Single mode mid-infrared silver halide asymmetric flat waveguide obtained from crystal extrusion

Area of Science:

• Optics and Photonics
• Materials Science
• Infrared Technology

Background:

• Mid-infrared (mid-IR) optics require specialized components for efficient light manipulation.
• Waveguides are crucial for directing and controlling light in optical systems.
• Silver halide (AgX) materials offer unique transmission properties in the mid-IR spectrum.

Purpose of the Study:

• To fabricate and characterize a novel flat waveguide for the middle infrared spectrum.
• To investigate the modal behavior and cut-off wavelength of the fabricated waveguide.
• To assess the potential applications of the waveguide in astronomical interferometry.

Main Methods:

• Co-extrusion of two silver halide crystals with different chemical compositions to form a flat waveguide.
• Transmission spectrum analysis using a Fourier Transform Spectrometer.
• Modal behavior characterization using a dedicated optical bench and spectral analysis.

Main Results:

• Successful fabrication of a mid-IR flat waveguide via co-extrusion.
• Determination of the waveguide's cut-off wavelength through spectral analysis.
• Observation of single-mode behavior for wavelengths longer than 8.83 micrometers, consistent with theoretical predictions.

Conclusions:

• The co-extrusion technique enables tailoring of waveguide properties for specific mid-IR applications.
• The demonstrated single-mode behavior makes the waveguide suitable for modal filtering in astronomical interferometers.
• This technology can advance the development of components like beam combiners and nullers for mid-IR astronomy.