U.S. patent application number 11/831291 was filed with the patent office on 2012-09-13 for electromagnetic wave receiving antenna.
Invention is credited to Alexandre M. Bratkovski, Shih-Yuan Wang, R. Stanley Williams.
Application Number | 20120228500 11/831291 |
Document ID | / |
Family ID | 46726460 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120228500 |
Kind Code |
A1 |
Bratkovski; Alexandre M. ;
et al. |
September 13, 2012 |
ELECTROMAGNETIC WAVE RECEIVING ANTENNA
Abstract
An electromagnetic wave receiving antenna includes a spiral
element configured to selectively attenuate electromagnetic waves
having a predetermined wavelength, selected wavelengths, or range
of wavelengths, and to concentrate electromagnetic waves having a
predetermined wavelength, selected wavelengths, or range of
wavelengths other than the attenuated wavelengths.
Inventors: |
Bratkovski; Alexandre M.;
(Mountain View, CA) ; Williams; R. Stanley;
(Portola Valley, CA) ; Wang; Shih-Yuan; (Palo
Alto, CA) |
Family ID: |
46726460 |
Appl. No.: |
11/831291 |
Filed: |
July 31, 2007 |
Current U.S.
Class: |
250/338.1 ;
250/227.11; 250/372 |
Current CPC
Class: |
H01Q 1/36 20130101; G01J
5/0837 20130101; H01Q 1/248 20130101; H01Q 1/38 20130101; G01J 1/04
20130101 |
Class at
Publication: |
250/338.1 ;
250/372; 250/227.11 |
International
Class: |
G01J 1/42 20060101
G01J001/42; G01J 5/02 20060101 G01J005/02 |
Claims
1. An electromagnetic wave receiving antenna, comprising: a spiral
element configured to selectively attenuate electromagnetic waves
having a predetermined wavelength, selected wavelengths, or range
of wavelengths, and to concentrate electromagnetic waves having a
predetermined wavelength, selected wavelengths, or range of
wavelengths other than the attenuated wavelengths, wherein the
spiral element is formed from a metal or heavily doped
semiconductor, and wherein the wave receiving antenna further
comprises: an electromagnetic wave amplifying layer disposed in
contact with the spiral element; and a metal plasmon collector
layer disposed in contact with the electromagnetic wave amplifying
layer and spaced from the spiral element by the electromagnetic
wave amplifying layer.
2. The electromagnetic wave receiving antenna as defined in claim
1, wherein the concentrated electromagnetic waves have wavelengths
within a band including infra-red light, visible light,
ultra-violet light, or combinations thereof.
3. The electromagnetic wave receiving antenna as defined in claim
1, wherein adjacent coils of the spiral element are spaced from
about 300 nm to about 850 nm apart.
4. An electromagnetic wave detector system, comprising: an
electromagnetic wave detector; and the electromagnetic wave
receiving antenna as defined in claim 1 operatively connected to
the electromagnetic wave detector.
5. The electromagnetic wave detector system as defined in claim 4
wherein the electromagnetic wave detector is a photo detector.
6. The electromagnetic wave detector system as defined in claim 5
wherein the photo detector is a PIN photodiode or an avalanche
photodetector.
7. The electromagnetic wave detector system as defined in claim 4,
further comprising at least one additional electromagnetic wave
receiving antenna, wherein the electromagnetic wave receiving
antennae are operatively disposed in a stack.
8. The electromagnetic wave receiving antenna as defined in claim 1
wherein the spiral element substantially conforms to a Cornu spiral
shape.
9. (canceled)
10. The electromagnetic wave receiving antenna as defined in claim
1, further comprising a dielectric substrate in contact with the
metal plasmon collector layer.
11. The electromagnetic wave receiving antenna as defined in claim
1 wherein the electromagnetic wave amplifying layer is formed from
Group III-V semiconductors, glass with erbium doping, or
combinations thereof.
12. The electromagnetic wave receiving antenna as defined in claim
1 wherein the metal plasmon collector layer has a metallic surface
contacting the wave amplifying layer, and includes plasmon
collecting notches formed in the metallic surface, wherein each of
the notches is substantially aligned with a respective adjacent
coil of the spiral element.
