Mid-infrared light generation in a lithium niobate microdisk without any periodic poling structure

Area of Science:

• Photonics
• Nonlinear Optics
• Materials Science

Background:

• Whispering gallery resonators (WGRs) enable low-threshold optical parametric oscillation (OPO).
• Periodic poling of lithium niobate (LN) allows wavelength tuning but adds fabrication complexity.
• Existing methods for LN-based OPO require additional poling steps, increasing production time.

Purpose of the Study:

• To demonstrate mid-infrared (MIR) laser output from a lithium niobate microdisk without using poling structures.
• To achieve efficient nonlinear conversion in a simplified fabrication process.
• To present a viable method for producing compact LN-based MIR light sources.

Main Methods:

• Utilizing Type I and modal phase matching in a lithium niobate microdisk.
• Fabricating a microdisk resonator with a high Q-factor.
• Characterizing the generated idler wavelengths and nonlinear conversion efficiency.

Main Results:

• Achieved a Q-factor of 1.23 × 10⁶ in the microdisk resonator.
• Generated idler wavelengths up to 4101 nm.
• Obtained a nonlinear conversion efficiency of approximately 4.2% without poling.

Conclusions:

• The proposed method enables efficient MIR laser generation from LN microdisks without poling.
• This approach significantly streamlines the fabrication workflow for LN-based optical devices.
• The results offer a practical solution for the development of compact and efficient MIR light sources.