Abstract: A laser medium includes a single crystal of chromium-doped LiScl-xInxGe1-ySiyO4, where 0?x?1 and 0?y?1. Preferably, x and y are not both 0. A laser, such as a tunable near infrared laser, can contain the laser medium.

Abstract: A method is described to improve and produce purer Cr4+-doped laser materials and lasers with reduced co-incorporation of chromium in any other valence states, such as Cr3+, Cr2+, Cr5+, and Cr6+. The method includes: 1) certain crystals of olivine structure with large cation (Ca) in octahedral sites such as Cr4+:Ca2GeO4, Cr4+:Ca2SiO4, Cr4+:Ca2GexSi1-xO4 (where 0<x<1), and/or 2) high-temperature solution growth techniques that enable the growth of the crystals below the temperature of polymorphic transitions by using low melting point solvent based on oxide, fluoride and/or chloride compounds. Purer Cr4+-doped laser materials are characterized by a relatively high concentration of Cr4+-lasing ion in crystalline host that makes these materials suitable for compact high power (thin disk/wedge) NIR laser applications.

Abstract: A laser medium includes a single crystal of Cr4+:Mg2-xMxSi1-yAyO4, where, where M is a bivalent ion having an ionic radius larger than Mg2+, and A is a tetravalent ion having an ionic radius larger than Si4+. In addition, either a) 0?x<2 and 0<y<1 or b) 0<x<2 and y is 0 or 1 with the proviso that if M is Ca2+ and x=1 then y is not 0. The laser medium can be used in a laser device, such as a tunable near infrared (NIR) laser.

Abstract: A laser medium includes a single crystal of Cr4+:Mg2-xMxSi1-yAyO4, where, where M is a bivalent ion having an ionic radius larger than Mg2+, and A is a tetravalent ion having an ionic radius larger than Si4+. In addition, either a) 0?x<2 and 0<y<1 or b) 0<x<2 and y is 0 or 1 with the proviso that if M is Ca2+ and x=1 then y is not 0. The laser medium can be used in a laser device, such as a tunable near infrared (NIR) laser.

Abstract: A laser medium includes a single crystal of chromium-doped LiScl-xInxGe1-ySiyO4, where 0?x?1 and 0?y?1. Preferably, x and y are not both 0. A laser, such as a tunable near infrared laser, can contain the laser medium.

Abstract: A method for maintaining amplifier saturation in a wavelength division multiplexed (WDM) optical network having a plurality of sub-bands, each sub-band including at least two signal channels which carry respective data signals, and a plurality of substitute signal transmitters, each substitute signal transmitter generating a substitute signal and corresponding to a respective one of the plurality of sub-bands, includes identifying signal channels having a predetermined characteristic within each of the plurality of sub-bands. A substitute signal transmitter is turned on if the sub-band corresponding to the substitute signal transmitter includes a predetermined number of signal channels having said predetermined characteristic. The data signals and the substitute signals are combined into a WDM signal, and the WDM signal is transmitted over an optical transmission fiber.

Abstract: A wavelength division multiplexed (WDM) optical network includes a plurality of optical transmitters, each optical transmitter generating a data signal sent over a respective one of a plurality of signal channels, the plurality of signal channels being divided into a number of sub-bands where each sub-band includes at least two signal channels, and a plurality of substitute signal transmitters, the number of substitute signal transmitters being equal to the number of sub-bands, each substitute signal transmitter generating a substitute signal which provides loading in a corresponding sub-band. The WDM optical network also includes a combining circuit which combines the data signals output from the plurality of optical transmitters and the substitute signals output from the plurality of substitute signal transmitters into a WDM signal, and an optical transmission fiber which receives the WDM signal from the combining circuit.

Abstract: A method of amplifying optical signals comprising providing a plurality of input radiation signals into the inputs of a P×V coupler, each of the input radiation signals having a respective input radiation profile having a set of pump wavelengths and pump powers corresponding to the respective wavelengths, wherein at least one set is different from at least one other set; providing V output pump radiation profiles from the outputs of the P×V coupler; and amplifying an optical data signal by coupling at least one of the V output pump radiation profiles with the optical data signal, wherein at least one of the V output pump radiation profiles has a different power than at least one other of the V output pump radiation profiles.

Abstract: An optical amplifier is described that can couple to and amplify optical signals along multiple fiber transmission paths. The optical amplifier includes a plurality of pump radiation sources, each pump radiation source adapted to produce radiation having a set of pump wavelengths and pump powers corresponding to the respective pump wavelengths, wherein at least one set is different from at least one other set. The optical amplifier also includes a plurality of pump radiation combiners, each pump radiation combiner coupling the radiation of a respective set of pump wavelengths of a respective source of the plurality of pump radiation sources and outputting the respective coupled radiation having coupled radiation profiles via a respective pump radiation combiner output. The optical amplifier also includes a coupler, such as a PxV coupler with P inputs and V outputs.

Abstract: 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.

Abstract: An optical coupler system is described. The optical coupler system is for coupling radiation from a plurality of radiation sources. The optical coupler system comprises a first optical coupler having at least a first and a second input and a first and a second output. The optical coupler also comprises a second optical coupler having at least a first and a second input and a first and a second output, wherein the first and second outputs of the first optical coupler are connected to the first and second inputs, respectively, of the second optical coupler via first and second optical links, and wherein the first and second links provide different optical paths between the first and second optical couplers such that portions of radiation energy that is input to the first input of the first optical coupler are combined incoherently at the first output of said second optical coupler.

