초록 ▼

A multi-spectral super-pixel photodetector for detecting four or more different bands of infrared radiation is described. The super-pixel photodetector includes two or more sub-pixel photodetectors, each of which includes a diffractive resonant optical cavity that resonates at two or more infrared r

A multi-spectral super-pixel photodetector for detecting four or more different bands of infrared radiation is described. The super-pixel photodetector includes two or more sub-pixel photodetectors, each of which includes a diffractive resonant optical cavity that resonates at two or more infrared radiation bands of interest. By detecting infrared radiation at two or more different applied biases and by generating a spectral response curve for each of the sub-pixel photodetectors at each of these biases, the response to each of the individual bands of infrared radiation can be calculated. The response to each band of infrared radiation can be found by deconvolving the response at each bias. The super-pixel photodetector finds use in military and medical imaging applications and can cover a broad portion of the infrared spectrum.

대표청구항 ▼

What is claimed is: 1. A multi-spectral infrared radiation super-pixel photodetector including a plurality of sub-pixel photodetectors, each of the plurality of sub-pixel photodetectors comprising: a plurality of elements for absorbing at least two bands of infrared radiation, each of the plurality

What is claimed is: 1. A multi-spectral infrared radiation super-pixel photodetector including a plurality of sub-pixel photodetectors, each of the plurality of sub-pixel photodetectors comprising: a plurality of elements for absorbing at least two bands of infrared radiation, each of the plurality of elements being elongate, each of the plurality of elements having first and second opposite longitudinal surfaces, the at least two bands of infrared radiation incident upon the first surfaces of the plurality of elements; a plurality of strips respectively being in electrical contact with and extending along the first surfaces of the plurality of elements, the plurality of strips being electrically interconnected; a bottom contact being in electrical contact with the second surfaces of the plurality of elements, the plurality of strips and the bottom contact to provide for current flow through the plurality of elements in a direction substantially transverse to an axis of the plurality of elements; and a reflector for the at least two bands of infrared radiation, the reflector being disposed on an opposite longitudinal surface of the bottom contact from the plurality of elements, a bias voltage source, said bias voltage source selectively providing a plurality of external bias voltages, wherein a ratio between a photoresponse to each of the at least two bands of infrared radiation is a function of which of the plurality of external bias voltages is applied between the plurality of strips and the bottom contact, wherein the plurality of elements, the plurality of strips, the bottom contact and the reflector comprise a diffractive resonant optical cavity for the at least two bands of infrared radiation, and wherein a diffractive resonant optical cavity for a first sub-pixel photodetector of the plurality of sub-pixel photodetectors is different from a diffractive resonant optical cavity for a second sub-pixel photodetector of the plurality of sub-pixel photodetectors. 2. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 1, wherein the plurality of elements of each sub-pixel photodetector comprise multiple quantum well material selected from the group consisting of GaAs, AlGaAs, InGaAs, InP and combinations thereof. 3. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 1, wherein the reflector of each sub-pixel photodetector is either a metallic reflector or a Bragg reflector. 4. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 1, wherein the at least two bands of infrared radiation is two bands of infrared radiation. 5. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 1, wherein the at least two bands of infrared radiation is three bands of infrared radiation. 6. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 1, wherein a quantity of the plurality of sub-pixel photodetectors is two sub-pixel photodetectors. 7. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 1, wherein a quantity of the plurality of sub-pixel photodetectors is four sub-pixel photodetectors. 8. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 7, wherein a diffractive resonant optical cavity for a third sub-pixel photodetector is substantially the same as the diffractive resonant optical cavity of the first sub-pixel photodetector, and wherein a diffractive resonant optical cavity for a fourth sub-pixel photodetector is substantially the same as the diffractive resonant optical cavity of the second sub-pixel photodetector. 9. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 7, wherein a diffractive resonant optical cavity for each sub-pixel photodetector within the super-pixel photodetector is different. 10. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 7, wherein the four sub-pixel photodetectors are arranged in a linear configuration. 11. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 7, wherein the four sub-pixel photodetectors are arranged in a quadrant configuration. 