Dispersion compensation type optical signal receiving apparatus, receiving circuit, receiving method, and receiving program

An optical receiving circuit, comprising:

• a photoelectric converting device for converting input signal light inputted from a transmission line into an electric signal;
• an amplifying device for amplifying the electric signal converted by the photoelectric converting device;
• a variable optical attenuation device provided for limiting a power of the input signal light inputted to the photoelectric converting device;
• and
• an attenuation amount controlling device for activating the variable optical attenuation device when the power of the input signal light is larger than a reference value with which an output amplitude of the amplifying device does not saturate, and controlling an attenuation amount of the variable optical attenuation device based on an output value outputted by a level detecting device in proportion to an output voltage of the amplifying device.

A dispersion compensation type optical signal receiving method, comprising the steps of:

• a photoelectric converting step for converting an input signal light inputted from a transmission line into an electric signal and amplifying the electric signal;
• an electronic dispersion compensating step for electrically compensating dispersion in the transmission line, targeted at a receiving signal that corresponds to the input signal light that is converted into the electric signal and amplified;
• a signal reproducing step for reproducing a clock and data from the receiving signal to which dispersion compensation is performed;
• and
• a variable optical attenuation step which is performed prior to an execution of the photoelectric converting step to control a power of the input signal light based on an output value which is in proportion to an output voltage of the amplification, when the power of the input signal light inputted to the photoelectrical converting device is larger than a reference value with which an output amplitude of the amplified electric signal does not saturate.

A signal processing program for receiving an optical signal, which allows a computer to execute:

• a function of comparing a power of a detected input signal light that is inputted from an optical transmission line with a reference value with which an output amplitude of an electric signal converted from the input signal light does not saturate;
• a function of sending the input signal light to a photoelectric converting device when a power of the compared input signal light is within the reference value;
• and
• a function of sending the input signal light to a photoelectric converting device after attenuating the power of the input signal light to the reference value level when the power of the compared input signal light is over the reference value with which the output amplitude of the electric signal converted from the input signal light does not saturate.