Optical receiver sensitivity system

Patent metadata

Field	Value
Publication number	US-10236995-B2
Application number	US-201615340351-A
Country	US
Kind code	B2
Filing date	Nov 1, 2016
Priority date	Dec 18, 2013
Publication date	Mar 19, 2019
Grant date	Mar 19, 2019

Abstract

A system includes a detector array having a plurality of level detectors to monitor an optical input signal. Each level detector of the detector array operates in a different operating range, and each operating range for each level detector has a different saturation level and a different cutoff level based on a power level of the optical input signal. A controller monitors the plurality of level detectors of the detector array to detect a present power level for the optical input signal by selecting the operating range that is associated with the level detector operating between its saturation level and its cutoff level.

First claim

What is claimed is:

1. A system comprising:
a receiving path to provide a first portion of an optical input signal to a delay loop and a second portion of the optical input signal to a set of optical splitters, where the set of optical splitters divides the second portion of the optical input signal into optical signals with different proportions of optical signal power of the second portion of the optical input signal;
a monitor array having a plurality of level detectors to monitor the second portion of the optical input signal from a respective one of the set of optical splitters, wherein each level detector of the monitor array employs a different integration time to sense differing power levels in the second portion of the optical input signal;
a controller to monitor the plurality of level detectors of the monitor array to detect a present power level of the optical input signal and to control an output signal attenuation level to a receiver photodetector based on the detected present power level of the optical input signal; and
at least one variable optical attenuator (VOA) to adjust the output signal attenuation level to the receiver photodetector in response to the controller.

2. The system of claim 1 , wherein each optical splitter in the set of optical splitters is a mirror or a prism configuration.

3. The system of claim 1 , wherein each of the plurality of level detectors of the monitor array include a photodiode and an integrating amplifier (IA) to convert the second portion of the optical input signal to an electrical signal.

4. The system of claim 3 , wherein each photodiode in each level detector of the plurality of level detectors is set to a different integration time to increase sensitivity of the monitor array.

5. The system of claim 4 , wherein each IA in each level detector of the plurality of level detectors is set to a different integration time to further increase the sensitivity of the monitor array.

6. The system of claim 1 , further comprising a delay line to operate with the at least one VOA to provide feed-forward adjustment of the attenuation level of the output signal to the receiver photodetector in response to the controller.

7. The system of claim 1 , wherein the at least one VOA is variable neutral density filter.

8. The system of claim 1 , wherein each level detector of the monitor array has a different operating range comprising a different saturation level and a different cutoff level.

9. The system of claim 1 ,
wherein a first level detector of the monitor array is operating at cutoff corresponding to a first level in response to the second portion of the optical input signal,
wherein a second level detector of the monitor array is operating at saturation corresponding to a second level in response to the second portion of the optical input signal,
wherein a third level detector of the monitor array is operating at a third level between the first level and the second level, wherein the third level is associated with the present power level of the second portion of the optical input signal.

10. The system of claim 9 , wherein controlling the output signal attenuation level to the receiver photodetector comprises dynamically adjusting a sensitivity level of the receiver photodetector in response to the detected present power level to control an attenuation level of the receiver photodetector.

11. The system of claim 1 , further comprising a range detector to provide distance data representing a distance between a source of the second portion of the optical input signal and the system to the controller, wherein the controller performs automated calibration to adjust an integration time of a respective level detector of the plurality of level detectors in response to the distance data.

12. The system of claim 11 , wherein the distance data is provided by a direct measurement via a RADAR system, provided by a round-trip transmit time measurement via an ancillary communication system or a laser system, or provided by a data input received from a communications channel or a global positioning system (GPS).

13. The system of claim 1 ,
wherein the delay loop is coupled to the at least one VOA and provides the first portion of the optical input signal to the at least one VOA,
wherein the at least one VOA adjusts the output signal attenuation level to the receiver photodetector in response to the controller.

14. The system of claim 1 , wherein the controller is one of a microprocessor, a micro-controller including on-board analog-to-digital (A/D) converters or a programmable controller system (PLC).

15. A system comprising:
a receiving path to provide a first portion of an optical input signal to a delay loop and a second portion of the optical input signal to a set of optical splitters, where the set of optical splitters divides the second portion of the optical input signal into optical signals with different proportions of optical signal power of the second portion of the optical input signal;
a monitor array having a plurality of level detectors to monitor the second portion of the optical input signal from a respective one of the set of optical splitters, wherein each level detector of the monitor array employs a different integration time to sense differing power levels in the second portion of the optical input signal and operates in a different operating range, each operating range for each level detector having a different saturation level and a different cutoff based on a power level of the second portion of the optical input signal;
a controller to monitor the plurality of level detectors of the monitor array to detect a present power level of the optical input signal and to control an output signal attenuation level to a receiver photodetector based on the detected present power level of the optical input signal; and
at least one variable optical attenuator (VOA) to adjust the output signal attenuation level to the receiver photodetector in response to the controller.

16. The system of claim 15 , further comprising a delay line to operate with the at least one VOA to provide feed-forward adjustment of the attenuation level of the output signal to the receiver photodetector in response to the controller.

17. The system of claim 15 ,
wherein a first level detector of the monitor array is operating at cutoff corresponding to a first level in response to the second portion of the optical input signal,
wherein a second level detector of the monitor array is operating at saturation corresponding to a second level in response to the second portion of the optical input signal,
wherein a third level detector of the monitor array is operating at a third level between the first level and the second level, wherein the third level is associated with the present power level of the second portion of the optical input signal,
wherein controlling the output signal attenuation level to the receiver photodetector comprises dynamically adjusting a sensitivity level of the receiver photodetector in response to the detected present power level to control an attenuation level of the receiver photodetector.

18. The system of claim 15 ,
wherein each of the plurality of level detectors of the monitor array include a photodiode and an integrating amplifier (IA) to convert the second portion of the optical input signal to an electrical signal,
wherein each photodiode in each level detector of the plurality of level detectors is set to a different integration time to increase sensitivity of the monitor array,
wherein each IA in e

Assignees

• Featherston John
• Cicchiello James M
• Harkrider Curtis J
• Archer Christopher A
• Bean Frederick D
• Northrop Grumman Systems Corp

Inventors

• Featherston John
• Cicchiello James M
• Harkrider Curtis J
• Archer Christopher A
• Bean Frederick D

Classifications

• H04B10/07955

  Monitoring or measuring power · CPC title

• H04B10/674 Primary

  using a variable optical attenuator · CPC title

• H04B10/2537

  due to scattering processes, e.g. Raman or Brillouin scattering · CPC title

• H04B10/2916

  using Raman or Brillouin amplifiers · CPC title

• H04B10/25

  Arrangements specific to fibre transmission · CPC title