13. The electromagnetic wave receiving antenna as defined in claim
1, further comprising at least one of corrugations, surface
undulations or periodic asperities disposed on a surface of the
spiral element, wherein the at least one of corrugations, surface
undulations or periodic asperities improve formation of surface
plasmons and substantially guide the plasmons to a center of the
wave receiving antenna.
14. The electromagnetic wave receiving antenna as defined in claim
1, wherein: the plasmonic collector is electrically or
electromagnetically connected to the spiral element; and at least
one plasmonic waveguide is electrically or electromagnetically
connected to the plasmonic collector.
15. The electromagnetic wave receiving antenna as defined in claim
14 wherein there is a plurality of concentrated electromagnetic
wavelengths, with one wavelength that is smallest, wherein the
plasmonic collector is an aperture substantially centered within
the spiral element, and wherein the aperture has an effective
diameter smaller than one half of the smallest concentrated
electromagnetic wavelength.
16. The electromagnetic wave receiving antenna as defined in claim
14 wherein there is a plurality of concentrated electromagnetic
wavelengths, with one wavelength that is largest, and wherein the
wave receiving antenna further comprises: at least one
semiconductor spiral element spaced radially from the metallic
spiral element, wherein the semiconductor spiral element has an
originating radius larger than the largest concentrated
electromagnetic wavelength; and at least one PIN diode structure
integrated with the at least one semiconductor spiral element, the
PIN diode structure configured to allow the at least one
semiconductor spiral element to be electrically pumped to amplify
the concentrated electromagnetic waves.
17. The electromagnetic wave receiving antenna as defined in claim
1, wherein the spiral element is metallic and is disposed on a
dielectric substrate.
18. A two-dimensional array of the electromagnetic wave receiving
antennae as defined in claim 1.
19. A method for harvesting electromagnetic signals, comprising:
providing a metallic spiral element with adjacent coils thereof
spaced to selectively attenuate electromagnetic waves having a
predetermined wavelength, selected wavelengths, or range of
wavelengths, and to concentrate electromagnetic waves having a
predetermined wavelength, selected wavelengths, or range of
wavelengths other than the attenuated wavelengths; coupling the
electromagnetic waves with plasmonic waves in the metallic spiral
element; electrically or electromagnetically connecting a plasmonic
collector to the metallic spiral element; electrically or
electromagnetically connecting a plasmonic waveguide to the
plasmonic collector; and using plasmonic waves from the plasmonic
waveguide as harvested electromagnetic signals.
20. The method as defined in claim 19, further comprising
operatively stacking layers of the metallic spiral elements,
thereby increasing gain.
21. The method as defined in claim 19, further comprising:
disposing a semiconductor spiral element spaced radially from the
metallic spiral element; and amplifying the concentrated
electromagnetic waves via the semiconductor spiral element.
22. The method as defined in claim 21 wherein there are at least
two layers, each of the at least two layers including the metallic
spiral element and the semiconductor spiral element, and wherein
the method further comprises increasing gain by operatively
stacking the at least two layers.
23. A method for harvesting electromagnetic signals, comprising:
providing a two-dimensional array of antenna cells, each antenna
cell including a metallic spiral element having adjacent coils
spaced to selectively attenuate electromagnetic waves having a
predetermined wavelength, selected wavelengths, or range of
wavelengths, and to concentrate electromagnetic waves having a
predetermined wavelength, selected wavelengths, or range of
wavelengths other than the attenuated wavelengths; disposing a
semiconductor spiral elements spaced radially from the metallic
spiral element in at least one cell; amplifying the concentrated
electromagnetic waves via the semiconductor spiral element in the
at least one cell; coupling the amplified electromagnetic waves
with plasmonic waves in the metallic spiral element in at least one
other cell that is the different from, or the same as the at least
one cell; electrically or electromagnetically connecting a
plasmonic collector to the metallic spiral element in the at least
one other cell; electrically or electromagnetically connecting a
plasmonic waveguide to the plasmonic collector in the at least one
other cell; and using plasmonic waves from the plasmonic waveguides
as the harvested electromagnetic signals.