12. A multi-spectral infrared radiation super-pixel photodetector including a plurality of sub-pixel photodetectors, each of the plurality of sub-pixel photodetectors comprising: a plurality of elements for absorbing at least two bands of infrared radiation, each of the plurality of elements being elongate, each of the plurality of elements having first and second opposite longitudinal surfaces, the at least two bands of infrared radiation incident upon the first surfaces of the plurality of elements; a plurality of strips respectively being in electrical contact with and extending along the first surfaces of the plurality of elements, the plurality of strips being electrically interconnected; a bottom contact being in electrical contact with the second surfaces of the plurality of elements, the plurality of strips and the bottom contact to provide for current flow through the plurality of elements in a direction substantially transverse to an axis of the plurality of elements; and a reflector for reflecting the at least two bands of infrared radiation, the reflector being disposed on an opposite longitudinal surface of the bottom contact from the plurality of elements, wherein the plurality of elements, the plurality of strips, the bottom contact and the reflector comprise a diffractive resonant optical cavity, the diffractive cavity having a first period in a first direction for diffracting a first band of the at least two bands of infrared radiation and a second period in a second direction for diffracting a second band of the at least two bands of infrared radiation, the second band of infrared radiation different from the first band of infrared radiation, the second direction being substantially perpendicular to the first direction, a bias voltage source, said bias voltage source selectively providing a plurality of external bias voltages, wherein a ratio between a photoresponse to each of the at least two bands of infrared radiation is a function of which of the plurality of external bias voltages is applied between the plurality of strips and the bottom contact, and wherein a diffractive resonant optical cavity for a first sub-pixel photodetector of the plurality of sub-pixel photodetectors is different from a diffractive resonant optical cavity for a second sub-pixel photodetector of the plurality of sub-pixel photodetectors. 13. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 12, wherein the plurality of elements of each sub-pixel photodetector comprise multiple quantum well material selected from the group consisting of GaAs, AlGaAs, InGaAs and combinations thereof. 14. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 12, wherein the reflector of each sub-pixel photodetector is either a metallic reflector or a Bragg reflector. 15. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 12, wherein the at least two bands of infrared radiation is two bands of infrared radiation. 16. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 12, wherein the at least two bands of infrared radiation is three bands of infrared radiation. 17. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 12, wherein a quantity of the plurality of sub-pixel photodetectors is two sub-pixel photodetectors. 18. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 12, wherein a quantity of the plurality of sub-pixel photodetectors is four sub-pixel photodetectors. 19. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 18, wherein a diffractive resonant optical cavity for a third sub-pixel photodetector is substantially the same as the diffractive resonant optical cavity of the first sub-pixel photodetector, and wherein a diffractive resonant optical cavity for a fourth sub-pixel photodetector is substantially the same as the diffractive resonant optical cavity of the second sub-pixel photodetector. 20. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 18, wherein a diffractive resonant optical cavity for each sub-pixel photodetector within the super-pixel is different. 21. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 18, wherein the four sub-pixel photodetectors are arranged in a linear configuration. 22. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 18, wherein the four sub-pixel photodetectors are arranged in a quadrant configuration. 23. A multi-spectral infrared radiation super-pixel photodetector including a plurality of sub-pixel photodetectors, each of the plurality of sub-pixel photodetectors comprising: a plurality of elements for absorbing three bands of infrared radiation, each of the three bands of infrared radiation being different from each of the other three bands of infrared radiation, each of the plurality of elements being elongate, each of the plurality of elements having first and second opposite longitudinal surfaces, the three bands of infrared radiation incident upon the first surfaces of the plurality of elements, the plurality of elements comprising multiple quantum well material including GaAs and AlGaAs; a plurality of strips respectively being in electrical contact with and extending along the first surfaces of the plurality of elements, the plurality of strips being electrically interconnected; a bottom contact being in electrical contact with the second surfaces of the plurality of elements, the plurality of strips and the bottom contact to provide for current flow through the plurality of elements in a direction substantially transverse to an axis of the plurality of elements; and a metallic reflector for the three bands of infrared radiation, the reflector being disposed on an opposite longitudinal surface of the bottom contact from the plurality of elements, a bias voltage source, said bias voltage source selectively providing a plurality of external bias voltages, wherein a ratio between a photoresponse to each of the three bands of infrared radiation is a function of which of the plurality of external bias voltages is applied between the plurality of strips and the bottom contact, wherein the plurality of elements, the plurality of strips, the bottom contact and the reflector comprise a diffractive resonant optical cavity for the three bands of infrared radiation, and wherein a diffractive resonant optical cavity for a first sub-pixel photodetector of the plurality of sub-pixel photodetectors is different from a diffractive resonant optical cavity for a second sub-pixel photodetector of the plurality of sub-pixel photodetectors. 