Abstract: A rotary disk module, having a rotary disk is interposed between a pair of heat sinks each spaced from the rotary disk by a gap. A motor is installed for driving the rotary disk to rotate. The gaps are filled with cooling medium such as helium, water or liquid nitrogen to remove the heat generated in the rotary disk by conduction, convection or evaporation. The rotary disk may be fabricated from various materials depending on the intended applications of the module, and the heat sink surfaces are preferably fabricated from materials with higher thermal conductivity. The rotation of the rotary disk allows the regions on which an optical pump radiation is delivered to be separated from the regions from which an optical radiation is extracted. In addition to improved heat dissipation effect, the rotation of the optical disk allows multiple directions of pump energy or multiple sources of pump energies and/or multiple beams of optical radiation to be applied and extracted simultaneously.

Abstract: An optical amplifier for amplifying an optical signal (1002), the optical amplifier comprising: an optical fibre, the optical fibre including a doped core, an inner cladding extending substantially radially outwardly from the doped core and an outer cladding extending substantially radially outwardly from the inner cladding; a signal coupler for receiving the optical signal and guiding the optical signal into the doped core; a first pump light source for producing a first pump light having a first power, the first pump light source being optically coupled to the optical fibre at a first location therealong for guiding the first pump light into the inner cladding at the first location; and a second pump light source for producing a second pump light having a second power, the second power being larger than the first power, the second pump light source being optically coupled to the optical fibre at a second location therealong for guiding the second pump light into the inner cladding at the second location; wh

Abstract: This invention pertains to a device and method for making same. The device includes a substrate supporting optical waveguide, an overlay waveguide and a mode coupler for coupling between the substrate-supported and overlay waveguides. One embodiment includes a high-confinement overlay waveguide capable of low-loss bends with small bend radii, down to tens of microns, which represents two orders of magnitude improvement over prior art. One embodiment includes a feedback path enabled by the high-confinement waveguide, capable of implementing tunable ring resonator filters with free spectral ranges over 100 GHz and modulators with compact and interferometrically stable feedback paths. Another embodiment includes a periodically poled lithium niobate section capable of integrating wavelength conversion within a compact feedback path. Another embodiment includes an amplifier section, which may be incorporated in the feedback path.

Abstract: A device for use in optical signal control is presented. The device comprises an amplification waveguide, including a pumpable medium, and a reference and a control inputs and an output selectively allowing transmission of light respectively into and out of said amplification waveguide. The reference input, the amplification waveguide and the output define together a transmission scheme for reference light through the pumpable medium. The control input and the amplification waveguide define a depletion scheme for the pumpable medium and control light. The device thus allows for controlling an output signal, formed by the transmission of the reference light, by controllable depletion of the pumpable medium.

Abstract: The present invention relates to a technique for tuning the transmission time of optical signal, which adopts an optical amplifier with a bending structure for enhancing the tunable time of optical signal. The effect of tunable time of optical signal can be achieved by adjusting the gain of the optical amplifier.

Abstract: An apparatus for suppressing optical power transients includes a variable optical attenuator receiving an input optical signal and outputting an output optical signal; an optical power sensing element coupled to the input optical signal and sensing a portion of the input optical signal; and a feedforward loop controller coupled to the variable optical attenuator and to the optical power sensing element; the feedforward control loop providing feedforward control of the variable optical attenuator to reduce optical power transients of the input optical signal and maintain a substantially constant output power based on the input optical power and a reference value; the variable optical attenuator having a default opaque state in which the input optical signal is substantially attenuated when power is not being supplied to said variable optical attenuator. Variations include feedback loop controllers and a combination feedback and feedforward loop controllers.

Abstract: A multi-channel optical amplifier arrangement operating over a particular bandwidth is provided. The amplifier arrangement includes at least one optical amplifier stage that includes a rare-earth doped optical waveguide, at least one pump source for supplying optical pump energy to the doped optical waveguide, and at least one coupler for coupling the optical pump energy to the doped optical waveguide. The amplifier arrangement also includes a dynamic range enhancer (DRE) having an input and an output and a plurality of distinct optical paths each selectively coupling the input to the output. At least two of the optical paths produce different gain spectra across the particular operating bandwidth. The DRE further includes an optical path selector for selecting any optical path from among the plurality of optical paths such that for all channels in the particular bandwidth the selected path optically couples the input to the output of the DRE.

