Abstract: An optical amplifier device (REG) comprises a variable optical attenuator (DG), a control unit (CTRL), and an optical amplifier (EDFA). The gain of the amplifier (EDFA) and the attenuation of the attenuator (DG) are adjusted by the control unit (CTRL) based on a correlation (KOR) of the levels of the optical signals at the output of the optical amplifier (EDFA).

Abstract: A system and method for selectively amplifying an optical signal depending upon the amplification needs of an optical system at one point in time. The optical amplifier has an adjustable gain that can be controlled by a remote systems controller. As a result, if an optical path in an optical system is changed, the needed degree of amplification associated with that new optical path can be provided for by adjusting the optical amplifier. The output at the end of the optical system can therefore be kept within a predetermined operational range regardless to how the optical signal is switched within the optical system.

Abstract: An optical equalizer for a wavelength-multiplexed optical communication system where an optical signal composed of a plurality of signal lights with different wavelengths is transmitted through an optical transmission line.

Abstract: A wavelength within an amplifying wavelength band of an optical amplifier is introduced into the optical amplifier at all times or when an interruption and/or reduction of a ray of input light is detected. When the interruption and/or reduction of the input light is detected, an output of the excited light is interrupted or reduced, an optical switch is controlled so that the input light is interrupted, and after the input light is restored, a transmittivity of the optical switch is progressively increased or the input light is passed for a constant period of protection time. Thus, when the input light has been restored, a light surge may be reduced without any adverse affect of a reverse distribution of the optical amplifier. In the case where the input light is abruptly raised during a period of moderation of the excited level, it is possible to suppress the light surge caused by the long service life due to the natural discharge of the excited level.

Abstract: We have found that it is possible to make a multistage optical fiber amplifier having a substantially flat gain band of spectral width of 40 nm or more, excellent noise figure (e.g.,<4 dB) and output power. Such amplifiers can advantageously be used, for instance, in multichannel WDM systems and analog CATV systems. A significant aspect of the amplifier is the provision of an optical loss element (exemplarily a multi-grating optical fiber filter) that provides, at least at one wavelength in the gain band, an attenuation of more than G/3 dB, where G is the average amplifier gain (in dB) in the gain band. A further significant aspect of the amplifier is the use of relatively longer amplifier fibers, which facilitates attainment of high output power and low noise figure. Exemplarily, the amplifier is a 2-stage amplifier comprising silica-based Er-doped amplifier fiber, with three-Gaussian filters between the stages.

Abstract: A WDM communication system utilizes a pump-mediated gain-shaped fiber amplifier having a predetermined nominal signal gain bandwidth and is pumped by a plurality of laser pump sources having different wavelength outputs with their outputs combined to provide a scaled power output of a weighted average of their wavelengths for launching into at least one end of the fiber amplifier. The weighted average of the output wavelengths of the individual sources is varied to produced a modified weighted average that broadens the predetermined nominal signal gain bandwidth. The wavelength weighted average of the combined pump sources may be modified by changing the operation of at least one of the pump laser sources, e.g., by changing the power level or the temperature level of one or more of the individual pump sources or by terminating the operation of one or of the individual pump sources.

Abstract: An insulated high temperature ceramic laser tube having substantially uniform insulation along the length of the tube is disclosed having particulate ceramic insulation positioned between the outer wall of the ceramic laser tube and the inner surface of tubular ceramic fiber insulation which surrounds the ceramic laser tube. The particulate ceramic insulation is preferably a ceramic capable of sintering to the outer surface of the ceramic laser tube and to the inner surface of the tubular ceramic fiber insulation. The addition of the particulate ceramic insulation to fill all the voids between the ceramic laser tube and the fibrous ceramic insulation permits the laser tube to be operated at a substantially uniform temperature throughout the length of the laser tube.

