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An all-fiber sensor capable of simultaneous measurement of temperature and strain is newly presented. The sensing head is formed by a fiber Bragg grating combined with a section of multimode fiber that acts as a Mach-Zehnder interferometer for temperature and strain discrimination. The strain and temperature coefficients of multimode fibers vary with the core sizes and materials. This feature can be used to improve the strain and temperature resolution by suitably choosing the multimode fiber. For a 10 pm wavelength resolution, a resolution of 9:21 με in strain and 0:26°C in temperature can be achieved.

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The numerical modeling of field-assisted ion exchange in glass through a finite aperture is carried out. The effects of unequal ion mobilities and thermal diffusion are included we believe for the first time in the 2-D case. This allows for the modeling of optical channel waveguides with graded index profiles. It is demonstrated that annealing of backdiffused channel guides is far superior to backdiffusion alone in improving their circular symmetry for better coupling to optical fibers.

A novel lateral force sensor based on a core-offset multi-mode fiber (MMF) interferometer is reported. High extinction ratio can be obtained by misaligning a fused cross section between the single-mode fiber (SMF) and MMF. With the variation of the lateral force applied to a short section of the MMF, the extinction ratio changes while the interference phase remains almost constant. The change of the extinction ratio is independent of temperature variations. The proposed force sensor has the advantages of temperature-and phase-independency, high extinction ratio sensitivity, good repeatability, low cost, and simple structure. Moreover, the core-offset MMF interferometer is expected to have applications in fiber filters and tunable phase-independent attenuators.