24. A multi-spectral infrared radiation super-pixel photodetector including four upper sub-pixel photodetectors and one lower sub-pixel photodetector, each of the four upper sub-pixel photodetectors comprising: a plurality of first elements for absorbing two or more bands of infrared radiation, each of the two or more bands of infrared radiation being different from each of the other two or more bands of infrared radiation, each of the plurality of first elements being elongate, each of the plurality of first elements having first and second opposite longitudinal surfaces, the two or more bands of infrared radiation incident upon the first surfaces of the plurality of first elements; a plurality of strips respectively being in electrical contact with and extending along the first surfaces of the plurality of first elements, the plurality of strips being electrically interconnected; a middle contact being in electrical contact with the second surfaces of the plurality of first elements, the plurality of strips and the middle contact to provide for current flow through the plurality of first elements in a direction substantially transverse to an axis of the plurality of first elements; and the one lower sub-pixel photodetector comprises: one or more second elements for absorbing at least one band of infrared radiation, each of the one or more second elements having first and second opposite longitudinal surfaces, the at least one band of infrared radiation incident upon the first surfaces of the one or more second elements, the one or more second elements being disposed on an opposite longitudinal surface of the middle contact from the plurality of first elements of each of the four upper sub-pixel photodetectors; a lower contact being in electrical contact with the second surfaces of the one or more second elements, the middle contact and the lower contact to provide for current flow through the one or more second elements in a direction substantially transverse to an axis of the one or more second elements; and a lower reflector for the at least one band of infrared radiation, the lower reflector being disposed on an opposite longitudinal surface of the lower contact from the one or more second elements, wherein a ratio between a photoresponse to each of the two or more bands of infrared radiation is a function of an external bias applied between the plurality of strips and the middle contact, wherein at least the plurality of first elements, the plurality of strips and the middle contact comprise a diffractive resonant optical cavity for the two or more bands of infrared radiation, wherein a diffractive resonant optical cavity for a first upper sub-pixel photodetector of the four upper sub-pixel photodetectors is different from a diffractive resonant optical cavity for a second upper sub-pixel photodetector of the four sub-pixel photodetectors, and wherein the four upper sub-pixel photodetectors are arranged in a quadrant configuration. 25. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 24, wherein the middle contact of each sub-pixel photodetector includes a Bragg reflector. 26. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 25, wherein the lower reflector is either a metallic reflector or a Bragg reflector. 27. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 25, wherein the lower reflector is a grating reflector for diffracting the at least one band of infrared radiation. 28. A multi-spectral infrared radiation super-pixel photodetector in accordance with claim 24: wherein the one or more second elements are elongate, and wherein at least the middle contact, the one or more second elements, the lower contact and the lower reflector comprise a diffractive resonant optical cavity for the at least one band of infrared radiation. 29. A multi-spectral infrared radiation imager including a plurality of super-pixel photodetectors, each of the plurality of super-pixel photodetectors including a plurality of sub-pixel photodetectors, each of the sub-pixel photodetectors comprising: a plurality of elements for absorbing at least two bands of infrared radiation, each of the plurality of elements being elongate, each of the plurality of elements having first and second opposite longitudinal surfaces, the at least two bands of infrared radiation incident upon the first surfaces of the plurality of elements; a plurality of strips respectively being in electrical contact with and extending along the first surfaces of the plurality of elements, the plurality of strips being electrically interconnected; a bottom contact being in electrical contact with the second surfaces of the plurality of elements, the plurality of strips and the bottom contact to provide for current flow through the plurality of elements in a direction substantially transverse to an axis of the plurality of elements; and a reflector for the at least two bands of infrared radiation, the reflector