Browsing by Author "Khaliq, Sarfraz"

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    Enhanced sensitivity fibre optic long period grating temperature sensor.
    (Iop Publishing Ltd, 2002-05-05T00:00:00Z) Khaliq, Sarfraz; James, Stephen W.; Tatam, Ralph P.
    Surrounding a long period grating, fabricated in a standard optical fibre, with a material with a high thermo-optic coefficient enhances the temperature sensitivity of a long period grating. Temperature sensitivities as high as 19nm/°C are reported over a temperature range of 1.1°. The temperatures at which the LPG exhibits enhanced sensitivity may be tailored by a suitable choice of material.
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    Fibre-optic long period gratings for sensing applications
    (Cranfield University, 2003-03) Khaliq, Sarfraz; James, Stephen W.; Tatam, Ralph P.
    Long period gratings (LPGs) are formed by inducing a permanent periodic modulation of the refractive index (RI) of the core of an optical fibre. The transmission spectrum of the LPG contains a series of attenuation bands centered at discrete wavelengths. The exact form of the transmission spectrum and the central wavelengths of the attenuation bands, are sensitive to the period and the length of the LPG and to the local environment. The sensitivity of a LPG to a particular measurand is dependant upon the composition of the fibre and upon the order of the cladding mode to which the guided mode is coupled to and is thus different for each attenuation band. Cont/d.