Infrared heterodyning using silver halide fibers

Infrared transmitting silver halide fibers 0.3 - 1 mm diameter were fabricated by extrusion, and were found to have losses of about 6 dB/m, at λ = 10.6 µm. Infrared heterodyne experiments have been carried out using these fibers. Two stabilized CO2 lasers, of frequencies ω₁ and ω₂, were used. The two laser beams were coupled into a single infrared fiber, using a Y coupler, with no other optics. Both beams were transmitted through this fiber to a fast IR detector. A heterodyne signal at a beat frequency ω₁ - ω₂ was obtained from the detector.