This paper proposes a novel fibre structure aiming at distributed temperature and strain sensing. Utilizing Al2O3 and CeO2 as dopants to form a w-shaped acoustic waveguide, it realizes modal coupling between longitudinal acoustic modes of its inner and outer core layers, leading to a dual-peak or multi-peak Brillouin gain spectrum. The relationship between the acoustic mode coupling properties and the fibre materials, doping concentrations and structural parameters are investigated, showing that the positions of mode coupling points in acoustic dispersion curves and the coupling intensities can be designed flexibly. A specific fibre design for the discriminative sensing of temperature and strain under a pump wavelength of 1.55 μm is given. The responses of its Brillouin gain properties on temperature and strain are analysed theoretically, demonstrating its potential for distributed fibre Brillouin sensing.
Pure zinc blende structure GaAs/AlGaAs axial heterostructure nanowires （NWs） are grown by metal organic chemical vapor deposition on GaAs（111） B substrates using Au-catalyzed vapor-liquid-solid mechanism. Al adatom enhances the influence of diameters on NWs growth rate. NWs are grown mainly through the contributions from the direct impingement of the precursors onto the alloy droplets and not so much from adatom diffusion. The results indicate that the droplet acts as a catalyst rather than an adatom collector.
We demonstrate an InP/InGaAs PIN photodetector with enhanced quantum efficiency by assembling silicon resonant waveguide gratings for the application of polarization sensitive systems. The measured results show that quantum efficiency of the photodetector with silicon resonant waveguide gratings can be increased by 31.6% compared with that without silicon resonant waveguide gratings at the wavelength range of 1500 to 1600 nm for TE-polarization.
The GaSb-based laser shows its superiority in the 3-4 ~tm wavelength range. However, for a quantum well （QW） laser structure of InGaAsSb/AIGaInAsSb multiple-quantum well （MQW） grown on GaSb, uniform content and high com- pressive strain in InGaAsSb/A1GaInAsSb are not easy to control. In this paper, the influences of the growth tempera- ture and compressive strain on the photoluminescence （PL） property of a 3.0μm lnGaAsSb/A1GaInAsSb MQW sample are analyzed to optimize the growth parameters. Comparisons among the PL spectra of the samples indicate that the Ino.485GaAso.184Sb/Alo.3Gao.45Ino.25Aso.22Sbo.78 MQW with 1.72% compressive strain grown at 460 ~C posseses the op- timum optical property. Moreover, the wavelength range of the MQW structure is extended to 3.83 μm by optimizing the parameters.