Abstract: The present invention relates to an optical gain waveguide having excellent gain flatness in C-band, and excellent tolerance against variations of a pumping light wavelength as well, and a method of controlling the same. The optical gain waveguide includes an optical waveguide region which is doped with Er element which can be pumped by irradiating pumping light with a wavelength of 976 nm or less, or a wavelength of 981 nm or more. A population inversion of Er is optimized so that a gain variation in the C-band becomes minimum, by the irradiation of the pumping light. At this time, a relative gain variation of the optical gain waveguide, which is defined by a peak gain value and a minimum gain value in the wavelength region of 1,530 nm to 1,560 nm becomes smaller than 11.5%. In addition, in the optical gain waveguide, a width of wavelength range producing the relative gain variation smaller than 11% is 36 nm or more.

Abstract: A reliable optical transmission system with an improved signal control mechanism that avoids abrupt power variations of light beams, thereby preventing optical supervisory channel (OSC) signals from experiencing errors. An optical amplifier amplifies main signals under the control of an optical amplifier controller, which spends a first predetermined time to raise the output power of the optical amplifier up to a desired level. A pump light source produces a pump beam for injection to a fiber-optic transmission line so as to make it serve as an amplifying medium. The pump light source is controlled by a pump light source controller that spends a second predetermined time to raise the pump beam to a desired power level. This stepwise start-up process of the amplifier power and pump beam power prevents OSC signals from experiencing abrupt power variations.

Abstract: An optical amplifier for amplifying light includes a light source for emitting pump light in accordance with current amount; a rear earth element doped optical fiber doped rear earth element, the rear earth element doped optical fiber pumped by the pump light from the light source; a detector for detecting upconversion light leaked from the rear earth element doped optical fiber; a memory for storing correspondence relationship data of the current amount for the light source and an intensity of the upconversion light in normal state of the light source; a difference calculator for calculating a difference between the intensity of the upconversion light being detected by the detector and a converted amount being converted the current amount for the light source by the use of the correspondence relationship data; and a discriminator for discriminating whether the difference calculated at the difference calculator exceeds a predetermined value.

Abstract: The specification describes an improved approach to suppressing fast transients in optical amplifier systems. The approach relies on operating the amplifier in an automatic power-mode control with an extra loss component. It is applicable to optical amplifiers based on rare earth amplifier media, such as erbium doped fiber amplifiers (EDFAs).

Abstract: A photonic bandgap fiber includes a core and a cladding that surrounds the core. In this photonic bandgap fiber, high refractive index portions which have a refractive index higher than that of a medium of the cladding are provided in the cladding so as to form a triangular lattice structure with a lattice constant ?, and the refractive index of the core is higher than the refractive index of the medium of the cladding and lower than the refractive index of the high refractive index portion. The coupling length between the core and the high refractive index portion that is closest to the core is longer than the coupling length between adjacent high refractive index portions, or a periodic structure formed by the high refractive index portions is not provided around the entirely of the area along the circumference of the core.

Abstract: An optical signal processing apparatus includes an input unit to which signal light is input; a wave coupling unit that couples the signal light from the input unit and pump light having a waveform different from that of the signal light; a first nonlinear optical medium that transmits light coupled by the wave coupling unit, the light being the signal light and the pump light; a dispersion medium that transmits the light that has been transmitted through the first nonlinear optical medium; and a second nonlinear optical medium that transmits the light that has been transmitted through the dispersion medium.

Abstract: The present invention discloses a fiber amplifier, a fabricating method thereof, and a fiber communication system. The fiber amplifier includes at least a pump laser, at least a gain medium and at least an integrated optical component. The integrated optical component includes multiple optical input/output ports, and the optical input/output ports are connected to the pump laser or gain medium directly or indirectly. The present invention may better address problems of unstable performance and difficulty in reducing the size of components in the prior art where fiber amplifiers are formed by a number of discrete components with many fiber fusion splices. In addition, the present invention may reduce the production complexity and costs of fiber amplifiers, and improve the productivity of fiber amplifiers.