Description
BACKGROUND
[0001] The present disclosure relates generally to electromagnetic
wave receiving antenna(e) and method(s) for forming the same.
[0002] Antennae for receiving light are important in electronic
imaging and energy conversion. Electronic imaging involves
converting electromagnetic waves to electrical signals, thereby
allowing the image to be stored, analyzed, or reproduced
electronically. Some current electronic imaging devices are used
in, e.g., digital cameras, infrared cameras, microscopes, night
vision goggles and document scanners. Energy conversion relates to
solar power cells that convert light energy to electrical
energy.
[0003] Spiral antennae have been used to capture broadband radio
signals. Some micro scale spiral antennae have been used as light
detectors.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Features and advantages of embodiments of the present
disclosure will become apparent by reference to the following
detailed description and drawings, in which like reference numerals
correspond to similar, though perhaps not identical, components.
For the sake of brevity, reference numerals or features having a
previously described function may or may not be described in
connection with other drawings in which they appear.
[0005] FIG. 1 is cross-sectional perspective view of an embodiment
of an electromagnetic wave receiving antenna;
[0006] FIG. 1A is a cut-away cross-sectional view taken along line
1A-1A of FIG. 1, showing an embodiment of a spiral element exposed
surface;
[0007] FIG. 2 is a cut-away bottom view of the electromagnetic wave
receiving antenna shown in FIG. 1;
[0008] FIG. 3 is a cross-sectional view taken along line 3-3 of
FIG. 4 showing a plasmonic waveguide;
[0009] FIG. 4 is a semi-schematic bottom view of an electromagnetic
wave receiving antenna operatively connected to a plasmon
waveguide, and showing a second plasmon waveguide in phantom;
[0010] FIG. 5 is a cut-away, cross-sectional perspective view of
another embodiment of an electromagnetic wave receiving antenna,
including an electromagnetic wave amplifying layer and a metal
plasmon collector layer;
[0011] FIG. 6 is a cut-away perspective view of an embodiment of an
electromagnetic wave detector system;
[0012] FIG. 7 is a cut-away perspective view of another embodiment
of electromagnetic wave detector system including a semiconductor
spiral element surrounding a metallic spiral element;
[0013] FIG. 8 is a semi-schematic top view of a two-dimensional
array of spiral wave receiving antennae; and
[0014] FIG. 9 is a cut-away, cross-sectional perspective view of an
embodiment of a stack of spiral wave receiving antennae.
DETAILED DESCRIPTION
[0015] Although spiral antennae have been used to capture broadband
radio signals, the application of nano scale spiral elements to
create a broadband electromagnetic wave harvesting device has not
previously been proposed. The present inventors have unexpectedly
and fortuitously discovered that nano scale spiral structures may
be used to collect wavelengths from broadband incident light and
selectively transmit the wavelength(s) of interest to subsequent
photonic or electronic devices. As a result, it is contemplated as
being within the purview of the present disclosure that nano scale
spiral antennae may be used to create arrays in such devices as
infra-red (IR), visible (vis) light, or ultra-violet (UV) imaging
systems. They may further be used as elements in optical and
photonic circuits, for example, connectors, repeaters, or the
like.
[0016] Embodiment(s) of the electromagnetic wave receiving antenna
as disclosed herein advantageously include a spiral element to
selectively attenuate electromagnetic waves having a predetermined
wavelength, selected wavelengths, or range of wavelengths, and to
concentrate electromagnetic waves having a predetermined
wavelength, selected wavelengths, or range of wavelengths other
than the attenuated wavelengths. As such, the electromagnetic wave
receiving antenna/e disclosed herein may generally act to
gather/harvest select wavelengths.
[0017] It is to be understood that the terms
"attenuate/attenuated/attenuating wavelength(s)" as used herein
refers to wavelengths that are substantially filtered out of the
electromagnetic waves impinging on the spiral antenna/e as
disclosed herein. It is to be further understood that the terms
"concentrate/concentrated/concentrating wavelength(s)" as used
herein refers to wavelengths that are gathered or harvested by the
spiral antenna/e as disclosed herein for subsequent use. Yet
further, it is to be understood that the intensity of the
concentrated wavelengths may increase near the central aperture of
the spiral antenna/e.
