Arrays of microstructured MIR fibers based on silver halides for medical applications

In this study, we developed and fabricate an array of microstructured MIR fibers of silver halide crystals. Firstly, the modal analysis of photonic crystal fiber arrays was carried out by means of program packages, which are based on offsurface integral- and differential-equation formulations, and the optimal parameters for medical thermography application were chosen. Then, the fibers were fabricated using extrusion technique and seven fiber segments were assembled. Each individual fiber has a matrix with the diameter of 525 μm, six hexagonally arranged inserts with lower refractive index than matrix’s one, and a central insert with a larger refractive index than matrix’s one. It was measured, that its cross-talk between adjacent fibers doesn’t exceed 5%. It was experimentally confirmed that the fiber structure allows transmitting infrared radiation with the wavelengths of 9.2-9.4 μm in a single-mode regime, yielding up to 100 μm in the mode field diameter for each individual fiber in the array. These wavelengths correspond to a temperature range of the human body, therefore the arrays may transmit thermal images of human tissues, including internal organs. We expect that such arrays can improve medical thermography techniques in the future.