Abstract: An optical fibre arrangement has at least two optical fibre sections, each optical fibre section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fibre arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fibre. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fibre and a first multiplexer connected to the input fibre. Each amplifier is configured such that at least one of the amplifying optical fibres is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: A method and apparatus for writing an apodised grating of improved quality into a photosensitive material using an interference pattern of fringe period gr. An unapodised part of the grating is written by exposing the photosensitive material with a succession of exposures separated from each other by an odd number of fringe periods and an apodised part of the grating is written by exposing the photosensitive material with a first set of N exposures, where N is an even number, separated from each other by an odd number of fringe periods, the first set of N exposures having a positive phase offset +&phgr; relative to the unapodised part of the grating and exposing the photosensitive material with a second set of N exposures separated from each other by an odd number of fringe periods, the second set of N exposures having a negative phase offset −&phgr; relative to the unapodised part of the grating.

Abstract: An interferometer comprising a beam source (PM, M1, L1) of first and second light beams. The interferometer has a first arm that routes the first light beam via a first pair of mirrors (M4, M5) arranged at right angles to each other in the manner of a corner cube to reverse the direction of the first light beam and a second arm that routes the second light beam via a second pair of mirrors (M2, M3). The beam source (PM, M1, L1) and the second mirror pair (M2, M3) are mounted on a linear translation stage (P1). The first and second light beams are incident on a focusing element (L2) symmetrically about and parallel to its optical axis and then converge at an angle (&phgr;) to form an interference pattern. The symmetric, balanced configuration of the interferometer is retained under motion of the positioning element, which varies the separation (d) of the first and second light beams on the focusing element.

Abstract: An apparatus for demultiplexing a wavelength division multiplexed optical signal includes a plurality of wavelength channels each having a different signal wavelength. The apparatus includes a signal port and a plurality of grating modules. Each grating module has a coupler and a fiber Bragg grating which has a unique wavelength. The grating modules each have an input port, an optical tap, and an output port. The grating modules are configured in a row having a first end and a second end. This is accomplished by connecting the output port of each grating module to the input port of another grating module. The first end of the row of grating modules is connected to the signal port. The Bragg gratings reflect different signal wavelengths.

Abstract: An optical waveguide grating if formed in a waveguide of nominally uniform diameter. A grating characteristic is varied at positions along the grating in a substantially inverse relationship to the diameter of the waveguide at those positions.

Abstract: Methods and apparatus for creating a Bragg grating in an optical waveguide having an optical fiber on which the Bragg grating is defined, the Bragg grating having an actual response which closely approximates a desired response. The Bragg grating comprises a plurality of lines, each line being defined by a respective strength, and each line having a relative displacement from adjacent lines. The Bragg grating is designed using a serial iterative response. The serial iterative process can be used to calculate the strength and the line spacing of at least some of the lines. The serial iterative process can further be a function of a coupling function, which is a function of the strength and line spacing of the lines of the grating. A moving window can be used to limit the number of reflections in the impulse response which is used to calculate the next serial line spacing.

Abstract: A method of fabricating a chirped optical fibre grating so that the grating has a predetermined desired wavelength-dependent response across an operational bandwidth comprises apodising the grating so that a degree of apodisation at a longitudinal position along the grating corresponds to the desired response at the optical wavelength reflected at that longitudinal position along the grating.