Raman Laser Patents (Class 372/3)
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Patent number: 6744556Abstract: In a distributed Raman amplification system, the pump laser and the fiber are chosen so as to have characteristics which result in broadening of the DRBS. For example, with a transmission fiber through which signal light of a wavelength &lgr;s propagates, and having zero dispersion at a wavelength &lgr;o; a pump laser producing counterpropagating pump light at a wavelength &lgr;p; where &lgr;p and &lgr;s are on opposite sides of the zero dispersion wavelength is used. The transmission fiber may be large effective area fiber. In a Raman amplification system suitable for use in a WDM optical fiber communication system, pump lasers having mode spacing which is less than the optical bandwidth of the signal channel have been found to be advantageous.Type: GrantFiled: March 14, 2002Date of Patent: June 1, 2004Assignee: Corning IncorporatedInventors: Stuart Gray, Kim Jepsen, Michael Vasilyev
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Publication number: 20040091000Abstract: A multiple spectral line Raman laser having adjustable relative power output between different spectral lines is provided. The laser includes a lasing cavity, first and second reflectors optically coupled to a back end of the cavity that reflects substantially all light having wavelengths of &lgr;1 and &lgr;2, respectively, and a tunable reflector assembly optically coupled to a front end of the cavity that reflects a selected proportion of said light having wavelengths of &lgr;1 and &lgr;2 in response to a single source of strain to control relative power output of light at these wavelengths. The lasing cavity may be a linear length of gain fiber, and the tunable reflector may include a single fiber Bragg grating (FBG) having a trapezoidal reflection profile, or a pair of fiber Bragg gratings mounted on either side of a flexible substrate such that when the substrate is bent, one FBG stretches while the other is compressed.Type: ApplicationFiled: November 12, 2002Publication date: May 13, 2004Inventor: Dmitri V. Kuksenkov
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Patent number: 6731423Abstract: A broad bandwidth optical amplifier (50) includes an optical pump source (52). A Raman chamber (56) is coupled to an output (54) of the optical pump source (52). An optical fiber ring (62) having a first end (64) is coupled to a first end (66) of the Raman chamber (56). A second end (60) of the optical fiber is coupled to a second end (58) of the Raman chamber (56). A doped optical fiber is coupled to a second end of the optical fiber ring. The Raman chamber produces a number resonant Raman stokes lines.Type: GrantFiled: August 15, 2001Date of Patent: May 4, 2004Assignee: Neumann Information Systems IncInventors: Jason Kenneth Brasseur, David Kurt Neumann
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Patent number: 6721088Abstract: In accordance with the invention, an optical fiber communication system comprising a source of optical signal channels and an optical fiber transmission line is provided with one or more single source, multiple-order Raman pumps downstream of the source. Each single source pump provides multiple-order Raman pump light for amplifying the signal channels.Type: GrantFiled: March 15, 2002Date of Patent: April 13, 2004Assignee: OFS FitelInventors: Khushvinder Brar, Clifford Headley, Jean-Christopher Bouteiller, Jake Bromage
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Patent number: 6721091Abstract: A system and method for controlling optical amplifier pumps. A path average intensity detector is provided for detecting a path average intensity for transmitted optical signals. In response to the detected path average intensity or a variation in path average intensity, a pump parameter controller dynamically adjusts at least one pump parameter of at least one amplifier to achieve a desired path average intensity.Type: GrantFiled: June 13, 2002Date of Patent: April 13, 2004Assignee: Tyco Telecommunications (US) Inc.Inventors: Dmitri Foursa, Morten Nissov
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Patent number: 6717963Abstract: A method and system by which a wide bandwidth continuous wave (CW) or substantially continuous wave composite (SCWC) pump with a flat spectrum is utilized to amplify an information-carrying signal. By using a wide bandwidth CW pump, substantially no ripple is introduced to the signal being amplified by the Raman amplifier.Type: GrantFiled: July 14, 2000Date of Patent: April 6, 2004Assignee: Tyco Telecommunications (US) Inc.Inventor: Dmitri Foursa
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Patent number: 6700696Abstract: A Raman optical amplifier for amplifying an optical signal propagating in an optical fiber associated with an optical communications system. The amplifier includes a first Raman pump source including a first pump laser coupled to the fiber to provide first order Raman pump light for amplifying the optical signal, and a second Raman pump source including a second pump laser coupled to the fiber to provide second order Raman pump light for amplifying the first order Raman pump light. The first and second order Raman pump light is introduced into the fiber in either a co-propagating or counter-propagating direction relative to the propagation direction of the optical signal in the fiber. The second pump laser may include first and second pump laser elements that generate the second order Raman pump light, where a center wavelength of the light generated by the first laser element is different than the center wavelength of the light generated by the second laser element.Type: GrantFiled: August 9, 2001Date of Patent: March 2, 2004Assignee: JDS Uniphase CorporationInventors: Vincent G. Dominic, Mehrdad Ziari, Atul Mathur
