Rare earth doped oxyfluoride glass-ceramics (GCs) have recently attracted much attention as a novel material candidate for solid state laser cooling application. In this study, highly transparent (~ 90 % in the infrared region) ytterbium doped aluminosilicate oxyfluoride glasses and glass ceramics containing YF3 nanocrystals prepared by the conventional melt quenching process have been investigated to determine and compare their potential to obtain high photoluminescence quantum yield (PLQY). The highest ASF emission intensity was observed in the GC composition with near-infrared PL emission centered at ~1010 nm under a laser excitation at 1020 nm. The PL spectra at different temperatures (25 °C – 200 °C) were measured using different excitation wavelengths varying from 920 nm to 1030 nm in order to understand the nature of Stokes and anti-Stokes emission in glass ceramics. The glass-ceramic has a net heating near to zero with an excitation between 1020 nm and 1030 nm showing its potential for optically induced heat-management applications. The optical properties such as refractive index, quantum efficiency and lifetime of GC and the precursor glass were also studied in detail in order to explore these properties for laser cooling applications.
This presentation explores the possibility of an using extrusion process in order to manufacture a new type of optical fiber based biomedical sensors. With the extrusion method, any number of fibers can be integrated in the sensor to fulfill different requirements. The extrusion process is known for its reliability and enables the manufacture of any length of sensor without reproducibility issues. The emphasis is placed on shape sensing of needles and catheters for minimally invasive surgery. Shape sensing is performed using the enhanced backscatter signal of our ROGUEs (random optical fiber gratings written by UV or ultrafast laser exposure).
This article proposes a process to manufacture optical fiber shape sensors for biomedical applications. By using polymer extrusion on three optical fibers, a triplet with a diameter below 600 μm is obtained which can be inserted into surgical needles or catheters. Furthermore, the fiber triplet position within the coating and the angle of the triplet are parameters that need to be controlled, to enable the best performance. The radial and angular positions of the optical fibers in the triplet are measured with an accuracy of 3μm and 4 degrees, respectively. The sensor incorporating our recently developed ROGUEs (random optical fiber gratings written by UV or ultrafast laser exposure) backscatter enhanced fibers, is then used for shape sensing demonstration with an OFDR technique.