Abstract: An optical gain block that is pumped by one or more pump input modules is disclosed. Each pump input module includes a pump source, a pump power control circuit and a bus interface. Each of the available pump input modules detect the presence and pump power of other available pump input modules in order to properly adjust the output power of its own pump source. By controlling the power provided by each of the available pump input modules, the gain block output will be maintained at a specified output power level while all pump input modules share in delivering the required total input pump power. Upon the insertion or removal of any pump input module, the remaining pump input modules will adjust their output power accordingly to maintain the gain block output power at the specified level.

Abstract: An apparatus which receives an input light having a spectrum, and determines a momental wavelength of the spectrum. The apparatus includes a decoupling unit, a weighting unit and a computation unit. The decoupling unit decouples a portion of the received input light, to provide a first signal representing the input light with the portion decoupled therefrom, and a second signal representing the decoupled portion. The weighting unit weights the second signal. The computation unit determines the momental wavelength from the power of the first signal and the power of the weighted second signal. An optical amplifier is also provided which determines the momental wavelength of an amplified light, and controls a gain tilt parameter of the optical amplifier in accordance with the determined momental wavelength, to reduce gain tilt. An optical communication system is also provided which includes a plurality of such optical amplifiers sequentially arranged along an optical transmission line.

Abstract: An optical amplifier is disclosed, which comprises an optical amplifying unit for amplifying an optical signal, a light output monitoring unit for monitoring the light output of the optical amplifying unit, a control unit for controlling the optical amplifying unit by comparing the light output of the optical amplifying unit monitored by the light output monitoring unit with a specified reference value so as to cause the light output of the optical amplifying unit to take a predetermined output value and an input light level detecting unit for detecting the input light level of the optical signal. The control unit controls the light output level of the optical amplifying unit by changing the reference value used for comparison according to the input light level detected by the input light level detecting unit.

Abstract: To enable the surveillance of a long-distance optical fiber line that a method using the reflection lights and Rayleigh backscatter lights cannot cover, a plurality of optical reflection elements P1-Pn are interposed in the optical fiber line at each specific distance. Each of the optical reflection elements P1-Pn reflects only a light signal of one of specific wavelengths .lambda.1-.lambda.n on a constant level. Light pulses of the specific wavelengths .lambda.1-.lambda.n are transmitted to the optical fiber line to measure intensities of the light pulses reflected by the optical reflection elements P1-Pn. From the measurement, surveillance of the optical fiber line can be done between the transmitter and each of positions of the optical reflection elements P1-Pn. The reflectance of the optical reflection elements P1-Pn can be set to 100%, and the surveillance becomes possible even if the length of the optical fiber line exceeds 200 km.

Abstract: Multi-wavelength light is transmitted from a sending station to a receiving station. An erbium-doped optical fiber is installed on the transmission path that connects the sending station and the receiving station. Pump light is supplied from a light source installed in the receiving station to the erbium-doped optical fiber. In the receiving station, the multi-wavelength light is decomposed into the component wavelength signals. The light level of each component wavelength signal is detected, and the power of the light emitted by the light source is controlled so as to equalize those light levels.

Abstract: An optical amplifier for a high power, solid state laser which includes a slab of a solid state laser material, for example, yttrium-aluminum-garnet (YAG) crystal. One or more diode arrays may be vertically stacked and configured to provide generally uniform energy distribution in the crystal in a vertical direction. By maintaining a relatively uniform energy distribution in the crystal in a vertical direction, thermal and stress aberrations of the resulting laser beam are minimized.

Abstract: The present invention relates to an optical filter for flattening the gain spectrum of an optical amplification system (including at least one optical amplifier) inserted in a transmission line for transmitting a plurality of signal light components having wavelengths different from each other, and a transmission system including the optical filter. The optical filter according to the invention has a transmission spectrum with inverse characteristics to those of the gain spectrum of the optical amplification system for amplifying the plurality of signal light components.