[0018] In an embodiment, the spiral element attenuates and
concentrates electromagnetic waves within a band including
infra-red light, visible light, ultra-violet light, or combinations
thereof. Without being bound to any theory, it is believed that the
spiral element will provide broadband wavelength harvesting
capability because the spiral has no particular length scale.
Furthermore, the spiral antenna/e disclosed herein may be used in a
variety of applications, including, but not limited to detecting
and/or harvesting electromagnetic waves.
[0019] Referring now to FIG. 1, an embodiment of an electromagnetic
wave receiving or spiral antenna 10 is depicted. The spiral antenna
10 includes a spiral element 20, with the innermost coil thereof
designated 20'. Adjacent coils of element 20 are spaced to
selectively concentrate electromagnetic waves having a particular
wavelength(s)/range of wavelengths, and to attenuate
electromagnetic waves having a wavelength(s)/range of wavelengths
other than the attenuated wavelength(s). It is to be understood
that the particular wavelength(s)/range of wavelengths may include
harmonics of the wavelength(s). In an embodiment, adjacent coils of
spiral element 20 are spaced from about 300 nm to about 850 nm
apart. In an alternate embodiment, adjacent coils of spiral element
20 are spaced from about 400 nm to about 600 nm apart. The coils
are generally spaced apart a distance sufficient to capture the
wavelength of interest, e.g., ranging from IR to UV. It is to be
understood that the terms "spaced" and "spacing," when referring to
adjacent coils of spiral element 20, refer to the "crest to crest"
distance between adjacent coils of spiral element 20, i.e. from the
center of a radial cross section of one coil of spiral element 20
to the center of a radial cross section of an adjacent coil of
spiral element 20.
[0020] The spiral element 20 may be formed on a substrate layer 30
(described further below). In an alternate embodiment, the spiral
element 20 may be integrally formed with, or may be formed on, a
metal plasmon collector layer 50 (shown in FIGS. 6 and 7).
Non-limiting examples of suitable metals for the layer 50 include
Ag, Au, Al, Rh, Pt, Ni, Cu, etc. In this embodiment, the spiral
element 20 is also formed of metal. It is to be understood that the
metal used to form the spiral element 20 may be the same or
different from the metal used to form the metal plasmon collector
layer 50. Generally, in embodiments in which the spiral element 20
is formed integrally with the layer 50, the metals are the same. In
embodiments in which the spiral element 20 is established on the
layer 50, the metals may be the same or different. As such, any of
the previously listed metals may be suitable for forming the spiral
element 20.
[0021] It is to be understood that, in some instances, the spiral
element 20 may be formed from non-metal materials, e.g., heavily
doped semiconductors. By "heavily," it is meant doping well over
10.sup.19 cm.sup.-3, or delta-doped surfaces with doping in excess
of 10.sup.20 cm.sup.-3.
[0022] The metal layer 50 and/or the spiral element 20 may be
formed via nanoimprint lithography, selective deposition processes,
or via non-selective deposition and patterning processes. Examples
of suitable deposition techniques include physical vapor
deposition, non-limitative examples of which include sputter
deposition or evaporation deposition (e.g., thermal or e-beam),
chemical vapor deposition (CVD), atomic layer deposition (ALD),
inkjet deposition, other suitable printing techniques, and/or
spin-coating. In a selective deposition process, a mask or blocking
layer may be used to coat any selected surfaces, in order to
prevent deposition on such surfaces during deposition of the metal
on the remaining un-masked surfaces. In a non-selective deposition
process, the metal is deposited on all exposed surfaces. Those
surfaces upon which the metal is desirable are then protected by a
masking layer, and any remaining unprotected portions of the metal
are subsequently removed. Generally, the masking layer is then
removed from the protected surfaces, which remain covered with the
metal.
