Abstract: An optical amplifier is proposed which has an optical waveguide structure) through which signal light and pump light are propagated. The optical waveguide structure has a core with a relatively high refractive index and a clad with a relatively low refractive index, where at least said core exhibits a nonlinear response of second or third order. In a result optical parametric amplification of said signal light is achieved. The amplifier has separate idler light filters for attenuating idler light, which is generated in the process of optical parametric amplification, The position of the idler light filters can be defined placed in said optical waveguide structure at a defined length Lmax.

Abstract: The invention concerns an optical coupler formed of a photonic optical fiber (2) assembled by melting and stretching with at least one multimode optical fiber (4, 6). The phototonic fiber can be used to inject or extract a signal, whereas the multimode fibers can be used to inject pump light. The invention is able to in particular effectively couple multimode pumps in a laser cavity formed by a double cladding fiber. In this case, the optical fiber is not used to inject a signal, but to provide the coupler with a digital opening and a diameter adapted to those of the cavity. The invention is also able to couple one or several multimode pumps in a double cladding fiber. In this case, this makes it possible to retain in the coupler for the signal transmitted through the photonic fiber a mode diameter greater than or equal to the mode diameter at the inlet or outlet of the coupler.

Abstract: Disclosed is a Raman amplifier (10) comprising at least one length of fiber (12) and at least a coupler (14) for coupling at least a first pump laser module (16) and a second pump laser module (18) to said Raman amplifying fiber (12), the first pump laser module (16) comprising a frequency discriminator (24) for selecting an optical frequency to be emitted with an optical power exceeding an optical power of remaining optical frequencies that are also emitted by said first pump laser module (16). The first optical frequency is selected to be spaced apart from a local maximum (28; 36; 48) in optical power of said remaining optical frequencies, and the second pump laser module (18) emits at an optical frequency one Stokes-frequency above the frequency of said local maximum (28; 36; 48). The firts optical frequency and the frequency of said local maximum are chosen on Stokes-frquency above the signal frequency range. As a consequence, the Raman gain provided in Raman amplifying fiber 12 is broadened.

Abstract: An optical fiber amplifier is considered comprising a mono-mode core, a first cladding around said core and at least a further cladding around said first cladding while said first cladding includes a ring shaped active region doped with rare earth material surrounding said mono-mode core. Advantageously, the first cladding is designed with a radial refractive index following an almost continuous decreasing function for increasing radius. The use of a continuously decreasing refractive index for the cladding at the outer border of the ring shaped active medium optimize the efficiency of the coupling between the core and the cladding.

Abstract: The invention relates to an optical fiber amplifier device with an optical signal input and output with first piece of amplifying fiber doped with lanthanide in a double-clad structure, a second piece of amplifying fiber doped with lanthanide in a ring structure and lasers for pumping the two fiber pieces with at least one pump module.

Abstract: A spatial light modulator (SLM) is made up of a cell filled with a liquid crystal (LC) based substance. Latter has a variable scattering property with respect to an electric field present in the cell. By using a plurality of electrodes in the direct vicinity of said cell, it is then possible to build an electric field inside it which will permit advantageously to modulate a continuous spectrum from optical signals transmitted through said cell. The different pass bands present in said continuous spectrum while at least few of them comprise at least a respective different wavelength will have to be transmitted through said cell at different regions. Latter will correspond to different values of the amplitude of scattering such to be adapted to modulate the respective different pass bands. Such SLM is used to build a dynamic spectral equalizer. Latter contains a spectral dispersive element placed on an optical path of an incident light beam.

Abstract: In a method of optically amplifying signals between a sender station and a receiver station connected by an optical fiber, the power of a primary optical signal circulating between the sender station and the receiver station is amplified in the fiber by first order stimulated Raman scattering by first and second secondary optical pump signals having first and second wavelengths and circulating between the sender station and the receiver station, the first and second secondary signals are modulated, and at least a first tertiary optical signal having a third wavelength adapted to amplify the power of the first and second secondary signals by second order stimulated Raman scattering is transmitted in the fiber between the sender station and the receiver station.

Abstract: The present invention relates to a cascaded multi-wavelength Raman fiber amplification stage with a length of optical fiber having input (15) and output (16) sections, pump laser means (11) for introducing pump radiation of wavelength &lgr;p into said length of optical fiber (13), at least two pairs of reflector means (151,161; . . . ;159, 169), spaced-apart the length of optical fiber (13), at least one of said pairs of reflector means has an output reflector mean (161, 162, 163), with a reflectivity lower than 100% and a feed back loop with: a tap coupler (20) for deriving a low percentage of the optical output signal as a optical monitor signal (28), at least one wavelength selecting element (21, 25,26, 27) for the optical monitor signal (28), at least one opto-electrical converter (23, 231,232,233) generating a electrical signal and a control circuit (27) for the electrical signal connected to adjustment means (181, 182, 183) adjusting the reflectivity of the output reflector means (161, 162, 163).

