Coherent supercontinuum generation in all-normal dispersion Si₃N₄ waveguides

Area of Science:

• Photonics and Optical Engineering
• Materials Science

Background:

• High repetition rate optical frequency combs are crucial for optical communications, radio-frequency photonics, and spectroscopy.
• Silicon nitride (Si3N4) waveguides in the anomalous dispersion regime enable octave-bandwidth supercontinuum generation, typically requiring femtosecond pulses for coherence.
• Supercontinuum generation in the normal dispersion regime is suitable for picosecond pulses but faces challenges in Si3N4 waveguides due to propagation length and loss requirements.

Purpose of the Study:

• To experimentally demonstrate coherent spectral broadening in silicon nitride waveguides using picosecond pulses.
• To explore the potential of optical wave breaking for generating octave-spanning spectra with longer pulses.
• To provide a new method for coherent spectral broadening using long-duration pulses, potentially replacing bulky optical components.

Main Methods:

• Utilizing silicon nitride (Si3N4) waveguides for spectral broadening.
• Employing picosecond (ps) pulses with a high repetition rate.
• Investigating optical wave breaking with higher energy pulses.

Main Results:

• Successfully achieved coherent spectral broadening using picosecond pulses in a Si3N4 waveguide.
• Demonstrated octave-spanning supercontinuum generation through optical wave breaking with higher energy picosecond pulses.
• Validated the feasibility of coherent broadening with long-duration pulses in Si3N4 waveguides.

Conclusions:

• The study presents a novel approach for coherent spectral broadening using picosecond pulses in silicon nitride waveguides.
• This method facilitates octave-spanning supercontinuum generation, offering a promising alternative to existing techniques.
• The findings open new avenues for compact and efficient optical systems in communications and spectroscopy.