Apparatus and method for optical heterodyne conversion
First Claim
1. A photomixer comprising:
- a substrate;
a first layer of at least one III-V compound, the bottom of the first layer facing the substrate and the first layer including molecules of the at least one compound bonded to form a uniform crystal lattice and additional atoms of a column V element in addition to those required to form the uniform crystal lattice, the additional atoms being disposed within the uniform crystal lattice to form defects in the uniform crystal lattice; and
a second electrically conductive layer formed over the first layer comprising a region of electrically conductive interdigitated electrodes with openings in the conductive layer exposing said first layer, whereby an electrical signal of a third frequency is coupled from the first layer to the electrically conductive layer as the first layer receives optical radiation of a first and second frequency, the third frequency being the difference between the first and second frequencies of the optical radiation.
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Accused Products
Abstract
An apparatus and method for optical heterodyne conversion and a radiation source and integrated diagnostics using the apparatus and method are disclosed. The radiation source can operate in a high-power narrow-band mode in which a constant-frequency output is provided or in a low-power broadband mode in which the frequency is tunable to allow the radiation source to act as a sweep oscillator. The apparatus or photomixer includes two sets of interdigitated conductive electrodes formed on top of a crystal lattice formed of column III-V compounds, particularly InAlGaAs compounds. Additional column V atoms are interspersed within the lattice structure to form defect energy states in the bandgap of the host material. The region of the material between the interdigitated electrodes is illuminated by optical radiation containing two different frequencies. Photon absorption in the material causes a current at the difference frequency to be generated and coupled to the interdigitated electrodes. The current is then coupled to a planar transmission line or antenna structure to generate coherent, continuous-wave, unimodal radiation in the microwave, millimeter-wave, or submillimeter-wave regions.
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Citations
34 Claims
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1. A photomixer comprising:
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a substrate; a first layer of at least one III-V compound, the bottom of the first layer facing the substrate and the first layer including molecules of the at least one compound bonded to form a uniform crystal lattice and additional atoms of a column V element in addition to those required to form the uniform crystal lattice, the additional atoms being disposed within the uniform crystal lattice to form defects in the uniform crystal lattice; and a second electrically conductive layer formed over the first layer comprising a region of electrically conductive interdigitated electrodes with openings in the conductive layer exposing said first layer, whereby an electrical signal of a third frequency is coupled from the first layer to the electrically conductive layer as the first layer receives optical radiation of a first and second frequency, the third frequency being the difference between the first and second frequencies of the optical radiation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11)
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8. A radiation source comprising:
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a first source of optical radiation for providing optical radiation of a first frequency; a second source of optical radiation for providing optical radiation of a second frequency; a photomixer comprising; a substrate; a first layer of at least one III-V compound formed on the substrate for receiving said optical radiation of a first frequency and said optical radiation of a second frequency, the bottom of the first layer facing the substrate and the first layer including molecules of the at least one compound bonded to form a uniform crystal lattice and additional atoms of a column V element in addition to those required to form the uniform crystal lattice, the additional atoms being disposed within the uniform crystal lattice to form defects in the uniform crystal lattice; and a second electrically conductive layer formed on the first layer comprising a region of electrically conductive interdigitated electrodes with openings in the conductive layer between the interdigitated electrodes which expose said first layer, whereby an electrical signal of a third frequency is coupled from the first layer to the electrically conductive layer as the first layer receives the radiation of the first and second frequencies, the third frequency being the difference between the first and second frequencies of the optical radiation; and an antenna coupled to the conductive layer to radiate said electrical signal of the third frequency away from the photomixer. - View Dependent Claims (9, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A photomixer comprising:
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a substrate; a low-temperature-grown epitaxial first layer of at least one III-V compound, the bottom of the first layer facing the substrate and the first layer including molecules of the at least one compound bonded to form a uniform crystal lattice and additional atoms of a column V element in addition to those required to form the uniform crystal lattice, the additional atoms being disposed within the uniform crystal lattice to form defects in the uniform crystal lattice; and a second electrically conductive layer formed over the first layer comprising a region of electrically conductive interdigitated electrodes with openings formed in the conductive layer between the electrodes to expose the first layer, whereby an electrical signal of a third frequency is coupled from the first layer to the electrically conductive layer as the first layer receives the optical radiation of a first and second frequency, the third frequency being the difference between the first and second frequencies of the optical radiation. - View Dependent Claims (23, 24, 25, 26)
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27. A radiation source comprising:
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a first source of optical radiation for providing optical radiation of a first frequency; a second source of optical radiation for providing optical radiation of a second frequency; a photomixer comprising; a substrate; a low-temperature-grown epitaxial first layer of at least one III-V compound formed on the substrate, the bottom of the first layer facing the substrate and the first layer including molecules of the at least one compound bonded to form a uniform crystal lattice and additional atoms of a column V element in addition to those required to form the uniform crystal lattice, the additional atoms being disposed within the uniform crystal lattice to form defects in the uniform crystal lattice; a second electrically conductive layer formed over the first layer comprising a region of electrically conductive interdigitated electrodes with openings formed in the conductive layer between the electrodes to expose the first layer, whereby an electrical signal of a third frequency is coupled from the first layer to the electrically conductive layer as the first layer receives the optical radiation of a first and second frequency, the third frequency being the difference between the first and second frequencies of the optical radiation; and an antenna coupled to the conductive layer to radiate a signal of the third frequency away from the photomixer. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. A sweep oscillator comprising:
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a first tunable source of optical radiation for providing optical radiation of a first frequency; a second tunable source of optical radiation for providing optical radiation of a second frequency; a photomixer comprising; a substrate; a first layer of at least one III-V compound formed on the substrate for receiving said optical radiation of a first frequency and said optical radiation of a second frequency, the bottom of the first layer facing the substrate and the first layer including molecules of the at least one compound bonded to form a uniform crystal lattice and additional atoms of a column V element in addition to those required to form the uniform crystal lattice, the additional atoms being disposed within the uniform crystal lattice to form defects in the uniform crystal lattice; and a second electrically conductive layer formed on the first layer comprising a region of electrically conductive interdigitated electrodes with openings in the conductive layer between the interdigitated electrodes which expose said first layer, whereby an electrical signal of a third frequency is coupled from the first layer to the electrically conductive layer as the first layer receives the radiation of the first and second frequencies, the third frequency being the difference between the first and second frequencies of the optical radiation, and being sweepable over a range of frequencies as at least one of the first and second tunable sources of optical radiation is tuned; and a planar antenna coupled to the conductive layer to radiate said electrical signal of the third frequency away from the photomixer.
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Specification