Abstract: An optical amplifier. The amplifier includes a plurality of pump radiation sources, each pump radiation source adapted to produce radiation having a set of pump wavelengths and pump powers corresponding to the respective pump wavelengths, wherein at least one set is different from at least one other set. The amplifier also includes a plurality of pump radiation combiners and a coupler. The coupler is optically coupled to the outputs of the pump radiation combiners, receives the coupled radiation from the pump radiation combiners and outputs pump radiation profiles to respective coupler outputs. The amplifier also includes pump-signal combiners, each optically coupled to a respective coupler output of the coupler outputs, which are adapted to couple an optical signal with the respective pump radiation profiles.

Abstract: An optical coupler system is described. The optical coupler system is for coupling radiation from a plurality of radiation sources. The optical coupler system comprises a first optical coupler having at least a first and a second input and a first and a second output. The optical coupler also comprises a second optical coupler having at least a first and a second input and a first and a second output, wherein the first and second outputs of the first optical coupler are connected to the first and second inputs, respectively, of the second optical coupler via first and second optical links, and wherein the first and second links provide different optical paths between the first and second optical couplers such that portions of radiation energy that is input to the first input of the first optical coupler are combined incoherently at the first output of said second optical coupler.

Abstract: A wavelength division multiplexed (WDM) optical network includes a plurality of optical transmitters, each optical transmitter generating a data signal sent over a respective one of a plurality of signal channels, the plurality of signal channels being divided into a number of sub-bands where each sub-band includes at least two signal channels, and a plurality of substitute signal transmitters, the number of substitute signal transmitters being equal to the number of sub-bands, each substitute signal transmitter generating a substitute signal which provides loading in a corresponding sub-band. The WDM optical network also includes a combining circuit which combines the data signals output from the plurality of optical transmitters and the substitute signals output from the plurality of substitute signal transmitters into a WDM signal, and an optical transmission fiber which receives the WDM signal from the combining circuit.

Abstract: A method for maintaining amplifier saturation in a wavelength division multiplexed (WDM) optical network having a plurality of sub-bands, each sub-band including at least two signal channels which carry respective data signals, and a plurality of substitute signal transmitters, each substitute signal transmitter generating a substitute signal and corresponding to a respective one of the plurality of sub-bands, includes identifying signal channels having a predetermined characteristic within each of the plurality of sub-bands. A substitute signal transmitter is turned on if the sub-band corresponding to the substitute signal transmitter includes a predetermined number of signal channels having said predetermined characteristic. The data signals and the substitute signals are combined into a WDM signal, and the WDM signal is transmitted over an optical transmission fiber.

Abstract: 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.

Abstract: An optical amplifier having redundancy and a dynamic range of pump power is provided. The amplifier contains a plurality of optical pump sources which are adapted to emit a plurality of pumps. The amplifier also contains a P×V coupler containing P inputs and V outputs, which is adapted to receive the pumps and to output V pump profiles, where P and V are positive integers >1 and P=V or P≠V. The pump profiles include a first set of pumps having a first set of wavelengths and having a first power and a second set of pumps having a second set of wavelengths different from the first set of wavelengths and having a second power different than the first power. The amplifier optionally contains at least one spare optical pump source which is adapted to be turned off during operation of the amplifier unless at least one of the plurality of optical pump sources becomes non operational during the operation of the amplifier.

Abstract: An optical amplifier is described that can couple to and amplify optical signals along multiple fiber transmission paths. The optical amplifier includes a plurality of pump radiation sources, each pump radiation source adapted to produce radiation having a set of pump wavelengths and pump powers corresponding to the respective pump wavelengths, wherein at least one set is different from at least one other set. The optical amplifier also includes a plurality of pump radiation combiners, each pump radiation combiner coupling the radiation of a respective set of pump wavelengths of a respective source of the plurality of pump radiation sources and outputting the respective coupled radiation having coupled radiation profiles via a respective pump radiation combiner output. The optical amplifier also includes a coupler, such as a P×V coupler with P inputs and V outputs.

Abstract: An optical amplification system is described. The system includes a series of optical amplifier groups optically connected in series. Each optical amplifier group comprising multiple optical amplifiers. The optical amplifiers of a particular amplifier group each produces pump radiation having a different set of pump wavelengths and pump powers corresponding to the respective pump wavelengths. Each amplifier group provides a desired gain profile, such as a substantially flat gain profile, over a first range of optical signal wavelengths.

Abstract: A laser-medium in the form of a dielectric crystal or glass doped with tetravalent chromium. The dielectric crystals are of olivine-like structure such as germanates of formula (A) (RE)GeO.sub.4 where (A=Na or Li, RE=Y, Lu or Gd), crystals of willemite structure Zn.sub.2 (Si or Ge)O.sub.4 tetrahedral sites, or any other single-crystal or polycrystalline compound containing the (Si.Ge)O.sub.4 tetrahedra in its crystal lattice, such as Ca.sub.3 La.sub.2 (SiO.sub.4).sub.6 and crystals such as YAG (Y.sub.3 Al.sub.5 O.sub.12).