Far-detuned mid-infrared frequency conversion via normal dispersion modulation instability in chalcogenide microwires

Area of Science:

• Nonlinear Optics
• Materials Science
• Photonics

Background:

• Modulation instability (MI) is a fundamental nonlinear optical phenomenon.
• Mid-infrared (mid-IR) light generation is crucial for spectroscopy and sensing.
• Hybrid polymer-chalcogenide microwires offer unique nonlinear properties.

Purpose of the Study:

• To experimentally demonstrate and investigate modulation instability in the mid-IR spectral region.
• To explore parametric frequency conversion in a hybrid polymer-chalcogenide microwire.
• To validate experimental findings with theoretical simulations.

Main Methods:

• Pumping a hybrid polymer-chalcogenide microwire with a femtosecond optical parametric oscillator at 2.6 μm.
• Analyzing spectral broadening and frequency conversion in the mid-IR.
• Employing stochastic nonlinear Schrödinger equation simulations.

Main Results:

• Observed modulation instability in the normal dispersion regime, driven by negative fourth-order dispersion.
• Achieved efficient, far-detuned parametric frequency conversion to 2 μm and 3.5 μm.
• Demonstrated MI and frequency conversion despite a strong absorption band near 2.8 μm.
• Experimental results showed excellent agreement with simulations.

Conclusions:

• Mid-IR modulation instability is achievable in hybrid polymer-chalcogenide microwires.
• This work highlights the potential of such materials for nonlinear frequency conversion in the mid-IR.
• The findings pave the way for novel mid-IR light sources and applications.