Acoustic Modulation

• US 20080166120A1
• Filed: 03/02/2006
• Published: 07/10/2008
• Est. Priority Date: 03/04/2005
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Heatley, David, Sikora, Edmund
• Granted Patent: US 7,697,795 B2
• Time in Patent Office: Days
• US Class Current: 398/33
• CPC Class Codes: G02F 1/125 in an optical waveguide structure

Abstract

The present invention relates to the modulation of light traveling along a waveguide, in particular to the acoustic modulation of the light. There is provide a modulator arrangement for acoustically modulating optical radiation. The modulator arrangement has: a waveguide portion formed from a flexible material; a vibrator element for generating acoustic vibrations; and, a coupling arrangement for releasably coupling the vibrating element to the waveguide portion, the coupling arrangement including a first coupling member secured to the waveguide portion, and a second coupling member secured to the vibrator element. The second coupling member is removable from the first coupling member, and the first coupling member has a substantially rigid portion for retaining the shape of the waveguide when the second coupling member is removed from the first coupling member.

Claims

1. A modulator arrangement for acoustically modulating optical radiation, the modulator arrangement comprising:

a waveguide portion formed from a flexible material;

a vibrator element for generating acoustic vibrations; and

, a coupling arrangement for releasably coupling the vibrating element to the waveguide portion, the coupling arrangement including a first coupling member secured to the waveguide portion, and a second coupling member secured to the vibrator element, wherein the second coupling member is removable from the first coupling member, and wherein the first coupling member has a substantially rigid portion for retaining the shape of the waveguide when the second coupling member is removed from the first coupling member.

2. A modulator arrangement as claimed in claim 1, wherein the first and second coupling members have a coupled state in which the vibrator means is coupled to the optical link, and a decoupled state in which the vibrator means is not coupled to the optical link, the first and second coupling members having respective first and second cooperating surfaces which oppose one another when the first and second coupling means are in the coupled state.

3. A modulator arrangement as claimed in claim 1, wherein a bore is provided in the first coupling member though which the optical waveguide portion extends.

4. A modulator arrangement as claimed in claim 1, wherein a cut out portion is provided in one of the first and second coupling members for receiving the other of the first and second coupling members.

5. A modulator arrangement as claimed in claim 1, wherein one of the first and second coupling members is provided with a wedge shaped portion, the other of the first and second coupling members being provided with a V-shaped groove for receiving the wedge shaped portion.

6. A modulator arrangement as claimed in claim 1, wherein a resilient member is provide for retaining the first and second coupling members in a coupled position.

7. A modulator arrangement as claimed in claim 1, wherein the optical waveguide is formed by an optical fibre, or an optical fibre cable having a protective sheath with one or more fibres therein.

8. A modulator arrangement as claimed in claim 1, wherein the vibration means includes at least one region of piezoelectric material for generating vibrations.

9. A modulator arrangement as claimed in claim 1, wherein at least the first coupling member is arranged to provide, in the coupled state, a coupling medium for carrying acoustic vibrations to the waveguide.

10. A modulator arrangement as claimed in claim 1, wherein the first and the second coupling members are arranged to provide, in the coupled state, a coupling path for carrying acoustic radiation between the vibration element and the waveguide portion.

11. Communications apparatus including an optical link, a monitoring station for receiving sensing signals previously transmitted onto the optical link, and a modulator arrangement according to any preceding claims for modulating data onto the sensor signals, wherein the sensing signals are formed by pairs of signal copies, which copies of a pair have a time delay relative to one another, and wherein the monitoring station is configured to combine the respective signals of a pair so as to extract the modulated data.

12. Communications apparatus as claimed in claim 11, wherein the monitoring station includes an optical source for transmitting the sensing signals onto the optical link, the sensing signals being returned along the link to the monitoring station.

13. Communications apparatus as claimed in claim 12, wherein reflector means are provided to return the sensing signals.

14. Communications apparatus as claimed in claim 11, wherein the time delay is greater than the inverse of the frequency of the modulation.

15. Communications apparatus as claimed in claim 11, wherein the delay is at least 30 μ

s, preferably at least 100 μ

s.

16. Communications apparatus as claimed in claim 11, wherein the monitoring station includes interferometer means having a path difference associated therewith for introducing a time delay between signal copies of a pair.

17. Communications apparatus as claimed in claim 16, wherein the interferometer means is used to temporally re-align the returned signal copies of a pair.

18. Communications apparatus as claimed in claim 12, wherein the optical source has a coherence time associated therewith, the coherence time being longer than the time delay between copies of a pair, preferably by at least a factor of 3, yet more preferably by at least a factor of 10.

21. A method as claimed in claim 1 including the further step of, after removing the modulator means from one access point, attaching the modulator means to another access point.

23. A modulator arrangement as claimed in claim 1, wherein the first coupling member includes a first component and a second component, each component having a respective arcuate receiving surface, such that when the first and second component are brought together, the receiving surfaces form a bore in which the optical link can reside.

19. A communication system including:

an optical waveguide;

a plurality of attachment points located at intervals along the optical waveguide;

a protective covering for protecting the waveguide between the attachment points, the protective covering having a coupling area associated therewith; and

, a removable acoustic modulator component for temporarily attaching to the waveguide at one of the attachment points, wherein at each attachment point there is provided a first coupling member permanently coupled to the waveguide, each first coupling member having a respective coupling area, the modulator component having a second coupling member for coupling to the coupling area of a first coupling member, the coupling area of each first coupling member being greater than the coupling area provided by the protective covering.

20. A method of using a communication arrangement which includes an optical waveguide, removable modulator means for acoustic modulating light travelling along the optical waveguide, a plurality of access points along the waveguide at which access points a respective coupling surface for coupling acoustic vibrations to the waveguide can be accessed, the fibre being inaccessible between the access points, the modulator component being releasably connectable to coupling surface an access point, wherein the method includes the steps of:

connecting the modulator means to one access point;

generating acoustic vibrations such that the acoustic vibration cause a modulation of light travelling along the waveguide; and

, removing the modulator means from the access point.

22. A method of using a communication arrangement which includes an optical waveguide, a removable modulator for causing acoustic vibrations which modulate light travelling along the optical waveguide, a plurality of attachment points along the waveguide at which the modulator can be attached, wherein the modulator is releasably connectable at the attachment points and is not connectable between access points, the method includes the steps of:

connecting the modulator to an access point;

causing acoustic vibrations such that the acoustic vibration cause a modulation of light travelling along the waveguide; and

, removing the modulator means from the attachment point.

24. A modulator arrangement for acoustically modulating optical radiation, the modulator arrangement comprising:

a waveguide portion formed from a flexible material;

a vibrator element for generating acoustic vibrations; and

, a coupling arrangement for releasably coupling the vibrating element to the waveguide portion, the coupling arrangement including a first coupling member secured to the waveguide portion, and a second coupling member secured to the vibrator element, wherein the second coupling member is removable from the first coupling member, and wherein the first coupling member has a substantially rigid portion for retaining the shape of the waveguide when the second coupling member is removed from the first coupling member.

25. A modulator arrangement as claimed in claim 24, wherein a bore is provided in the first coupling member though which the optical waveguide portion extends, the bore being arranged such that the waveguide portion is retained in the bore when the second coupling member is removed from the first coupling member.