Visible blue-to-red 10  GHz frequency comb via on-chip triple-sum-frequency generation

Area of Science:

• Photonics and Waveguide Technology
• Nonlinear Optics
• Optical Frequency Combs

Background:

• Optical frequency combs are crucial for precise optical measurements.
• Generating visible light frequency combs is challenging.
• Silicon nitride photonics offers a promising platform for nonlinear optical processes.

Purpose of the Study:

• To demonstrate a novel method for generating a broadband visible light frequency comb.
• To leverage on-chip silicon nitride waveguides for efficient frequency conversion.
• To link mature telecommunication technologies to the visible spectrum.

Main Methods:

• Generation of ultra-short pulses from a continuous-wave laser via electro-optic modulation.
• Spectral broadening into a near-infrared supercontinuum within a silicon nitride waveguide.
• Triple-sum-frequency generation enabled by modal phase matching for visible light conversion.

Main Results:

• A broadband visible (VIS) frequency comb spanning blue-to-red wavelengths was generated.
• The comb covers over 250 THz, from below 400 nm to above 600 nm.
• The process utilizes a 10 GHz repetition rate and 150 pJ pulse energy.

Conclusions:

• The developed scheme successfully generates a visible light frequency comb using on-chip nonlinear optics.
• This method provides a direct link between telecommunication band technology and the visible spectrum.
• Potential applications include astronomical spectrograph calibration and continuous-wave laser referencing.