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Patent number: 6693740Abstract: An optical amplifier comprises: (i) an input port for providing optical signal to the amplifier; (ii) an output port for providing amplified optical signal out of the amplifier; (iii) at least two optical fibers, one optical fiber having positive dispersion D1 of greater than 10 ps/nm/km in a 1550 nm to 1620 nm wavelength range, the other fiber having negative dispersion D2 of less than −5 ps/nm/km in a 1550 nm to 1620 nm wavelength range, wherein the length of each of said optical fiber is chosen to provide the amplifier with a predetermined amount of dispersion.Type: GrantFiled: August 7, 2002Date of Patent: February 17, 2004Assignee: Corning IncorporatedInventors: Stuart Gray, George F Wildeman
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Patent number: 6693737Abstract: A broadband nonlinear polarization amplifier includes an input port for inputting an optical signal having a wavelength &lgr;. A distributed gain medium receives and amplifiers the optical signal through nonlinear polarization. The distributed gain medium has zero-dispersion at wavelength &lgr;0. A magnitude of dispersion at &lgr; is less than 50 ps/nm-km. One or more semiconductor lasers are operated at wavelengths &lgr;p for generating a pump light to pump the distributed gain medium. An output port outputs the amplified optical signal.Type: GrantFiled: March 5, 2001Date of Patent: February 17, 2004Assignee: Xtera Communications, Inc.Inventor: Mohammed N. Islam
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Publication number: 20040028090Abstract: The present invention relates to a stable solid-state Raman laser (1), the solid-state Raman laser including: (a) a resonator cavity defined by at least two reflectors (M1 and M2), (b) a laser material (2A) located in the resonator cavity and capable of generating a cavity laser beam which propagates within the resonator cavity, (c) a solid Raman medium (7) located in the resonator cavity for shifting the frequency of the cavity laser beam to produce a Raman laser beam which propagates within the resonator cavity; and (d) an output coupler (M2) for coupling and outputting the Raman laser beam from the resonator cavity, wherein at least one parameter selected from the group consisting of (i) the position of the laser material (2A) relative to the position of the Raman medium (7) in the cavity, (ii) the length of the cavity and (iii) the curvature of at least one of the reflectors (M1 or M2), is selected such that changes in the focal lengths of both the laser material (2A) and the Raman medium (7) as a resultType: ApplicationFiled: September 2, 2003Publication date: February 12, 2004Inventors: Helen M. Pask, James A. Piper
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Patent number: 6690507Abstract: A double pumped Raman amplifier is provided that increases gain over a same length of gain fiber without significantly increasing a percentage of noise. The amplifier may include a source of pump light coupled to the output end of a coil of Raman gain fiber, and a reflector coupled to the input end of the coil which may be either a mirror, or a fiber Bragg grating. Alternatively, a beam splitter may be connected to the source of pump light and the resulting split output may be coupled to both the input and output ends of the gain fiber. The increase in amplification efficiency allows the optical fiber used in components such as dispersion compensating modules to also be used as Raman gain fiber in such amplifiers.Type: GrantFiled: January 30, 2002Date of Patent: February 10, 2004Assignee: Corning IncorporatedInventors: Stuart Gray, Stephen C Guy, James R Passalugo
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Patent number: 6674773Abstract: A multi-wavelength Raman laser comprising a Raman fiber forming part of an optical ring, preferably most parts of which are formed by optical fiber. The ring includes a periodic filter selectively transmitting optical power at a number of equally spaced wavelengths corresponding to the wavelengths of the laser output. Radiation at the signal wavelengths propagating in one direction on the ring is tapped onto an output fiber. An optical isolator is formed either in the ring or fiber tapped into the ring to suppress radiation propagating in the reverse direction on the ring. A frequency shifter may be inserted into the loop to prevent power from concentrating in a single mode, thereby allowing wide band lasing. A band pass filter may be inserted into the loop to restrict the lasing band.Type: GrantFiled: October 29, 2002Date of Patent: January 6, 2004Assignee: Corning IncorporatedInventors: Jean-Charles J. C. Cotteverte, Bruno Desruelle, Stefan M. Hess, Nicholas J. Traynor
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Patent number: 6665114Abstract: A hybrid optical signal amplifier is provided which includes the combination of a Raman amplifier and an EDFA assembly. The Raman amplifier has an output defined by regions of higher and lower gain levels, and the EDFA assembly has an output having a region, near the longer wavelengths thereof, that includes a maximum noise figure. The spectrum region of higher gain level of the Raman amplifier is selected to correspond to the spectrum region of the EDFA assembly that includes the maximum noise figure in order to lower the maximum noise figure of the resulting optical signal amplifier, as well as to flatten the gain across the output spectrum.Type: GrantFiled: February 26, 2002Date of Patent: December 16, 2003Assignee: Corning IncorporatedInventors: Seldon D Benjamin, Alan F Evans, Stephen P Hegarty, Ashiqur Rahman
