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One- and two-order cascaded Raman fibre lasers are demonstrated by using home-made P-doped Raman fibres. An output power of 2.8 W at 1245 nm with a slope efficiency of 33.4% and an output power of 2.0 W at 1495 nm with a slope efficiency of 23.5% are obtained with the pump source at 1069.7 nm.

We present a systematic experimental investigation on visible light collimation by a nanostructured slit flanked with a pair of periodic array of grooves in gold thin film. A wide variety of aspects are considered, such as the polarization state, the transport path of incident light, the groove—groove spacing, the groove width and depth. Our results clearly show that the relationship between the collimation wavelength and the periodicity of the slit-groove structure accords well with the surface plasmon dispersion model proposed by previous researchers. Furthermore, the surface plasmon wave phase retardation effect induced by the surface structure is also verified via the measurement for samples with different groove widths and depths. These results indicate that the detailed geometry of the groove structure has obvious impacts on the collimation effect and the angular distribution of the diffraction light in the subwavelength plasmonic system.

A novel fiber Bragg grating thermal tuning scheme is proposed, theoretically analyzed and experimentally studied. The device made from this scheme is named doubleshoulder beam (DSB). Experimental results demonstrate that DSB is an effective thermal tuning technique. A thermal sensitivity of 0436?nm/℃, 50 times that of the bare fiber grating, is experimentally achieved. To our knowledge, this is the largest thermal sensitivity ever demonstrated. The repeatability and lin earity of the technique is very well. The most important advantage of DSB, as a breakthrough to conventional thermal tuning technique, is its great flexibility. It makes the thermaltuning efficiency of fiber grating no longer limited by the thermalexpansion coefficient of the drive materials, but can be designed according to practical requirements. This technique is expected to have a vast application in fields such as laser tuning, high sensitivity temperature sensing, sensor demultiplexing and so forth.