Optical communication apparatus and control method thereof

Abstract

An optical communication apparatus includes a variable resistor unit, a measurement unit, and a control unit. The variable resistor unit is arranged at a pre-stage of an electrical/optical conversion unit, which converts an electrical signal obtained by converting an input packet to an optical signal having a waveform corresponding to a potential difference between a positive phase component and a negative phase component of the electrical signal by using the potential difference. The variable resistor unit provides a resistor that varies a midpoint of potential of the positive phase component or the negative phase component. The measurement unit measures a ratio of a presence period, which is a period where the input packet is present, to a sum of the presence period and a non-presence period. The control unit controls a value of the resistor provided to the positive phase component or the negative phase component based on the ratio.

What is claimed is: 
     
       1. An optical communication apparatus comprising:
 a variable resistor unit that is arranged at a pre-stage of an electrical/optical conversion unit, which converts an electrical signal obtained by converting an input packet to an optical signal having a waveform corresponding to a potential difference between a positive phase component and a negative phase component of the electrical signal by using the potential difference, and that provides, to the positive phase component or the negative phase component, a resistor that varies a midpoint of potential of the positive phase component or the negative phase component to be input to the electrical/optical conversion unit; 
 a measurement unit that measures a ratio of a presence period, which is a period where the input packet is present, to a sum of the presence period and a non-presence period, which is a period other than the presence period; and 
 a control unit that controls a value of the resistor provided by the variable resistor unit based on the ratio measured by the measurement unit in such a manner that the midpoint of the potential of the positive phase component and the midpoint of the potential of the negative phase component, which would be apart in opposite directions in the non-presence period, get closer to each other. 
 
     
     
       2. The optical communication apparatus according to  claim 1  further comprising
 a comparison unit that compares the ratio measured this time and the ratio measured last time by the measurement unit, wherein 
 the control unit stops controlling the resistance value when the ratio measured this time and the ratio measured last time by the measurement unit match as a result of the comparison by the comparison unit. 
 
     
     
       3. The optical communication apparatus according to  claim 1  further comprising:
 a holding unit that temporarily holds the electrical signal obtained by converting the input packet; and 
 a generation unit that reads the electrical signal held in the holding unit, generates the positive phase component and the negative phase component from the read electrical signal, and outputs the generated positive phase component and negative phase component to the electrical/optical conversion unit, wherein 
 the control unit reports, after completing the control of the resistance value, a signal for permitting the generation unit to read the electrical signal to the holding unit. 
 
     
     
       4. A control method of an optical communication apparatus, the method comprising:
 measuring a ratio of a presence period, which is a period where an input packet is present, to a sum of the presence period and a non-presence period, which is a period other than the presence period; and 
 controlling a resistance value of a variable resistor unit that is arranged at a pre-stage of an electrical/optical conversion unit, which converts the electrical signal to an optical signal having a waveform corresponding to a potential difference between a positive phase component and a negative phase component of an electrical signal obtained by converting the input packet by using the potential difference, and that provides, to the positive phase component or the negative phase component, a resistor that varies a midpoint of potential of the positive phase component or the negative phase component to be input to the electrical/optical conversion unit based on the measured ratio in such a manner that the midpoint of the potential of the positive phase component and the midpoint of the potential of the negative phase component, which would be apart in opposite directions in the non-presence period, get closer to each other.