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Patent number: 6657777Abstract: A modular interleaved Raman amplifier structure is exploited to reap the advantages provided by the high Raman gain coefficient and small effective area of highly nonlinear fibers without incurring penalties caused by nonlinear effects and double-Rayleigh backscattering noise. Very tight WDM channel spacings may be accommodated. The amplifier structure may be implemented at very low initial cost and with high reliability, scalability, and modularity.Type: GrantFiled: December 5, 2001Date of Patent: December 2, 2003Assignee: Cisco Technology, IncInventors: Fausto Meli, Fabrizio Di Pasquale, Giovanni Sacchi
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Patent number: 6657774Abstract: An amplifier system includes: (i) a distributed Raman fiber amplifier and; (ii) a discrete Raman fiber amplifier that includes dispersion compensated fiber. The discrete Raman fiber amplifier is operatively connected to the distributed Raman fiber amplifier and amplifies signals received from the distributed Raman fiber amplifier. In one embodiment, at least one source of pump signal is coupled to the distributed and to the discrete Raman fiber amplifier. The distributed Raman fiber amplifier and the discrete Raman fiber amplifier in this embodiment share optical pump power provided by the shared pump. In one embodiment of the present invention an Erbium doped fiber amplifier (EDFA) is operatively connected to a discrete Raman fiber amplifier and the Erbium dope fiber amplifier amplifies signals received from the discrete Raman fiber amplifier.Type: GrantFiled: August 18, 2000Date of Patent: December 2, 2003Assignee: Corning IncorporatedInventors: Alan F. Evans, George F. Wildeman
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Patent number: 6654162Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.Type: GrantFiled: June 22, 2001Date of Patent: November 25, 2003Assignee: The Furukawa Electric Co., Ltd.Inventors: Youichi Akasaka, Yoshihiro Emori, Shu Namiki
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Patent number: 6646785Abstract: An optical amplifier is provided comprising an optical fiber ring, and a pump light emitting device providing a primary pump wavelength. The pump light emitting device is optically coupled to the optical fiber ring and utilizes the primary pump wavelength to generate a secondary pump wavelength. Optical signal amplification and secondary pump wavelength lasing occur within the same section of the optical fiber ring.Type: GrantFiled: January 31, 2002Date of Patent: November 11, 2003Assignee: Corning IncorporatedInventor: Dmitri V Kuksenkov
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Patent number: 6631025Abstract: A Raman amplifier assembly includes a Raman amplifier configured to receive a signal from a signal source. The signal travels in an upstream direction in the Raman amplifier. A first pump source is coupled to the Raman amplifier. The first pump source produces a first pump beam that travels in a downstream direction and is counter-propagating relative to the signal. A second pump source is coupled to the Raman amplifier and produces a second pump beam that travels in the upstream direction. The second pump source has an average relative intensity noise of less than −80 dB/Hz.Type: GrantFiled: January 12, 2001Date of Patent: October 7, 2003Assignee: Xtera Communications, Inc.Inventors: Mohammed N. Islam, Michael Freeman
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Patent number: 6631028Abstract: An in-line broadband amplifier includes at least one input fiber and a WDM splitter coupled to the input fiber. The splitter splits an optical signal into at least a first wavelength and a second wavelength. A transition from a stop band to a pass band of the splitter occurs in 20 nm or less. A Raman amplifier and a rare-earth doped optical amplifier are coupled to the splitter. A WDM combiner is coupled to the Raman amplifier and the rare-earth doped optical amplifier. The WDM combiner combines an optical signal into at least a first wavelength and a second wavelength. A transition from a stop band to a pass band of the combiner occurs in 20 nm or less. An output fiber is coupled to the WDM combiner.Type: GrantFiled: April 11, 2000Date of Patent: October 7, 2003Assignee: Xtera Communications, Inc.Inventor: Mohammed N. Islam
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Patent number: 6625347Abstract: Raman amplifiers are provided for amplifying signals on optical communications links. The Raman amplifiers may be pumped using an unpolarized Raman pump source. Gain for the source may be provided by a semiconductor device that provides linearly-polarized pump light. A polarization-maintaining fiber may be coupled directly to the semiconductor device at a 45° orientation with respect to the polarization of the light emitted by the device. Light from the semiconductor device may be launched equally into both the slow and fast axes of the fiber. A fiber Bragg grating reflector may be used to stabilize the pump. Pump light traveling along the slow and fast axes becomes spatially separated by more than the coherence length of the multiple quantum well device. The pump light exiting the end of the polarization-maintaining fiber is therefore unpolarized.Type: GrantFiled: March 6, 2001Date of Patent: September 23, 2003Assignee: Onetta, Inc.Inventor: Yongan Wu
