2549-0079

FREE SPACE INTERCHIP COMMUNICATIONS

CROSS-REFERENCE TO CO-PENDING APPLICATIONS

[0001] The present invention is related to the following co-pending U.S. Patent applications: (1) U.S. Patent Application No. 11/238,991, [atty. docket 2549-0003], entitled "Ultra-Small Resonating Charged Particle Beam Modulator," filed September 30, 2005; (2) U.S. Patent Application No. 10/917,511 ₅ filed on August 13, 2004, entitled "Patterning Thin Metal Films by Dry Reactive Ion Etching;" (3) U.S. Application No. 11/203,407, filed on August 15, 2005, entitled "Method Of Patterning Ultra-Small Structures"; (4) U.S. Application No. 11/243,476 [Atty. Docket 2549-0058], entitled "Structures And Methods For Coupling Energy From An Electromagnetic Wave," filed on October 5, 2005; (5) U.S. Application No. 11/243,477 [Atty. Docket 2549-0059], entitled "Electron beam induced resonance," filed on October 5, 2005; (6) U.S. Application No. 11/325,432 [Atty. Docket 2549-0021], entitled "Resonant Structure-Based Display," filed on January 5, 2006; (7) U.S. Application No. 11/325,448 [Atty. Docket 2549- 0060], entitled "Selectable Frequency Light Emitter," filed on January 5, 2006; (8) U.S. Application No. 11/325,571 [Atty. Docket 2549-0063], entitled "Switching Micro-Resonant Structures By Modulating A Beam Of Charged Particles" filed on January 5, 2006; and (9) U.S. Application No. 11/400,280 [Atty. Docket 2549-0068], entitled "Resonant Detector For Optical Signals" filed on even date herewith. AU of the above-references co-pending applications are commonly owned with the present application, and the entire contents of those applications are incorporated herein by reference.

FIELD OF INVENTION

[0002] This relates to the production of electromagnetic radiation (EMR) at selected frequencies and to the coupling of high frequency electromagnetic radiation to elements on a chip or a circuit board.

INTRODUCTION

[0003] In the above-identified patent applications, the design and construction methods for ultra- small structures for producing electromagnetic radiation are disclosed. When using plural chips to form an integrated device (e.g., such as in a multi-chip module (MCM)), separately fabricated chips can be connected together electrically by providing interconnection lines between the MCMs. However, chips that are electrically connected in that manner have experienced constrained communication speeds as compared to optical connections. Accordingly, it would be advantageous to be able to interconnect various chips or integrated circuits using optical interconnections instead.

[0004] In one such embodiment, at least two integrated circuits are "interconnected" optically by providing on at least a first integrated circuit a resonant structure that emits electromagnetic radiation (EMR) that is received optically or wirelessly by the second integrated circuit. In at least one embodiment, an optical "backplane" is created which comprises at least one optical element (e.g., a mirror, a lens, or a prism) for aiding signals transmitted by a first integrated circuit to be received optically or wirelessly by a second integrated circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The following description, given with respect to the attached drawings, may be better understood with reference to the non-limiting examples of the drawings, wherein:

[0006] Figure 1 is a generalized block diagram of a generalized resonant structure and its charged particle source;

[0007] Figure 2A is a top view of a non-limiting exemplary resonant structure for use with the present invention;

[0008] Figure 2B is a top view of the exemplary resonant structure of Figure 2 A with the addition of a backbone;

[0009] Figures 2C-2H are top views of other exemplary resonant structures for use with the present invention;

[0010] Figure 3 is a top view of a single wavelength element having a first period and a first

"finger" length according to one embodiment of the present invention;

[0011] Figure 4 is a top view of a single wavelength element having a second period and a second "finger" length according to one embodiment of the present invention;

[0012] Figure 5 is a top view of a single wavelength element having a third period and a third

"finger" length according to one embodiment of the present invention;

[0013] Figure 6A is a top view of a multi-wavelength element utilizing two deflectors according to one embodiment of the present invention;

[0014] Figure 6B is a top view of a multi- wavelength element utilizing a single, integrated deflector according to one embodiment of the present invention;

[0015] Figure 6C is a top view of a multi- wavelength element utilizing a single, integrated deflector and focusing charged particle optical elements according to one embodiment of the present invention;

