Mid-infrared generation via Raman soliton self-frequency shift in fluoride fibers: a comparative study

Area of Science:

• Nonlinear Optics
• Laser Physics
• Materials Science

Background:

• Mid-infrared (mid-IR) light generation is crucial for various applications.
• Raman soliton self-frequency shift (SSFS) is a promising nonlinear optical process for frequency conversion.
• Fluoride fibers offer unique properties for mid-IR applications.

Purpose of the Study:

• To achieve mid-infrared generation up to 4 µm via SSFS.
• To comparatively study different fluoride fibers for optimal performance.
• To identify key fiber parameters influencing spectral broadening and frequency conversion.

Main Methods:

• Utilizing a mode-locked Cr:ZnS laser emitting at 2.3 µm as the pump source.
• Performing SSFS experiments in six different commercially available ZBLAN and InF3 fluoride fibers.
• Conducting a comparative analysis of fiber properties and spectral broadening.
• Investigating the relative intensity noise of the generated mid-IR radiation.
• Employing numerical modeling to determine limitations for further spectral extension.

Main Results:

• Generation of mid-IR radiation up to 4 µm was successfully achieved.
• The broadest spectral coverage of SSFS using Cr:ZnS/Se lasers to date was demonstrated.
• Key fiber parameters responsible for spectral broadening were identified.
• The relative intensity noise was measured to be 0.2%, indicating high source stability.
• Limitations for extending mid-IR generation beyond 4 µm were determined through modeling.

Conclusions:

• The study provides practical guidance for SSFS-based mid-IR generation using Cr:ZnS/Se lasers.
• Optimal fluoride fiber selection and parameters are crucial for efficient frequency conversion.
• The demonstrated technology offers a stable and broad spectral coverage for mid-IR applications.