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Patent number: 6624928Abstract: In a first aspect, a Raman amplifier is pumped using pumps just above and below the fiber water peak. This enables lower power pumps to be used, as the high attenuation is avoided. In a second aspect, a first pump provides a signal having a first wavelength and a first power, and a second pump source provides a plurality of signals, each having a power lower than the first power and a wavelength in a range approximately one Stokes shift higher than the first wavelength. In this way, the second pump source signals are amplified by the Raman effect by the first pump source signal, and the amplified second pump source signals cause signal amplification. The amplified second pump source signals can then include wavelengths above and below the water peak.Type: GrantFiled: May 24, 2001Date of Patent: September 23, 2003Assignee: Nortel Networks LimitedInventors: Jowan Masum-Thomas, Andrew V Maroney, Richard Thomas, Christopher R Fludger
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Patent number: 6625180Abstract: The invention relates to the field of laser engineering and fiber optics and is industrially used to pump optical amplifiers used in wide band fiber-optical communication systems. The subject matter of the invention is a Raman fiber laser based on a phosphosilicate fiber, comprising a pumping radiation source 1, a length 2 of a phosphosilicate fiber, at least two pairs of Bragg gratings as reflectors 3 and 4, wherein each pair of Bragg gratings forms an optical resonator, wherein the transmission of energy between the resonators is effected due to stimulated Raman scattering, both at relatively high frequency intramolecular oscillations, related to the presence of phosphorus oxide in the fiber (the frequency difference of such resonators being selected from the range of 1305-1355 cm−1), and at relatively low frequency oscillations related to a silicate matrix of the fiber, the shift of frequencies between such resonators being selected from the range of 50-560 cm−1.Type: GrantFiled: February 2, 2001Date of Patent: September 23, 2003Assignee: Nauchny Tsentr Volokonnoi Optiki Pri Institute Obschei Fiziki Rossiiskoi Akademii NaukInventors: Igor Alexeevich Bufetov, Evgeny Mikhailovich Dianov, Andrei Semenovich Kurkov
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Patent number: 6621835Abstract: An optical gain device preferably uses stimulated Raman scattering and is in a ring configuration. Fused fiber couplers are used in one embodiment in combination with wavelength selective reflectors to input pump energy to the ring, and to output the desired output wavelengths. The couplers and reflectors are arranged so that the relative phase shifting induced by the couplers allows the optical energy to be directed as desired. The system may also make use of a redirecting reflector at the output wavelength that keeps output light in the ring propagating in the proper direction. A plurality of reflectors may also be used in the ring to select the desired wavelengths at the different Stokes orders being used. In an alternative embodiment, thin film type couplers are used rather than fused fiber couplers.Type: GrantFiled: June 12, 2000Date of Patent: September 16, 2003Assignee: JDS Uniphase CorporationInventor: Bernard G. Fidric
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Patent number: 6621621Abstract: A line amplification system connected on the fiber between two flexibility sites of a wavelength switched network is built with a number of modules that can be arranged in a line amplifier, preamplifier and postamplifier configurations. The line and preamplifiers include a Raman module and a two-stage EDFA module provided with mid-stage access. A dynamic gain equalizer is connected in the mid-stage in the line amplification configurations. As well, dispersion compensating module may be connected in the mid-stage whenever/if needed. A line monitoring and control system operates the line amplification system so that all channels traveling along a link have substantially the same power, in the context of channels being added and removed to/from the line arbitrarily.Type: GrantFiled: October 11, 2001Date of Patent: September 16, 2003Assignee: Innovance, Inc.Inventors: Kevan Peter Jones, Mark Stephen Wight, Alan Glen Solheim, Paul Edward Beer
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Publication number: 20030151798Abstract: Methods and apparatus for maintaining a quality of a Raman medium in a Raman conversion cell. In various examples, a flow velocity of the Raman medium is tailored based on a spatial nonuniformity of heat deposition resulting from the Raman conversion in the cell. In particular, in one example, the flow velocity of the Raman medium may be tailored to be higher where the heat deposition/temperature rise is larger and smaller elsewhere in the cell. This type of flow velocity profile reduces the overall required volumetric flow of the Raman medium in the cell without significantly affecting a quality of the Raman medium.Type: ApplicationFiled: November 21, 2002Publication date: August 14, 2003Inventors: Allen Flusberg, James Moran, Paul Lewis
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Patent number: 6606187Abstract: An apparatus and method are described for exploiting almost the full almost 25 THz of bandwidth available in the low-loss window in optical fibers (from 1430 nm to 1620 nm) using a parallel combination of optical amplifiers. The low-loss window at about 1530 nm-1620 nm can be amplified using erbium-doped fiber amplifiers (EDFAs). However, due to the inherent absorption of the erbium at shorter wavelengths, EDFAs cannot be used below about 1525 nm without a significant degradation in performance. For the low-loss window at approximately 1430-1530 nm, amplifiers based on nonlinear polarization in optical fibers can be used effectively. A broadband nonlinear polarization amplifier (NLPA) is disclosed which combines cascaded Raman amplification with parametric amplification or four-wave mixing. In particular, one of the intermediate cascade Raman order wavelengths &lgr;r should lie in close proximity to the zero-dispersion wavelength &lgr;0 of the amplifying fiber.Type: GrantFiled: October 23, 2000Date of Patent: August 12, 2003Assignees: The Regents of the University of Michigan, Xtera Communications, Inc.Inventors: Mohammed Nazrul Islam, Hayden Henry Harris
