Chalcogenide Glass Optical Waveguides for Infrared Biosensing

Abstract

Due to the remarkable properties of chalcogenide (Chg) glasses, Chg optical waveguides should play a significant role in the development of optical biosensors. This paper describes the fabrication and properties of chalcogenide fibres and planar waveguides. Using optical fibre transparent in the mid-infrared spectral range we have developed a biosensor that can collect information on whole metabolism alterations, rapidly and in situ. Thanks to this sensor it is possible to collect infrared spectra by remote spectroscopy, by simple contact with the sample. In this way, we tried to determine spectral modifications due, on the one hand, to cerebral metabolism alterations caused by a transient focal ischemia in the rat brain and, in the other hand, starvation in the mouse liver. We also applied a microdialysis method, a well known technique for in vivo brain metabolism studies, as reference. In the field of integrated microsensors, reactive ion etching was used to pattern rib waveguides between 2 and 300 μm wide. This technique was used to fabricate Y optical junctions for optical interconnections on chalcogenide amorphous films, which can potentially increase the sensitivity and stability of an optical micro-sensor. The first tests were also carried out to functionalise the Chg planar waveguides with the aim of using them as (bio)sensors.

RF sputtered amorphous chalcogenide thin films for surface enhanced infrared absorption spectroscopy

“…The main constituents of these vitreous materials are chalcogens elements (sulfur, selenium and tellurium); they are associated with other elements such as arsenic, germanium, gallium, or antimony for example. They can be drawn into optical fibers [11,12] or fabricated as thin films (waveguides) [13,14]. Other properties, specifically their extended optical transmission window from the visible to the far infrared (up to 20 µm), their high refractive index (usually between 2 and 3) or their nonlinear optical properties make them a class of optical materials with growing interest [15,16].…”

Short range order in Ge–As–Se glasses

“…Chalcogenide glasses have nonlinearity several orders of magnitude greater than silica glass, which makes them useful for all-optical processing of telecommunication signals at extreme speeds [3,4]. Chalcogenide glass optical fibers are employed in numerous devices, for example in IR optical fiber lasers and amplifiers [5,6], Raman lasers [7,8] or fiber-based chemical and biomedical sensor devices [9][10][11][12]. Several other applications were considered, such as medical endoscopy [13], environmental metrology [14] or spatial interferometry.…”

Te-As-Se glass destabilization using high energy milling

“…The optical fiber of chalcogenide glass can thus be used for the detection of chemical species in the liquid or gaseous state. Indeed, the use of this type of glass as a chemical sensor has already been demonstrated [3][4]. It is thus possible to produce biosensors from chalcogenide fibers such as Te 20 As 30 Se 50 (TAS) glass composition that enable faster and less invasive diagnostics for infectious diseases, chronic, and cancer [5].…”