Attenuation, absorption, and scattering in silver halide crystals and fibers in the mid-infrared

Abstract

Absorption measurements on silver bromide crystals and fibers in the infrared J. Appl. Phys. 113, 043111 (2013); 10.1063/1.4789633 Mid-infrared (λ=8.4-9.9μm) light scattering from porcine tissue Appl. Phys. Lett. 101, 093705 (2012); 10.1063/1.4748331Hot free-electron absorption in nonparabolic III-V semiconductors at mid-infrared wavelengths Absorption spectrum of silver bromide crystals and fibers in the 9-11 μm wavelength rangeThe attenuation and the absorption of silver halide crystal and fibers in the mid-IR were measured. The absorption coefficients of silver halide crystals, deformed crystals, and fibers were measured by laser calorimetry at several different wavelengths in the near-IR and the mid-IR. The absorption coefficients of the fibers were higher than those of the deformed crystals and these were higher than those of the un-deformed crystals. We suggest that the absorption behavior is best described by a weak absorption tail. The total attenuation in fibers was measured using the cut back method.The scattering values were calculated by subtracting the absorption coefficients from the total attenuation coefficients. The scattering in the silver halide fibers was ascribed to pores of estimated size of 0.7 lm. We showed that the main contribution to the attenuation of fibers in the mid-IR range was due to scattering and suggested that reducing the scattering will dramatically improve the transmission of silver halide fibers in the mid-IR. V C 2014 AIP Publishing LLC.

Review of diverse optical fibers used in biomedical research and clinical practice

“…[79][80][81] These fibers can be classified into single-crystal and polycrystalline fiber types. Although there are many varieties of halide crystals with excellent IR transmission features, only a few have been fabricated into optical fibers because most of the materials do not meet the required physical property specifications needed to make a durable fiber.…”

“…Polycrystalline silver-halide fibers with AgBr cores and AgCl claddings have exhibited excellent crystalline IR fiber properties. [78][79][80][81] There are several extrinsic absorption bands for Ag-halide fibers, for example, 3 and 6.3 μm due to residual water ions. The attenuation of Ag-halide fibers is normally <1 dB∕m in the 5-to 12-μm spectral band and 0.3 to 0.5 dB∕m at 10.6 μm and can be as low as 0.2 dB∕m at this wavelength.…”

“…[72][73][74][75][76][77][78][79][80][81] Compared to conventional telecom silica fibers, IR fibers usually are more fragile and have larger refractive indices, lower melting or softening points, and greater thermal expansion. Typically, in biomedical photonics, IR fibers are used in lengths <2 to 3 m for fiber optic sensors and optical power delivery applications.…”

Fabrication of Shatter-Proof Metal Hollow-Core Optical Fibers for Endoscopic Mid-Infrared Laser Applications

“…Common silica-glass fibers cannot transmit mid-infrared light with wavelengths longer than 2 µm because of absorption in the silica-glass material [1], so many types of infrared optical fibers have been developed, such as chalcogenide-glass fibers [2,3], metal-halide polycrystalline fibers [4,5], and hollow-core optical fibers [6,7]. Hollow-core optical fibers that confine light in an air core have some advantages over solid-core fibers for high-power laser delivery.…”