Abstract: The present invention relates to an optical amplifier and the like having a flatter gain spectrum in the wavelength band of 1490 nm to 1520 nm than before. The optical amplifier according to the present invention comprises an Er-doped optical waveguide and a Tm-doped optical waveguide having gain spectra difference from each other in the wavelength band. The signal light entered through the input end is first amplified by the Er-doped optical waveguide, and thereafter is amplified by the Tm-doped optical waveguide. The gain deviation of the amplified signal light, which has been amplified in the Er- and Tm-doped optical waveguides and outputted through the output end, can be reduced over the wavelength band.

Abstract: A first step, in which P2O5-containing glass is deposited inside a silica glass pipe, and a second step, in which a Cl2-containing gas is introduced into the pipe and the P2O5-containing glass is dehydrated by heating the pipe, are repeated alternately. A third step, in which glass that does not contain P2O5 is deposited on the inside of the silica glass pipe, may further be provided such that the first step, the second step, and the third step are repeatedly performed in this order. A rare-earth-doped optical fiber, which has a attenuation of 15 dB/km or less at a wavelength of 1200 nm, comprises a core region and a cladding region enclosing the core region, wherein the core region includes phosphorus of 3 wt % or more, aluminum of 0.3 wt % or more, a rare-earth element of 500 wtppm or more, and chlorine of 0.03 wt % or more, and the cladding region has a refractive index that is lower than the refractive index of the core region.

Abstract: The present invention relates to an optical module that has a structure for protecting a pumping light source at a low cost. The optical module comprises an amplification optical fiber, an optical coupler, a pumping light source, a delay optical fiber, a seed light source, an optical fiber, a photodetector, an optical fiber, an optical isolator, an optical isolator, and a control section. Through the insertion of the delay optical fiber between the pumping light source and the optical coupler, the timing of the output control of the pumping light source which is carried out after the photodetector detects return light leads the timing with which the return light enters the pumping light source. Hence, the time with which the return light enters the pumping light source is shortened and the accumulative damage time of the pumping light source is reduced.

Abstract: A device for receiving optical signals comprising a light-guiding object having an irradiation surface for receiving optical signals adjacent to a propagation path along which light primarily travels within the light-guiding means. The light-guiding object is substantially constructed of a synthetic material capable of causing elastic dispersion of optical signals received through the irradiation surface at angles between about 0 and 90 degrees relative to the irradiation surface. The synthetic material is further capable of undergoing a population inversion by energetic excitation. The system further includes an excitation unit for inducing a population inversion within the synthetic material. An optical signal is coupled into the light-guiding means through the irradiation surface resulting in a radiation component of the optical signal in the direction of the propagation path of the light-guiding object due to elastic dispersion of the optical signal caused by the synthetic material.

Abstract: An optical amplifier may be quickly returned from a shutdown state to a regular state after getting recovery information of a fault. Gain setting by ASE is conducted to the repeaters on the up-stream side during the shutdown state, by outputting ASE light with the same intensity as the WDM signal. Accordingly, before realizing the recovery of shutdown, the gain setting is completed with the light whose intensity is within the safe criterion. After realizing the recovery of shutdown, the optical transmission system can be returned quickly to the regular operating state after recovery of shutdown state.

Abstract: To induce a targeted non-linear optical effect by a high-peak-power light by using a light pulse from a semiconductor laser without using a light pulse from a large, high-average-power solid laser such as titanium sapphire laser. A semiconductor laser pulse beam with a wavelength of 1550 nm (for example, repeatability of 1 MHz) from a semiconductor laser (laser diode: LD) is efficiently amplified in two stages, front-end and main EDFAs. An optical filter removes a spontaneous emission light component that is noise. An optical filter picks up, from the amplified pulse beam, second harmonic light pulse produced by the non-linearity of an optical device (frequency polarization inversion Mg-added LiNbO3:PPMgLN) to produce a super-continuum light in a 800 nm wavelength region from a photonic crystal fiber (PCF).

Abstract: An optical fiber amplifier pumping technique based on multiple stimulated Raman scattering (SRS) for optical communication systems includes a plurality of pump signals with increasing wavelength which are injected into a fiber. The wavelengths of such pump signals are such that, in cascade, each pump signal of the plurality is amplified by the pump signal of wavelength immediately shorter, while it amplifies that with the wavelength immediately higher with the pump signal of highest wavelength which, in turn, pumps a remote rare earth doped optical fiber amplifier.