[0023] In an embodiment, the spiral element 20 or at least a
portion of the metal plasmon collector layer 50 is established on a
substrate layer 30. The substrate layer 30 may be formed of any
suitable dielectric material. It is to be understood that the
dielectric material may be an organic dielectric material, an
inorganic dielectric material and/or a hybrid mixture of organic
and inorganic dielectric materials. A non-limitative example of the
organic dielectric material is poly(vinylphenol) (PVP), and
non-limitative examples of the inorganic dielectric material are
silicon nitride, silicon dioxide, and aluminum oxide (alumina).
[0024] As shown in FIG. 1, the innermost coil 20' of spiral element
20 has, or is connected to, a subwavelength aperture/plasmonic
collector 36 located substantially at the center of the spiral
element 20. The plasmonic collector 36 is electrically or
electromagnetically connected to the spiral element 20. In one
embodiment, such connection is via the metal plasmon collector
layer 50. As shown in FIG. 1, the innermost coil 20' of the spiral
element 20 extends through the substrate 30 and substantially
surrounds the plasmonic collector/aperture 36. In an example, a
metallic spiral element 20, a metallic plasmonic collector 36 and
the metal plasmon collector layer 50 may respectively be
electrically disconnected from each other, but may be
electromagnetically connected, since each of these features
supports plasmons.
[0025] In an embodiment, the spiral element 20 substantially
conforms to a Cornu spiral shape.
[0026] It is to be understood that the subwavelength
aperture/plasmonic collector 36 has an effective diameter or
opening, which may be of any suitable shape and/or configuration.
As non-limiting examples, the effective diameter may be
substantially round, a slit, or the like. It is to be further
understood that the effective diameter may be any suitable size, as
desired, and is dependent upon the wavelength for which the antenna
is tuned. In one embodiment, the effective diameter is smaller than
one half the wavelength of the smallest of a plurality of
concentrated electromagnetic wavelengths (where the wavelength is
measured in free space, not when converted to plasmons) that is
desired to be collected. In a non-limiting example, the
aperture/plasmonic collector 36 has an effective diameter ranging
from about 150 nm to about 425 nm, and the smallest electromagnetic
wavelength to be collected ranges from about 300 nm to about 850
nm.
[0027] It is believed that coupling the free-space electromagnetic
waves with plasmons allows the electromagnetic waves to be
propagated in the form of plasmons, and to be converted back to
electromagnetic waves at the aperture/plasmonic collector 36.
[0028] In the embodiment shown in FIG. 1, the innermost coil 20' of
the spiral element 20 and the plasmonic collector 36 are
electrically or electromagnetically connected to a plasmonic
waveguide 28. When electromagnetic waves (e.g., light waves)
impinge on the spiral element 20, predetermined wavelengths of
light interact with the free electrons in the spiral element 20 to
create plasmons. In an embodiment, the plasmons propagate from the
spiral element 20, through the metal plasmon collector layer 50,
and to the plasmonic collector 36. The plasmons may then be
radiated back into light, conducted by the plasmonic waveguide 28
for processing by logic elements (not shown), or combinations
thereof.
[0029] Referring now to FIG. 1A, a surface of the spiral element 20
exposed to incident electromagnetic radiation may include
corrugations, surface undulations and/or periodic asperities 42. It
is believed that these feature(s) 42 may improve the coupling of
the electromagnetic waves and plasmons, and guide them along the
respective coils of the spiral element 20 toward the plasmonic
collector 36. In some instances, it is believed that this may
improve wavelength selectivity when compared to metallic spiral
elements without the corrugations, surface undulations and/or
periodic asperities 42.
[0030] Referring now to FIG. 2, a cut-away bottom view of the
spiral antenna 10 of FIG. 1 is depicted. As shown and as previously
described, the plasmonic waveguide 28 is electrically or
electromagnetically connected to both the innermost coil 20' of
spiral element 20 and the plasmonic collector 36. FIG. 3
illustrates a cross-sectional view of the plasmonic waveguide 28 of
FIG. 4. As depicted in FIG. 3, the plasmonic waveguide 28 has a
notch 24. FIG. 3 also illustrates that the E-field in the plasmonic
waveguide 28 is generally strongest at the nadir 26 of the notch
24.