being disposed on an opposite longitudinal surface of the bottom contact from the plurality of elements, a bias voltage source, said bias voltage source selectively providing a plurality of external bias voltages, wherein a ratio between a photoresponse to each of the at least two bands of infrared radiation is a function of which of the plurality of external bias voltages is applied between the plurality of strips and the bottom contact, wherein the plurality of elements, the plurality of strips, the bottom contact and the reflector comprise a diffractive resonant optical cavity for the at least two bands of infrared radiation, and wherein a diffractive resonant optical cavity for a first sub-pixel photodetector of the plurality of sub-pixel photodetectors is different from a diffractive resonant optical cavity for a second sub-pixel photodetector of the plurality of sub-pixel photodetectors. 30. A multi-spectral infrared radiation imager in accordance with claim 29, wherein the plurality of elements of each sub-pixel photodetector comprise multiple quantum well material selected from the group consisting of GaAs, AIGaAs, InGaAs, InP and combinations thereof. 31. A multi-spectral infrared radiation imager in accordance with claim 29, wherein the reflector of each sub-pixel photodetector is either a metallic reflector or a Bragg reflector. 32. A multi-spectral infrared radiation imager in accordance with claim 29, wherein the multi-spectral infrared radiation imager is a one-dimensional multi-spectral infrared radiation imager. 33. A multi-spectral infrared radiation imager in accordance with claim 29, wherein the multi-spectral infrared radiation imager is a two-dimensional multi-spectral infrared radiation imager. 34. A multi-spectral infrared radiation imager in accordance with claim 29, wherein the at least two bands of infrared radiation is two bands of infrared radiation. 35. A multi-spectral infrared radiation imager in accordance with claim 29, wherein the at least two bands of infrared radiation is three bands of infrared radiation. 36. A multi-spectral infrared radiation imager in accordance with claim 29, wherein a quantity of the plurality of sub-pixel photodetectors is two sub-pixel photodetectors. 37. A multi-spectral infrared radiation imager in accordance with claim 29, wherein a quantity of the plurality of sub-pixel photodetectors is four sub-pixel photodetectors. 38. A multi-spectral infrared radiation imager in accordance with claim 37, wherein a diffractive resonant optical cavity for a third sub-pixel photodetector is substantially the same as the diffractive resonant optical cavity of the first sub-pixel photodetector, and wherein a diffractive resonant optical cavity for a fourth sub-pixel photodetector is substantially the same as the diffractive resonant optical cavity of the second sub-pixel photodetector. 39. A multi-spectral infrared radiation imager in accordance with claim 37, wherein a diffractive resonant optical cavity for each sub-pixel photodetector within each super-pixel photodetector of the plurality of super-pixel photodetectors is different. 40. A multi-spectral infrared radiation imager in accordance with claim 37, wherein the four sub-pixel photodetectors are arranged in a linear configuration. 41. A multi-spectral infrared radiation imager in accordance with claim 37, wherein the four sub-pixel photodetectors are arranged in a quadrant configuration. 42. A multi-spectral infrared radiation imager including a plurality of super-pixel photodetectors, each of the plurality of super-pixel photodetectors including a plurality of sub-pixel photodetectors, each of the plurality of sub-pixel photodetectors comprising: a plurality of elements for absorbing at least two bands of infrared radiation, each of the plurality of elements being elongate, each of the plurality of elements having first and second opposite longitudinal surfaces, the at least two bands of infrared radiation incident upon the first surfaces of the plurality of elements; a plurality of strips respectively being in electrical contact with and extending along the first surfaces of the plurality of elements, the plurality of strips being electrically interconnected; a bottom contact being in electrical contact with the second surfaces of the plurality of elements, the plurality of strips and the bottom contact to provide for current flow through the plurality of elements in a direction substantially transverse to an axis of the plurality of elements; and a reflector for reflecting the at least two bands of infrared radiation, the reflector being disposed on an opposite longitudinal surface of the bottom contact from the plurality of elements, wherein the plurality of elements, the plurality of strips, the bottom contact and the reflector comprise a diffractive resonant optical cavity, the diffractive cavity having a first period in a first direction for diffracting a first band of infrared radiation of the at least two bands of infrared radiation and a second period in a second direction for diffracting a second band of infrared radiation of the at least two bands of infrared radiation, the second band of infrared radiation different from the first band of infrared radiation, the second direction being substantially perpendicular to the first direction, a bias voltage source, said bias voltage source selectively providing a plurality of external bias voltages, wherein a ratio between a photoresponse to each of the at least two bands of infrared radiation is a function of which of the plurality of external bias voltages is applied between the plurality of strips and the bottom contact, and wherein a diffractive resonant optical cavity for a first sub-pixel photodetector of the plurality of sub-pixel photodetectors is different from a diffractive resonant optical cavity for a second sub-pixel photodetector of the plurality of sub-pixel photodetectors. 