Abstract: An optical amplifier that receives an optical signal at an input of the optical amplifier is arranged so that it amplifies the signal and then adjusts the level of the amplified input signal to a predetermined level. The optical amplifier, which includes a filter to substantially decrease the wavelength dependence of the optical amplifier, then amplifies the adjusted signal and supplies the resulting signal to an output.

Abstract: An optical fiber used as the active amplifying medium in a fiber laser is arranged to have a high insertion loss at an undesired frequency, while retaining a low insertion loss at a desired lasing frequency. In one embodiment, loss at a Raman-shifted frequency is introduced by using an optical fiber which has multiple claddings with an index profile that includes an elevated index region located away from the core, but within the evanescent coupling region of the core. A distributed loss, which can be enhanced by bending, is produced at the Raman frequency which effectively raises the threshold at which Raman scattering occurs in the fiber and therefore results in a frequency-selective fiber. In another embodiment, an absorbing layer is placed around the core region. The absorbing layer is chosen to have a sharp absorption edge so that it absorbs highly at the Raman-shifted wavelength, but minimally at the desired lasing wavelength.

Abstract: There are provided a plurality of etalon filters arranged in concatenation, a light output portion for outputting a light to the etalon filters, and a light input portion to which a light transmitting the etalon filters is inputted, and the plurality of etalon filters have mutually different free spectrum regions. A plurality of etalon plates applied with semipermeable films to both surfaces of a thin glass plate and having mutually different periods and amplitudes are cascade-connected. By combining a plurality of etalon films having different characteristics with one another, it is possible to realize an optical equalizer having low loss polarized light dependency and capable of compensating optional gain wavelength dependency. By using such an optical equalizer as a repeater by combining the optical equalizer with an optical amplifier, a level difference caused by the difference of the gain among wavelengths of optical signals is neither produced in a wavelength multiple optical transmission apparatus.

Abstract: Disclosed is a bidirectional optical amplifier circuit having a function that achieves reliable detection of reflections from an exposed end at low cost. Received optical power is detected; if the detected power is less than a prescribed discrimination level, it is then decided that the detected light is not received signal light but transmitted signal light sent in the direction opposite from it and reflected at an exposed fiber end, and the bias current for a laser diode in the opposite path is reduced to lower the optical output level of an EDF.

Abstract: The invention set forth in this document discloses an optical amplifying circuit which includes a dielectric multilayer interference filter disposed at an output side or an input side of the optical amplifying element that is a part of the optical amplifying circuit. The dielectric multilayer interference filter suppresses off-band spontaneous emission.

Abstract: Disclosed is a system for amplification of ultrashort optical pulses. The disclosed system has reduced size and increased robustness, reliability and cost-effectiveness. The disclosed invention is particularly effective in chirped pulse amplification (CPA) systems wherein pulses are stretched, amplified, and re-compressed. According to one aspect of the invention a compact stretcher is used with a bulk compressor, and compatibility between them is achieved by inserting a telescope in the path of the collimated beam. Alternatively, compatibility between the stretcher and the compressor is achieved by creating nonlinearly chirped bragg grating in the fiber stretcher. According to another aspect of the invention, a fiber and a bulk amplifiers are used to amplify the pulse, and compatibility between them is achieved by inserting a doubling crystal in the path of the pulse between the two amplifiers.

Abstract: A significant part of signal-to-noise degradation in WDM optical fiber communications, due to Raman crosstalk, is found to be deterministic in nature. Shaping of amplifier output to offset depletion of high frequency channels improves signal capacity by an order of magnitude.

Abstract: An amplifying optical fiber (111) whose wavelength dependency of gain is approximated by a second-order function of wavelength in which the coefficient of square term of wavelength is a negative value and an amplifying optical fiber (112) whose wavelength dependency of gain is approximated by a second-order function of wavelength in which the coefficient of square term of wavelength is a positive value are cascaded to each other. The amplifying optical fiber (112) is realized as the kind and amount of co-dopant element are appropriately selected. To these amplifying optical fibers, pumping light is supplied by way of fiber type couplers (123, 132) after the light intensities of the pumping light output from pumping light sources (121, 131) are adjusted by light intensity adjusting devices (122, 132).