Abstract: An optical fiber amplifier system is described and comprises a first optical fiber having a doped core with a first gain spectral profile upon being pumped. The first optical fiber is adapted to receive an optical signal from a light source. A second optical fiber has a doped core with a second gain spectral profile upon being pumped. The second optical fiber is optically coupled to the first optical fiber. A continuous wave pump light system is optically coupled to the fibers so as to store energy in the fibers for a subsequent amplification of the optical signal from the light source. An overlapping configuration is provided between the first gain spectral profile and the second gain spectral profile so as to reduce energy depletion in one of the optical fibers from amplification of spontaneous emission generated by another of the optical fibers.

Abstract: An optical apparatus design and method for suppressing cladding-mode gain in fiber- and other waveguide-amplification devices. In some embodiments, a signal-wavelength-absorbing core or region is included within the pump cladding or the pump waveguide, in order to absorb signal-wavelength radiation that occurs in the regions where only pump-wavelength radiation is wanted. This absorbing region prevents cladding-mode gain, thus preserving more pump-wavelength excitation for amplifying the desired signal radiation. In other embodiments, the refractive-index profile of the fiber or other waveguide is adjusted to reduce the numeric aperture and thus reduce the angle of light that will remain in the cladding.

Abstract: Provided is an optical fiber for amplification and an optical fiber amplifier for use in L-band, in which optical fiber the increase of transmission loss and the degradation of hydrogen-resistant characteristic can be restrained. The optical fiber is basically made of silica glass and comprises: a core region doped with erbium and P element of 2 wt % to 5 wt % concentration, Ge not being added thereto; and a cladding region enclosing the core region and doped with F element, wherein the optical fiber has a gain at least in a wavelength range of 1570 to 1620 nm. The optical fiber amplifier comprises: the optical fiber; a pump light source for outputting the pump light capable of exciting a rare-earth element added to the core region of the optical fiber; and an optical coupler for introducing into the optical fiber the pump light having been output from the pump light source.

Abstract: An apparatus for amplifying optical communications systems is provided in which one or more amplifier modules, each containing an optical amplifier and at least two pump lasers, are optically isolated from a plurality of control modules. Each control module controls a single pump laser in one or more of the amplifier modules. A control module can thus be removed without disabling any amplifier module, while the plurality of pump lasers in each amplifier module allow for effective operation even if one of the pump lasers should fail. The pump lasers in each module are controlled by a master-slave relationship, whereby the master pump laser is adjusted to optimise overall output, while the slave laser(s) are adjusted to equalize the power output of the lasers.

Abstract: Provided is an all-optical gain-clamped fiber amplifier, comprising transmission and isolation means for periodically transmitting an optical signal or reflecting amplified spontaneous emission (ASE) back to a gain medium. The transmission and isolation means can be embodied by an optical interleaver or a number of optical fiber Bragg gratings. Accordingly, an optical signal can be amplified across the entire C-band, and an ASE reflector-based gain-clamped fiber amplifier having a wider dynamic range than conventional amplifiers can be implemented.

Abstract: The present invention relates to an optical component comprising an acceptance fibre, e.g. a photonic crystal fibre, for propagation of pump and signal light, a number of pump delivery fibres and a reflector element that reflects pump light from the pump delivery fibres into the acceptance fibre. It is an object of the invention to provide a fibre coupler for coupling two or more light sources into a multi-clad (e.g. double clad) optical fibre, which has practical advantages with respect to handling, loss and back reflection.

Abstract: The specification describes optical devices and related methods wherein an input mode is converted by multiple LPG mode transformers to produce an output with multiple predetermined modes.

Abstract: In a LMA optical fiber the index of the core region is graded (i.e., as viewed in a radial cross-section) and has a grading depth of ?ng, as measured from a central maximum at or near the axis to a lower level that is not greater than the central maximum and not less than the index of the cladding region. When the fiber is to be bent at a bend radius, the grading depth, the radius of the core region, and the difference between the central maximum index and the cladding region index are configured to reduce bend distortion. They may also advantageously be configured to maximize the effective mode-field area of the fundamental mode, suppress higher order modes, and reduce bend loss. In a preferred embodiment, the core region includes a centralized gain region, which in turn includes a dark region that is no more than 30% of the area of the gain region. Also described is a method of making such LMA fibers.

