MOCVD deposition of zinc and bismuth chalcogenides films on the surface of silica optical fibres

Metal organic chemical vapour deposition (MOCVD) technology is adapted for the deposition of thin zinc and bismuth chalcogenides films on the surface of silica optical fibres with short tapered sections. Growth runs were carried out in a special tubular quartz reactor at atmospheric pressure of hydrogen at 425°C temperature using ZnEt2, BiMe3, Et2Te and i-Pro2Se as organometallic precursors. During the deposition of chalcogenides, the transmittance spectra of the fibre were recorded in regular short time intervals. In the transmittance spectra of the fibre with a tapered section coated by ZnSe and ZnTe, lossy mode resonances (LMR) were observed at a diameter of the tapered waist below 30 μm. After the deposition of very thin Bi2Te3 and Bi2Se3 island films on the tapered waist with a diameter about 10 μm optical fibres were built into erbium fibre ring lasers. A pulsed generation mode was achieved in some of lasers due to resonator Q-factor modulation. These results can be applied for the design of LMR fibre sensors and passively Q-switch pulsed fibre lasers.

Analysis of the efficacy of ozone therapy on different types of lumbar disc herniation: a new guidance is coming? [abstract]

PURPOSE: To investigate the sub-types of lumbar disc herniation, compare efficacies of ozone treatment in various types of lumbar disc herniation and analyze the mechanisms. MATERIAL AND METHODS: A total of 250 patients (159 males, 91 females; age range: 14 - 85 years) diagnosed of lumbar disc herniation from January 2009 to Jun 2014 in Nanfang Hospital were enrolled. Disc Lesions, classified by Magnetic Resonance examinations and images when injecting ozone under Digital Subtraction Angiography, were divided into four types: type I: Non-prominent nucleus pulposus with ruptured fibre ring; type II: Prominent nucleus pulposus with ruptured fibre ring; type III: Non-prominent nucleus pulposus with Non-ruptured fibre ring; type IV: Prominent nucleus pulposus with Non-ruptured fibre ring. All patients underwent intradiscal and paravertebral injection of oxygen-ozone. Visual Analogue Scale (VAS) weighted score was administered for the measurement of low back pain before treatment, and the evaluation of efficacy respectively at 1 week, 1 month, 6 month and 12 month follow-up period. RESULTS: Most of the patients (about 4/5) showed better response to ozone treatment. Herniated disc shrinkage was obtained among type II and IV. The type II had the most reduction of average score while the type III had the least. The proportion of patients who had once experienced pain relief at the follow up interval, namely the curative efficacy, showed significant difference: type I occupied the most, type IV occupied the least. CONCLUSION: Ozone treatment is effective and safe for all types of lumbar disc herniation, but efficacy varies according the types, of which type I has the best results and type IV has the worst ones.

Methane Gas Photonic Sensor Based on Resonant Coupled Cavities

In this paper we report methane gas photonic sensors exploiting the principle of absorption-induced redirection of light propagation in coupled resonant cavities. In particular, an example of implemented architecture consists of a Fabry–Pérot (FP) resonator coupled to a fibre ring resonator, operating in the near IR. By changing the concentration of the methane gas in the FP region, the absorption coefficient of the FP changes. In turn, the variation of the methane gas concentration allows the redirection of the light propagation in the fibre ring resonator. Then, the methane gas concentration can be evaluated by analysing the ratio between the powers of two resonant modes, counter-propagating in the fibre ring resonator. In this way, a self-referenced read-out scheme, immune to the power fluctuations of the source, has been conceived. Moreover, a sensitivity of 0.37 ± 0.04 [dB/%], defined as the ratio between resonant modes at different outputs, in a range of methane concentration included between the 0% and 5%, has been achieved. These results allow a detection limit below the lower explosive limit (LEL) to be reached with a cost-effective sensor system.