Background:

• Conventional optical cavities link free spectral range (FSR) and resonance frequencies.
• Independent FSR control is crucial for advanced photonic devices but challenging to achieve.

Purpose of the Study:

• To systematically investigate techniques for tuning waveguide dispersion in thin-film lithium niobate microring resonators (TFLN MRRs).
• To enable independent control of FSR without altering specific resonance wavelengths.
• To explore the impact of electro-optic and thermo-optic tuning on FSR and dispersion.

Main Methods:

• Experimental characterization of electro-optic and thermo-optic tuning effects on TFLN MRRs.
• Analysis of waveguide mode dispersion tuning mechanisms.
• Engineering FSR by varying waveguide width to study geometric and material dispersion interplay.

Main Results:

• Demonstrated independent tuning of FSR in TFLN MRRs.
• Revealed distinct waveguide mode dispersion tuning behaviors for electro-optic versus thermo-optic effects.
• Showcased FSR engineering through waveguide width variation, highlighting geometric and material dispersion interactions.

Conclusions:

• Independent FSR control in TFLN MRRs is achievable through waveguide dispersion tuning.
• Electro-optic and thermo-optic tuning mechanisms offer different pathways for dispersion engineering.
• Geometric control via waveguide width provides an additional method for FSR management in integrated photonic devices.