Bidirectional optical transmission system

• US 5,572,612 A
• Filed: 12/14/1994
• Issued: 11/05/1996
• Est. Priority Date: 12/14/1994
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Perrier, Philippe A., Delavaux, Jean-Marc P.
• Primary Examiner(s): Lee, John D.
• Assistant Examiner(s): Palmer, Phan T. H.
• Application Number:
  US08/355,943
• Time in Patent Office: 692 Days
• Field of Search: 385/24, 385/23, 385/3, 385/4, 385/7, 385/31, 385/46, 359/118, 359/119, 359/121, 359/127, 359/124
• US Class Current: 385/24
• CPC Class Codes: H04B 10/2587 using a single light source for multiple stations
• CPC Class Codes: H04J 14/0201 Add-and-drop multiplexing
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• 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

Bidirectional transmission over a single optical fiber is obtained in an optical communications system by using a three port circulator in customer premises equipment together with an optical fiber amplifier and a narrow band filter. The fiber amplifier can be locally or remotely pumped. The acousto-optic modulator is advantageously used because it reduces the coherent Rayleigh noise by detuning upstream and downstream wavelengths.

Claims

1. Apparatus comprising:

an optical circulator having at least three ports;

a fiber amplifier optically coupled to two of said ports;

a filter optically connected to at least one of said ports;

a modulator optically coupled to one of said ports and to said fiber amplifier, said modulator having a port for receiving data; and

a multiplexer coupler optically connected to said fiber amplifier and to said modulator.

2. Apparatus as recited in claim 1 in which said modulator comprises an acousto-optic modulator.

3. Apparatus as recited in claim 1 further comprising a receiver, said receiver being optically connected to said multiplexer.

4. Apparatus as recited in claim 1 further comprising a pump laser, said pump laser being optically connected to said multiplexer coupler.

5. An optical communications system comprising:

a plurality of transmitters;

a coupler connected to said plurality of transmitters and to at least one pump laser;

an optical fiber, said optical fiber being connected to said coupler;

an optical circulator having at least three ports, one of said ports being connected to said optical fiber;

a fiber amplifier optically coupled to at least one of said ports;

a modulator optically coupled to one of said ports and to said fiber amplifier; and

a multiplexer coupler optically connected to said fiber amplifier.

6. An optical communications system as recited in claim 5 further comprising a demultiplexer, said demultiplexer being optically connected to said coupler.

7. An optical communications system as recited in claim 6 further comprising a plurality of receivers, said receivers being optically connected to said coupler.