ATTENUATION SYSTEMS AND METHODS FOR USE WITH AN OPTICAL DETECTOR IN AN OPTICAL COMMUNICATION SYSTEM

• US 20090041477A1
• Filed: 10/21/2008
• Published: 02/12/2009
• Est. Priority Date: 10/13/2000
• Status: Active Grant

• Current Assignee: Xylon LLC (Intellectual Ventures LLC)
• Original Assignee: Kiribati Wireless Ventures LLC (Intellectual Ventures LLC)
• Inventors: Alwan, James J., O'Brien, Hugh Michael IV, Pyka, Werner, Hoiseth, Glenn Claude, Rogers, Raymond D., Bloom, Scott Harris, Platenberg, Scott, Chan, Victor J., Binun, Paul William
• Granted Patent: US 7,831,154 B2
• Time in Patent Office: Days
• US Class Current: 398/202
• CPC Class Codes: H04B 10/0799 Monitoring line transmitter or line receiver equipment
• CPC Class Codes: H04B 10/1123 Bidirectional transmission
• CPC Class Codes: H04B 10/674 using a variable optical attenuator

Abstract

Systems and methods for use with an optical communication beam are disclosed. The system allows the beam of light to operate at an adequate power level that provides a robust optical link while minimizing any safety risk to humans. The system calibrates and controls the gain for an avalanche photodiode detector (APD). A detector circuit is used to calibrate the APD. Once calibrated, the detector circuit further provides an electrical bias to the APD to process or condition the electrical signal to produce a detector output. The systems and methods disclosed herein attenuate the power level of an incoming communication beam to prevent oversaturation of an APD. The system further provides an alignment signal, which is effective over a wide dynamic range of incoming power levels.

Claims

1. A method comprising:

receiving a communication beam by an optical detector;

monitoring a Receive (Rx) power level indicative of strength of the communication beam received by the optical detector;

determining if the Rx power level exceeds a saturation threshold level for the optical detector;

if the Rx power level exceeds a saturation threshold level of the optical detector, incrementing attenuation of the communication beam by incrementally activating an optical attenuator, wherein the optical attenuator is located in a path of the communication beam and the optical detector, wherein the optical attenuator is operable to attenuate the strength of the communication beam received by the optical detector;

wherein the optical attenuator has a first area, wherein said incrementally activating the optical attenuator comprises turning on a first portion of the optical attenuator, wherein the first portion is smaller than the first area.

2. The method of claim 1, further comprising:

if the optical detector is not engaged, engaging the optical attenuator.

3. The method of claim 2,

wherein the optical attenuator is movable into and out of the path of the communication beam.

4. The method of claim 1,

wherein a communication system comprises a first node and a second node, wherein the second node is configured to transmit the communication beam to the first node, and wherein the first node includes the optical attenuator.

5. The method of claim 1,

wherein the first area comprises a plurality of sectors;

and

wherein the first portion comprises one or more sectors of the plurality of sectors.

6. The method of claim 1,

wherein the first area comprises a plurality of concentric circles;

and

wherein the first portion comprises one or more concentric circles of the plurality of concentric circles.

7. The method of claim 1, wherein the optical detector comprises one or more of:

an avalanche photodiode detector (APD);

a charge coupled device (CCD);

a photomultiplier tube (PMT);

or

any other type of a photo detector.

8. The method of claim 1, further comprising:

converting the communication beam into a first signal;

measuring the strength of the first signal to produce a received signal strength indicator (RSSI) for the first signal; and

aligning the optical detector with the communication beam based on one or more of the RSSI or the Rx power level.

9. A method comprising:

receiving a communication beam by an optical detector;

monitoring a Receive (Rx) power level indicative of strength of the communication beam received by the optical detector;

determining if the Rx power level is below a minimum threshold level for the optical detector;

if the Rx power level is below the minimum threshold level of the optical detector, decrementing attenuation of the communication beam by incrementally deactivating an optical attenuator, wherein the optical attenuator is located in a path of the communication beam and the optical detector, wherein the optical attenuator is operable to attenuate the strength of the communication beam received by the optical detector;

wherein the optical attenuator has a first area, wherein said incrementally deactivating comprises turning off a first portion of the optical attenuator, wherein the first portion is smaller than the first area.

10. The method of claim 9, further comprising:

if the attenuation of the optical attenuator is below a minimum level, disengaging the optical attenuator.

11. The method of claim 9,

wherein the optical attenuator is movable into and out of the path of the communication beam.

12. The method of claim 9,

wherein a communication system comprises a first node and a second node, wherein the second node is configured to transmit the communication beam to the first node, and wherein the first node includes the optical attenuator.

13. The method of claim 9,

wherein the first area comprises a plurality of sectors;

and

wherein the first portion comprises one or more sectors of the plurality of sectors.

14. The method of claim 9,

wherein the first area comprises a plurality of concentric circles;

and

wherein the first portion comprises one or more concentric circles of the plurality of concentric circles.

15. The method of claim 9, wherein the optical detector comprises one or more of:

an avalanche photodiode detector (APD);

a charge coupled device (CCD);

a photomultiplier tube (PMT);

or

any other type of a photo detector.

16. The method of claim 9, further comprising:

converting the communication beam into a first signal;

measuring the strength of the first signal to produce a received signal strength indicator (RSSI) for the first signal; and

aligning the optical detector with the communication beam based on one or more of the RSSI or the Rx power level.

17. A system comprising:

an optical detector configured to receive a communication beam, wherein the optical detector is operable to generate a receive (Rx) power level indicative of strength of the communication beam;

an optical attenuator located in a path of the communication beam and the optical detector, wherein the optical attenuator is operable to attenuate the strength of the communication beam received by the optical detector, wherein the optical attenuator has a first area; and

an attenuator control module coupled to the optical attenuator, wherein the attenuator control module is operable to receive the Rx power level and control the optical attenuator based on the Rx power level;

wherein if the Rx power level exceeds a saturation threshold level of the optical detector, the attenuator control module is operable to send one or more control signals to the optical attenuator incrementing attenuation of the communication beam, wherein said incrementing attenuation comprises turning on a first portion of the optical attenuator, wherein the first portion is smaller than the first area.

18. A system comprising:

an optical detector configured to receive a communication beam, wherein the optical detector is operable to generate a receive (Rx) power level indicative of strength of the communication beam;

an optical attenuator located in a path of the communication beam and the optical detector, wherein the optical attenuator is operable to attenuate the strength of the communication beam received by the optical detector, wherein the optical attenuator has a first area; and

an attenuator control module coupled to the optical attenuator, wherein the attenuator control module is operable to receive the Rx power level and control the optical attenuator based on the Rx power level;

wherein if the Rx power level is below a minimum threshold level of the optical detector, the attenuator control module is operable to send one or more control signals to the optical attenuator decrementing attenuation of the communication beam, wherein said decrementing attenuation comprises turning off a first portion of the optical attenuator, wherein the first portion is smaller than the first area.