[0031] FIG. 4 illustrates multiple plasmonic waveguides 28
electrically or electromagnetically connected to the innermost coil
20' of a spiral antenna 10. As depicted, the plasmonic waveguide(s)
28 may be substantially straight, or may be curved as desired.
Furthermore, the waveguides 28 may power various devices 100, 100'.
Such devices include, but are not limited to various electronics of
an integrated circuit board. As shown in FIG. 4, the devices 100,
100' may be operatively located adjacent an end of the waveguide
28, or at any suitable location. Although two waveguides 28 are
shown, it is to be understood that any number of waveguides 28 may
be used (within the limits of the particular size/geometry of the
innermost coil 20' of the spiral element 20), as desired.
[0032] Referring now to FIG. 5, another embodiment of the spiral
antenna 10' is depicted. In this embodiment, the nano scale spiral
element 20 is formed on/in contact with an electromagnetic wave
amplifying layer 40. In an embodiment, the electromagnetic wave
amplifying layer 40 is formed from direct gap semiconductor
materials with a suitable size gap (e.g., group III-V semiconductor
materials (e.g., GaAs, InP, etc.)), glass with erbium doping, or
combinations thereof.
[0033] As depicted, the electromagnetic wave amplifying layer 40 is
established on/in contact with the metal plasmon collector layer
50. As such, in this embodiment, the metal plasmon collector layer
50 is spaced from the spiral element 20. The metal plasmon
collector layer 50 may have plasmon collecting grooves or notches
32 formed in a surface S of the metal plasmon collector layer 50
that is adjacent the electromagnetic wave amplifying layer 40. In
one embodiment, each notch 32 is formed such that it is
substantially aligned with a respective coil of spiral element 20
(as shown in FIG. 5). Such alignment aids in substantially
preventing scattering.
[0034] The electromagnetic wave amplifying layer 40 may be formed
via any of the methods previously described herein for the metal
layer 50 and/or for the spiral element 20. In an embodiment, for a
communication wavelength where .lamda.=1.55 .mu.m, the
electromagnetic wave amplifying layer 40 may be tailored from an
InP/InGaAsP quantum well, via overgrowth of metal on top of it. In
a further embodiment, for light within a visible wavelength, the
electromagnetic wave amplifying layer 40 may be tailored from a
GaAs/AlGaAs quantum well, via overgrowth of metal on top of it. In
yet a further embodiment, for light within the blue wavelength, the
electromagnetic wave amplifying layer 40 may be tailored from a
GaN/AlN quantum well, via overgrowth of metal on top of it. The
metal overgrown in each case above may be silver (Ag); however, it
is to be understood that any suitable metal may be used, e.g., Au,
Al, Rh, Pt, Ni, Cu, etc.
[0035] The metal plasmon collector layer 50 may also be established
on a dielectric substrate layer 30. In an embodiment, the
dielectric substrate layer 30 electrically insulates the metal
plasmon collector layer 50 from any potentially undesirable sources
or sinks for electrons. However, it is also to be understood that
in any of the embodiments disclosed herein, all or a portion of the
substrate layer 30 may be removed, for example, via a selective
etching process (as shown on the right hand side of FIG. 5). In one
embodiment, the dielectric substrate layer 30 may be removed via
reactive ion etching. As such, the substrate layer 30 is present in
some embodiments of the antenna 10, 10' and is removed in other
embodiments.
[0036] The dielectric substrate layer 30 may be established by any
suitable technique, including, but not limited to plasma enhanced
chemical vapor deposition (PECVD), atomic layer deposition (ALD),
low temperature chemical vapor deposition, physical vapor
deposition sputtering, physical vapor deposition evaporation, and
spin on glass.
