Electro-absorption modulator adaptive equalizer systems and methods

Patent metadata

Field	Value
Publication number	US-2016248609-A1
Application number	US-201514630638-A
Country	US
Kind code	A1
Filing date	Feb 24, 2015
Priority date	Feb 24, 2015
Publication date	Aug 25, 2016
Grant date	—

Abstract

A system and method for adaptive equalization in a communication system. The system can include a modulator, a processor coupled to the modulator, and a memory coupled to the processor. The memory can store software instructions that, when executed by the processor, cause the processor to perform operations that can include generating, for each of one or more scan frequencies of interest, an optimal bias setting of the modulator. Data indicating a selection of a range of frequencies to be processed by the communication system can be received at the processor. The operations can include determining, responsive to the receiving, the optimal bias setting corresponding to the selected range of frequencies. A bias of the modulator can be adjusted based on the determined optimal bias setting, the adjusting providing adaptive equalization of the flatness response of the communication system.

First claim

What is claimed is:

1 . A communication system comprising:
a modulator; a processor coupled to the modulator; and a memory coupled to the processor, the memory having stored therein software instructions that, when executed by the processor, cause the processor to perform operations including:
generating, for each of one or more scan frequencies of interest, an optimal bias setting of the modulator;
receiving, at the processor, data indicating a selection of a range of frequencies to be processed by the communication system;
determining, responsive to the receiving, the optimal bias setting corresponding to the selected range of frequencies; and
adjusting a bias of the modulator based on the determined optimal bias setting,
the adjusting providing adaptive equalization of the flatness response of the communication system.

2 . The communication system of claim 1 , wherein the modulator is an electro-absorption modulator.

3 . The communication system of claim 1 , further comprising:
a modulator bias controller coupled to the modulator; and a digital-to-analog converter coupled to the modulator bias controller and to the processor, the processor being coupled to the modulator controller via the digital-to-analog converter, wherein the adjusting includes adjusting, responsive to the selecting, the bias of the modulator based on the selected optimal bias using the digital-to-analog converter and the modulator controller.

4 . The communication system of claim 1 , the operations further comprising:
storing each generated optimal bias setting in a lookup table, wherein the determining the optimal bias setting corresponding to the selected range of frequencies includes selecting, from the lookup table, the optimal bias setting corresponding to the selected range of frequencies.

5 . The communication system of claim 1 , the operations further comprising:
updating the respective optimal bias setting of one or more of the scan frequencies of interest.

6 . The communication system of claim 1 , wherein the generating is performed during internal calibration of the communication system.

7 . The communication system of claim 1 , wherein the generating includes receiving data from a digital receiver coupled to the communication system in a digital feedback loop.

8 . An adaptive equalizer configured to be coupled to a photonic radio frequency (RF) converter comprising a modulator, the adaptive equalizer comprising:
a modulator bias controller; a processor coupled to the modulator bias controller; and a memory coupled to the processor, the memory having stored therein software instructions that, when executed by the processor, cause the processor to perform operations including:
generating, for each of one or more scan frequencies of interest, an optimal bias setting of the modulator;
storing, in the memory, each generated optimal bias setting of the modulator in a lookup table;
receiving, at the processor, a tuning word/command indicating a selected range of frequencies to be processed by the photonic RF converter;
selecting, from the lookup table and responsive to the receiving, the optimal bias setting of the modulator corresponding to the selected range of frequencies indicated by the tuning word/command; and
adjusting a bias of the modulator via the modulator bias controller based on the selected optimal bias setting, the adjusting the bias of the modulator providing adaptive equalization of the flatness response of the photonic RF converter.

9 . The adaptive equalizer of claim 8 ,
wherein the modulator is an electro-absorption modulator, and wherein the adjusting includes adjusting a DC bias of the electro-absorption modulator via the modulator bias controller based on the selected optimal bias setting.

10 . The adaptive equalizer of claim 8 , further comprising:
a digital-to-analog converter coupled to the modulator bias controller and to the processor, the processor being coupled to the modulator controller via the digital-to-analog converter, wherein the adjusting includes adjusting the bias of the modulator based on the selected optimal bias by transmitting, from the processor, data to the digital-to-analog converter, the data adapted to cause the digital-to-analog converter to transmit a signal to the modulator bias controller, the signal adapted to cause the modulator bias controller to transmit a bias control signal to the photonic RF converter, the bias control signal configured to cause the photonic RF converter to adjust the bias of the modulator.

11 . The adaptive equalizer of claim 8 , the operations further comprising:
updating the respective optimal bias setting of one or more of the scan frequencies of interest.

12 . The adaptive equalizer of claim 8 , wherein the generating is performed during internal calibration of the photonic RF converter.

13 . The adaptive equalizer of claim 8 , wherein the generating includes receiving data from a digital receiver coupled to the photonic RF converter and the adaptive equalizer in a digital feedback loop.

14 . A method for adaptive equalization in a communication system comprising a photonic radio frequency (RF) converter that comprises a modulator, the method comprising:
generating, at a processor of the communication system, for each of one or more scan frequencies of interest, an optimal modulator bias setting; receiving, at the processor, data indicating a selected range of frequencies to be processed by the communication system; determining, responsive to the receiving, the optimal modulator bias setting corresponding to the selected range of frequencies; and adjusting, responsive to the determining, a bias of the modulator based on the selected optimal modulator bias, the adjusting causing the modulator to adaptively equalize the flatness response of the photonic RF converter.

15 . The method of claim 14 , wherein the modulator is an electro-absorption modulator.

16 . The method of claim 14 ,
wherein the communication system further comprises a digital-to-analog converter, and wherein the adjusting includes adjusting, responsive to the determining, the bias of the modulator based on the selected optimal modulator bias via the digital-to-analog converter.

17 . The method of claim 14 , the method further comprising:
storing, at a memory of the communication system coupled to the processor, each generated optimal modulator bias setting in a lookup table, wherein the determining includes selecting, from the lookup table, the optimal modulator bias setting corresponding to the selected range of frequencies.

18 . The method of claim 14 , the method further comprising:
updating the respective optimal modulator bias setting of one or more of the scan frequencies of interest.

19 . The method of claim 14 , wherein the generating is performed during internal calibration of the communication system.

20 . The method of claim 14 , wherein the modulator is a phase modulator.

21 . A computer readable medium having stored thereon software instructions that, when executed by a processor of a communication system comprising the processor and an optical modulator, cause the processor to perform operations comprising:
generating, for each of one or more scan frequencies of interest, an optimal bias setting; receiving, at the processor, data indicating a selected range of frequencies to be processed; selecting, responsive to the receiving, the optimal bias setting corre

Assignees

• Lockheed Corp

Inventors

• Schaefer Andrew F
• Ceccherelli John C
• Coyne Paul T
• Parsons Daniel S
• Robertson Stephen V

Classifications

• H04B10/6165

  Estimation of the phase of the received optical signal, phase error estimation or phase error correction · CPC title

• H04B10/548

  Phase or frequency modulation · CPC title

• H04L25/03159 Primary

  operating in the frequency domain (H04L25/03165, H04L25/03178 take precedence) · CPC title

• G02F1/0123 Primary

  Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops · CPC title

• H04B10/588

  in external modulation systems · CPC title