Extreme polarization-dependent supercontinuum generation in an uncladded silicon nitride waveguide

Area of Science:

• Photonics and Waveguide Optics
• Nonlinear Optics
• Materials Science

Background:

• Supercontinuum generation is crucial for various photonic applications.
• Silicon nitride (Si3N4) waveguides offer unique nonlinear properties.
• Controlling supercontinuum properties via dispersion engineering is an active research area.

Purpose of the Study:

• To experimentally demonstrate a polarization-sensitive supercontinuum source in an air-clad silicon nitride waveguide.
• To achieve tunable supercontinuum generation by manipulating dispersion properties.
• To explore applications in sensing, pulse compression, and few-cycle pulse generation.

Main Methods:

• Fabrication of an uncladded silicon nitride waveguide.
• Pumping the waveguide at a 2.1 µm wavelength.
• Utilizing dispersion engineering to achieve different dispersion regimes for TE and TM modes.
• Adjusting the input polarization state to switch between supercontinuum generation mechanisms.

Main Results:

• Generation of a short-wave infrared supercontinuum with extreme polarization sensitivity.
• Demonstration of switching between soliton fission-driven (anomalous dispersion) and self-phase modulation-driven (all-normal dispersion) supercontinuum generation.
• Observation of an octave-spanning supercontinuum with fine spectral structure and a flat, smooth supercontinuum.
• Experimental results show excellent agreement with numerical simulations.

Conclusions:

• The developed silicon nitride waveguide platform enables polarization-sensitive supercontinuum generation.
• Tunable supercontinuum generation is achieved by exploiting engineered dispersion differences between polarization modes.
• This polarization-sensitive source offers a versatile platform for advanced photonic applications.