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Patent number: 6603778Abstract: An object is provision of a method and apparatus for generating ultrashort optical pulses through use of a Raman resonator, which can generate preferentially rotational Raman lines which resonate within the resonator, which can lower the threshold for generation of rotational Raman lines to thereby increase efficiency, and which enables generation of high-order rotational Raman lines to thereby obtain ultrashort optical pulses. An apparatus for generating ultrashort optical pulses by use of a Raman resonator includes a first laser (101); a second laser (102); a first wavemeter (111) for confirming the emitting wavelength of the first laser (101); a second wavemeter (121) for confirming the emitting wavelength of the second laser (102); and a Raman cell (130). These two laser beams are aligned by a beam splitter (113) to become coaxial and are focused by a lens (124) into the Raman cell (130).Type: GrantFiled: November 8, 2001Date of Patent: August 5, 2003Assignee: Kitakyushu Foundation for the Advancement of Industry, Science and TechnologyInventor: Totaro Imasaka
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Patent number: 6594288Abstract: A tunable Raman laser and amplifier include a pair of tunable optical units optically connected by a length of optical fiber having an associated Raman gain. The tunable optical units tune respective optical waveguides, each of which includes an inner core disposed within an outer cladding. A plurality of Bragg gratings is written in each core of the waveguides. The reflection wavelengths of each Bragg grating of the input waveguide is the same as the reflection wavelength of a matched grating of the output waveguide, to thereby form a plurality of cascaded resonance cavities. Each resonance cavity has a reflecting wavelength equal to the center wavelength of successive Stokes orders associated with optical fiber. The Bragg gratings of each waveguide are written into a corresponding stepped region ground into the outer cladding of the waveguides. The tuning (e.g.Type: GrantFiled: November 6, 2000Date of Patent: July 15, 2003Assignee: CiDRA CorporationInventors: Martin A. Putnam, Alan D. Kersey
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Patent number: 6570702Abstract: The invention is a ribbon of an optical material with a plurality of cores that run along its length. The plurality of cores includes lasing impurity doped cores in an alternating spaced arrangement with index-modifying impurity doped cores. The ribbon comprises an index of refraction that is substantially equal to or greater than the indices of refraction of said array of lasing impurity doped cores. Index-increasing impurity doped cores promote antiguiding and leaky modes which provide more robust single “supermode” operation.Type: GrantFiled: February 16, 2001Date of Patent: May 27, 2003Assignee: The Regents of the University of CaliforniaInventors: Russel B. Wilcox, Ralph H. Page, Raymond J. Beach, Michael D. Feit, Stephen A. Payne
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Publication number: 20030095745Abstract: A pump source for a fiber Raman amplifier used in a WDM optical communication system is formed to generate an RF-modulated pump signal (as opposed to the prior art CW signals). The modulation frequency and index of the RF-modulated pump signal are controlled to impart a sufficient degree of “randomness” to the presence of the pump signal at each wavelength, thus minimizing cross talk between the signals and improving the transfer of power from the pump signal to the plurality of optical input signals.Type: ApplicationFiled: November 21, 2001Publication date: May 22, 2003Inventor: Narayan L. Gehlot
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Patent number: 6567430Abstract: In one embodiment, a Raman oscillator includes at least one laser cavity and a distributed gain fiber positioned in the at least one laser cavity having a single spatial mode over a pumping wavelength to a signal wavelength. The oscillator also includes a coupler adapted to be coupled to a pumping mechanism to pump the distributed gain fiber at the pumping wavelength to obtain an optical signal wherein distributed gain is provided by Raman amplification over at least one cascade order corresponding to the pumping wavelength. A filter is positioned in the at least one laser cavity and has at least one pass band with a transmission peak placed approximately at the at least one cascade order to filter the optical signal to obtain a filtered optical signal having the signal wavelength. The filter has a substantially continuous sinusoidal filter function over at least one period of the filter function.Type: GrantFiled: September 21, 1999Date of Patent: May 20, 2003Assignees: Xtera Communications, Inc., The Regents of the University of MichiganInventors: Mohammed N. Islam, Michael J. Freeman, Hayden H. Harris
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Patent number: 6567605Abstract: A fiber optic projection device is provided that includes red, green and blue fiber optic sources, each of which includes at least one fiber amplifier for emitting an amplified signal of a predetermined wavelength. To provide signals that are scalable to high power levels, each fiber optic source can include a master oscillator, a plurality of fiber amplifiers for amplifying the input signals provided by the master oscillator and a combiner for combining the amplified signals emitted by each of the fiber amplifiers. While the fiber amplifier of each fiber optic source can be a dual core fiber that is appropriately doped, the red fiber optic source can include fiber amplifiers that rely upon Raman gain to provide the desired amplification. The red fiber optic source therefore not only includes a master oscillator, but also includes a red subharmonic oscillator for generating signals having a Raman seed wavelength for amplification by the fiber amplifiers.Type: GrantFiled: August 25, 2000Date of Patent: May 20, 2003Assignee: The Boeing CompanyInventors: Robert Rex Rice, Neil F. Ruggieri, Mark Steven Zediker
