Optical reception device, station-side device, pon system, preamplifier, optical reception method, and method for suppressing output inversion of integrator

An optical line terminal connected to a plurality of optical network units via an optical transmission line formed by an optical fiber, the optical line terminal comprising:

• a light receiving element configured to receive an optical signal in a burst state from each optical network unit;
• an amplifier configured to receive and amplify a current based on an input current from the light receiving element;
• a direct-current adjustment circuit connected to an input electric path extending from the light receiving element to the amplifier, the direct-current adjustment circuit being configured to remove an offset current included in the input current;
• an alternating-current adjustment circuit connected to the input electric path and configured to cause a part of the input current to flow therein;
• and
• a controller configured to control the direct-current adjustment circuit and the alternating-current adjustment circuit on the basis of an output of the amplifier and a reference voltage, wherein
• the controller includes
• an integrator configured to integrate the output of the amplifier and output a resultant output to two electric paths of a positive phase and a negative phase, and
• an inversion suppression circuit configured to operate so as to inject a current to the positive phase and extract a current from the negative phase when a negative phase potential of the output of the integrator is higher than a positive phase potential thereof.

A PON system comprising:

• a plurality of optical network units;
• an optical transmission line formed by an optical fiber;
• and
• an optical line terminal configured to communicate with the plurality of optical network units via the optical transmission line, wherein
• an optical reception device installed at least to the optical line terminal among the optical network units and the optical line terminal includes
• a light receiving element configured to receive an optical signal in a burst state from each optical network unit,
• an amplifier configured to receive and amplify a current based on an input current from the light receiving element,
• a direct-current adjustment circuit connected to an input electric path extending from the light receiving element to the amplifier, the direct-current adjustment circuit being configured to remove an offset current included in the input current,
• an alternating-current adjustment circuit connected to the input electric path and configured to cause a part of the input current to flow therein, and
• a controller configured to control the direct-current adjustment circuit and the alternating-current adjustment circuit on the basis of an output of the amplifier and a reference voltage, and
• the controller includes
• an integrator configured to integrate the output of the amplifier and output a resultant output to two electric paths of a positive phase and a negative phase, and
• an inversion suppression circuit configured to operate so as to inject a current to the positive phase and extract a current from the negative phase when a negative phase potential of the output of the integrator is higher than a positive phase potential thereof.

A preamplifier comprising:

• an amplifier configured to receive and amplify a current based on an input current from a light receiving element configured to receive an optical signal in a burst state;
• a direct-current adjustment circuit connected to an input electric path extending from the light receiving element to the amplifier, the direct-current adjustment circuit being configured to remove an offset current included in the input current;
• an alternating-current adjustment circuit connected to the input electric path and configured to cause a part of the input current to flow therein;
• and
• a controller configured to control the direct-current adjustment circuit and the alternating-current adjustment circuit on the basis of an output of the amplifier and a reference voltage, wherein
• the controller includes
• an integrator configured to integrate the output of the amplifier and output a resultant output to two electric paths of a positive phase and a negative phase, and
• an inversion suppression circuit configured to operate so as to inject a current to the positive phase and extract a current from the negative phase when a negative phase potential of the output of the integrator is higher than a positive phase potential thereof.

An optical reception method for receiving an optical signal in a burst state, the optical reception method comprising, in a stage of preamplification:

• receiving and amplifying, by an amplifier, a current based on an input current from a light receiving element configured to receive the optical signal;
• removing an offset current included in the input current and releasing a part of the input current, on the basis of an output of the amplifier and a reference voltage;
• and
• integrating, by an integrator, the output of the amplifier and outputting a resultant output to two electric paths of a positive phase and a negative phase, and when a negative phase potential of the output to the two electric paths is higher than a positive phase potential thereof, injecting a current to the positive phase and extracting a current from the negative phase.

A method for suppressing inversion of an output of an integrator in a preamplifier for optical reception, the method comprising:

• receiving and amplifying a current based on an input current from a light receiving element configured to receive an optical signal in a burst state;
• removing an offset current included in the input current and releasing a part of the input current, on the basis of an output obtained through amplification and a reference voltage;
• and
• integrating, by the integrator, the output and outputting a resultant output to two electric paths of a positive phase and a negative phase, and when a negative phase potential of the output to the two electric paths is higher than a positive phase potential thereof, injecting a current to the positive phase and extracting a current from the negative phase.