Dynamic gain equalizer

Patent metadata

Field	Value
Publication number	US-10419125-B1
Application number	US-201816005257-A
Country	US
Kind code	B1
Filing date	Jun 11, 2018
Priority date	Jun 11, 2018
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

A dynamic gain equalizer (DGE) for an optical communication device and related method which are capable of reducing power variations among wavelength division multiplexing (WDM) signals. The DGE and method use an optical attenuation device configured such that the ratio of pixel gap distance to the channel beam diameter at the point of incident to the optical attenuation device is less than or equal to 0.06. The DGE can produce output signal sets that have ripple increases of less than 0.1 db over the input signal sets.

First claim

We claim:

1. A dynamic gain equalizer for an optical communication path, comprising:
an input port to receive an input signal set from the optical communication path, the input signal comprises a plurality of optical signals, each optical signal being at a respective one of a plurality of wavelengths with each of the wavelengths having a power level;
an optical system configured to separate the input signal set into spatially separated channel beams based on wavelength and based on polarization components for each of the wavelengths, wherein each of the channel beams has an optical power, and wherein the optical system is further configured to reintegrate an attenuated channel beam set so as to produce an output signal set, wherein the output signal set has a flattened spectrum from the input signal set such that the power levels across the plurality of wavelengths has been equalized;
an optical attenuation device configured to receive the channel beams incident on the optical attenuation device from the optical system, attenuate the optical power of one or more of the channel beams so as to produce the attenuated channel beam set, and transmit the attenuated channel beam set to the optical system; and
an optical output port configured to transmit the output signal set from the optical system to the optical communication path.

2. The dynamic gain equalizer of claim 1 , wherein the optical attenuation device comprises a matrix of at least 40 pixels configured such that each pixel can be independently electrically driven and each pixel has a variable optical attenuation from 0 to 30 db.

3. The dynamic gain equalizer of claim 2 , wherein each of the channel beams has a diameter “d” when the channel beam is incident on the optical attenuation device.

4. The dynamic gain equalizer of claim 3 , the matrix of pixels are separated by a gap distance “g” and the optical attenuation device and the optical system are configured such that the ratio g/d is less than or equal to 0.06.

5. The dynamic gain equalizer of claim 4 , wherein the optical attenuation device and the optical system are configured such that the ratio g/d is less than or equal to 0.04.

6. The dynamic gain equalizer of claim 4 , wherein the optical attenuation device and the optical system are configured such that the ratio g/d is less than or equal to 0.037.

7. The dynamic gain equalizer of claim 4 , wherein the optical system comprises:
a compact planar array of optical elements, which planar array is configured to separate the input signal set into the spatially separated channel beams and configured to reintegrate the attenuated channel beam set so as to produce the output signal set, and wherein the optical elements are arranged such that the planar array is a folded optical system having a zigzag beam path laying in a single plane; and
a mirror configured to redirect the spatially separated channel beams so as to be incident on an incident face of the optical attenuation device, wherein the incident face is parallel to the single plane.

8. The dynamic gain equalizer of claim 7 , wherein the compact planar array of optical elements comprises:
a collimator configured to collimate the input signal set and transmit the input signal set along the beam path;
a polarization splitter disposed in the beam path and configured to split the input signal set into a pair of polarization components for each of the wavelengths;
a polarization rotator disposed in the beam path and configured to rotate one of the pair of polarization components;
a wavelength separator disposed in the beam path and configured to spatially separate the plurality of wavelengths into the channel beams; and
one or more lenses disposed within the beam path and configured to focus the channel beams such that the channel beams have the diameter “d” when the channel beams are incident on the optical attenuation device.

9. The dynamic gain equalizer of claim 8 , wherein the optical attenuation device and the optical system are configured such that the ratio g/d is less than or equal to 0.04.

10. The dynamic gain equalizer of claim 8 , wherein the optical attenuation device and the optical system are configured such that the ratio g/d is less than or equal to 0.037.

11. A method of manipulating an input signal set formed from a plurality of optical signals, each optical signal being at a respective one of a plurality of wavelengths with each of the wavelengths having a power level, the method comprising:
separating the input signal set into spatially separated channel beams based on wavelength and based on polarization components for each of the wavelengths to form a dispersed spectrum, wherein each of the channel beams has an optical power; and
attenuating the optical power of one or more of the channel beams so as to produce an attenuated channel beam set, wherein the step of attenuating the optical power comprises impinging the channel beams on a surface of an optical attenuation device, wherein the optical attenuation device comprises a matrix of at least 40 pixels, and wherein each position on pixel array is associated with a frequency in the dispersed spectrum with a p/d ratio less than 1, and wherein for the matrix has a chromatic dispersion of less than 10 ps/nm across from about 184,000 GHz to about 196,000 GHz.

12. The method of claim 11 , wherein each of the channel beams has a diameter “d” when the channel beam is incident on the optical attenuation device.

13. The method of claim 12 , the matrix of pixels are divided by a gap distance “g” and the optical attenuation device and the optical system are configured such that the ratio g/d is less than or equal to 0.06.

14. The method of claim 13 , wherein the ratio g/d is less than or equal to 0.04.

15. The method of claim 14 , wherein the ratio g/d is less than or equal to 0.037.

16. The method of claim 13 , further comprising:
reintegrating the attenuated channel beam set so as to produce an output signal set, wherein the output signal set has a flattened spectrum from the input signal set such that the power levels across the plurality of wavelengths has been equalized.

17. The method of claim 16 , wherein the output signal set has an increase in spectral ripple over the input signal set that is 0.1 db or less.

18. The method of claim 17 , wherein the ratio g/d is less than or equal to 0.04.

19. The method of claim 17 , wherein the ratio g/d is less than or equal to 0.037.

Assignees

• Molex Llc

Inventors

• Hu Gongjian
• Gong Lifu
• Liao Yi
• Zhu Tian

Classifications

• H04B10/2941

  using an equalising unit, e.g. a filter (H04B10/296 takes precedence) · CPC title

• H04B10/25073 Primary

  using spectral equalisation, e.g. spectral filtering · CPC title

• H04B10/564 Primary

  Power control · CPC title

• H04J14/02

  Wavelength-division multiplex systems · CPC title