Photonic direct sampling digital receiver

Patent metadata

Field	Value
Publication number	US-9843398-B1
Application number	US-201615161052-A
Country	US
Kind code	B1
Filing date	May 20, 2016
Priority date	May 20, 2016
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

A photonic analog to digital converter (pADC) includes an electronic I/Q generator, an optical sampler, and an optical detector. The electronic I/Q generator is configured to receive an RF signal and to generate an electronic in-phase signal I and an electronic quadrature-phase signal Q based on the received RF signal. The optical sampler includes one or more optical intensity modulators configured to receive the electronic I and Q signals from the electronic I/Q generator, and to modulate optical pulses to provide modulated optical I and Q signals based on the received electronic I and Q signals from the electronic I/Q generator. The optical detector includes a plurality of photodetectors, and is arranged to receive the modulated optical I and Q signals from the optical sampler and to convert the modulated optical I and Q signals into modulated electronic I and Q signals.

First claim

What is claimed is:

1. A photonic analog to digital converter (pADC), comprising:
an electronic I/Q generator configured to receive an RF signal and to generate an electronic in-phase signal I and an electronic quadrature-phase signal Q based on the received RF signal;
an optical sampler, coupled to the electronic I/Q generator, and including a plurality of optical intensity modulators, the plurality of optical intensity modulators being amplitude modulators, configured to receive the electronic I and Q signals from the electronic I/Q generator, to modulate optical pulses to provide modulated optical I and Q signals based on the received electronic I and Q signals from the electronic I/Q generator, the plurality of optical intensity modulators comprising a first optical intensity modulator configured to receive electronic I signals from the electronic I/Q generator, to modulate optical pulses to provide modulated optical I signals based on the received electronic I signals from the electronic I/Q generator, and a second optical intensity modulator configured to receive electronic Q signals from the electronic I/Q generator, to modulate optical pulses to provide modulated optical Q signals based on the received electronic Q signals from the electronic I/Q generator and
an optical detector, coupled to the optical sampler, and comprising a plurality of photodetectors, arranged to receive the modulated optical I and Q signals from the optical sampler and to convert the modulated optical I and Q signals into modulated electronic I and Q signals.

2. The pADC of claim 1 , further comprising:
an optical clock comprising an optical pulse source, configured to provide the optical pulses to the optical sampler.

3. The pADC of claim 1 , wherein the optical pulse source comprises a mode locked laser and oscillator.

4. The pADC of claim 1 , wherein each of the first and second optical intensity modulators comprises a mach-zehnder modulator.

5. The pADC of claim 1 , wherein the plurality of photodetectors comprise:
a first pair of photodetectors arranged in a balanced arrangement to receive a pair of modulated optical I signals from the optical sampler and to provide a single electronic I signal based on the pair of modulated optical I signals, and
a second pair of photodetectors arranged in a balanced arrangement to receive a pair of modulated optical Q signals from the optical sampler and to provide a single electronic Q signal based on the pair of modulated optical Q signals.

6. The pADC of claim 5 , wherein each of the first pair of photodetectors and the second pair of photodetectors are arranged as differential photodetectors.

7. The pADC of claim 6 , wherein the photodetectors comprise photodiodes.

8. The pADC of claim 5 , wherein the pair of modulated optical I signals are 180° out of phase with each other and the pair of modulated optical Q signals are 180° out of phase with each other.

9. The pADC of claim 5 , wherein each of the first and second optical intensity modulators comprises a mach-zehnder modulator.

10. The pADC of claim 9 , wherein the pair of modulated optical I signals are 180° out of phase with each other and the pair of modulated optical Q signals are 180° out of phase with each other.

11. The pADC of claim 1 , further comprising:
an opto-electronic receiver and quantizer configured to receive the modulated electronic I and Q signals from the optical detector, and to quantize the modulated electronic I and Q signals from the optical detector received from the opto-electronic receiver and quantizer.

12. The pADC of claim 1 , further comprising amplifiers configured to amplify the electronic I and Q signals from the electronic I/Q generator.

13. A processing system comprising:
a photonic analog to digital converter (pADC), comprising:
an electronic I/Q generator configured to receive an RF signal and to generate an electronic in-phase signal I and an electronic quadrature-phase signal Q based on the received RF signal;
an optical sampler, coupled to the electronic I/Q generator, including a plurality of optical intensity modulators, the plurality of optical intensity modulators being amplitude modulators, configured to receive the electronic I and Q signals from the electronic I/Q generator, to modulate optical pulses to provide modulated optical I and Q signals based on the received electronic I and Q signals from the electronic I/Q generator, the plurality of optical intensity modulators comprising a first optical intensity modulator configured to receive electronic I signals from the electronic I/Q generator, to modulate optical pulses to provide modulated optical I signals based on the received electronic I signals from the electronic I/Q generator, and a second optical intensity modulator configured to receive electronic Q signals from the electronic I/Q generator, to modulate optical pulses to provide modulated optical Q signals based on the received electronic Q signals from the electronic I/Q generator;
an optical detector, coupled to the optical sampler, and comprising a plurality of photodetectors, arranged to receive the modulated optical I and Q signals from the optical sampler and to convert the modulated optical I and Q signals into modulated electronic I and Q signals; and
an opto-electronic receiver and quantizer, coupled to the optical detector, and configured to receive the modulated electronic I and Q signals from the optical detector, and to quantize the modulated electronic I and Q signals from the optical detector received from the opto-electronic receiver and quantizer; and

processing electronics, coupled to the opto-electronic receiver and quantizer, and configured to receive the quantized I and Q signals from the pADC and to provide further signal processing on the quantized I and Q signals.

14. The pADC of claim 13 , wherein each of the first and second optical intensity modulators comprises a mach-zehnder modulator.

15. The pADC of claim 13 , wherein the plurality of photodetectors comprise:
a first pair of photodetectors arranged in a balanced arrangement to receive a pair of modulated optical I signals from the optical sampler and to provide a single electronic I signal based on the pair of modulated optical I signals, and
a second pair of photodetectors arranged in a balanced arrangement to receive a pair of modulated optical Q signals from the optical sampler and to provide a single electronic Q signal based on the pair of modulated optical Q signals.

16. A method of photonic analog to digital conversion, comprising:
receiving an RF signal;
generating an electronic in-phase signal I and an electronic quadrature-phase signal Q based on the received RF signal;
amplitude modulating the optical I signals to provide modulated optical I signals based on the generated electronic I signals;
amplitude modulating the optical Q signals to provide modulated optical Q signals based on the generated electronic Q signals; and
converting the modulated optical I and Q signals into modulated electronic I and Q signals.

17. The method of claim 16 , wherein each of the first and second optical intensity modulators comprises a mach-zehnder modulator.

18. The method of claim 16 , wherein the converting the modulated optical I and Q signals into modulated electronic I and Q signals is performed using balanced photodetector pairs.

Assignees

• Rockwell Collins Inc

Inventors

• Zanoni Raymond
• Richter Jerzy K
• Pelteku Altin E
• King Oliver S

Classifications

• H04B10/612 Primary

  for optical signals modulated with a format different from binary or higher-order PSK [X-PSK], e.g. QAM, DPSK, FSK, MSK, ASK · CPC title

• H04B1/0007 Primary

  wherein the AD/DA conversion occurs at radiofrequency or intermediate frequency stage · CPC title

• H04B2210/006

  Devices for generating or processing an RF signal by optical means · CPC title

• H04B10/00

  Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication · CPC title