Abstract: An exemplary method is provided for determining a maximum transmission distance for an optical link that has heterogeneous types of optical fiber segments. The method includes retrieving from a database a maximum transmission reach value for each type of optical fiber present in the optical link. A length of each type of the optical fiber to reach a distance is computed, where, for each type of the optical fiber present in the optical link, segments are summed from a starting point to the distance to determine the length of each type of the optical fiber along the optical link. The length for each type of the optical fiber in the optical link is normalized by multiplying the length of each type of the optical fiber by a weight chosen as a function of the maximum transmission reach value for each type of said optical fiber.

Abstract: A method, for determining a maximum transmission distance (Dmax) for an optical link comprising heterogeneous types of optical fibre segments, comprising: for a type of optical fibre present in said optical link: retrieve a maximum transmission reach (Mi), determine along said optical link, a length (xi) of optical fibre of said type, to reach a distance (D), normalize said length (xi), by multiplying said length (xi) by a weight (?i) function of said maximum transmission reach (Mi), sum said normalized lengths for a plurality of types of optical fibre, determine the maximum transmission distance (Dmax) of the optical link as the distance (D) for which said sum equals a given threshold.

Abstract: To produce a representation of the physical degradation in an optical communication network comprising transparent switching nodes (1, 2, 3, 4) mutually connected by optical links (11, 12, 21, 22, 31, 32, 41, 42), the method involves: Associating a pair of counter-directional optical links as a bi-directional link (10, 20, 30, 40), Providing at least one respective physical degradation parameter for each of said counter-directional optical links of said pair, Determining at least one physical degradation parameter characteristic of said bi-directional link from said physical degradation parameters of the counter-directional optical links of said pair, Storing a descriptor of the bi-directional link comprising said at least one physical degradation parameter characteristic of said bi-directional link.

Abstract: An amplifier or laser using the stimulated Raman diffusion effect comprises a light guide (6), and a light pump (10) for producing a pump wave. In order to increase amplification efficiency, the light guide comprises a core structure that includes at least one optically active component that presents an electron transition energy corresponding to a wavelength that is close to the wavelength of the pump wave while nevertheless not being identical thereto. The invention is applicable to optical transmission systems.

Abstract: A Raman amplification active optical fiber comprises a core containing silica oxide (SiO2), lithium oxide (Li2O), germanium oxide (GeO2), and barium oxide (BaO). The core contains 30 to 90 molar percent of SiO2 and less than 50 molar percent of the combination of LiO2, GeO2, and BaO. Application of the fiber to a multiwavelength Raman fiber laser.

Abstract: Disclosed is a Raman laser device (10) having a first cavity in which lasing occurs at a first frequency, and at least one second cavity in which lasing occurs at a second frequency. Thereby respective first and second waves inside the respective cavities are generated having a first power and a second power, respectively. Further, beams propagating outside the cavities are generated by coupling out a part of the first power and a part of the second power utilizing respective output mirrors. The part of the second power that is coupled out is attenuated without attenuating the complementary part of the second power remaining in the second cavity. The Raman laser device is characterized in that the part of the second power that is coupled out is attenuated utilizing at least one Fiber Bragg Grating (46, 62).

Abstract: An amplifier or laser using the stimulated Raman diffusion effect comprises a light guide (6), and a light pump (10) for producing a pump wave. In order to increase amplification efficiency, the light guide comprises a core structure that includes at least one optically active component that presents an electron transition energy corresponding to a wavelength that is close to the wavelength of the pump wave while nevertheless not being identical thereto. The invention is applicable to optical transmission systems.

Abstract: The gain characteristic of a distributed Raman amplifier (RA) is controlled by estimating its gain curve in a simulation, selecting NP data channels (?1, ?2, ?3) for an online measurement and determining target gain values for the selected channels from the simulated gain curve (24). The number of selected channels corresponds to the number of pump wavelengths (?P1, ?P2, ?P3). A controller (CTR) varies the power of at least one of the pump light signals (?1, ?2, ?3) to minimize a power difference between the measured power value of any of the NP signal channels and its estimated target gain value.

Abstract: A method for adjusting the relative output power of individual output wavelengths of a multi-output-wavelength Raman laser (10) is disclosed. The method is characterized by the steps of suppressing the relative output power of a potentially most powerful output wavelength (98) in a first step (108), adjusting the relative output power of the shortest output wavelength (94) in a second step (110), adjusting the relative output power of further output wavelengths (96, 100, 102, 104) in a third step (112), and adjusting the relative output power of the potentially most powerful output wavelength (98) in a fourth step (114). Further, a device (68) that performs such a method is disclosed, i.e. a device for adjusting the relative output power of individual output wavelengths (94, 96, 98, 100, 102, 104) of such a laser (10).

