Visible light emission from a silica microbottle resonator by second- and third-harmonic generation

Area of Science:

• Nonlinear optics
• Photonics
• Materials science

Background:

• Silica microbottle resonators are promising for nonlinear optical applications.
• Understanding nonlinear optical phenomena is crucial for developing advanced photonic devices.

Purpose of the Study:

• To report the first observation of coupled nonlinear harmonic generation and stimulated Raman scattering (SRS) in a silica microbottle resonator.
• To investigate the roles of second-order (χ(2)) and third-order (χ(3)) nonlinearities in these processes.
• To explore the potential of third-harmonic generation (THG) for mode profile identification.

Main Methods:

• Utilizing a silica microbottle resonator.
• Generating nonlinear optical phenomena including third-harmonic generation (THG), second-harmonic generation (SHG), and sum frequency generation (SFG).
• Coupling these phenomena with stimulated Raman scattering (SRS).
• Analyzing visible light emission and optical microscope images for mode profiling.

Main Results:

• Observed THG in both tapered fiber output and optical microscope images, useful for axial mode profile identification.
• Observed SFG via three- and four-wave mixing between pump light and SRS-generated light.
• Attributed SHG and SFG to χ(2) induced by surface effects and multipole excitations in silica.

Conclusions:

• Demonstrated simultaneous nonlinear harmonic generation and SRS in a silica microbottle resonator.
• Showcased the potential of THG for characterizing resonator modes.
• Provided insights into the underlying nonlinear mechanisms (χ(2) and χ(3)) in silica microresonators.