Abstract: A high capacity optical fiber network operative with wavelength division multiplexing. Contemplated systems can utilize span distances in excess of 100 km, signal amplification within spans, and provide plural multiplexed channels operative at multiple gigabits per second.

Abstract: A control apparatus for an optical amplifier such as an erbium-doped optical-fiber (EDF) amplifier suppresses overshooting of ALC control at power on and at the time of input light restoration from an off condition, while ensuring quick starting. At power on and at the time of input light restoration from an off condition, an idling current (IDC) reference value generating circuit generates an IDC reference voltage that increases to a value sufficiently greater than a value in a normal operating condition with a time constant corresponding to a rise time of the EDF, and thereby controls a laser diode for pumping the EDF. The voltage may be set to a value larger than the value in the normal operating condition for a predetermined period of time by using a timer.

Abstract: An ultrashort optical pulse amplifier that incorporates a gain medium preferentially cooled along a crystalline axis for partially ameliorating the thermally induced distortions and losses created by cylindrically symmetric cooled designs. The ultrashort pulse amplifier can be pumped with higher pump powers without degradation of the output spatial mode structure and the overall efficiency of extraction of energy from the gain medium is improved. The gain medium preferably has a rectangular cross section and cooling means are provided in thermal contact with only selected opposing surfaces of the gain medium so that thermal gradients lie approximately along a crystalline axis to reduce thermally-induced birefringence.

Abstract: An apparatus which receives an input light having a spectrum, and determines a momental wavelength of the spectrum. The apparatus includes a decoupling unit, a weighting unit and a computation unit. The decoupling unit decouples a portion of the received input light, to provide a first signal representing the input light with the portion decoupled therefrom, and a second signal representing the decoupled portion. The weighting unit weights the second signal. The computation unit determines the momental wavelength from the power of the first signal and the power of the weighted second signal. An optical amplifier is also provided which determines the momental wavelength of an amplified light, and controls a gain tilt parameter of the optical amplifier in accordance with the determined momental wavelength, to reduce gain tilt. An optical communication system is also provided which includes a plurality of such optical amplifiers sequentially arranged along an optical transmission line.

Abstract: A variable optical attenuator is provided at an input terminal of a rare-earth doped optical fiber. The variable optical attenuator attenuates a multiwavelength light under the control of an AGBC circuit. The rare-earth doped optical fiber, which is excited by an excitation light generated by a light source, amplifies the multiwavelength light output from the variable optical attenuator. An ALC circuit controls the light source in such a way that an average optical level of the multiwavelength light output from the rare-earth doped optical fiber is kept constant. The wavelength division multiplexing coupler selects two optical signals having different wavelengths from the multiwavelength light amplified by the rare-earth doped optical fiber. The AGBC circuit controls the attenuation of the variable optical attenuator in such a way that the above described two optical signal levels match each other.

Abstract: An optical fiber amplifier includes an optical filter, an optical isolator for blocking a reverse flow of a reflected light, the optical isolator including a lens coated with an integral filter having a predetermined bandwidth and an output end tab for monitoring the intensity of the output signal, the optical filter being coupled between the optical isolator and output end tab so as to only pass a specified wavelength band.

Abstract: A rare earth-doped optical fiber is supplied with a input signal light and an excitation light, so that the input signal light is amplified to be supplied to an output as an amplified signal light. At this time, an intensity of an amplification of spontaneous emission (ASE) is detected to be compared with a predetermined intensity, thereby to provide a difference signal. An amount of the excitation light is controlled by the difference signal to equalize the ASE to the predetermined intensity.

