Long period grating was UV inscribed into a multicore fiber consisting of 120 single mode cores. The multicore fiber that hosts the grating was fusion spliced into a single mode fiber at both ends. The splice creates a taper transition between the two types of fiber that produces a nonadiabatic mode evolution; this results in the illumination of all the modes in the multicore fiber. The spectral characteristics of this fiber device as a function of curvature were investigated. The device yielded a significant spectral sensitivity as high as 1.23  nm/m(-1) and 3.57  dB/m(-1) to the ultra-low curvature values from 0 to 1  m(-1). This fiber device can also distinguish the orientation of curvature experienced by the fiber as the long period grating attenuation bands producing either a blue or red wavelength shift. The finite element method (FEM) model was used to investigate the modal behavior in multicore fiber and to predict the phase-matching curves of the long period grating inscribed into multicore fiber.

Smart structure sensors based on embedded fibre Bragg grating (FBG) arrays in aluminium alloy matrix by ultrasonic consolidation (UC) technique have been proposed and demonstrated successfully. The temperature, loading and bending responses of the embedded FBG arrays have been systematically characterized. The embedded FBGs exhibit an average temperature sensitivity of ∼36 pm °C−1, which is three times higher than that of normal FBGs, a bending sensitivity of 0.73 nm/m−1 and a loading responsivity of ∼0.1 nm kg−1 within the dynamic range from 0 kg to 3 kg. These initial experimental results clearly demonstrate that the UC produced metal matrix structures can be embedded with FBG sensor arrays to become smart structures with capabilities to monitor the structure operation and health conditions in applications.

We have proposed and demonstrated a single-and dual-wavelength switchable Erbium doped fiber laser (EDFL) by utilizing intra-cavity polarization selective filters based on tilted fiber gratings (TFGs). In the cavity, one 45°-TFG is functioning as an in-fiber polarizer and the other 77°-TFG is used as a fiber polarization dependent loss (PDL) filter.The combined polarization effect from these two TFGs enables the laser to switch between the single-and dual-wavelength operation with single polarization state at room temperature. The laser output at each wavelength shows an optical signal to noise ratio (OSNR) of > 60dB and a side mode suppression ratio (SMSR) >50dB and a polarization extinction ratio of ~35dB. The proposed EDFL can give stable output under laboratory condition.2

The properties of etched large angle tilted gratings (81 o ) are investigated. The attenuation peaks of the modes are found to shift to shorter wavelengths at a rate of ~5nm/min in a solution of 10% HF acid. The most sensitive modes are examined for different etching times creating the relationship that longer etching times results in an increase in overall sensitivity. Comparing the sensitivity of the tilted fibre grating, etched for 6 hours, 506.9nm/unri and the most sensitive LPG, period 164µm, 389.2nm/unri in the RI range 1.30-1.40 shows that the produced tilted grating is more sensitive than the LPG and in this range would ideally be suited for the used in Bio-sensing applications.

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