ABSTRACT
An ultrafast laser plasma doping (ULPD) technique is used for high concentration doping of erbium ions into silica-on-silicon substrate. The method uses a femtosecond laser to ablate material from TeO2-ZnO-Na2O-Er2O3 (Er-TZN) target glass. The laser-generated plasma modifies the silica network, producing a high-index-contrast optical layer suited to the production of on-chip integrated optical circuits. Cross-sectional analysis using scanning electron microscope with energy dispersive x-ray spectroscopy revealed homogeneous intermixing of the host silica with Er-TZN, which is unique to ULPD. The highly doped layer exhibits spectroscopic characteristics of erbium with photoluminescence lifetimes from 10.79 to 14.07 ms.
ABSTRACT
Chemical dissimilarity of tellurium oxide with silica glass increases phase separation and crystallization tendency when mixed and melted for making a glass. We report a novel technique for incorporating an Er(3+)-doped tellurite glass composition into silica substrates through a femtosecond (fs) laser generated plasma assisted process. The engineered material consequently exhibits the spectroscopic properties of Er(3+)-ions, which are unachievable in pure silica and implies this as an ideal material for integrated photonics platforms. Formation of a well-defined metastable and homogeneous glass structure with Er(3+)-ions in a silica network, modified with tellurite has been characterized using high-resolution cross-sectional transmission electron microscopy (HRTEM). The chemical and structural analyses using HRTEM, Rutherford backscattering spectrometry (RBS) and laser excitation techniques, confirm that such fs-laser plasma implanted glasses may be engineered for significantly higher concentration of Er(3+)-ions without clustering, validated by the record high lifetime-density product 0.96 × 10(19) s.cm(-3). Characterization of planar optical layers and photoluminescence emission spectra were undertaken to determine their thickness, refractive indices and photoluminescence properties, as a function of Er(3+) concentration via different target glasses. The increased Er(3+) content in the target glass enhance the refractive index and photoluminescence intensity of the modified silica layer whilst the lifetime and thickness decrease.
ABSTRACT
Capsule endoscopes are effective diagnostic tools for the gastro intestinal tract disorders at patient's comfort. However the present capsule endoscopes lack efficient localization techniques to specify a pathological area that may require further diagnosis or treatment. This paper presents the development of a tagging module based novel method for the real-time localization of the site of interest. The tagging module consists of a bio compatible micro tag, compressed spring with a string latch and thermal igniter. The module can be integrated with the capsule endoscope and activated using an external trigger signal. On activation, the micro tag releases instantly and penetrates the mucosa layer of GI tract, region of interest. X-ray imaging is used to detect the location of micro tag embedded in GI tract wall. The radiopaque micro tags provide pre-operative valuable position information of the infected area to facilitate further clinical procedures.
