Broadband second-harmonic generation in an angle-cut lithium niobate-on-insulator waveguide by a temperature gradient

Area of Science:

• Nonlinear optics
• Integrated photonics
• Materials science

Background:

• Frequency conversion is crucial for laser spectral broadening, impacting fields like optical communication and quantum information.
• High conversion efficiency and broad phase matching bandwidth are essential for advanced applications.
• Lithium niobate-on-insulator (LNOI) platforms offer potential for integrated nonlinear optics.

Purpose of the Study:

• To demonstrate broadband birefringence phase matching (BPM) second-harmonic generation (SHG) in LNOI ridge waveguides.
• To investigate the use of a temperature gradient scheme for tuning phase matching properties.
• To achieve efficient broadband SHG using a femtosecond laser source.

Main Methods:

• Fabrication of angle-cut LNOI ridge waveguides.
• Implementation of a temperature gradient across the waveguide.
• Characterization of second-harmonic generation (SHG) spectrum and bandwidth.
• Utilizing a telecom C-band femtosecond laser for broadband SHG demonstration.

Main Results:

• Successful demonstration of broadband birefringence phase matching (BPM) second-harmonic generation (SHG) in LNOI ridge waveguides.
• Effective tuning of phase matching spectrum bandwidth and shift via temperature gradient control.
• Achieved broadband SHG from a telecom C-band femtosecond laser.

Conclusions:

• The temperature gradient scheme provides a novel method for tunable broadband nonlinear frequency conversion in LNOI.
• This approach enhances the applicability of integrated photonics for laser spectral manipulation.
• The demonstrated technique may pave the way for new tunable broadband nonlinear frequency conversion platforms.