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Patent number: 6563844Abstract: A Q-switch modulator for a high power laser having a randomly polarized output beam and large divergence angle employs a cascaded arrangement of longitudinal mode acousto-optic modulators, each of which has a Raman Nath or near Raman Nath interaction length. The modulators are optically cascaded such that the distance the randomly polarized laser beam travels through the modulators is effectively confined to the sum of the non coherent interaction lengths thereof. Due to the substantial power level of the laser output, there is heating of the bulk material, which usually results in a shift in the Bragg angle. This has minimal if any effect on the shorter interaction length of the Q-switch modulator of the invention. Also, heating of the bulk material is countered by the incorporation of cooling fluid channels in a heat sink support block coupled in thermal communication with the bulk material.Type: GrantFiled: August 5, 1999Date of Patent: May 13, 2003Assignee: Neos Technologies, Inc.Inventors: Eddie H. Young, Robert V. Belfatto, Sr., Carlos M. Carbonell
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Patent number: 6560247Abstract: A dual wavelength optical fiber laser includes a first and a second optical fibers which generating stimulated scattering by a pump light source; two short period optical fiber gratings that is resonating each of a first and a second wavelength light which are generated by the optical fibers and regulating reflecting characteristics according to the first and the second wavelengths; a WDM optical fiber coupler which inputs a pump wavelength to the optical fibers and outputs a laser operation wavelength; and an interference removing unit which is connected between the optical fibers and removes an interference in the first and the second wavelength of resonating.Type: GrantFiled: November 5, 2001Date of Patent: May 6, 2003Assignee: Electronics and Telecommunications Research InstituteInventors: Do-Il Chang, Min-Yong Jeon, Kyong-Hon Kim
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Patent number: 6556342Abstract: An optical transmission system is provided comprising a thulium doped optical fiber, a light emitting pump device optically coupled to the thulium doped fiber, and a Raman amplifier fiber optically coupled to the thulium doped optical fiber. The light emitting pump device in combination with the thulium doped fiber generates a first amplification pump wavelength and the Raman amplifier receives the first amplification pump wavelength. The first pump wavelength amplifies an optical signal in the Raman amplifier, the Raman amplifier operating at a signal wavelength in the range of about 1530 nm to about 1625 nm.Type: GrantFiled: May 31, 2002Date of Patent: April 29, 2003Assignee: Corning IncorporatedInventors: Adam J Ellison, John D Minelly, Bryce N Samson, Nicholas J Traynor, Donnell T Walton
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Publication number: 20030058898Abstract: A multibeam laser light source, comprising a plurality of individual laser light sources arranged in an array and including a first and a second laser light source for emitting respective light beams spaced from one another, said first laser light source having a resonator with a given pump energy distribution therethrough, the spacing of the light beam emitted by said first laser light source from the light beam emitted by said second laser light source being variable by varying said given pump energy distribution through said resonator of said first laser light source; an image-setting or imaging device therewith; a printing form exposer with the imaging device combination; a printing unit with the imaging device combination; and a printing press with the printing unit combination.Type: ApplicationFiled: September 17, 2002Publication date: March 27, 2003Inventor: Bernard Beier
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Publication number: 20030048815Abstract: A continuous wave laser device (40) comprises a convoluted path or fibre (43) of Raman laser material that has been micromachined onto a substrate, the laser material fibre being covered by protective cladding (30). A 1 cm diameter substrate can have tens of metres of fibre fabricated on it and with a suitable choice for the laser material, e.g. Diamond, can output tens of hundreds of Watts of laser power. One possible use envisaged is a multicolour laser diodes, for example for projection television systems.Type: ApplicationFiled: June 26, 2002Publication date: March 13, 2003Inventor: Gary Cook
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Patent number: 6529672Abstract: In a fiber optic link signal or pump sending power limitations due to stimulated Raman scattering are pushed back by using attenuation in the Raman gain region. Various techniques are proposed for limiting stimulated Raman scattering. In particular, the use of optical fiber lightly doped with dysprosium, the attenuation of which increases rapidly beyond 1 500 nm, is proposed. The use of this fiber to transport pump power at 1 480 nm towards remote amplifiers would enable injection of pump power up to an order of magnitude of 10 W, whereas the limit is currently 1.3 W. This technique would enable the range of links to be increased approximately 80 km.Type: GrantFiled: January 12, 1999Date of Patent: March 4, 2003Assignee: AlcatelInventors: Jean-Pierre Blondel, Eric Brandon, Jean-François Marcerou, Mireille Marcerou