[0037] In the embodiment shown in FIG. 5, electromagnetic waves,
such as light, having predetermined wavelength(s)/range(s) of
wavelengths impinging on the spiral element 20 are transmitted by
the spiral element 20 to the electromagnetic wave amplifying layer
40. In a non-limitative example, a group III-V semiconductor is
used as the electromagnetic wave amplifying layer 40. The group
III-V semiconductor is electrically pumped and amplifies the light
waves, thereby transferring the light waves to the metal plasmon
collector layer 50, where the amplified light waves couple with
plasmons. In an embodiment, the semiconductor wave amplifying layer
40 includes one or more quantum wells in a heterojunction p-i-n
configuration (similar to 1550 nm wavelength semiconductor laser
active layers). Electrical contacts are made to the p and n layers,
and forward biased to generate gain in the quantum well active
layer/semiconductor wave amplifying layer 40.
[0038] The plasmonic collector 36 propagates the plasmons to the
center of the antenna 10', where they are converted to light,
conducted by the plasmonic waveguide 28 for processing by logic
elements (not shown), or combinations thereof.
[0039] In another non-limitative example, glass with erbium doping
is used as the electromagnetic wave amplifying layer 40. Light from
a laser, diode, or other light source may be used to pump the
erbium doped glass amplifying layer 40. In an embodiment, a 980 nm
pump wavelength may be pumped from the sides (e.g., edge coupled),
or from the top or from the bottom. The layer 40 amplifies the
light waves, thereby transferring them to the metal plasmon
collector layer 50 where the amplified light waves couple with
plasmons. As previously described, the plasmonic collector 36
propagates the plasmons to the center of the antenna 10', where
they are converted to light, conducted by the plasmonic waveguide
28 for processing by logic elements (not shown), or combinations
thereof.
[0040] Referring now to FIG. 6, an embodiment of an electromagnetic
wave detector system 1000 is depicted. The system 1000 includes an
embodiment of the spiral antenna 10, 10' (antenna 10' is not shown
in this Figure), and an electromagnetic wave detector 34
established in/in contact with the subwavelength aperture/plasmonic
collector 36.
[0041] As a non-limiting example, the electromagnetic wave detector
34 is a photo detector, such as a PIN photodiode or an avalanche
photodetector.
[0042] The coils of the spiral element 20 of the antenna 10, 10'
are arranged substantially concentrically about the aperture 36. As
previously described, the adjacent coils of the spiral element 20
are spaced so as to selectively attenuate electromagnetic waves
having a predetermined wavelength, selected wavelengths, or range
of wavelengths, and to concentrate electromagnetic waves having a
predetermined wavelength, selected wavelengths, or range of
wavelengths other than the attenuated wavelengths. The concentrated
wavelengths/range of wavelengths are concentrated to the
aperture/plasmonic collector 36 where the electromagnetic wave
detector 34 is configured to detect the concentrated
electromagnetic waves.
[0043] Still another embodiment of the system 1000' is depicted in
FIG. 7. This embodiment of the system 1000' includes still another
embodiment of the spiral antenna 10''. In this embodiment of the
antenna 10'', a semiconductor spiral element 38 is connected to
(designated semi-schematically at line L) the spiral element 20,
and is spaced radially from and surrounds inner coil(s) of the
spiral element 20. It is to be understood that the other layers 30,
40, 50 and plasmonic collector 36 of the antennae 10, 10' disclosed
in reference to FIGS. 1 and 5 may be included in the embodiment of
the antenna 10'' shown in FIG. 7. It is believed that the
semiconductor spiral element 38 amplifies the impinging
electromagnetic waves. In an embodiment, the semiconductor spiral
element 38 has a diameter that is larger than the largest
concentrated electromagnetic wavelength. The semiconductor spiral
element 38 may include one or more electromagnetic wave detector(s)
34, e.g., a PIN diode structure, integrated therewith.
[0044] In any of the embodiments herein, it is to be understood
that the size of the wave detector 34 may be any suitable size
sufficient to effectively pick up most or all of the radiation
through the aperture 36. In an embodiment, the wave detector 34 is
substantially larger than the aperture 36. The electromagnetic wave
detector 34, e.g., the PIN diode structure is configured to allow
the semiconductor elements 38 to be electrically pumped to amplify
the concentrated electromagnetic waves. In an embodiment, the
electromagnetic wave detector 34, e.g., a photodiode, may be
connected in parallel, similar to nanowire photodiodes that consist
of many nanowires connected in parallel, where each acts as a
photodiode.
