Mid-infrared difference-frequency generation directly pumped by a fiber four-wave mixing source

Area of Science:

• Optics and Photonics
• Nonlinear Optics
• Laser Physics

Background:

• Generating mid-infrared (mid-IR) pulses is crucial for various spectroscopic and sensing applications.
• Existing methods for mid-IR generation can be complex or inefficient.
• Four-wave mixing (FWM) in photonic crystal fibers (PCFs) offers a promising route for generating specific wavelengths.

Purpose of the Study:

• To demonstrate a new, simplified method for generating mid-infrared pulses.
• To utilize the inherent temporal and spatial overlap of FWM-generated Stokes pulses with the pump pulse in PCFs.
• To achieve efficient difference frequency generation (DFG) in the mid-IR region.

Main Methods:

• Utilizing four-wave mixing (FWM) in a specially engineered photonic crystal fiber (PCF) to generate Stokes pulses.
• Combining the generated Stokes pulses with the residual pump pulse at the PCF output.
• Focusing the combined pulses into a nonlinear crystal phase-matched for difference frequency generation (DFG).

Main Results:

• Successfully generated mid-infrared pulses via DFG.
• Achieved 160 mW of mid-infrared light output at approximately 3 µm.
• Employed a 1.064 µm pump source and a PCF producing Stokes pulses around 1.65 µm.

Conclusions:

• The demonstrated method provides a simple and efficient way to generate mid-infrared pulses.
• The inherent pulse overlap from FWM in PCFs simplifies the DFG process.
• This technique has potential for applications requiring tunable mid-IR sources.