University of Southampton

Spi Lasers UK Limited

Pirelli Cavi E Sistemi S.p.a.

Morten Ibsen

Michael Nickolaos Zervas

Lars Johan Albinsson Nilsson

Michael Kevan Durkin

Anatoly Borisovich Grudinin

Paul William Turner

Dave Neil Payne

Richard Ian Laming

David John Richardson

Andrew Malinowski

Laurent LeFort

Jonathan Hugh Vaughan Price

Shinji Yamashita

David Neil Payne

Sze Yun Set

Peh Chiong Teh

Ju Han Lee

Periklis Petropoulos

Peh Choing Teh

Erland Ronnekleiv

Periklis Petropoulis

An optical amplifier includes at least one pump source and an optical fiber cable which includes an amplifying optical fiber and a pump optical fiber that are defined by respective lengths. The amplifying optical fiber and the pump optical fiber are coated with a common coating along a portion of their respective lengths, and the fibers are in optical contact with each other along a coating length within the common coating. The common coating has a refractive index which is lower than a refractive index of a cladding material of the pump optical fiber. The fibers are made substantially from glass. The amplifying optical fiber includes a core and a cladding, and is doped with a rare earth dopant. The pump optical fiber is defined by a first end and a second end, the first end of the pump optical fiber being connected to the pump source.

Multi-fibre arrangement for high power fibre lasers and amplifiers

An optical fiber arrangement has at least two optical fiber sections, each optical fiber 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 fiber arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fiber. 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 fiber and a first multiplexer connected to the input fiber. Each amplifier is configured such that at least one of the amplifying optical fibers is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

A source of pulses of coherent radiation at a wavelength of approximately 1 &#x3bc;m, comprises a pump source for producing pump light; a laser cavity comprising an Yb-doped gain medium arranged to receive the pump light, the laser cavity being modelocked to generate laser pulses at a defined repetition rate; a pulse detector arranged to generate a pulse selection signal indicative of the repetition rate; a pulse selector arranged to reduce the repetition rate of the laser pulses responsive to the pulse selection signal from the pulse detector by passing only selected ones of the laser pulses; and at least one optical amplifier for amplifying the laser pulses of reduced repetition rate. The at least one optical amplifier can be configured for chirped or parabolic pulse amplification.

Pulsed light sources

Apparatus for providing timing jitter tolerant optical modulation of a first signal by a second signal, the first signal having a first wavelength, the second signal including a plurality of second signal pulses having a second pulse shape and a second wavelength. The apparatus includes a first signal input port, a second signal input port, a coupler, a grating and a non-linear optical device. The apparatus is configured to direct the second signal at the second signal input port to the non-linear optical device via the coupler and the grating, and to direct the first signal at the first signal input port to the non-linear optical device. The grating is a superstructured fibre Bragg grating that converts the second signal pulses into intermediary pulses each having an intermediary pulse shape. The intermediary pulse shape is such that it provides a switching window within the non-linear optical device.

Apparatus for providing timing jitter tolerant optical modulation of a first signal by a second signal

A method of fabricating a distributed feedback optical fiber laser, comprises the step of exposing an optical fiber () to a transverse light beam () to form a grating structure in a section of the optical fiber, the writing light beam being polarized in a direction not parallel to the axis of the section () of optical fiber ().

Optical fiber laser

A WDM transmitter comprising an array of M pump lasers multiplexed by an M&#xd7;N multiplexer, in the form of a coupler, and used to feed an array of N optically pumped fiber lasers emitting at wavelengths &#x3bb;, &#x3bb;, . . . &#x3bb;. The parameter M determines the number of pump lasers as well as the number of inputs of the pump-multiplexing coupler and can be smaller or equal to parameter N that determines the number of optically pumped lasers. The fiber laser outputs are passed through N isolators before entering N modulators were the signals are monolithically modulated. The outputs of the modulators are passed through an array of N tunable attenuators. Finally all the individual channel outputs are recombined into a single output in a combiner. The output will typically lead to an optical network. The proposed architecture may also be used for optical amplifiers, especially fiber-based optical amplifiers.

WDM transmitter

A source of pulses of coherent radiation at a wavelength of approximately 1 &#x3bc;m, comprises a pump source for producing pump light, a laser cavity comprising an Yb-doped gain medium arranged to receive the pump light, the laser cavity being modelocked to generate laser pulses at a defined repetition rate; a pulse detector arranged to generate a pulse selection signal indicative of the repetition rate; a pulse selector arranged to reduce the repetition rate of the laser pulses responsive to the pulse selection signal from the pulse detector by passing only selected ones of the laser pulses; and at least one optical amplifier for amplifying the laser pulses of reduced repetition rate. The at least one optical amplifier can be configured for chirped or parabolic pulse amplification.

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.

Multi-fibre arrangements for high power fibre lasers and amplifiers

Optical code division multiple access (OCDMA) coder:decoder gratings have been fabricated. The modulated refractive index profile that makes up the OCDMA coder:decoder grating incorporates changes in polarity between OCDMA chips by discrete phase shifts, thereby to provide bipolar coding through phase modulation. (In another embodiment quadrupolar coding is achieved). For NRZ modulation, each grating section is either in phase with, or has a predetermined phase shift relative to, the preceding grating section, depending on whether the OCDMA signature has a change in polarity between chips. RZ modulation is also possible. Results are presented from specific examples of bipolar OCDMA with NRZ modulation, which show higher data rates (10 Gbit/s), shorter chip-lengths (6.4 ps) and far longer code sequences (63 bits) than previously demonstrated. Other embodiments relate to optical packet switching, for example using the Internet Protocol (IP) or Asynchronous Transfer Mode (ATM).

Optical code generation and detection

An optical grating fabrication apparatus having a phase mask for dividing an incident light beam into a plurality of diffracted beams and a focusing arrangement for receiving light from the phase mask and converging at least two non-zero-order diffracted beams together so as to generate an interference region of a characteristic period between the converged beams so that a grating structure can be impressed on an optical waveguide placed in the interference region. Further, a translation stage is arranged to move the phase mask and at least a part of the focusing arrangement with respect to one another under control of a control circuit so as to alter the angle of convergence of the converged beams and thus controllably tune the characteristic period.

Fabrication of optical waveguide gratings

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.

Fabricating optical waveguide gratings and/or characterising optical waveguides

An optical fiber, a section of length (L,) which is modulated in refractive index so as to form a grating with a plurality of characteristics reflection wavelength channels, has a refractive index modulation comprising an amplitude modulation having an underlaying higher frequency component defining the shape of the reflection profile of each of the wavelength channels and, superposed thereon, a lower frequency component of period P imposing repeated envelopes over the higher frequency component and defining the separation of the wavelength channels. In one embodiment, the lower frequency component has the shape of a sinc-function with varying refractive index (&dgr;n) and with discrete &pgr;-phase shifts (&dgr;&phgr;) each envelope, to form a sinc-sampled grating. Chirped multi-channel optical fiber gratings may thus be provided for dispersion compensation in long-haul transmission links.

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Southampton, United Kingdom

Morten Ibsen