Abstract: A method of free space fibre-to-fibre coupling includes providing a first optical fibre and a second optical fibre spaced apart from one another by a free space distance having a pair of spaced-apart achromatic collimating lenses within the free space distance. Essentially single mode light is launched from the first fibre at a wavelength ? or a range of ?s that provides at least a portion of its light at wavelength(s) below a cut-off wavelength for the first fibre. The first optical fibre and second optical fibre are both <50 m and sufficiently short to provide essentially single mode operation. The essentially single mode light after the launching propagates as free space light through said free space distance and is received by and propagates in the second optical fibre as essentially single mode light.

Abstract: A method of free space fiber-to-fiber coupling includes providing a first optical fiber and a second optical fiber spaced apart from one another by a free space distance having a pair of spaced-apart achromatic collimating lenses within the free space distance. Essentially single mode light is launched from the first fiber at a wavelength ? or a range of ?s that provides at least a portion of its light at wavelength(s) below a cut-off wavelength for the first fiber. The first optical fiber and second optical fiber are both <50 m and sufficiently short to provide essentially single mode operation. The essentially single mode light after the launching propagates as free space light through said free space distance and is received by and propagates in the second optical fiber as essentially single mode light.

Abstract: In an optical waveguide fabricated to provide spectral filtering by a periodic mode coupling between the core and cladding the spectral profile may be shifted in wavelength if the core or cladding is photosensitive. This is especially useful in the case of long period gratings used as gain flattening filters, as a relatively low dose of radiation, compared with that typically required to fabricate a Reflection Bragg Grating in the same fiber, provides a sufficient shift for filter tuning purposes. Subsequent thermal exposure can stabilize the filter performance over the expected temperature range, while exposure to higher temperature reverses the radiation induced shift.

Abstract: In an optical waveguide fabricated to provide spectral filtering by a periodic mode coupling between the core and cladding the spectral profile may be shifted in wavelength if the core or cladding is photosensitive. This is especially useful in the case of long period gratings used as gain flattening filters, as a relatively low dose of radiation, compared with that typically required to fabricate a Reflection Bragg Grating in the same fiber, provides a sufficient shift for filter tuning purposes. Subsequent thermal exposure can stabilize the filter performance over the expected temperature range, while exposure to higher temperature reverses the radiation induced shift.

Abstract: A blast cabinet (10) for ice blasting an article, the cabinet comprising a housing (11) having an interior support (19) for supporting the article. At least one ice blast nozzle (80) is disposed inside the housing and operable to direct a high speed stream of ice particles towards the article. In an embodiment the ice blast nozzle(s) is mounted on a articulated mount (82) wherein the nozzle can be articulated. An energy management system (30, 130) comprising a heating system is provided to facilitate the removal of spent ice particles, and prevent ice accumulation in the enclosure. In an embodiment of the blast cabinet, the energy management system (130) includes a piping assembly (36) a heat exchanger (37) both disposed in the housing.