Mult-wavelength pulsed optical test instrument

Patent metadata

Field	Value
Publication number	US-10801918-B2
Application number	US-201816024227-A
Country	US
Kind code	B2
Filing date	Jun 29, 2018
Priority date	Mar 9, 2018
Publication date	Oct 13, 2020
Grant date	Oct 13, 2020

Abstract

A test instrument tests an optical component of a fiber optic network. The test instrument determines signal parameters describing pulses to be emitted by lasers of the test instrument to test the optical component, and directly modulates the lasers to repeatedly emit the pulses at different wavelengths on a single fiber optic cable in a time division multiplexing manner. The test instrument triggers powering measurements to coincide with the emitted pulses, and determines performance parameters of the optical component based on the triggered power measurements.

First claim

What is claimed is:

1. A test instrument to test optical components, the test instrument comprising:
lasers, wherein each laser is to emit an optical signal at a different wavelength;
a power meter to measure optical power; and
a processing circuit to control the lasers to test a device under test,
wherein to control the lasers comprises selectively modulating the lasers to emit a pulse train of optical signals at the different wavelengths on a single fiber optic cable in a time division multiplexing manner, and
wherein to selectively modulate the lasers, the processing circuit is to:
determine signal parameters describing the pulse train, wherein the signal parameters comprise a system period for the pulse train, a period for each pulse in the pulse train, and a pulse start time delay indicating a delay from a start of the system period for each pulse in the pulse train emitted from the lasers,
determine whether the signal parameters comply with a restriction by
determining whether a sum of the periods for pulses of the pulse train and the pulse start time delays for the pulses is less than or equal to the system period, and
based on a determination that the sum is less than or equal to the system period, then determining that the signal parameters comply with the restriction, and

based on a determination that the signal parameters comply with the restriction, control the lasers in accordance with the signal parameters to emit the pulse train; and

the processing circuit is further to trigger power measurements by the power meter to coincide with the emitted pulse train; and determine performance parameters of the device under test based on the triggered power measurements.

2. The test instrument of claim 1 , wherein to selectively modulate the lasers, the processing circuit is to:
output an electrical modulating signal to directly modulate the lasers in accordance with the signal parameters to cause the lasers to emit the pulse train described by the signal parameters.

3. The test instrument of claim 1 , wherein to determine whether the signal parameters comply with the restriction, the processing circuit is to:
determine whether the system period includes only one pulse for each wavelength; and
based on a determination that the system period includes only one pulse for each wavelength, then determine that the signal parameters comply with the restriction.

4. The test instrument of claim 1 , wherein to trigger power measurements that coincide with the emitted pulse train, the processing circuit is to:
calculate, for each pulse in the pulse train, a delay as a function of latency to directly modulate a corresponding laser for the pulse, the period for the pulse and the pulse start time delay for the pulse; and
trigger a power measurement for each pulse based on the calculated delay for each pulse.

5. The test instrument of claim 1 , wherein the pulse train comprises a single pulse for each wavelength.

6. The test instrument of claim 1 , wherein the processing circuit controls the lasers to repeatedly emit the pulse train over multiple consecutive system periods, and the processing circuit is to:
trigger power measurements for each pulse train;
determine the performance parameters for each pulse train; and
store the performance parameters.

7. The test instrument of claim 6 , wherein the pulse trains are transmitted in frames, wherein there is no gap between the frames.

8. The test instrument of claim 1 , wherein the performance parameters comprise at least one of insertion loss, return loss, or polarization dependent loss.

9. The test instrument of claim 1 , comprising:
a first port connectable to the device under test to transmit the emitted pulse train of optical signals to the device under test; and
a second port connectable to the device under test to receive the optical signals after the optical signals pass through the device under test,
wherein the power measurements comprise power measurements of the emitted optical signals and the received optical signals.

10. A test instrument comprising:
lasers, wherein each laser is to emit an optical signal at a different wavelength;
a power meter to measure optical power; and
a processing circuit to:
determine signal parameters describing pulses to be emitted by the lasers to test a device under test, wherein the signal parameters comprise a system period for a pulse train including the pulses, a period for each pulse in the pulse train, and a pulse start time delay indicating a delay from a start of the system period for each pulse in the pulse train emitted from the lasers;
based on the signal parameters, directly modulate the lasers to repeatedly emit the pulses at the different wavelengths on a single fiber optic cable in a time division multiplexing manner;
trigger power measurements by the power meter to coincide with the emitted pulses by
calculating, for each pulse, a delay as a function of latency to directly modulate a corresponding laser for the pulse, the period for the pulse and the pulse start time delay for the pulse, and
triggering a power measurement for each pulse based on the calculated delay for each pulse; and

determine performance parameters of the device under test based on the triggered power measurements.

11. The test instrument of claim 10 , wherein to directly modulate the lasers, the processing circuit is to:
determine whether the signal parameters comply with a restriction; and
based on a determination that the signal parameters comply with the restriction, directly modulate the lasers to repeatedly emit the pulses.

12. The test instrument of claim 11 , wherein to determine whether the signal parameters comply with the restriction, the processing circuit is to:
determine whether a sum of the periods for the pulses in the pulse train and the pulse start time delays for the pulses the pulse train is less than or equal to the system period.

13. The test instrument of claim 11 , wherein to determine whether the signal parameters comply with the restriction, the processing circuit is to:
determine whether the system period includes only one pulse for each wavelength.

14. The test instrument of claim 10 , wherein the performance parameters comprise at least one of insertion loss, return loss, or polarization dependent loss.

15. A method for testing an optical component of a fiber optic network with a test instrument, the method comprising:
determining signal parameters describing a pulse train to be emitted by lasers of the test instrument to test the optical component;
determining whether the signal parameters comply with a restriction by
determining whether a sum of periods for pulses of the pulse train and pulse start time delays for the pulses is less than or equal to a system period for the pulse train, and
based on a determination that the sum is less than or equal to the system period, the determining that the signal parameters comply with the restriction;

based on a determination that the signal parameters comply with the restriction, directly modulating the lasers to repeatedly emit the pulses at different wavelengths on a single fiber optic cable connecting the optical component to the test instrument, wherein the pulses are time division multiplexed on the fiber optic cable;
triggering powering measurements by a power meter of the test instrument to coincide with the emitted pulses; and
determining performance parameters of the optical component based on the triggered power measurements.

Assignees

• Viavi Solutions Inc

Inventors

• Adams Robert Matthew
• Philipson Joshua
• Wagner Chris
• Tessaro Grant

Classifications

• G01M11/3127 Primary

  using multiple or wavelength variable input source · CPC title

• G01M11/333

  using modulated input signals · CPC title