Abstract: An optically amplifying transmission system available for wider signal bands includes an optical transmission line 42 divided into two sections 42a and 42b, optically amplifying repeaters 48a having 7 m-long erbium-doped optical fibers to repeat transmission optical fibers 46a in the section 42a, and optically amplifying repeaters 48b having 10.8 m-long erbium-doped optical fibers to repeat transmission optical fibers 46b in the section 42b. The transmission optical fibers 46a an 46b are optical fibers absolutely identical in construction and length.

Abstract: An optical fiber amplifier including, in addition to an amplification medium for amplifying signal light, an excitation light source which generates excitation light to be input into the amplification medium and a photocoupler for coupling the excitation light to the amplification medium, a modulator for amplitude the excitation light, a sub-signal generator for generating a sub-signal which is superimposed on the excitation light for amplitude modulation and a frequency filter for converting the frequency characteristic of the sub-signal to input it to the the modulator means, for superimposing the sub-signal due to change in gain of the amplification medium for intensity modulation of the excitation light. High-frequency components of the sub-signal are previously emphasized through the frequency filter, and the excitation light is amplitude-modulated by the sub-signal with the emphasized high-frequency components, to superimpose the satisfactory, waveform distortion-free sub-signal on the signal light.

Abstract: A semiconductor diode laser amplifier (100) includes an active layer (4) which is situated between two cladding layers (1A, (3,6)) and in which a strip-shaped active region is present which is bounded in longitudinal direction by two end faces (7,8) which are practically perpendicular to the active region and are provided each with an antireflection layer (71,81).The amplification ripple of such a laser amplifier (100) is comparatively high, in particular when radiation of different wavelengths is present in the laser (100), such as the TE and TM portions of the radiation to be amplified.

Abstract: In an optical filter module and an optical amplification apparatus for a wavelength division multiplex (WDM light), the respective wavelength intervals of the plural passing center wavelengths and the filter characteristics in the vicinities of the respective center wavelengths can be set independently, whereby the BPF1 is provided with different passing center wavelengths .lambda.1, .lambda.2 . . . .lambda.n and different filter characteristics. And, when the WDM signal light including wavelengths .lambda.1, .lambda.2 . . . .lambda.n is inputted into the port 2-1a, the .lambda.k (k=1,2 . . . n) component is transmitted by the corresponding BPF1-k, and the transmitted light is multiplexed sequentially and outputted from the port 2-nb and the other wavelength components (noise light components) are reflected by all of the BPFs and outputted from the port 2-nc. When the WDM signal light including wavelengths except for .lambda.1, .lambda.2 . . . .lambda.

Abstract: An optical pulse signal produced by modulating a continuous laser light by means of a first pulse having a period sufficiently shorter than the atomic lifetime in the upper energy state of a rare earth doped fiber is input to an optical amplifier to be measured, while an output signal from the optical amplifier is modulated by a second pulse synchronized with the first pulse and having a phase difference relative to the first pulse which can be optionally set so that rapid phase adjustment relative to the first pulse is possible based on the phase at the time of minimum optical power. The noise figure of the optical amplifier is then measured based on, the maximum photoelectric power (P.sub.AMP +P.sub.ASE) and the minimum photoelectric power P.sub.ASE of the resultant optical signal.

Abstract: A hybrid, erbium doped fiber amplifier device has a dynamic gain tilt that is less than the gain tilt of any of the constituent fibers. The hybrid amplifying device has at most one less pumping source than the number of constituent waveguides of the device. The hybrid device automatically provides an effective change in the pump distribution among the constituent doped waveguide sections so as to achieve a readjustment of the relative gains of the constituent sections. As such, a change in the aggregate gain of the hybrid device will be as nearly spectrally uniform as possible over a range of gain values compared to the constituent doped waveguides. A method for constructing a hybrid optical amplifying device having improved dynamic gain tilt is also provided.

