Pixel structure using a tapered core waveguide, image sensors and camera using same
A pixel structure having a cladding and tapered core waveguide, the core dimensioned to refract EM radiation through the cladding at differing depth dependent on the wavelength of the radiation, and a plurality of transducers disposed to convert the band of radiation they receive into electrical signals. In some embodiments the transducers are disposed within lateral waveguides, and in some embodiments below the tapered core waveguide. Further disclosed is an image array sensor comprising a plurality of such pixel structures. Further disclosed is an array comprising stacked layered waveguides having transducers disposed therewithin, and a plurality of refractors to refract different bands of EM radiation into differing waveguides.
1. A camera comprising:
an enclosure;
an image sensor for sensing electromagnetic (EM) radiant energy within a spectral range of interest, the sensor comprising:
a plurality of lateral waveguides having superposed orientation therebetween;
a plurality of spectral dispersers disposed to refract different bands of wavelengths of the EM radiation into respective different waveguides; and,
a plurality transducers disposed within the respective waveguides, for producing an electrical signal indicative of the intensity the band of wavelengths impinged on the respective waveguide; and,
an optical front end system disposed in the path of radiant energy impinging on the image sensor.
2. A camera as claimed in claim 1 , wherein the at least one of the plurality of transducers utilizes rectennas.
3. A camera as claimed in claim 1 , wherein at least one of the refractors comprises a waveguide having a tapered core and cladding disposed thereabout, the taper being dimensioned to have in at least one dimension, a width equal to the emission width of the longest wave of the spectral range, and a width equal to the emission width of a shorter wave of the spectral range of interest.
4. A camera as claimed in claim 1 , wherein the tapered core is characterized by having an index of refraction lower than the index of refraction of the cladding disposed thereabout.
5. A camera as claimed in claim 3 , wherein the at least one of the plurality of lateral waveguide comprises a metal cladding.
6. A method of making a stratum for a camera sensor, the stratum having a plurality of superposed waveguides, the method comprising the steps of:
providing at least a first and a second waveguides disposed at least partially in superposed relationship therebetween, each waveguide comprising:
a core layer and an upper and a lower metal cladding layers disposed respectively on opposite sides of the core layer, the core layer having at least one energy transducer disposed therein;
wherein the core layer being substantially transparent to radiant energy impinging thereupon; the core comprises materials selected from optical dielectric material, conductive material, electron donor material, electron acceptor material, and any combination thereof; and,
wherein each waveguide thickness is dimensioned to optimize guiding of energy within the range of energy convertible by the transducer.
7. A method of making a stratum as claimed in claim 6 , wherein the transducer having bandgap energy slightly higher than the energy associated with radiant energy of the lowest frequency which can propagate in the respective waveguide.
8. A method of making a stratum as claimed in claim 6 , wherein a transducer disposed in the first waveguide has a different bandgap energy than the bandgap energy of a transducer disposed in the second waveguide.
9. A method of making a stratum as claimed in claim 6 , further comprising charge transport layers disposed between the cladding layers and core layers.