[0016] Figure 6D is a top view of a multi- wavelength element utilizing plural deflectors along various points in the path of the beam according to one embodiment of the present invention;

[0017] Figure 7 is a top view of a multi-wavelength element utilizing two serial deflectors according to one embodiment of the present invention;

[0018] Figure 8 is a perspective view of a single wavelength element having a first period and a first resonant frequency or "finger" length according to one embodiment of the present invention;

[0019] Figure 9 is a perspective view of a single wavelength element having a second period and a second "finger" length according to one embodiment of the present invention;

[0020] Figure 10 is a perspective view of a single wavelength element having a third period and a third "finger" length according to one embodiment of the present invention;

[0021] Figure 11 is a perspective view of a portion of a multi- wavelength element having wavelength elements with different periods and "finger" lengths;

[0022] Figure 12 is a top view of a multi-wavelength element according to one embodiment of the present invention;

[0023] Figure 13 is a top view of a multi- wavelength element according to another embodiment of the present invention;

[0024] Figure 14 is a top view of a multi- wavelength element utilizing two deflectors with variable amounts of deflection according to one embodiment of the present invention;

[0025] Figure 15 is a top view of a multi-wavelength element utilizing two deflectors according to another embodiment of the present invention;

[0026] Figure 16 is a top view of a multi-intensity element utilizing two deflectors according to another embodiment of the present invention;

[0027] Figure 17 A is a top view of a multi-intensity element using plural inline deflectors;

[0028] Figure 17B is a top view of a multi-intensity element using plural attractive deflectors above the path of the beam;

[0029] Figure 17C is a view of a first deflectable beam for turning the resonant structures on and off without needing a separate data input on the source of charged particles and without having to turn off the source of charged particles;

[0030] Figure 17D is a view of a second deflectable beam for turning the resonant structures on and off without needing a separate data input on the source of charged particles and without having to turn off the source of charged particles;

[0031] Figure 18 A is a top view of a multi-intensity element using finger of varying heights;

[0032] Figure 18B is a top view of a multi-intensity element using finger of varying heights;

[0033] Figure 19A is a top view of a fan-shaped resonant element that enables varying intensity based on the amount of deflection of the beam;

[0034] Figure 19B is a top view of another fan-shaped resonant element that enables varying intensity based on the amount of deflection of the beam;

[0035] Figure 20 is a microscopic photograph of a series of resonant segments;

[0036] Figure 21 A is a side-view of a set of optically interconnected integrated circuits according to the present invention;

[0037] Figure 21B is a side-view of a set of optically interconnected integrated circuits according to the present invention; and

[0038] Figure 21 C is a top view of a set of circuits interconnected hierarchically by the frequencies used to communicate between them.

DISCUSSION OF THE PREFERRED EMBODIMENTS

[0039] Turning to Figure 1, according to the present invention, a wavelength element 100 on a substrate 105 (such as a semiconductor substrate or a circuit board) can be produced from at least one resonant structure 110 that emits light (such as infrared light, visible light or ultraviolet light

or any other electromagnetic radiation (EMR) 150 at a wide range of frequencies, and often at a frequency higher than that of microwave). The EMR 150 is emitted when the resonant structure 110 is exposed to a beam 130 of charged particles ejected from or emitted by a source of charged particles 140. The source 140 is controlled by applying a signal on data input 145. The source 140 can be any desired source of charged particles such as an electron gun, a cathode, an ion source, an electron source from a scanning electron microscope, etc.

[0040] Exemplary resonant structures are illustrated in Figures 2A-2H. As shown in Figure 2A, a resonant structure 110 may comprise a series of fingers 115 which are separated by a spacing 120 measured as the beginning of one finger 115 to the beginning of an adjacent finger 115. The finger 115 has a thickness that takes up a portion of the spacing between fingers 115. The fingers also have a length 125 and a height (not shown). As illustrated, the fingers of Figure 2 A are perpendicular to the beam 130.

