Optical Network Testing

• US 20100266275A1
• Filed: 04/20/2009
• Published: 10/21/2010
• Est. Priority Date: 04/20/2009
• Status: Active Grant

• Current Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Original Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Inventors: Xia, Tiejun J., Wellbrock, Glenn A.
• Granted Patent: US 8,811,815 B2
• Time in Patent Office: Days
• US Class Current: 398/16
• CPC Class Codes: H04B 10/0773 Network aspects, e.g. central monitoring of transmission parameters
• 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 14/0258 Wavelength identification or labelling

Abstract

A method includes generating a test signal and modulating the test signal. The method may also include transmitting the test signal on an optical path, where the optical path may include a number of add-drop multiplexer devices and amplifiers. The method may also include receiving the test signal at a destination device and converting the received test signal into an electrical signal. The method may further include identifying a portion of the electrical signal that is associated with the modulated test signal.

Claims

1. A method, comprising:

generating a test signal;

modulating the test signal;

transmitting the test signal on an optical path, the optical path including a plurality of add-drop multiplexer devices and a plurality of amplifiers;

receiving the test signal at a destination device;

converting the received test signal into an electrical signal; and

identifying the alternating current (AC) portion of the electrical signal.

2. The method of claim 1, further comprising:

determining a pass-band characteristic of the optical path based on the identified AC portion of the electrical signal.

3. The method of claim 1, further comprising:

identifying an idle channel on the optical path on which the test signal will be transmitted; and

ensuring that the identified channel will be powered or kept alive during testing of the optical path.

4. The method of claim 1, wherein the generating, modulating and transmitting is performed by a transmitter test device, the method further comprising:

adjusting a tunable frequency of a first filter at the transmitter test device based on a frequency of a selected channel upon which the test signal is to be transmitted; and

filtering the generated test signal with the first filter, and wherein the generating a test signal comprises;

turning on an amplified stimulated emission source (ASE) at the transmitter test device to generate the test signal.

5. The method of claim 4, wherein the first filter has a 0.5-decibel (dB) bandwidth of approximately 50 gigahertz (GHz), a 3-dB bandwidth of approximately 70 GHz and a 20-dB bandwidth of approximately 100 GHz.

6. The method of claim 1, wherein the receiving, converting and identifying is performed by a receiver test device, the method further comprising:

filtering the received test signal with a second filter at the receiver test device based on a frequency of a selected channel upon which the test signal is transmitted.

7. The method of claim 6, wherein the second filter has a 3-dB bandwidth of approximately 3 GHz and a 20-dB bandwidth of approximately 10 GHz.

8. The method of claim 1, further comprising:

at least one of generating a curve representing a pass-band characteristic of the optical path or generating a pass/fail indication associated with the pass-band characteristic of the optical path, based on the identified AC portion of the electrical signal.

9. The method of claim 1, wherein the optical path includes a plurality of reconfigurable optical add-drop multiplexers.

10. The method of claim 1, wherein at least one of the generating, modulating, transmitting receiving, converting or identifying is done remotely with respect to the optical path.

11. A device, comprising:

a signal source configured to emit a test signal on an optical fiber;

a filter coupled to the signal source, the filter configured to filter the signal from the signal source based on a frequency associated with a channel of the optical fiber on which an optical path test is to be performed; and

a modulator coupled to the signal source, the modulator configured to modulate output of the signal source and forward the modulated signal onto the optical fiber.

12. The device of claim 11, wherein the signal source comprises an incoherent source of electromagnetic radiation.

13. The device of claim 12, wherein the incoherent source of electromagnetic radiation comprises an amplified stimulated emission source.

14. The device of claim 11, wherein the modulator is configured to modulate output of the signal source at a frequency ranging from about 400 megahertz (MHz) to about 600 MHz.

15. A device, comprising:

a receiver coupled to a last node in an optical path being tested, the receiver being configured to receive electromagnetic radiation transmitted through the optical path, wherein the optical path includes a first node configured to receive a modulated test signal, and a plurality of other nodes, wherein at least some of the nodes in the optical path include optical add-drop multiplexers;

a filter coupled to the receiver, the filter configured to filter the received electromagnetic radiation;

circuitry configured to convert the filtered electromagnetic radiation into electrical signals; and

logic configured to measure a portion of the electrical signals corresponding to electromagnetic radiation associated with the modulated test signal.

16. The device of claim 15, wherein when measuring a portion of the electrical signals, the logic is configured to:

measure an alternating current (AC) portion of the electrical signals, the AC portion representing electromagnetic radiation associated with the modulated test signal, and wherein the logic is further configured to;

determine a pass-band of the optical path based on the measured AC portion.

17. The device of claim 15, wherein the circuitry comprises a photo detector and the filter comprises a tunable filter, the tunable filter having −

3 dB bandwidth of approximately 3 GHz and a 20-dB bandwidth of approximately 10 GHz.

18. A system, comprising:

a first test device configured to be coupled to a first node in an optical path, the first test device comprising;

a signal source configured to generate test data, and

a modulator coupled to the signal source, the modulator configured to modulate output of the signal source and forward modulated test data onto the optical path; and

a second test device configured to be coupled to a last node in the optical path, the second test device comprising;

a filter configured to filter electromagnetic radiation received at the second test device,

circuitry configured to convert the filtered electromagnetic radiation into electrical signals, and

logic configured to measure a portion of the electrical signals corresponding to electromagnetic radiation associated with the modulated test data.

19. The system of claim 18, wherein the first test device further comprises:

a filter configured to filter output of the signal source prior to modulating the test data or filter output of the modulator prior to forwarding the modulated test data onto the optical path.

20. The system of claim 18, wherein the signal source comprises an amplified stimulated emission source.

21. The system of claim 18, wherein when measuring a portion of the electrical signals, the logic is configured to:

measure an alternating current (AC) portion of the electrical signals, the AC portion representing electromagnetic radiation associated with the modulated test data.

22. The system of claim 21, wherein the logic is further configured to:

generate a graph representing a pass-band characteristic of the optical path.