Abstract: In an optical amplifier for use in, for example, a wavelength multiplexing optical communication system, in order to allow an excitation light source to be enlargeable or removable in accordance with an increase/decrease in the number of channels in signal light even if the optical communication system is in operation, there are included an optical amplifying section (2) for amplifying and outputting inputted signal light, a plurality of excitation light sources (3, 4) and an excitation light source control section (5) for controlling operations of the excitation light sources (3, 4), wherein the excitation light sources are composed of a main excitation light source (3) and an auxiliary excitation light source (4), and the excitation light source control section (5) is equipped with a control section (7) which, when the number of channels in the inputted signal light is equal to or less than a predetermined number of channels, executes control whereby the main excitation light source (3) supplies excitation

Abstract: A reliable and inexpensive method for deploying, operating and maintaining optical amplifiers in a variety of optical networks under a wide range of conditions using channel number reference tables. A preferred embodiment of the current invention may control one or more optical amplifiers or gain blocks operating in a variety of modes such as AGC mode, ALC mode and hybrid AGC/ALC mode without requiring the use of expensive channel counters. Channel number reference tables may be calculated based on initial input optical power output readings and a count of the number of channels initially served by the amplifier. According to the current invention, changes in the number of channels may be monitored and used to control a gain block by monitoring the gain block input optical power output, converting to a gain block voltage and referencing the channel number reference table.

Abstract: The present invention aims at providing a controlling apparatus and a controlling method for a wavelength division multiplexing optical amplifier to reduce the controlling error due to the affection of noise light included in the monitoring light to be used for controlling the wavelength division multiplexing optical amplifier, to thereby realize precise controlling of the optical amplifier. To this end, the controlling apparatus for a wavelength division multiplexing optical amplifier according to the present invention: branches, by a photocoupler, a portion of WDM signal light amplified by a light level controlling part; and separates the thus branched light into groups of even-numbered channel components and odd-numbered channel components making use of a wavelength channel separate filter. Further, monitor signals corresponding to the light powers of the even-numbered group and odd-numbered group, respectively, are generated by respective photoelectric converting parts and LPF's.

Abstract: In an optical amplifier for use in, for example, a wavelength multiplexing optical communication system, in order to allow an excitation light source to be enlargeable or removable in accordance with an increase/decrease in the number of channels in signal light even if the optical communication system is in operation, there are included an optical amplifying section (2) for amplifying and outputting inputted signal light, a plurality of excitation light sources (3, 4) and an excitation light source control section (5) for controlling operations of the excitation light sources (3, 4), wherein the excitation light sources are composed of a main excitation light source (3) and an auxiliary excitation light source (4), and the excitation light source control section (5) is equipped with a control section (7) which, when the number of channels in the inputted signal light is equal to or less than a predetermined number of channels, executes control whereby the main excitation light source (3) supplies excitation

Abstract: The present invention provides a wavelength division multiplex light communication system using an optical amplifier which can amplifying and translating a multiplex light signal obtained by wavelength division multiplexing a plurality of channel light signals and can perform its control such that when the number of channels n is the maximum number of channels nmax, the total light output power Pt is maximum, Pmax and such that when the number of channels n for light signals is smaller than nmax, the total light output power Pt obtained by amplifying said multiplex light signal is substantially Pt>Pmax×n/nmax.

Abstract: A variable attenuator is inserted into an optical input part and a feedback control is performed so that an optical input to an amplifying optical fiber becomes constant. Further, a control for changing a total optical output and an optical input to the amplifying optical fiber is performed on the basis of channel number information obtained from a supervisory signal. When light to/from an intermediate optical component is detected and the absence of the component is detected, pumping is suppressed, thereby avoiding occurrence of an optical surge at the time of connection of the optical component and a signal indicative of detachment of the optical component is generated.