[0045] It is to be understood that there may be any number of the
spiral antennae 10, 10', 10'' disclosed herein; and further, that
such antennae 10, 10', 10'' may be arranged in a two dimensional
array 10,000 (see FIG. 8), a stack 100,000 (see FIG. 9), or in a
stack 100,000 of two dimensional arrays 10,000. When the spiral
antennae 10, 10', 10'' are arranged in a stack 100,000, the
concentrated electromagnetic waves output from one antenna 10, 10',
10'' are impinged upon another antenna 10, 10', 10'' for selection
of wavelengths, amplification, attenuation, or other manipulation
of the electromagnetic waves. It is believed that including the
spiral antennae 10, 10', 10'' in a stack 100,000 advantageously
increases the gain.
[0046] A single spiral antenna 10, 10', 10'' is generally tuned to
one wavelength A and higher harmonics (e.g., .lamda./n, where n=2,
3, 4 . . .). If it is desirable to collect more than one
wavelength, a two dimensional array 10,000 may be used, with the
array 10,000 including two or more "different" spiral antennae 10,
10', 10'', each patch tuned for a specific A of interest. Adjacent
antennae 10, 10', 10'' in an array may be spaced apart (i.e., crest
to crest from an outermost coil of the spiral element 20 of one
antenna 10, 10', 10'' to an outermost coil of the spiral element 20
of an adjacent antenna 10, 10', 10'') any suitable distance as
desired. Generally, this spacing is similar to spacing between
adjacent coils of the spiral element 20 within a single antenna 10,
10', 10'', as described above.
[0047] In an embodiment of the method for harvesting
electromagnetic signals, adjacent coils of the spiral element 20
(including, in an embodiment, adjacent coils of semiconductor
spiral element 38), spaced to selectively attenuate electromagnetic
waves having a predetermined wavelength, selected wavelengths, or
range of wavelengths, and to concentrate electromagnetic waves
having a predetermined wavelength, selected wavelengths, or range
of wavelengths other than the attenuated wavelengths, is provided.
A plasmonic collector 36 is electrically or electromagnetically
connected to the spiral element(s) 20, 38, and a plasmonic
waveguide 28 is electrically or electromagnetically connected to
the plasmonic collector 36. Amplified electromagnetic waves are
coupled with plasmonic waves in the spiral element(s) 20, 38; and
the plasmonic waves from the plasmonic waveguide 28 may be used as
harvested electromagnetic signals.
[0048] In another embodiment of the method for harvesting
electromagnetic signals, a two-dimensional array 10,000 of antennae
10, 10', 10'' is provided. In this embodiment, each antenna 10, 10'
includes the metallic spiral element 20. At least one of the
antennae 10'' also includes a semiconductor spiral element 38
connected to the metallic spiral element 20, as described above.
The concentrated electromagnetic waves are amplified via the
semiconductor spiral element 38 in the antenna 10''.
[0049] The amplified electromagnetic waves may then be coupled with
plasmonic waves in the metallic spiral elements 20, 20' of another
antenna 10, 10', 10'' that is different from, or the same as the
antenna 10'' in which the electromagnetic waves are amplified. In
this embodiment, a plasmonic collector 36 is electrically or
electromagnetically coupled to the spiral elements 20, 20', and a
plasmonic waveguide 28 is electrically or electromagnetically
coupled to the plasmonic collector 36 in the other antenna 10, 10',
10''. It is to be understood that the geometry of the connection
(as well as of any of the connections mentioned herein, including
the connection between the metallic spiral element 20 and the
semiconductor spiral element 38) is desirably substantially without
sharp changes in cross section and/or without other disruptions.
The plasmonic waves from the plasmonic waveguides may be used as
the harvested electromagnetic signals.
[0050] While several embodiments have been described in detail, it
will be apparent to those skilled in the art that the disclosed
embodiments may be modified. Therefore, the foregoing description
is to be considered exemplary rather than limiting.
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