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Publication number: 20030021301Abstract: The present invention is a Raman laser and methods related thereto. In the preferred embodiments, the Raman laser comprises a laser pump signal in a fiber waveguide which is optically coupled to a micro-resonator through a fiber taper. The micro-resonator is constructed from a material that has a high Q when it is formed into a micro-resonator and is phase matched to the waveguide. The lasing frequency can be determined based upon the pump input or the micro-resonator material. In the preferred embodiments, the micro-resonator is constructed from a fused silica material. The present invention provides a compact laser with improved emissions and coupling efficiencies and the ability to use stimulated Raman scattering effects to create lasers having frequencies that are otherwise difficult to obtain. Alternative configurations include multiple micro-resonators on a single fiber waveguide and/or utilizing multiple waveguides attached to one or more micro-resonators.Type: ApplicationFiled: July 9, 2002Publication date: January 30, 2003Applicant: California Institute of TechnologyInventors: Kerry J. Vahala, Sean M. Spillane, Tobias J. Kippenberg
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Publication number: 20030021302Abstract: A Raman cascade laser comprising a 1060 nm pump source, an input waveguide and a ring waveguide coupled to the input waveguide. The ring waveguide is at least in part formed of phosphosilicate fiber so as to Raman scatter the pump beam from the pump wavelength to a gain wavelength that is offset from the pump wavelength by a first Raman step of 1330 cm−1. Light is coupled out with an output waveguide coupled to the ring waveguide at an emission wavelength offset by a second Raman step of 1330 cm−1 from the gain wavelength. Other embodiments provide incoherent sources based on the same 2-step Raman cascade, or a 2-step Raman cascade based on a first phosphosilicate 1330 cm−1 Raman step followed by a second step of 680-820 cm−1. With the invention, it is possible to avoid a Raman cascade involving a larger number of steps while at the same time avoiding use of 1300 nm pump sources.Type: ApplicationFiled: July 12, 2002Publication date: January 30, 2003Inventors: Anatoly Borisovich Grudinin, Johan Nilsson
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Patent number: 6501593Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.Type: GrantFiled: June 22, 2001Date of Patent: December 31, 2002Assignee: The Furukawa Electric Co., Ltd.Inventors: Youichi Akasaka, Yoshihiro Emori, Shu Namiki
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Publication number: 20020181859Abstract: A pump assembly for an optical amplifier includes a plurality of pump radiation sources, each pump radiation source producing radiation at a respective one of a first number of pump wavelengths. A coupler is optically coupled to each of the plurality of pump radiation sources, receives each of the first number of pump wavelengths from the plurality of pump radiation sources, and outputs each of the first number of pump wavelengths to each one of a second number of outputs. The pump assembly also includes a plurality of pump signal combiners, each pump signal combiner optically coupled to a respective one of the second number of outputs of the coupler and receiving each of the first number of pump wavelengths output from the coupler. Each pump signal combiner placing each of the first number of pump wavelengths output from the coupler in co-propagation with a respective one of a plurality of data signals propagating on a respective one of a plurality of optical fibers.Type: ApplicationFiled: May 29, 2001Publication date: December 5, 2002Inventors: Thomas Clark, William Shieh, Vladimir Petricevic
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Publication number: 20020172234Abstract: Short-pulse Raman laser is used to perform precision working of a substance without causing thermal effects on it or examine the interior of the skin or process the interior of a transparent material such as glass. By typically choosing a suitable Raman medium to be illuminated with a pump laser, the short-pulse Raman laser can have a wavelength that matches the wavelength of absorption by the substance of interest.Type: ApplicationFiled: November 1, 2001Publication date: November 21, 2002Inventors: Takashi Arisawa, Kyoichi Deki, Fumiaki Matsuoka
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Patent number: 6483633Abstract: A Raman amplifier applicable to a wavelength division multiplexing optical transmission system is proposed. The Raman amplifier, which can make good use of a wavelength range, comprises an optical fiber for Raman amplification and a pump light introducing means. The zero-dispersion wavelength of the optical fiber and the wavelength of the pump light are nearly equal. The wavelength of pump light is preferably in the range where the absolute magnitude of the chromatic dispersion of the optical fiber is less than 0.3 ps.nm−1.km−1. A range near a zero-dispersion wavelength cannot be utilized as a signal range because waveform deterioration of signal light occurs due to four wave mixing. This range can be utilized effectively as a wavelength range of exciting light for Raman amplification.Type: GrantFiled: July 10, 2001Date of Patent: November 19, 2002Assignee: Sumitomo Electric Industries, Ltd.Inventors: Masashi Onishi, Toshiaki Okuno