Abstract: The invention relates to an optical amplifier comprising an input and a beamsplitter connected by a first optical fiber arranged to transmit an optical signal from said input to said beamsplitter via an optical amplifying means and an optical isolator. The optical amplifier includes a second optical fiber connected between said input and said beam splitter and is arranged to transmit a second signal from said beamsplitter to said input. Preferably, the optical amplifier also incorporates an optical element which is adapted to prevent any signal from said input propagating along said second optical fiber and to prevent any signal from said second optical fiber from propagating along said first optical fiber.

Abstract: A high capacity optical fiber network operative with wavelength division multiplexing. Contemplated systems can utilize span distances in excess of 100 km, signal amplification within spans, and provide plural multiplexed channels operative at multiple gigabits per second.

Abstract: A nonlinear optical loop mirror device having a distributed directional asymmetry. A dispersion decreasing optical fiber is formed into a loop by an optical coupler which divides input pulses into two component pulses that propagate around the loop in opposite directions, and which transmits and/or reflects returning component pulses in accordance with their relative phases. The parameters of the loop, such as its length, effective area, rate of change of dispersion, etc. are selected so that input pulses may be switched or transmitted in accordance with whether their widths or amplitudes are above or below predetermined threshold values.

Abstract: A travelling-wave semiconductor laser amplifier having suppressed self-oscillation is provided. When incorporated into a master oscillator power amplifier device, such a device has improved light output versus amplifier current characteristics. Also provided is a method for suppressing self-oscillation in travelling-wave semiconductor laser amplifier structures for improving the characteristics of the device into which the amplifier is incorporated.

Abstract: An optical amplifier having high overall gain and low gain tilt, useful in an optical transmission system or the like. The amplifier has a doped optical fiber as the amplification medium and two pumps, the shorter wavelength one propagating with the signal being amplified and the longer wavelength one propagating opposite the signal being amplified. A wavelength selective reflective fiber grating is disposed along the doped fiber to reflect the second pump signal. The addition of the grating allows the amplifier to have a higher gain with a lower gain tilt than amplifiers without the grating. Positioning the grating along the fiber allows for the control of the overall gain with respect to the gain tilt for a given fiber length.

Abstract: A method and apparatus for measuring the noise level in an optical amplifier in the presence of a signal at a signal wavelength. The signal is detuned to a second wavelength different from the signal wavelength. A difference function corresponding to the difference in noise levels before and after detuning of the signal as a function of wavelength is determined. The noise level at the signal wavelength is measured. The value of the difference function at the signal wavelength is added to the noise level measured in the previous step.

Abstract: A nonlinear optical loop mirror device having a distributed directional asymmetry. A dispersion decreasing optical fiber is formed into a loop by an optical coupler which divides input pulses into two component pulses that propagate around the loop in opposite directions, and which transmits and/or reflects returning component pulses in accordance with their relative phases. The parameters of the loop, such as its length, effective area, rate of change of dispersion, etc. are selected so that input pulses may be switched or transmitted in accordance with whether their widths or amplitudes are above or below predetermined threshold values.

Abstract: In an optical amplification monitoring apparatus of the invention, the number of signal light beams actually being transmitted is detected and an optical amplifier is controlled in accordance with the detected number. There is provided a means for monitoring intermodulation light beams resulting from signal light beams of two wavelengths which means includes a nonlinear medium and a WDM coupler that are provided on a light transmission path, an optical fiber grating for allowing passage of only intermodulation light components among the branched light beams, and a photodetector for converting the detected intermodulation light components into currents. A dispersion-shift optical fiber having a zero-dispersion wavelength in the 1.55-.mu.m band is used as the nonlinear medium. Intermodulation light beams are generated only when both signal light beams having different wavelengths w1 and w2 exist in the nonlinear medium.