43. A multi-spectral infrared radiation imager in accordance with claim 42, wherein the plurality of elements of each sub-pixel photodetector comprise multiple quantum well material selected from the group consisting of GaAs, AlGaAs, InGaAs and combinations thereof. 44. A multi-spectral infrared radiation imager in accordance with claim 42, wherein the reflector of each of the pixel structures is either a metallic reflector or a Bragg reflector. 45. A multi-spectral infrared radiation imager in accordance with claim 42, wherein the multi-spectral infrared radiation imager is a one-dimensional multi-spectral infrared radiation imager. 46. A multi-spectral infrared radiation imager in accordance with claim 42, wherein the multi-spectral infrared radiation imager is a two-dimensional multi-spectral infrared radiation imager. 47. A multi-spectral infrared radiation imager in accordance with claim 42, wherein the at least two bands of infrared radiation is two bands of infrared radiation. 48. A multi-spectral infrared radiation imager in accordance with claim 42, wherein the at least two bands of infrared radiation is three bands of infrared radiation. 49. A multi-spectral infrared radiation imager in accordance with claim 42, wherein a quantity of the plurality of sub-pixel photodetectors is two sub-pixel photodetectors. 50. A multi-spectral infrared radiation imager in accordance with claim 42, wherein a quantity of the plurality of sub-pixel photodetectors is four sub-pixel photodetectors. 51. A multi-spectral infrared radiation imager in accordance with claim 50, wherein a diffractive resonant optical cavity for a third sub-pixel photodetector is substantially the same as the diffractive resonant optical cavity of the first sub-pixel photodetector, and wherein a diffractive resonant optical cavity for a fourth sub-pixel photodetector is substantially the same as the diffractive resonant optical cavity of the second sub-pixel photodetector. 52. A multi-spectral infrared radiation imager in accordance with claim 50, wherein a diffractive resonant optical cavity for each sub-pixel photodetector within each super-pixel photodetector of the plurality of super-pixel photodetectors is different. 53. A multi-spectral infrared radiation imager in accordance with claim 50, wherein the four sub-pixel photodetectors are arranged in a linear configuration. 54. A multi-spectral infrared radiation imager in accordance with claim 50, wherein the four sub-pixel photodetectors are arranged in a quadrant configuration. 55. A multi-spectral infrared radiation imager comprising: a plurality of super-pixel photodetectors, each of the plurality of super-pixel photodetectors including four sub-pixel photodetectors, each of the sub-pixel photodetectors comprising: a plurality of elements for absorbing three bands of infrared radiation, each of the three bands of infrared radiation being different from each of the other three bands of infrared radiation, each of the plurality of elements being elongate, each of the plurality of elements having first and second opposite longitudinal surfaces, the three bands of infrared radiation incident upon the first surfaces of the plurality of elements, the plurality of elements comprising multiple quantum well material including GaAs and AlGaAs; a plurality of strips respectively being in electrical contact with and extending along the first surfaces of the plurality of elements, the plurality of strips being electrically interconnected; a bottom electrical contact being in electrical contact with the second surfaces of the plurality of elements, the plurality of strips and the bottom contact to provide for current flow through the plurality of elements in a direction substantially transverse to an axis of the plurality of elements; and a metallic reflector for the three bands of infrared radiation, the reflector being disposed on an opposite longitudinal surface of the bottom contact from the plurality of elements, a bias voltage source, said bias voltage source selectively providing a plurality of external bias voltages, wherein a ratio between a photoresponse to each of the three bands of infrared radiation is a function of which of the plurality of external bias voltages is applied between the plurality of strips and the bottom contact, wherein the plurality of elements, the plurality of strips, the bottom contact and the reflector comprise a diffractive resonant optical cavity for the three bands of infrared radiation, and wherein the diffractive resonant optical cavity for each of the four sub-pixel photodetectors within the super-pixel photodetector is different; and a readout integrated circuit, the readout integrated circuit for applying first, second and third external biases between the plurality of strips and the bottom contact of each of the sub-pixel photodetectors of each of the plurality of super-pixels thereby creating a corresponding photoresponse of each of the sub-pixel photodetectors of each of the plurality of super-pixel photodetectors, the readout integrated circuit for multiplexing the photoresponse of each of the sub-pixel photodetectors of each of the plurality of super-pixel photodetectors at each of the first, second and third external biases.