Abstract: The present invention is to provide an automatic gain-controlled optical fiber amplifier, comprising: a first optical branch for branching a portion of an optical signal inputted into the optical fiber amplifier; a second optical branch for branching a portion of an optical signal outputted from the optical fiber amplifier; an optical distributor for receiving the optical signal of an input side branched partially by the first optical branch and for outputting it separately; a first wavelength selector for receiving the optical signal of a one side distributed by the optical distributor and for selecting a predetermined wavelength optical signal; a second wavelength selector for receiving the optical signal of an output side branched partially by the second optical branch and for selecting the predetermined wavelength optical signal; a signal processor for receiving the optical signal of a second side distributed by the optical distributor and the predetermined wavelength optical signal selected by the first

Abstract: An optical communication system having a transmitting station for outputting WDM (wavelength-division multiplexing) signal light, an optical fiber transmission line, a receiving station, and an optical repeater including an optical amplifier. The transmitting station includes a supervisory circuit for detecting the number of channels of the WDM signal light and transmitting supervisory information including the number of channels to the optical repeater. The optical repeater further includes a circuit for controlling the optical amplifier so that the output level of the optical amplifier becomes a target level. The target level is set according to the supervisory information. According to the structure, it can be possible to provide a system which can easily respond to a change in the number of WDM channels.

Abstract: An optical direct amplifier includes an O/E converter for converting a branched output light into an electric signal, a frequency variable filter for detecting a modulated frequency specific to a signal light from the electric signal, a counter for counting the number of modulated frequencies detected, and a control circuit. When the count value (number of signal lights) output from the counter changes, the control circuit controls the output of the optical direct amplifier such that the optical output level per signal light can be equal to the optical output level per signal light indicated before the count value (number of signal lights) changes.

Abstract: A wavelength-division multiplexing optical communication system for wavelength-division multiplexing a plurality of optical signals having different wavelengths and transmitting a wavelength-division multiplexed signal via an optical fiber transmission line. The wavelength-division multiplexing system includes a multiplexing unit that wavelength-multiplexes a plurality of optical signals having different wavelengths. A storing unit stores information regarding an addition or subtraction of an optical signal to be wavelength-multiplexed, into a predetermined time slot of a frame signal that is composed of a plurality of time slots. The wavelength-division multiplexing system outputs a monitor/control frame signal, based upon the stored information. A transmitting device transmits the monitor/control signal as an optical signal having a wavelength different from the wavelengths of the multiplexed optical signals.

Abstract: A variable attenuator is inserted into an optical input part and a feedback control is performed so that an optical input to an amplifying optical fiber becomes constant. Further, a control for changing a total optical output and an optical input to the amplifying optical fiber is performed on the basis of channel number information obtained from a supervisory signal. When light to/from an intermediate optical component is detected and the absence of the component is detected, pumping is suppressed, thereby avoiding occurrence of an optical surge at the time of connection of the optical component and a signal indicative of detachment of the optical component is generated.

Abstract: An optical amplifying apparatus which includes an optical amplifier, an optical attenuator and a controller. The optical amplifier amplifies a light signal having a variable number of channels. The optical attenuator passes the amplified light signal and has a variable light transmissivity. Prior to varying the number of channels in the light signal, the controller varies the light transmissivity of the optical attenuator so that a power level of the amplified light signal is maintained at an approximately constant level that depends on the number of channels in the light signal prior to the varying the number of channels. While the number of channels in the light signal is being varied, the controller maintains the light transmissivity of the optical attenuator to be constant.

Abstract: An optical amplifying apparatus which includes an optical amplifier, an optical attenuator and a controller. The optical amplifier amplifies a light signal having a variable number of channels. The optical attenuator passes the amplified light signal and has a variable light transmissivity. Prior to varying the number of channels in the light signal, the controller varies the light transmissivity of the optical attenuator so that a power level of the amplified light signal is maintained at an approximately constant level that depends on the number of channels in the light signal prior to the varying the number of channels. While the number of channels in the light signal is being varied, the controller maintains the light transmissivity of the optical attenuator to be constant.

Abstract: An optical amplifying module having an internal pumping source is provided. WDM signal light obtained by wavelength division multiplexing a plurality of optical signals allocated to different wavelength channels is supplied to the optical amplifying module. An output power from the internal pumping source is adjusted so that the optical amplifying module provides a gain for the WDM signal light. A booster module having an external pumping source for supporting the gain is connected to the optical amplifying module. An output power from the external pumping source is set according to the number of channels of the WDM signal light. This method allows easy response to a change in the number of channels of the WDM signal light.