Optical receiver

Abstract

In an optical receiver, a light receiving element receives the optical packet signals and converts the optical packet signals to electrical signals. A bias voltage supply section supplies bias voltage to the light receiving element. A monitoring section monitors an input level of each optical packet signal or each electrical signal and transmits a monitored value to the bias voltage supply section. In addition, the bias voltage supply section temporarily increases the bias voltage according to magnitude of the monitored value after an end of receiving of each optical packet signal.

1 . (canceled) 
     
     
         2 . (canceled) 
     
     
         3 . An optical receiver for receiving optical packet signals transmitted in burst mode, the optical receiver comprising:
 a light receiving element which receives the optical packet signals and converts the optical packet signals to electrical signals;   a monitoring section which monitors each electrical signal and outputs a monitor signal;   a signal processing section which processes the monitor signal to generate a compensation signal; and   an adding section which adds the compensation signal to bias voltage applied to the light receiving element and supplies a signal obtained to the light receiving element,   wherein the signal processing section generates the compensation signal which is used for temporarily increasing the bias voltage after an end of receiving of each optical packet signal.   
     
     
         4 . The optical receiver according to  claim 3 , wherein:
 the monitoring section is a current mirror circuit, makes a copy of electrical signal current, and outputs the copy as the monitor signal; or   the monitoring section is a resistance element connected to a section which supplies the bias voltage to the light receiving element, and outputs current which flows because of a drop in the bias voltage as the monitor signal.   
     
     
         5 . The optical receiver according to  claim 3 , wherein if a low optical level packet signal an input level of which is low is received after receiving of a high optical level packet signal an input level of which is high, the signal processing section generates the compensation signal for increasing the bias voltage for multiplication factor return time it takes a multiplication factor of the light receiving element which falls because of the receiving of the high optical level packet signal to return to a predetermined value in order to compensate for a fall in the multiplication factor at the time of receiving of the low optical level packet signal. 
     
     
         6 . The optical receiver according to  claim 5 , wherein the signal processing section differentiates the monitor signal, amplifies a differential waveform to any level, and generates the compensation signal. 
     
     
         7 . The optical receiver according to  claim 6 , further comprising a filter which is positioned on a side of the signal processing section from which the compensation signal after amplification is outputted, and removes high-frequency components. 
     
     
         8 . The optical receiver according to  claim 5 , wherein the signal processing section integrates the monitor signal, amplifies an integral waveform to any level, and generates the compensation signal. 
     
     
         9 . The optical receiver according to  claim 5 , wherein the signal processing section detects a peak of the monitor signal, amplifies a peak detection waveform to any level, and generates the compensation signal. 
     
     
         10 . An optical receiver for receiving optical packet signals transmitted in burst mode, the optical receiver comprising:
 a light receiving element which receives the optical packet signals and converts the optical packet signals to electrical signals;   a monitoring section which monitors an input level of each optical packet signal or each electrical signal, and generates a monitor signal;   a compensation pulse signal generation section which generates a compensation pulse signal on the basis of the monitor signal with a detection pulse indicative of detection of each optical packet signal as a trigger; and   a bias voltage compensation section which adds the compensation pulse signal to bias voltage applied to the light receiving element, to generate a bias voltage compensation signal with the bias voltage temporarily increased, and supplies the bias voltage compensation signal to the light receiving element.   
     
     
         11 . The optical receiver according to  claim 10 , wherein the compensation pulse signal generation section uses, as the detection pulse, one of a reset pulse which indicates inputting of each optical packet signal and is transmitted from an upper system, a signal detection pulse transmitted from an amplification section which amplifies each electrical signal outputted from the light receiving element, and a clock slip pulse transmitted from a clock extraction section which is positioned behind the amplification section and extracts a clock. 
     
     
         12 . The optical receiver according to  claim 10 , wherein the compensation pulse signal generation section stores in advance data associating a monitored value of the monitor signal with a corresponding amplitude value, determines an amplitude value according to magnitude of the monitored value on the basis of the data at the time of receiving the monitor signal, and generates the compensation pulse signal having the determined amplitude value. 
     
     
         13 . The optical receiver according to  claim 10 , wherein:
 the bias voltage compensation section includes a time constant circuit and an adder;   the adder generates a total signal by adding the compensation pulse signal to the bias voltage; and   if a low optical level packet signal an input level of which is low is received after receiving of a high optical level packet signal an input level of which is high, the time constant circuit exercises time constant control and generates the bias voltage compensation signal by converting a waveform of the total signal to a waveform which exhibits a characteristic reverse to a multiplication factor fluctuation characteristic which the light receiving element exhibits until a return of a multiplication factor which falls because of the receiving of the high optical level packet signal to a predetermined value.   
     
     
         14 . The optical receiver according to  claim 10 , wherein:
 the bias voltage compensation section includes a time constant circuit and an adder;   if a low optical level packet signal an input level of which is low is received after receiving of a high optical level packet signal an input level of which is high, the time constant circuit exercises time constant control and converts a waveform of the compensation pulse signal to a waveform which exhibits a characteristic reverse to a multiplication factor fluctuation characteristic which the light receiving element exhibits until a return of a multiplication factor which falls because of the receiving of the high optical level packet signal to a predetermined value; and   the adder generates the bias voltage compensation signal by adding a signal having the waveform which exhibits the characteristic reverse to the multiplication factor fluctuation characteristic to the bias voltage.   
     
     
         15 . The optical receiver according to  claim 10 , wherein the compensation pulse signal generation section inclines falling of a waveform of the pulse-like monitor signal by exercising time constant control, and generates as the compensation pulse signal a waveform obtained by finding a product of an inclined portion of the monitor signal and the detection pulse. 
     
     
         16 . The optical receiver according to  claim 10 , wherein when the compensation pulse signal generation section recognizes from the monitor signal that an excessively high optical level packet signal is inputted, the compensation pulse signal generation section shuts down the bias voltage compensation section. 
     
     
         17 . An optical receiver for receiving optical packet signals transmitted in burst mode, the optical receiver comprising:
 a light receiving element which receives the optical packet signals and converts the optical packet signals to electrical signals;   an amplification section which amplifies each electrical signal;   a monitoring section which monitors an input level of each optical packet signal or each electrical signal and generates a monitor signal;   a compensation pulse signal generation section which generates a compensation pulse signal on the basis of the monitor signal with a detection pulse indicative of detection of each optical packet signal as a trigger; and   a gain compensation section which exercises time constant control over the compensation pulse signal, generates a gain compensation signal for compensating gain of the amplification section, and transmits the gain compensation signal to the amplification section.   
     
     
         18 . The optical receiver according to  claim 17 , wherein if a low optical level packet signal an input level of which is low is received after receiving of a high optical level packet signal an input level of which is high, the gain compensation section increases the gain of the amplification section for multiplication factor return time it takes a multiplication factor of the light receiving element which falls because of the receiving of the high optical level packet signal to return to a predetermined value in order to compensate for a fall in the multiplication factor at the time of receiving of the low optical level packet signal. 
     
     
         19 . The optical receiver according to  claim 17 , wherein the compensation pulse signal generation section stores in advance data associating a monitored value of the monitor signal with a corresponding amplitude value, determines an amplitude value according to magnitude of the monitored value on the basis of the data at the time of receiving the monitor signal, and generates the compensation pulse signal having the determined amplitude value. 
     
     
         20 . The optical receiver according to  claim 17 , wherein when the compensation pulse signal generation section recognizes from the monitor signal that an excessively high optical level packet signal is inputted, the compensation pulse signal generation section shuts down the gain compensation section.