Abstract: The present invention relates to a cascaded multi-wavelength Raman fiber laser adapted for emitting radiation of at least one wavelength &lgr;s1, with a length of optical fiber (13) having input (15) and output (16) sections, means (11) for introducing pump radiation of wavelength &lgr;p into said length of optical fiber (13), at least one pair of spaced-apart reflector means (151,161; . . .

Abstract: The invention concerns an optical coupler formed of a photonic optical fibre (2) assembled by melting and stretching with at least one multimode optical fibre (4, 6). The phototonic fibre can be used to inject or extract a signal, whereas the multimode fibres can be used to inject pump light.

Abstract: The invention proposes an optical amplifier for the C and L bands having a first stage with an amplification fiber (8) common to the C and L bands, a second stage with a branch (14) for C-band signals and a branch (12) for L-band signals with an amplification fiber (20). According to the invention, most of the power in the C band is created in the common amplification stage. The amplifier has a coupler (24) in the branch for C-band signals coupling pumping light for the amplification fiber of the first stage in the contrapropagating direction. The invention simplifies the structure of the amplifier and limits the number of devices through which L-band signals pass after they are amplified in the common amplification fiber of the first stage. It improves the L-band signal/noise ratio.

Abstract: The invention relates to an optical fiber amplifier device with an optical signal input and output with first piece of amplifying fiber doped with lanthanide in a double-clad structure, a second piece of amplifying fiber doped with lanthanide in a ring structure and lasers for pumping the two fiber pieces with at least one pump module.

Abstract: An optical fiber amplifier is proposed comprising at least one pump light source (3), at least one amplifying fiber section (10), and at least one coupler (8) which establishes a connection between the input fiber (1) of the fiber type I, the pump light source (3), the amplifying fiber section (10), and the output fiber (12) of the fiber type I. The amplifying fiber section (10) consists of a fiber type II, and the the splices (2, 11) between the fiber type I and the fiber type II are arranged relative to the amplifying fiber section (10) such that light propagated in the direction opposite to the signal direction and light propagated in the signal direction passes through means absorbent of short wavelengths before it reaches the splices.

Abstract: The invention proposes a double-clad photonic optical fiber presenting:

Abstract: An optical fiber with a large effective surface area has holes at points in at least two layers concentric with the fiber of points of a regular matrix. The holes in one layer have the same dimensions and occupy all the available points in the layer. In at least two layers the holes have different dimensions and there is at least one layer with no holes.

Abstract: An optical fiber with a large effective surface area has holes at points in at least two layers concentric with the fiber of points of a regular matrix. The holes in one layer have the same dimensions and occupy all the available points in the layer. In at least two layers the holes have different dimensions.

Abstract: The invention is related to a waveguide amplifier with an input for optical signals and an output for optical signals with at least one piece of amplifying waveguide with at least one mean for coupling pump laser modules to the amplifying waveguide which contains Tm ions. The invention is also related to a pumping scheme for waveguide amplifier feeding two different wavelengths in to the waveguide.

Abstract: The present invention provides a WDM optical communication system, comprising input means and output means for an optical signal, an optical fibre path connecting signal-transmissively said input and output means, wherein the optical signal is amplified by means of Raman amplification and said optical fibre path comprises at least one Raman amplifier, further comprising WDM means for coupling at least two polarized pump radiation wavelengths with wavelengths less than the signal radiation wavelength into said Raman amplifier, wherein one pump radiation wavelength has a selected different polarization with respect to the polarization of the other pump radiation wavelengths.

Abstract: A fiber amplifier comprises an amplifying double-clad fiber (DCF). The fiber has a core having a first refractive index, an inner cladding surrounding the core and having a second refractive index lower than the first refractive index and an outer cladding surrounding the inner cladding. The core is doped with Erbium (Er) and co-doped with Ytterbium (Yb), and further co-doped with Cerium (Ce). The Ytterbium (Yb) enables pump energy transfer from Ytterbium (Yb) ions being in the excited state to Erbium (Er) ions being in the ground state (4I15/2). The Cerium enables a resonant energy transfer between the Erbium (Er) excited state (4I11/2) and Cerium (Ce) ground state (4F7/2). This leads to a lower population of the Erbium 4I11/2 state and thereby increases energy transfer from Ytterbium to Erbium.

Abstract: To optimize the efficiency of optical amplifiers operating in the L-band, an L-band optical amplifier includes a doped fiber having a cut-off wavelength greater than 1 535 nm and a coupler for coupling into the fiber a pump supplying light in the C-band. The C-band pump is a high-power pump, with a power rating of at least 10 mW, which supplies at least 10% of the pumping energy. A pump operating at a wavelength below the C-band can also be coupled into the fiber, for example a 980 nm or 1 480 nm pump.