Abstract: A method for generating a linear single-polarization output beam comprises providing an optically active linearly birefringent and linearly dichroic fiber for propagating light and having a single polarization wavelength range and a gain bandwidth; optically pumping the optically active linearly birefringent and linearly dichroic fiber for obtaining fluorescence within the gain bandwidth; and aligning the single-polarization wavelength range to overlap a desired spectral region of the gain profile.

Abstract: A method is provided for optical amplification using a silicon (Si) nanocrystal embedded silicon oxide (SiOx) waveguide. The method provides a Si nanocrystal embedded SiOx waveguide, where x is less than 2, having a quantum efficiency of greater than 10%. An optical input signal is supplied to the Si nanocrystal embedded SiOx waveguide, having a first power at a first wavelength in the range of 700 to 950 nm. The Si nanocrystal embedded SiOx waveguide is pumped with an optical source having a second power at a second wavelength in a range of 250 to 550 nm. As a result, an optical output signal having a third power is generated, greater than the first power, at the first wavelength. In one aspect, the third power increases in response to the length of the waveguide strip.

Abstract: The effect of bending is anticipated in an optical fiber design, so that resonant coupling remains an effective strategy for suppressing HOMs. The index profile of the fiber and its bend radius are configured so that there is selective resonant coupling of at least one HOM, but not the fundamental mode, in the bent segment of the fiber. In an illustrative embodiment, the bend radius (or predetermined range of bend radii) of an optical fiber is known a priori. The core and cladding regions are configured to support (guide) the propagation of signal light in a fundamental transverse mode and at least one higher-order transverse mode in the core region. The cladding region includes an outer cladding region and an annular trench region. The trench region includes at least one axially extending, raised-index pedestal (waveguide) region having a refractive index higher than that of the outer cladding region.

Abstract: An apparatus for suppressing optical power transients includes a variable optical attenuator receiving an input optical signal and outputting an output optical signal; an optical power sensing element coupled to the input optical signal and sensing a portion of the input optical signal; and a feedforward loop controller coupled to the variable optical attenuator and to the optical power sensing element; the feedforward control loop providing feedforward control of the variable optical attenuator to reduce optical power transients of the input optical signal and maintain a substantially constant output power based on the input optical power and a reference value; the variable optical attenuator having a default opaque state in which the input optical signal is substantially attenuated when power is not being supplied to said variable optical attenuator. Variations include feedback loop controllers and a combination feedback and feedforward loop controllers.

Abstract: Provided are a passive optical network system and a method of transmitting a broadcasting signal in the same system. A central office (CO) generates a broadcasting signal and a downstream optical data signal using a coding method guaranteeing a run-length, multiplexes the downstream optical data signal and the broadcasting signal, and transmits the multiplexed downstream optical data signal and broadcasting signal. A remote node (RN) transmits the multiplexed downstream optical data signal and broadcasting signal received from the CO to one or more optical network units (ONUs). A gain medium, which is located on a transmission line between the CO and the RN, amplifies the broadcasting signal using the downstream optical data signal as a pump light source. Accordingly, a high gain can be obtained by amplifying the broadcasting signal using the gain medium located on the transmission line without a separate pump light source.

Abstract: A device and method for reducing amplified Rayleigh backscatter at a Raman pump. A pump assembly for an optical amplifier includes a set of pump radiation sources for Raman pumping an optical transmission span. Each pump radiation source is adapted to produce radiation having a pump wavelength and a pump power. The optical transmission span is adapted to provide Raman amplification of an optical data signal when pumped by the set of pump radiation sources. At least one optical isolator is selectively located between at least one selected pump radiation source and the optical transmission span to reduce amplified Rayleigh backscatter at the pump wavelength of the selected pump radiation source from feeding back into the selected at least one pump radiation source.

