Towards mid-infrared supercontinuum generation: Ge-Sb-Se mid-infrared step-index small-core optical fiber

Abstract

In the 21 st century, cancer has become a common and feared illness. Early detection is crucial for delivering the most effective treatment of patients, yet current diagnostic tests depend upon the skill of a consultant clinician and histologist for recognition of the cancerous cells. Therefore it is necessary to develop a medical diagnostic system which can analyze and image tissue instantly, removing the margin of human error and with the additional benefit of being minimally invasive. The molecular fingerprint of biological tissue lies within the mid-infrared (IR) region of the electromagnetic spectrum, 3-25µm wavelength. This can be used to determine a tissue spectral map and provide information about the absence or existence of disease, potentially in real-time and in vivo. However, current mid-IR broadband sources are not bright enough to achieve this. One alternative is to develop broadband, mid-IR, supercontinuum generation (SCG). Chalcogenide glass optical fibers have the potential to provide such mid-IR SC light. A popular chalcogenide glass fiber type is based on Ge-As-Se. For biomedical applications it is prudent to avoid the use of arsenic, on account of its toxicity. This paper investigates replacing arsenic with antimony, towards Ge-Sb-Se smallcore optical fibers for SCG. Physical properties of candidate glass pairs are investigated for glass stability via differential thermal analysis etc. and fiber optical loss measurements of associated fibers are assessed. These results are compared to analogous arsenic-containing chalcogenide glasses and optical fibers, and conclusions are drawn focusing on whether there is potential for antimony chalcogenide glass to be used for SCG for mid-infrared medical diagnostics.

Chemical Short-Range Order in Selenide and Telluride Glasses

“…Among the commercially available infrared optical materials, several Ge–As–Se glasses, such as GASIR (Ge 22 As 20 Se 58 ) or AMTIR-1 (Ge 33 As 12 Se 55 ), are used. Because of the toxicity of arsenic, the use of antimony is beneficial, for example, in biomedical applications . Furthermore, the substitution of As with Sb, which has a higher polarizability, may increase the linear and nonlinear indices. − The presence of Sb reduces the photosensitivity of the material, producing a more stable and stronger network structure. , …”

Numerical investigation on W-type index chalcogenide fiber based MIR supercontinuum generation

“…Here i, j, and k are cyclical, and therefore we can write the longitudinal component as We choose the testing function T t and T z corresponding to the vectorial and nodal shape functions, respectively (T t =W tm and T z =α i ), we substitute Eq. (15) Solving the previous equations yields the propagation constants  or the eigenvalues. The effective refractive index neff is obtained by using the relation 14 :…”

“…The chromatic dispersion   D  is calculated from the effective index neff values versus the wavelength λ by the following expression 15 .…”

Numerical simulation of the Ge28Sb12Se60 fiber extrusion process

“…Extrusion could be used for both perform and fiber fabrication. 8,9 However, additional glass treatment at temperatures close to the glass transition temperature T g can lead to such problems as phase transformations, the appearance of mechanical stresses in the volume of the material, 10 a change in the refractive index of the glass. 11 The temperature profile of the heating element and the speed of the extruded fiber in the temperature field made by the heater largely determine the optical and mechanical properties of the resulting optical fiber.…”