Optical receiver and light receiving method

Patent metadata

Field	Value
Publication number	US-9344199-B2
Application number	US-201414444010-A
Country	US
Kind code	B2
Filing date	Jul 28, 2014
Priority date	Feb 23, 2012
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

An optical receiver receives coherent light. The optical receiver includes an amplitude adjuster, a signal processor, and a controller. The amplitude adjuster adjusts amplitude of an input signal to output an analog signal. The signal processor receives a digital signal generated from the analog signal output from the amplitude adjuster, extracts clock components from the digital signal, and after establishing synchronization between the clock components and data components, extracts the data components from the digital signal to process the data components. The controller sets amplitude of the analog signal to first amplitude before establishment of synchronization by the digital signal, and changes the set amplitude to second amplitude that is smaller than the first amplitude after the establishment of synchronization.

First claim

What is claimed is:

1. An optical receiver that receives coherent light, the optical receiver comprising:
an amplitude adjuster that adjusts amplitude of an input signal to output an analog signal;
a signal processor that receives a digital signal generated from the analog signal output from the amplitude adjuster, extracts clock components from the digital signal, and after establishing synchronization between the clock components and data components, extracts the data components from the digital signal to process the data components; and
a controller that sets amplitude of the analog signal to first amplitude before establishment of synchronization by the digital signal, and changes the set amplitude to second amplitude that is smaller than the first amplitude after the establishment of synchronization, wherein
the controller increases gain of the input signal until synchronization is established to provide good stability for establishing synchronization, and, after synchronization is established, performs feedback control so that gain of an analog input signal is optimized to be in an input dynamic range by constantly monitoring digital values that have been analog-to-digital (AD) converted.

2. The optical receiver according to claim 1 , wherein the first amplitude includes a value equal to or larger than an amplitude value with which the signal processor is able to establish synchronization between the clock components and the data components by using the digital signal.

3. The optical receiver according to claim 1 , wherein the second amplitude includes a value within a range of amplitude values with which the signal processor is able to extract the data components from the digital signal.

4. The optical receiver according to claim 1 , wherein the controller limits the second amplitude to amplitude within a range having linearity with respect to a gain characteristic of output amplitude over control voltage applied to the amplitude adjuster after the establishment of synchronization.

5. A light receiving method comprising:
adjusting amplitude of an input signal to output an analog signal;
receiving a digital signal generated from the output analog signal;
extracting clock components from the digital signal;
extracting, after establishing synchronization between the clock components and data components, the data components from the digital signal to process the data components;
setting amplitude of the analog signal to first amplitude before establishment of synchronization by the digital signal;
changing the set amplitude to second amplitude that is smaller than the first amplitude after the establishment of synchronization; and
increasing gain of the input signal until synchronization is established to provide good stability for establishing synchronization, and, after synchronization is established, performing feedback control so that gain of an analog input signal is optimized to be in an input dynamic range by constantly monitoring digital values that have been analog-to-digital (AD) converted.

Assignees

• Fujitsu Optical Components Ltd

Inventors

• Kawazoe Kenichi
• Ishii Yuji
• Akashi Tamotsu
• Terada Koji

Classifications

• H04B10/616 Primary

  Details of the electronic signal processing in coherent optical receivers · CPC title

• H04B10/693

  Arrangements for optimizing the preamplifier in the receiver · CPC title

• A61M5/1456

  with a replaceable reservoir comprising a piston rod to be moved into the reservoir, e.g. the piston rod is part of the removable reservoir · CPC title

• A61M2209/084

  Supporting bases, stands for equipment · CPC title

• A61M2209/082

  Mounting brackets, arm supports for equipment · CPC title