Phase-dependent interference between frequency doubled comb lines in a χ⁽²⁾ phase-matched aluminum nitride microring

Area of Science:

• Photonics and Optical Science
• Nonlinear Optics
• Quantum Optics

Background:

• Optical frequency combs are crucial for precise measurements and advanced spectroscopy.
• Nonlinear optical conversion is essential for generating new frequencies and manipulating light.
• Generating shorter wavelength combs is vital for applications requiring higher resolution.

Purpose of the Study:

• To demonstrate efficient frequency doubling of optical frequency combs.
• To explore the combination of second-harmonic generation (SHG) and sum-frequency generation (SFG) for comb line generation.
• To confirm the phase coherence of the nonlinear conversion processes.

Main Methods:

• Utilizing a high Q, phase-matched nonlinear susceptibility χ(2) microring resonator.
• Implementing a combined SHG and SFG process on an input frequency comb.
• Analyzing phase-dependent interference patterns of frequency-doubled comb lines.

Main Results:

• Achieved efficient frequency doubling of the input optical frequency comb.
• Demonstrated simultaneous SHG and SFG processes within the microring resonator.
• Confirmed phase coherence between the SHG and SFG nonlinear conversion through interference measurements.

Conclusions:

• The demonstrated method provides an efficient route for frequency doubling optical frequency combs.
• The use of a microring resonator enables precise control over nonlinear optical conversion.
• Phase-coherent generation of doubled comb lines opens possibilities for advanced metrology and spectroscopy.