Method for transmission and receipt of coherent light signals

• US 5,301,053 A
• Filed: 12/06/1991
• Issued: 04/05/1994
• Est. Priority Date: 12/06/1990
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Shikada, Minoru
• Primary Examiner(s): PASCAL, LESLIE C
• Application Number:
  US07/803,417
• Time in Patent Office: 851 Days
• Field of Search: 359/114, 359/126, 359/173, 359/190, 359/191, 359/125, 455/75, 455/85, 455/86, 455/87
• US Class Current: 398/72
• CPC Class Codes: H04B 10/60 Receivers
• CPC Class Codes: H04B 10/64 Heterodyne , i.e. coherent receivers where, after the opto-electronic conversion, an electrical signal at an intermediate frequency [IF] is obtained
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0282 WDM tree architectures

Abstract

Each subscriber is provided with an optical heterodyne detection circuit. An oscillation light of an optical local oscillator is divided to a local oscillation light for the heterodyne detection and a transmitting light for data communication. A channel for those lights is selected from vacant communication channels. The transmitting light may be obtained from a transmission light oscillator which is controlled by a control unit common to the optical local oscillator.

Claims

1. A method for transmission and receipt of coherent light signals, comprising the steps of:

providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers;

providing an oscillation light signal having a first predetermined wavelength in one of said subscribers;

transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station;

transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers;

combining said second light signal and said oscillation light signal to provide an intermediate light signal;

converting said intermediate light signal to an intermediate electric signal; and

demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers, wherein;

at least one of said oscillation light signal and said first light signal is used to correct a reference wavelength during a non-communication state between said station and said one of said subscribers, and wherein a wavelength of said first light signal is set based on said reference wavelength during a communication state between said station and said one of said subscribers.

2. A method for transmission and receipt of coherent light signals, comprising the steps of:

providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength division multiplexing via optical fibers;

providing an oscillation light having a first predetermined wavelength which light is divided into first and second light signals at one of said subscribers;

transmitting over a common signaling channel said first light signal from said one of said subscribers to said station;

transmitting over said common signaling channel a third light signal having a second predetermined wavelength from said station to said one of said subscribers;

combining said second light signal and said third light signal to provide an intermediate light signal;

converting said intermediate light signal to an intermediate electric signal;

demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers, wherein;

said first and third light signals are assigned to a common signaling channel only during a non-communication state and during an initial stage of a communication state.

3. A method for transmission and receipt of coherent light signals, comprising the steps of:

providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength division multiplexing by optical fibers;

providing an oscillation light having a first wavelength which light is divided into first and second light signals at one of said subscribers;

transmitting over a common signaling channel said first light signal from said one of said subscribers to said station;

transmitting over said common signaling channel a third light signal having a second wavelength from said station to said one of said subscribers;

combining said second light signal and said third light signal to provide an intermediate light signal;

converting said intermediate light signal into an intermediate electric signal;

demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers;

shifting said first and second light signals to have a third wavelength and said third light signal, to have a fourth wavelength; and

assigning said first and third shifted light signals to a communication channel different from said common signaling channel selected from vacant communication channels, wherein;

said first light signal having said first wavelength and said third light signal having said second wavelength are assigned to said common signaling channel only during a non-communication state and during an initial stage of a communication state.

4. A method for transmission and receipt of coherent light signals, according to claim 3, wherein:

shifting of said first and third wavelengths uses a wavelength of said common signaling channel as a reference wavelength.

5. A method for transmission and receipt of coherent light signals, comprising the steps of:

providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers;

providing an oscillation light signal having a first predetermined wavelength in one of said subscribers;

transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station;

transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers;

combining said second light signal and said oscillation light signal to provide an intermediate light signal;

converting said intermediate light signal to an intermediate electric signal;

demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers; and

supplying said first light signal to a transmission member having a predetermined wavelength property to provide transmission peaks equal to a wavelength division of communication channels, said first light signal being swept in wavelength to be set to one of said communication channels-by counting said transmission peaks.

6. A method for transmission and receipt of coherent light signals, comprising the steps of:

providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers;

providing an oscillation light signal having a first predetermined wavelength in one of said subscribers;

transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station;

transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers;

combining said second light signal and said oscillation light signal to provide an intermediate light signal;

converting said intermediate light signal to an intermediate electric signal;

demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers;

controlling said first and second predetermined wavelengths using a wavelength of a common signaling channel as a reference wavelength; and

setting up a line connection between said one of said subscribers and another subscriber on a channel different from said common signaling channel;

wherein;

said second predetermined wavelength is for an up line signal and said third predetermined wavelength is for a down line signal.

7. A method for transmission and receipt of coherent light signals, comprising the steps of:

providing a station and subscribers connected to each other to transmit and receive coherent light signals of wavelength multiplexing by optical fibers;

providing an oscillation light signal having a first predetermined wavelength in one of said subscribers;

transmitting a first light signal having a second predetermined wavelength from said one of said subscribers to said station;

transmitting a second light signal having a third predetermined wavelength from said station to said one of said subscribers;

combining said second light signal and said oscillation light signal to provide an intermediate light signal;

converting said intermediate light signal to an intermediate electric signal;

demodulating said intermediate electric signal to provide data transmitted from said station to said one of said subscribers;

assigning said first predetermined wavelength to a common signaling channel;

controlling a beat frequency between said oscillation light signal and said first light signal to be a predetermined value; and

setting up a line connection between said one of said subscribers and a designated subscriber of said subscribers on a channel different from said common signaling channel.