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Patent number: 6456425Abstract: A method and apparatus to amplify an optical signal is described. A first filter splits an optical signal into a first and second parts. A first raman amplifier amplifies the first part. A second raman amplifier amplifies the second part. A combiner combines the amplified first and second parts.Type: GrantFiled: June 7, 2000Date of Patent: September 24, 2002Assignee: Tyco Telecommunications (US) Inc.Inventors: Dimitri Foursa, Howard Kidorf, Alexei Pilipetski
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Publication number: 20020126956Abstract: A multi-wavelength cascaded Raman resonator (“MWCRR”). The MWCRR has an optical source for pumping optical radiation centered around an input wavelength. The MWCRR further includes a Raman fiber having at least a first set of optical gratings for converting the pumped optical radiation to wavelengths other than the input wavelength. The Raman fiber also has at least one adjustable output coupler having a variable reflectivity for controlling the power of the optical radiation propagating from the at least one set of optical gratings at the wavelengths other than the input wavelength.Type: ApplicationFiled: September 27, 2001Publication date: September 12, 2002Inventors: Jean-Christophe Bouteiller, Benjamin John Eggleton, Clifford Headley, Paul Steinvurzel
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Patent number: 6449408Abstract: A soliton pulse generator is formed by providing an input continuous wave, stimulating Brillouin scattering of an input wave having a frequency determined by the frequency of the input continuous wave to generate a backscattered wave, coupling a continuous wave having a frequency determined by the input continuous wave with the backscattered wave to generate a sinusoidal output signal, and then compressing the sinusoidal output to form a soliton pulse train. Because the wavelength shift of the backscattered wave is essentially independent of the input wavelength and power, coupling of the second wave and the backscatterred wave results in a highly stable and controllable sinusoidal output signal. A highly stable and controllable soliton pulse train is provided by compressing the sinusoidal signal with use of a dispersion decreasing fiber or with use of an alternative pulse compressing device.Type: GrantFiled: April 14, 2000Date of Patent: September 10, 2002Assignees: Corning Incorporated, University of RochesterInventors: Alan F. Evans, Andrew J. Stentz
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Publication number: 20020118934Abstract: A dispersion management device utilizing a high order mode fiber, mode transformers, a trim fiber and a Raman pump configured to generate substantially complete dispersion and dispersion slope compensation for an attached optical span, without losses. The trim fiber is optimized for Raman amplification while completing the dispersion compensation of the high order mode fiber. The dispersion management device in one embodiment generates at least 5 dB of overall amplification. In one embodiment the trim fiber is a non-zero dispersion shifted fiber, while in another embodiment it is a reverse dispersion fiber. In yet another embodiment the trim fiber is dispersion shifted fiber. In yet another embodiment the trim fiber is standard SMF. In an exemplary embodiment the Raman pump comprises multiple sources, each of which are independently controlled, thus allowing for the operation without a variable optical attenuator. The mode transformer in a preferred embodiment is a transverse mode transformer.Type: ApplicationFiled: February 22, 2002Publication date: August 29, 2002Inventors: Yochay Danziger, Yongqian Liu
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Publication number: 20020118709Abstract: This invention describes new developments in Sagnac Raman amplifiers and cascade lasers to improve their performance. The Raman amplifier bandwidth is broadened by using a broadband pump or by combining a cladding-pumped fiber laser with the Sagnac Raman cavity. The broader bandwidth is also obtained by eliminating the need for polarization controllers in the Sagnac cavity by using an all polarization maintaining configuration, or at least using loop mirrors that maintain polarization. The polarization maintaining cavities have the added benefit of being environmentally stable and appropriate for turn-key operation. The noise arising from sources such as double Rayleigh scattering is reduced by using the Sagnac cavity in combination with a polarization diversity pumping scheme, where the pump is split along two axes of the fiber. This also leads to gain for the signal that is independent of the signal polarization.Type: ApplicationFiled: December 19, 2001Publication date: August 29, 2002Inventor: Mohammed N. Islam
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Patent number: 6434172Abstract: The disclosed fiber Raman device comprises means for coupling pump radiation of a first wavelength &lgr;1 and a second wavelength &lgr;2 into a length of silica-based fiber, with &lgr;1 being different from &lgr;2, and with both of &lgr;1 and &lgr;2 being less than an output radiation &lgr;0 of the fiber Raman device. The Raman device further comprises at least a first and a second wavelength-selective element disposed to provide one or more optical cavities for Raman shifting of light in the fiber. At least one of the optical cavities is selected such that at least one of &lgr;1 and &lgr;2 is off resonance. Exemplarily, the Raman device is a topologically linear or circular Raman laser or amplifier, and the wavelength selective element is a fiber Bragg grating or a WDM. The Raman device is advantageously used in an optical fiber communication system.Type: GrantFiled: August 6, 1999Date of Patent: August 13, 2002Assignee: Fitel USA Corp.Inventors: David John DiGiovanni, Daryl Inniss, Ralph Stephen Jameson, Sandra Greenberg Kosinski