Abstract: A cascaded Raman laser (10) has a pump radiation source (12) emitting at a pump wavelength ?p, an input section (14) and an output section (16) made of an optical medium. Each section (14, 16) comprises wavelength selectors (141, 142, . . . , 145 and 161, 162, . . . , 165) for wavelengths ?1, ?2, . . . , ?n?k, where n?3, ?p<?1<?2< . . . <?n?1<?n and ?n?k+1, ?n?k+2, . . . , ?n being k?1 emitting wavelengths of the laser (10). The laser further comprises an intracavity section (18) that is made of a non-linear optical medium, has a zero-dispersion wavelength ?0 and is disposed between the input (14) and the output (16) section. The wavelengths ?1, ?2, . . . , ?n?k of the wavelength selectors (141, 142, . . . , 145 and 161, 162, . . . , 165) and the zero-dispersion wavelength ?0 of the intracavity section (18) are chosen such that energy is transferred between different wavelengths by multi-wave mixing.

Abstract: It is proposed to use a Raman laser with a new optical resonant cavity for the Roman radiation ?RR. Such resonant cavity is made out of an unpaired reflector rRR with a reflecting wavelength corresponding to said Raman radiation ?RR. The second reflector at the output needed to build an optical resonant cavity is advantageously defined by Rayleigh scattering to take place at least at a portion of the optical fiber between the reflector rRR and the output of that Raman laser. With the use of the Rayleigh scattering as a complementary reflector to be associated with the unpaired reflector, it is then possible to obtain an optical resonant cavity for the Raman radiation ?RR with an output reflectivity of less than 1% i.e. with optimized Raman radiation. Such Raman laser is particularly appropriated to be used as a second order Raman laser.

Abstract: The present invention relates to a Raman laser comprising a Raman fiber (10), wherein said Raman fiber (10) comprises a plurality of wavelength selectors (16, 18, 20, 22, 24, 26, 28, 30) for closing a plurality of laser cavities (32, 34, 36, 38, 40). Some laser cavities (38, 40) have a single common first wavelength selector (44) so as to reduce the number of wavelength selectors. The present invention further relates to a method of manufacturing a Raman laser.

Abstract: A Raman amplification active optical fiber comprises a core containing silica oxide (SiO2), lithium oxide (Li2O), germanium oxide (GeO2), and barium oxide (BaO). The core contains 30 to 90 molar percent of SiO2 and less than 50 molar percent of the combination of LiO2, GeO2, and BaO. Application of the fiber to a multiwavelength Raman fiber laser.

Abstract: A method for adjusting the relative output power of individual output wavelengths of a multi-output-wavelength Raman laser (10) is disclosed. The method is characterized by the steps of suppressing the relative output power of a potentially most powerful output wavelength (98) in a first step (108), adjusting the relative output power of the shortest output wavelength (94) in a second step (110), adjusting the relative output power of further output wavelengths (96, 100, 102, 104) in a third step (112), and adjusting the relative output power of the potentially most powerful output wavelength (98) in a fourth step (114). Further, a device (68) that performs such a method is disclosed, i.e. a device for adjusting the relative output power of individual output wavelengths (94, 96, 98, 100, 102, 104) of such a laser (10).

Abstract: Disclosed is a Raman laser device (10) having a first cavity in which lasing occurs at a first frequency, and at least one second cavity in which lasing occurs at a second frequency. Thereby respective first and second waves inside the respective cavities are generated having a first power and a second power, respectively. Further, beams propagating outside the cavities are generated by coupling out a part of the first power and a part of the second power utilizing respective output mirrors. The part of the second power that is coupled out is attenuated without attenuating the complementary part of the second power remaining in the second cavity. The Raman laser device is characterized in that the part of the second power that is coupled out is attenuated utilizing at least one Fiber Bragg Grating (46, 62).

Abstract: A cascaded Raman laser (10) has a pump radiation source (12) emitting at a pump wavelength &lgr;p, an input section (14) and an output section (16) made of an optical medium. Each section (14, 16) comprises wavelength selectors (141, 142, . . . , 145 and 161, 162, . . . , 165) for wavelengths &lgr;1, &lgr;2, . . . , &lgr;n−k, where n≧3, &lgr;p<&lgr;1<&lgr;2< . . . <&lgr;n−1<&lgr;n and &lgr;n−k+1, &lgr;n−k+2, . . . , &lgr;n being k≧1 emitting wavelengths of the laser (10). The laser further comprises an intracavity section (18) that is made of a non-linear optical medium, has a zero-dispersion wavelength &lgr;0 and is disposed between the input (14) and the output (16) section. The wavelengths &lgr;1, &lgr;2, . . . , &lgr;n−k of the wavelength selectors (141, 142, . . . , 145 and 161, 162, . . .

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: 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 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 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.