Active mode selection by defects in lithium niobate on insulator microdisks

Area of Science:

• Photonics
• Materials Science
• Optical Engineering

Background:

• Whispering gallery mode (WGM) optical microcavities are crucial for integrated photonic circuits.
• Controlling transverse modes in these cavities is vital for various applications.

Purpose of the Study:

• To demonstrate active mode selection in lithium niobate on insulator (LNOI) microdisks.
• To investigate the impact of engineered defects on WGM characteristics.

Main Methods:

• Fabrication of LNOI microdisks using focused ion beam (FIB) milling.
• Introduction of precisely sized and located nano slits as defects on the microdisk perimeter.
• Analysis of transmission spectra to evaluate mode selection and quality factor.

Main Results:

• Successfully thinned transmission spectra of microdisks by introducing defects.
• Preserved high optical quality factors despite defect introduction.
• Achieved selective retention of either fundamental or high-order transverse WGMs through defect design.

Conclusions:

• Engineered defects provide an effective method for active WGM selection in LNOI microdisks.
• This approach offers a pathway towards single-mode lasing and enhanced nonlinear optical devices.