System and method for removing far field limitations in microwave photonic arbitrary waveform generators

Patent metadata

Field	Value
Publication number	US-2016323036-A1
Application number	US-201514980178-A
Country	US
Kind code	A1
Filing date	Dec 28, 2015
Priority date	Mar 15, 2013
Publication date	Nov 3, 2016
Grant date	—

Abstract

A photonic waveform generator and a method of generating an electrical waveform based on a photonic signal are disclosed. The generator includes an input port for receiving an optical signal, a pulse shaper coupled to the input port and configured to Fourier transform the optical signal and apply a pre-distort waveform onto optical spectrum of the optical signal, a dispersive pulse stretcher coupled to the pulse shaper, an optical-to-electrical converter coupled to the dispersive pulse stretcher, and an output port coupled to the optical-to-electrical converter, the pre-distortion removes distortion of the electrical signal that exists in the absence of the pre-distortion caused by violation of far field limitation between the optical signal and the electrical signal.

First claim

1 . A photonic waveform generator, comprising:
an input port for receiving an optical signal; a pulse shaper coupled to the input port and configured to Fourier transform the optical signal and apply a pre-distortion waveform onto optical spectrum of the optical signal resulting in a shaped optical signal having both optical amplitude and optical phase spectral shaping; a dispersive pulse stretcher coupled to the pulse shaper and configured to provide a frequency dependent delay which disperses the shaped optical signal; an optical-to-electrical converter coupled to the dispersive pulse stretcher and configured to convert an optical input corresponding to the dispersed shaped optical signal to an electrical output; and an output port coupled to the optical-to-electrical converter and configured to output an electrical signal corresponding to the electrical output, the pre-distortion waveform of the transformed optical signal removes distortion of the electrical signal that exists in the absence of the pre-distortion waveform caused by violation of far field limitation between the optical signal and the electrical signal.

2 . The photonic waveform generator of claim 1 , wherein the optical-to-electrical converter is a photodetector.

3 . The photonic waveform generator of claim 2 , wherein the photodetector is a photodiode.

4 . The photonic waveform generator of claim 1 , wherein the dispersive pulse stretcher comprises an optical element having a non-zero dispersion characteristic.

5 . The photonic waveform generator of claim 1 , wherein the pulse shaper comprises:
a spatial modulator; an optical grating; and a reflective surface, wherein the spatial modulator is a liquid crystal module, disposed between the optical grating and the reflective surface, wherein the reflective surface is a mirror, and where the spatial modulator is a transmissive film resulting in one of a spatial pattern of polarization change, transmission loss, transmission phase shift, or a combination thereof.

6 . The photonic waveform generator of claim 1 , wherein an input and an output of the pulse shaper are co-linear.

7 . The photonic waveform generator of claim 1 , where time bandwidth product of the electrical signal is capable of being about 50% to about 100% the maximum time bandwidth product available from the pulse shaper.

8 . A method for generating an electrical pulse with controlled spectral characteristics, the method comprising:
receiving an optical signal; Fourier transforming the optical signal using a pulse shaper to generate a transformed optical signal; pre-distorting the transformed optical signal to generate a pre-distorted transformed optical signal; and stretching the pre-distorted transformed optical signal through a dispersive pulse stretcher; and converting the stretched pre-distorted transformed optical signal to an electrical signal by an optical-to-electrical converter, wherein the pre-distortion of the transformed optical signal removes distortion of the electrical signal that exists in the absence of the pre-distortion caused by violation of far field limitation between the optical signal and the electrical signal.

9 . The method of claim 8 , wherein the optical-to-electrical converter is a photodetector.

10 . The method of claim 9 , wherein the photodetector is a photodiode.

11 . The method of claim 10 , photonic waveform generator of claim 1 , wherein the dispersive pulse stretcher comprises an optical element having a non-zero dispersion characteristic.

12 . The method of claim 8 , wherein the pulse shaper comprises:
a spatial modulator; an optical grating; and a reflective surface, wherein the spatial modulator is a liquid crystal module, disposed between the optical grating and the reflective surface, wherein the reflective surface is a mirror, and where the spatial modulator is a transmissive film resulting in one of a spatial pattern of polarization change, transmission loss, transmission phase shift, or a combination thereof.

13 . The method of claim 8 , wherein an input and an output of the pulse shaper are co-linear.

14 . The method of claim 13 , where time bandwidth product of the electrical signal is capable of being about 50% to about 100% the maximum time bandwidth product available from the pulse shaper.

Assignees

• Purdue Research Foundation

Inventors

• Weiner Andrew Marc
• Dezfooliyan Amir

Classifications

• H04B10/2575

  Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier · CPC title

• H04B10/2507 Primary

  for the reduction or elimination of distortion or dispersion · CPC title

• H04B10/58

  Compensation for non-linear transmitter output · CPC title

• H03K3/84 Primary

  Generating pulses having a predetermined statistical distribution of a parameter, e.g. random pulse generators · CPC title

• H04B2210/006

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