Frequency offset monitoring device and optical coherent receiver

Abstract

The present invention provides a frequency offset monitoring device and an optical coherent receiver. A low speed frequency offset monitoring device comprises a signal speed lowering section, for lowering the speed of an inputted signal and outputting the speed lowered signal, and a frequency offset monitor, for monitoring frequency offset of the speed lowered signal outputted by the signal speed lowering section.

1 . An optical coherent receiver, comprising:
 the low speed frequency offset monitoring device according to  claim 1 , for monitoring a frequency offset of an inputted optical signal;   a control logic, for outputting a first control signal and a second control signal in accordance with the frequency offset to control the frequency offset;   a local oscillator, for supplying a local oscillator optical signal;   a first optical frequency shifter, for shifting a frequency of the local oscillator optical signal in accordance with the first control signal from the control logic;   a second optical frequency shifter, for shifting a frequency of the inputted optical signal in accordance with the second control signal from the control logic;   an optical hybrid, for mixing the inputted optical signal having been shifted frequency with the local oscillator optical signal having been shifted frequency;   first and second twin photoelectric detectors, for converting the optical signal outputted from the optical hybrid into electrical base band signals; and   a signal processing device, for processing the converted signal to obtain a data output;   wherein the low speed frequency offset monitoring device monitors the frequency offset of the inputted optical signal in accordance with the converted signal.   
     
     
         2 . An optical coherent receiver, comprising:
 the low speed frequency offset monitoring device according to  claim 1 , for monitoring a frequency offset of an inputted optical signal;   a control logic, for outputting a control signal in accordance with the frequency offset to control the frequency offset;   a local oscillator, for supplying a local oscillator optical signal;   an optical frequency shifter, for shifting a frequency of the local oscillator optical signal in accordance with the control signal from the control logic;   an optical hybrid, for mixing the inputted optical signal with the local oscillator optical signal having been shifted frequency;   first and second twin photoelectric detectors, for converting the optical signal outputted from the optical hybrid into electrical base band signals; and   a signal processing device, for processing the converted signal to obtain a data output;   wherein the low speed frequency offset monitoring device monitors the frequency offset of the inputted optical signal in accordance with the converted signal.   
     
     
         3 . An optical coherent receiver, comprising:
 the low speed frequency offset monitoring device according to  claim 1 , for monitoring a frequency offset of an inputted optical signal;   a control logic, for outputting a control signal in accordance with the frequency offset to control the frequency offset;   a local oscillator, for supplying a local oscillator optical signal;   an optical frequency shifter, for shifting a frequency of the inputted optical signal in accordance with the control signal from the control logic;   an optical hybrid, for mixing the inputted optical signal having been shifted frequency with the local oscillator optical signal;   first and second twin photoelectric detectors, for converting the optical signal outputted from the optical hybrid into electrical base band signals; and   a signal processing device, for processing the converted signal to obtain a data output;   wherein the low speed frequency offset monitoring device monitors the frequency offset of the inputted optical signal in accordance with the converted signal.   
     
     
         4 . The optical coherent receiver according to claim  7 , further comprising:
 first and second A/D converters, for respectively converting the base band electrical signals outputted from the first and the second twin photoelectric detectors into digital signals;   wherein the first and second A/D converters are respectively connected between the first and second twin photoelectric detectors and the low speed frequency offset monitoring device.   
     
     
         5 . The optical coherent receiver according to claim  8 , further comprising:
 first and second A/D converters, for respectively converting the base band electrical signals outputted from the first and the second twin photoelectric detectors into digital signals;   wherein the first and second A/D converters are respectively connected between the first and second twin photoelectric detectors and the low speed frequency offset monitoring device.   
     
     
         6 . The optical coherent receiver according to claim  9 , further comprising:
 first and second A/D converters, for respectively converting the base band electrical signals outputted from the first and the second twin photoelectric detectors into digital signals;   wherein the first and second A/D converters are respectively connected between the first and second twin photoelectric detectors and the low speed frequency offset monitoring device.