Broadband yellow-orange light generation based on a step-chirped PPMgLN ridge waveguide

Area of Science:

• Photonics and Optical Engineering
• Nonlinear Optics
• Materials Science

Background:

• Conventional methods for generating yellow-orange light, such as Raman or optical parametric oscillation, suffer from narrow bandwidths and bulky setups.
• Broad spectral bandwidth and flatness are crucial for advanced applications like photodynamic therapies, spectroscopy, and optogenetics.
• Existing technologies limit the functional scope and compactness of light sources in the yellow-orange spectrum.

Purpose of the Study:

• To engineer a compact and broad-band yellow-orange light source with enhanced spectral flatness.
• To investigate the efficacy of a step-chirped periodically poled magnesium-doped lithium niobate (PPMgLN) ridge waveguide for sum frequency generation (SFG).
• To achieve high optical conversion efficiency in the yellow-orange spectral region using integrated photonics.

Main Methods:

• Design and fabrication of a step-chirped PPMgLN ridge waveguide with precisely controlled grating periods.
• Utilizing sum frequency generation (SFG) within the engineered waveguide to produce yellow-orange light.
• Characterization of the generated light's spectral bandwidth, flatness, and optical conversion efficiency.

Main Results:

• A compact broad-band yellow-orange light source was successfully demonstrated, exhibiting a bandwidth of 5.6 nm.
• An unprecedented spectral flatness of less than 1.5 dB was achieved, surpassing previous reports.
• The highest optical conversion efficiency of 232.08%/W for SFG in the yellow-orange region using PPMgLN was recorded.

Conclusions:

• The designed step-chirped PPMgLN ridge waveguide enables efficient generation of broad-band, flat-spectrum yellow-orange light.
• This compact light source offers significant advantages over conventional methods for photodynamic therapies, spectroscopy, and optogenetics.
• The developed approach is adaptable for generating broad-band light across the visible-to-infrared spectrum in integrated structures.