Abstract: A semiconductor substrate includes an active waveguide to guide optical signals to be amplified occupying signal channels within a gain band of the waveguide. A stabilizer system comprises two Bragg reflectors tuned to a resonant wavelength in the gain band but outside the signal channels. It includes a gain segment in a resonant cavity. Two rejector Bragg reflectors sandwiching the resonant cavity between them are tuned to the resonant wavelength. Applications include telecommunication systems.

Abstract: A solid-state laser architecture producing a beam of extremely high quality and brightness, including a master oscillator operating in conjunction with a zig-zag amplifier, an image relaying telescope and a phase conjugation cell. One embodiment of the laser architecture compensates for birefringence that is thermally induced in the amplifier, but injects linearly polarized light into the phase conjugation cell. Another embodiment injects circularly polarized light into the phase conjugation cell and includes optical components that eliminate birefringence effects arising in a first pass through the amplifier. Optional features permit the use of a frequency doubler assembly to provide output at twice optical frequencies, and an electro-optical switch or Faraday rotator to effect polarization angle rotation if the amplifier material can only be operated at one polarization.

Abstract: In an optical amplifying device, an optical direct amplifier (11) amplifies input optical signals subjected to wavelength division multiplexing (WDM). A beam splitter (12) splits the amplified WDM signals into two. An optical filter (13A) separates a particular optical signal from one of the two outputs of the beam splitter (12). An optoelectrical converter (14) converts the separated optical signal to a corresponding electric signal. A gain controller (15) controls the gain of the direct amplifier (11) on the basis of the electric signal output from the converter (14). The optical filter 13A may be replaced with an optical variable filter (13B) and controlled by control means when the optical signal for gain control is shut off or sharply varied in wavelength. Because the gain of the direct amplifier (14) is controlled by use of particular one of the plurality of WDM signals, the individual optical signal is controlled to a preselected level even when the number of WDM signals is changed.

Abstract: A fiberoptic amplifier system having an optical amplifier, which receives an input signal and generates an amplified signal and amplified spontaneous emission noise, and a variable polarization beam splitter, which receives the amplified signal and amplified spontaneous emission noise from the optical amplifier. The amplified spontaneous emission (ASE) noise is a broadband optical noise with a random polarization state in a rare earth-doped fiber optical amplifier. In a semiconductor laser diode optical amplifier, the ASE noise is partially polarized depending upon the waveguide structure of the laser diode.

Abstract: An optical amplifier of the type including an inlet for a light signal to be amplified and an outlet for an amplified light signal that has been amplified by means of an amplifying waveguide that is controlled by regulation light coming from a pumping diode; the amplifier comprising: an optical circulator having an inlet port receiving the light signal to be amplified, an outlet port delivering the amplified light signal, and two intermediate ports, the first of the intermediate ports being connected to the amplifying waveguide; and regulation means having an inlet connected to the second of the intermediate ports and an outlet connected to the pumping diode, whereby the amplifying waveguide has equalized gain for all of the carrier waves constituting the amplified light signal.

Abstract: The present invention relates to a laser amplification system (1). The system (1) is constituted by a laser light source (2) for providing a main laser beam (LB); a laser light amplifier (3) for amplifying the main laser beam (LB) and apparatus for supplying a bleed laser beam (BO) to the laser radiation amplifier (3). The bleed laser beam (BO) is amplified by the laser radiation amplifier (3) at least when the main laser beam (LB) has a low or zero power valve substantially to prevent super-radiance.

Abstract: An optical amplifying-repeating transmission system is disclosed which is composed of an optical fiber for transmitting a lightwave signal with digital information added to return-to-zero lightwave pulses and a plurality of optical amplifying repeaters inserted in the optical fiber for transmission use. The mean value of wavelengths at which the wavelength dispersion of the optical fiber is zero is smaller than the wavelength of the lightwave signal which is transmitted over the system. The accumulated wavelength dispersion value of the optical fiber tends to increase with the distance of transmission, from a macroscopic viewpoint. The optical fiber for transmission is divided into a plurality of sections.