High pump depletion second-harmonic generation using domain engineered thin-film lithium niobate waveguides

Area of Science:

• Integrated nonlinear optics
• Photonics
• Materials science

Background:

• Thin-film lithium niobate (TFLN) offers strong nonlinear properties for integrated optics.
• Domain engineering in TFLN is crucial for phase matching in nonlinear processes.
• Previous devices achieved high length-normalized efficiencies but lacked absolute energy conversion due to fabrication limits.

Purpose of the Study:

• To achieve effective on-chip nonlinear energy conversion in TFLN devices.
• To overcome fabrication limitations hindering absolute energy conversion.
• To develop low-loss, high-quality domain-engineered TFLN waveguides with long interaction lengths.

Main Methods:

• Utilized ion beam trimming (IBT) for precise fabrication.
• Implemented an etching-prior-poling workflow.
• Fabricated low-loss, domain-engineered TFLN waveguides with extended interaction lengths.

Main Results:

• Demonstrated an overall second-harmonic generation (SHG) efficiency of 2,590%/W.
• Achieved a high pump depletion of 85.7% under continuous-wave operation.
• Confirmed strong nonlinear energy conversion through experimental characterization.

Conclusions:

• The developed TFLN waveguides enable efficient on-chip nonlinear energy conversion.
• These advancements address the need for absolute energy conversion in practical applications.
• The results hold potential for breakthroughs in classical and quantum frequency conversion and quantum light generation.