Disorder robust, ultra-low power, continuous-wave four-wave mixing in a topological waveguide.

Area of Science:

• Nonlinear Optics
• Topological Photonics
• Materials Science

Background:

• Four-wave mixing (FWM) is crucial for wavelength conversion and signal processing in nonlinear optical systems.
• Existing methods often require high pump powers and are sensitive to fabrication imperfections.
• Ultra-silicon-rich nitride (USRN) offers high Kerr nonlinearity and low loss, suitable for nonlinear optics.

Purpose of the Study:

• To demonstrate low-power continuous-wave (CW) four-wave mixing (FWM) in a USRN topological waveguide.
• To investigate the impact of disorder on FWM efficiency in Su-Schrieffer-Heeger (SSH) waveguide arrays.
• To explore the potential for compact and robust wavelength conversion systems.

Main Methods:

• Fabrication of a USRN topological waveguide based on the SSH model.
• Experimental demonstration of CW FWM with ultra-low pump power.
• Characterization of wavelength tunability and conversion efficiency.
• Introduction of controlled disorder in the waveguide array to assess robustness.

Main Results:

• Achieved CW FWM at an ultra-low pump power of 510 µW.
• Demonstrated wavelength tunability of 54 nm with an on/off conversion efficiency of -57 dB at 3 mW pump power.
• Observed similar FWM conversion efficiencies in the presence and absence of disorder (±80% randomness in coupling coefficients).

Conclusions:

• USRN topological waveguides enable efficient, low-power CW FWM.
• The FWM process exhibits remarkable robustness against disorder, suggesting tolerance to fabrication errors.
• This work facilitates the development of compact, tunable, and reliable wavelength conversion devices.