Automatic optical level adjuster and optical signal receiving system having the adjuster
First Claim
1. An optical signal receiving system in which a receiving signal light which is transmitted through a single mode fiber having a zero-velocity-dispersion wavelength and has a wavelength different from the zero-dispersion wavelength, is received while performing dispersion compensation on the signal light, said system comprising:
- optical receiving means; and
automatic optical level adjustment means for automatically adjusting always to a predetermined level the level of optical signal to be received by said optical receiving means when the amount of dispersion compensation on the signal light is newly set.
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Accused Products
Abstract
An automatic optical output level adjuster has a plurality of couplers for branching an optical signal, an optical switch for switching optical signal paths, a variable attenuator for attenuating the optical signal, a variable optical amplifier for amplifying the optical signal, photodetectors, and a CPU for control. The photodetectors detect the level of an optical input to the automatic optical output level adjuster and the level of an optical output from the adjuster. The CPU controls the optical switch on the basis of the detected optical input level and controls the amount of attenuation by the variable attenuator or the optical output from the variable amplifier on the basis of the detected optical output level. In a wavelength-multiplex optical transmission receiving system having the automatic optical output level adjuster inserted between a dispersion compensating fiber and an optical receiver, the level of an optical signal input to the optical receiver is automatically adjusted to an optimum light receiving level even when the set value of the amount of dispersion compensation by the dispersion compensating fiber is changed.
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Citations
21 Claims
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1. An optical signal receiving system in which a receiving signal light which is transmitted through a single mode fiber having a zero-velocity-dispersion wavelength and has a wavelength different from the zero-dispersion wavelength, is received while performing dispersion compensation on the signal light, said system comprising:
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optical receiving means; and
automatic optical level adjustment means for automatically adjusting always to a predetermined level the level of optical signal to be received by said optical receiving means when the amount of dispersion compensation on the signal light is newly set. - View Dependent Claims (2, 3, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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4. An automatic optical level adjuster for automatically adjusting always to a predetermined level the level of a signal to be received by light receiving means, said adjuster comprising:
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a variable optical attenuator for changing the amount of attenuation of light on the basis of first control information;
a variable optical amplifier for variably producing an optical output according to second control information;
optical switch means for switching on the basis of third information between an output optical path for output of input light by transmission through said variable optical attenuator and an output optical path for output of input light by transmission through said variable optical amplifier; and
control means for controlling the level of light output from each of said output optical paths to a preset level by outputting the third control information from comparison information obtained by comparing the level of the input light with a preset level, and the first or second control information from comparison information obtained by comparing the level of light output from said output optical path with a preset level. - View Dependent Claims (5, 6, 7, 8, 9)
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Specification