High frequency modulation circuits based on photoconductive wide bandgap switches

Patent metadata

Field	Value
Publication number	US-9893679-B2
Application number	US-201414218860-A
Country	US
Kind code	B2
Filing date	Mar 18, 2014
Priority date	Mar 15, 2013
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

Methods, systems, and devices for high voltage and/or high frequency modulation. In one aspect, an optoelectronic modulation system includes an array of two or more photoconductive switch units each including a wide bandgap photoconductive material coupled between a first electrode and a second electrode, a light source optically coupled to the WBGP material of each photoconductive switch unit via a light path, in which the light path splits into multiple light paths to optically interface with each WBGP material, such that a time delay of emitted light exists along each subsequent split light path, and in which the WBGP material conducts an electrical signal when a light signal is transmitted to the WBGP material, and an output to transmit the electrical signal conducted by each photoconductive switch unit. The time delay of the photons emitted through the light path is substantially equivalent to the time delay of the electrical signal.

First claim

What is claimed is:

1. An optoelectronic modulation device, comprising:
an array of two or more photoconductive switch units, each photoconductive switch unit including a wide bandgap photoconductive material coupled to a first electrode and a second electrode interfaced at opposite ends of the wide bandgap photoconductive material such that each photoconductive switch is electrically connected to all other photoconductive switches in a parallel configuration, such that a first electrode of one of the photoconductive switch units is in electrical contact with the first electrode of all other photoconductive switch units, and a second electrode of one of the photoconductive switch units is in electrical contact with the second electrode of all other photoconductive switch units, wherein a total capacitance of the array is distributed among the two or more photoconductive switch units to allow generation of electrical signals having a frequency of at least 1 GHz;
a light source optically coupled to the wide bandgap photoconductive material of each photoconductive switch unit via a light path, the light path splitting into multiple light paths to optically interface with each wide bandgap photoconductive material; and
a plurality of electrical wires forming multiple electrical paths that lead to an electrical output providing an output voltage for the array, each of the plurality of electrical wires coupled to a corresponding photoconductive switch to transmit an electrical signal conducted by the wide bandgap photoconductive material in each photoconductive switch unit to the electrical output, and
one or more optical delay elements optically coupled along at least one of the multiple light paths, wherein the one or more optical delay elements are configured to provide an optical time delay associated with activation of a first photoconductive switch with respect to a second photoconductive switch that is substantially equal to, and thus compensates for, an electrical time delay of appearances of the electrical signals associated with the first and the second photoconductive switches at the electrical output, such that the electrical signals from the first and second photoconductive switches simultaneously reach the electrical output.

2. The device of claim 1 , wherein the light source includes a coherent light source of energetic photons.

3. The device of claim 1 , wherein the one or more optical delay elements include active crystals of Lithium Niobate to provide the optical time delay.

4. The device of claim 1 , wherein the one or more optical delay elements include optical fiber to produce the optical time delay of the emitted light on at least one of the multiple light paths.

5. The device of claim 1 , wherein the wide bandgap photoconductive material includes SiC.

6. The device of claim 1 , comprising:
a temperature controller coupled to the wide bandgap photoconductive material to maintain the wide bandgap photoconductive material at a low temperature to obtain a short recombination time for the wide bandgap photoconductive material.

7. A method to modulate an electric signal, comprising:
providing a circuit having at least two photoconductive switches connected in parallel, wherein a first electrode of one of the photoconductive switches is in electrical contact with a first electrode of all other photoconductive switches, and a second electrode of one of the photoconductive switches is in electrical contact with a second electrode of all other photoconductive switches, and wherein each photoconductive switch does not conduct an electrical current in absence of light and become electrically conductive when being exposed to light and each photoconductive switch including a wide bandgap photoconductive material, and wherein a total capacitance of the array is distributed among the two photoconductive switches to allow generation of modulated electrical signals having a frequency of at least 1 GHz;
directing two light beams in two optical paths to the two photoconductive switches, respectively, to optically activate the two photoconductive switches at two different times such that the photoconductive switches become electrically conductive with a time delay with respect to one another;
directing modulated electrical signals produced by the two photoconductive switches through two electrical paths to an output of the circuit, wherein the time delay between the two optical paths configured to be substantially equal to, and thus compensate for, a time delay between the two electrical paths, such that the modulated electrical signals produced by the two photoconductive switches simultaneously reach the output of the circuit.

8. The method of claim 7 , comprising:
using a single light source to produce light for the two light beams; and
splitting the light from the single light source into the two light beams directed to the two photoconductive switches.

9. The method of claim 8 , comprising:
control light paths of the two light beams to control the time delay.

10. The method of claim 8 , comprising:
using two different light sources to produce the two light beams, respectively.

11. The method of claim 8 , comprising:
maintaining the wide bandgap photoconductive material at a low temperature to obtain a short recombination time for the wide bandgap photoconductive material.

Assignees

• L Livermore Nat Security Llc

Inventors

• Sampayan Stephen

Classifications

• H03C7/025 Primary

  using semiconductor devices · CPC title