Abstract: The invention relates to a light source apparatus having a structure for effectively suppressing a negative effect due to a nonlinear effect generated in propagation of an amplifying light, and realizing a stable operation. In the light source apparatus, light amplified in an optical amplifier fiber is emitted to the outside of the apparatus through an optical output fiber whose one end is connected to an output connecter. At this time, a part of Raman scattered light, generated in the optical output fiber, propagates toward an pumping light source through the optical amplifier fiber from the optical output fiber. An optical component having an insertion loss spectrum that attenuates the Raman scattered light but allows pumping light or light to be amplified to transmit therethrough, is provided on a propagation path of the Raman scattered light, due to the light component, the intensity of the Roman scattered light reaching the pumping light source is effectively reduced.

Abstract: An electronic circuit for controlling a laser system consisting of a pulse source and high power fiber amplifier is disclosed. The circuit is used to control the gain of the high power fiber amplifier system so that the amplified output pulses have predetermined pulse energy as the pulse width and repetition rate of the oscillator are varied. This includes keeping the pulse energy constant when the pulse train is turned on. The circuitry is also used to control the temperature of the high power fiber amplifier pump diode such that the wavelength of the pump diode is held at the optimum absorption wavelength of the fiber amplifier as the diode current is varied. The circuitry also provides a means of protecting the high power fiber amplifier from damage due to a loss of signal from the pulse source or from a pulse-source signal of insufficient injection energy.

Abstract: An optical system including a gain material pumped by pump energy bands delivered to the gain material from different directions and separated sufficiently to prevent crosstalk between pump energy sources. Embodiments of the pump energy sources may be configured to pump the gain material with pump energy bands that correspond to absorption bands of the gain material.

Abstract: An doped fiber optical amplifier featuring an optical component having first wavelength division multiplexer, an isolator and a second wavelength division multiplexer is described. The isolator supports the propagation of optical signals within a predetermined signal wavelength range in one direction. Pump signals having a wavelength within a pump wavelength range are diverted by the wavelength division multiplexers to inhibit coupling of the pump signals with the isolator. The optical amplifier supports the use of relatively high-powered optical pump lasers. The optical component is optically disposed between different lengths of doped fiber and serves to reduce optical noise within the amplifier.

Abstract: In each of a plurality of submarine observation apparatus (1 to n), a branching unit (63) branches fixed-wavelength light (?1) from an incoming wavelength-multiplexed light signal. An observation signal modulating unit (64) modulates the intensity of the branched fixed-wavelength light (?1) with observation information multiplexed by an observation signal multiplex unit (61). A combining unit (65) combines light signals (?2) to (?n) passing through the branching unit (63) and the fixed-wavelength light (?1a) modulated by the observation signal modulating unit (64) into a composite light signal, and outputs it to an optical fiber (12a). Therefore, in each of the plurality of submarine observation apparatus (1 to n), there is no necessity for providing a wavelength-division-multiplexing-transmission optical transmitter which requires high wavelength stability.

Abstract: An optical buffer employing Bragg scattering (BS), in which two pump signals are combined with an input (data) signal in a four-wave mixing (FWM) medium to frequency convert the input signal into an idler signal, which is applied to a dispersive medium, in which the idler signal propagates at a speed different from that of the input signal. By selectively turning on and off a pump, e.g., at bit-level switching rates, the BS-based frequency conversion can be selectively performed on particular bits in the input signal, e.g., to generate an output signal having reordered bits. A BS-based optical buffer can (1) be tuned to achieve different amounts of delay; (2) support single-channel or multiple-channel, classical or quantal communications; (3) be implemented with co-phased pump-phase modulation to suppress stimulated Brillouin scattering, while inhibiting spectral broadening of the idler signal; and (4) provide polarization independence using standard polarization-diversity techniques.

Abstract: An apparatus and method for pumping optical fibers. An optical element is disposed for directing pump energy into the inner cladding of a dual clad optical fiber, where the optical element has a refractive index greater than the refractive index of the inner cladding. A gradient refractive index structure is disposed between the optical element and the inner cladding to provide for a smooth transition from the refractive index of the optical element to the refractive index of the inner cladding.

Abstract: The present invention relates to an optical module which is capable of amplifying light to be amplified to high power and which has a structure for effectively reducing influences of damage to other optical parts, and heat generation. The optical module includes a fiber unit constituted by an optical coupler, an amplification optical fiber, and an absorption optical fiber. Each of the amplification optical fiber and the absorption optical fiber has a core, a first cladding, a second cladding, and a third cladding. Further, each of the fibers allows the light to be amplified to propagate in a single mode in each of the cores, and allows pumping light to propagate in a multimode in the core, the first cladding, and the second cladding. The core of the amplification optical fiber is doped with an amplification dopant for amplifying the light to be amplified. The second cladding of the absorption optical fiber is doped with an absorption dopant for absorbing the pumping light.

