Telecommunications system

• US 20030016418A1
• Filed: 09/16/2002
• Published: 01/23/2003
• Est. Priority Date: 07/19/1996
• Status: Active Grant

• Current Assignee: NextG Networks
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Westbrook, Leslie D., Moodie, David G.
• Granted Patent: US 6,731,880 B2
• Time in Patent Office: Days
• US Class Current: 398/115
• CPC Class Codes: G02F 1/0157 using electro-absorption effects, e.g. Franz-Keldysh [FK] effect or quantum confined stark effect [QCSE]
• CPC Class Codes: H04B 10/25758 between a central unit and a single remote unit by means of an optical fibre
• CPC Class Codes: H04B 10/29 Repeaters

Abstract

An optical communications network includes a terminal which can simultaneously receive and modulate an optical signal. The terminal includes an optical modulator which is controlled by varying the bias voltage applied to it.

Claims

1. A method of communicating between a first node and one or more further nodes in an optical communications system, the method comprising:

i) receiving at the first node, an optical signal transmitted from a first further node over an optical fibre link;

ii) detecting, at the first node, the optical signal using an electro-absorption modulator and producing thereby an electrical signal representing information carried by the optical signal; and

iii) imposing, using said electro-absorption modulator, an information-carrying modulation onto the received optical signal and feeding the thus modulated optical signal into an optical fibre link to transmit it to a second further node;

wherein step ii and step iii are carried out with the electro-absorption modulator subject to the same DC operating conditions.

2. A method as claimed in claim 1, wherein step ii and step iii are carried out simultaneously.

3. A method as in claim 1, wherein said first further node and said second further node are a single node.

4. A method as claimed in claim 1, wherein said electrical signal is an RF or microwave signal.

5. A method as claimed in claim 4, wherein the electrical signal is applied to an antenna.

6. A method as claimed in claim 1, wherein in step iii said information-carrying modulation is an RF or microwave signal.

7. A method as claimed in claim 6, wherein said information-carrying signal is an RF or microwave signal provided from an antenna.

8. A method as claimed in claim 7 wherein the electrical signal is applied to an antenna, the antenna to which the electrical signal is applied and the antenna which provides said information carrying signal are constituted by a single antenna.

9. A method as claimed in claim 7, wherein the electrical signal is applied to a single antenna.

10. A method as claimed in claim 9, wherein the base station, in use, supports the GSM and DECT systems.

11. An optical communications network includes a remote terminal characterised in that said terminal comprises an electro-absorption modulator that

i) detects an incoming optical signal from a first portion of the optical communications network whilst simultaneously

ii) modulating said incoming optical signal, said optical signal being transmitted to a further portion of the optical communications network.

12. An optical communications network according to claim 11, wherein the optical communications network uses a frequency division multiplexing system.

14. A bidirectional optical-electrical signal transducer as in claim 13 wherein said electro-absorption modulator functions simultaneously and at the same DC operating bias conditions to produce said output optical and electrical signals.

15. A bidirectional optical-electrical signal transducer as in claim 13 further comprising at least one RF antenna electrically connected to said electrical signal input/output port.

13. A bi-directional optical-electrical signal transducer comprising:

an electro-absorption modulator having optical signal input and output ports and an electrical signal input/output port, whereby;

first information-bearing optical signals presented to said optical signal input port produce corresponding first information-bearing electrical signals at said electrical signal input/output port, and

second information-bearing electrical signals presented to said electrical signal input/output port produce corresponding second information bearing optical signals modulated onto an optical signal at said optical signal output port.