Abstract: A fibre laser is disclosed comprising a single mode or low-order-mode cladding pumped fibre laser oscillator or preamplifier, a cladding pumped fibre laser power amplifier to guide multiple transverse modes, wherein an output from the oscillator or preamplifier is applied through a mode mixing means to the power amplifier. The laser power amplifier is of greater core and cladding diameter than the oscillator or preamplifier, thus enabling lower brightness pump sources to be employed.

Abstract: The invention relates to a multistage fibre amplifier having a first amplifying fibre (EDFI) and at least one further amplifying fibre (EDF2) connected in series, and also a pump source (2D), a first pump signal (A1) being fed to the first amplifying fibre (EDFI) and a further pump signal (A2) being fed to the further amplifying fibre (EDF2). The multistage fibre amplifier is distinguished by the fact that the further pump signal (A2) is fed to the further amplifying fibre (EDF2) via a power-dependent attenuation element (ZFED). The attenuation element (ZFED) is formed in such a way that, as the pump power increases, small further pump signals are attenuated to a greater extent than large further pump signals. The power-dependent attenuation of the pump signal (A2) fed to the further amplifying fibre primarily results in improvements in the noise figure of the multistage amplifier. A method for adapting the pump power of the multistage fibre amplifier according to the invention is furthermore specified.

Abstract: A signal light transmitting apparatus from which signal light is led into a transmission optical fiber, the transmission optical fiber transmitting the led signal light, includes: a signal light power changer which changes power of signal light led thereto, the changed signal light being led into the transmission optical fiber therefrom; a scattering pump light source which emits scattering pump light producing scattered light in the transmission optical fiber; a scattered light power measure which measures the power of the produced scattered light; and a controller which controls the signal light power changer based on the measured power of the scattered light.

Abstract: Optical apparatus includes a multimode, gain-producing fiber for providing gain to signal light propagating in the core of the fiber, and a pump source for providing pump light that is absorbed in the core, characterized in that (i) the pump source illustratively comprises a low brightness array of laser diodes and a converter for increasing the brightness of the pump light, (ii) the pump light is coupled directly into the core, and (iii) the area of the core exceeds approximately 350 ?m2. In one embodiment, the signal light propagates in a single mode, and the pump light co-propagates in at least the same, single mode, both in a standard input fiber before entering the gain-producing fiber, and a mode expander is disposed between the input fiber and the gain-producing fiber. In another embodiment, multiple pumps are coupled into the core of the gain-producing fiber. The pumps may generate light of the same wavelength or of different wavelengths.

Abstract: 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.

Abstract: The present invention provides a solar-pumped active device which utilizes a holographic antenna grating on a solar energy silicon substrate to select specific diffracted wavelength and couple pump wavelength in an approximately vertical way and converge the pump wavelength to excite an optical gain medium so that an optical amplifier or a laser can be obtained. The present invention requires no big size and is flexible over the surface shape and is suitable for free space optical communications on the ground and satellite optical communications. It means that the holographic antenna grating can be applied on the top floor of a building or on the glass surface of an outer wall. If it is applied to a satellite, the present invention can be deposited on a solar energy cell substrate to form a high optical amplification so that not only the electricity required in satellite optical communications can be reduced, but also a high-speed and large capacity of data can be transferred between satellites.

Abstract: An optical signal amplifier includes a light source, a depolarizer, and a gain medium that transfers energy from a pump beam output from the depolarizer to the optical signal. The depolarizer may include one or more birefringent optical fibers which support two polarization modes, a fast mode and a slow mode. The light propagates in the fast mode at a higher velocity than the light propagates in the slow mode so as to impart phase delay as the light propagates in the birefringent optical fibers, thereby at least partially depolarizing the beam. A method for using the amplifier with different types of transmission fibers enables the matching of depolarizers with relatively high percentage of degree of polarization, depending on fiber type, while staying below polarization dependent gain requirements.