[0041] Resonant structures 110 are fabricated from resonating material (e.g., from a conductor such as metal (e.g., silver, gold, aluminum and platinum or from an alloy) or from any other material that resonates in the presence of a charged particle beam). Other exemplary resonating materials include carbon nanotubes and high temperature superconductors. [0042] When creating any of the elements 100 according to the present invention, the various resonant structures can be constructed in multiple layers of resonating materials but are preferably constructed in a single layer of resonating material (as described above). [0043] In one single layer embodiment, all the resonant structures 110 of a resonant element 100 are etched or otherwise shaped in the same processing step. In one multi-layer embodiment, the resonant structures 110 of each resonant frequency are etched or otherwise shaped in the same processing step. In yet another multi-layer embodiment, all resonant structures having segments of the same height are etched or otherwise shaped in the same processing step. In yet another embodiment, all of the resonant elements 100 on a substrate 105 are etched or otherwise shaped in the same processing step.

[0044] The material need not even be a contiguous layer, but can be a series of resonant elements individually present on a substrate. The materials making up the resonant elements can be produced by a variety of methods, such as by pulsed-plating, depositing, sputtering or etching. Preferred methods for doing so are described in co-pending U.S. Application No. 10/917,571, filed on August 13, 2004, entitled "Patterning Thin Metal Film by Dry Reactive Ion Etching,"

and in U.S. Application No. 11/203,407, filed on August 15, 2005, entitled "Method Of Patterning Ultra-Small Structures," both of which are commonly owned at the time of filing, and the entire contents of each of which are incorporated herein by reference. [0045] At least in the case of silver, etching does not need to remove the material between segments or posts all the way down to the substrate level, nor does the plating have to place the posts directly on the substrate. Silver posts can be on a silver layer on top of the substrate. In fact, we discovered that, due to various coupling effects, better results are obtained when the silver posts are set on a silver layer, which itself is on the substrate.

[0046] As shown in Figure 2B, the fingers of the resonant structure 110 can be supplemented with a backbone. The backbone 112 connects the various fingers 115 of the resonant structure 110 forming a comb-like shape on its side. Typically, the backbone 112 would be made of the same material as the rest of the resonant structure 110, but alternate materials may be used. In addition, the backbone 112 may be formed in the same layer or a different layer than the fingers 110. The backbone 112 may also be formed in the same processing step or in a different processing step than the fingers 110. While the remaining figures do not show the use of a backbone 112, it should be appreciated that all other resonant structures described herein can be fabricated with a backbone also.

[0047] The shape of the fingers 115R (or posts) may also be shapes other than rectangles, such as simple shapes (e.g., circles, ovals, arcs and squares), complex shapes (e.g., such as semicircles, angled fingers, serpentine structures and embedded structures (i.e., structures with a smaller geometry within a larger geometry, thereby creating more complex resonances)) and those including waveguides or complex cavities. The finger structures of all the various shapes will be collectively referred to herein as "segments." Other exemplary shapes are shown in Figures 2C-2H, again with respect to a path of a beam 130. As can be seen at least from Figure 2C, the axis of symmetry of the segments need not be perpendicular to the path of the beam 130. [0048] Turning now to specific exemplary resonant elements, in Figure 3, a wavelength element IOOR for producing electromagnetic radiation with a first frequency is shown as having been constructed on a substrate 105. (The illustrated embodiments of Figures 3, 4 and 5 are described as producing red, green and blue light in the visible spectrum, respectively. However, the spacings and lengths of the fingers 115R, 115G and 115B of the resonant structures HOR, HOG and 11OB, respectively, are for illustrative purposes only and not intended to represent any

actual relationship between the period 120 of the fingers, the lengths of the fingers 115 and the frequency of the emitted electromagnetic radiation.) However, the dimensions of exemplary resonant structures are provided in the table below.

[0049] As dimensions (e.g., height and/or length) change the intensity of the radiation may change as well. Moreover, depending on the dimensions, harmonics (e.g., second and third harmonics) may occur. For post height, length, and width, intensity appears oscillatory in that finding the optimal peak of each mode created the highest output. When operating in the velocity dependent mode (where the finger period depicts the dominant output radiation) the alignment of the geometric modes of the fingers are used to increase the output intensity. However it is seen that there are also radiation components due to geometric mode excitation during this time, but they do not appear to dominate the output. Optimal overall output comes when there is constructive modal alignment in as many axes as possible.

[0050] Other dimensions of the posts and cavities can also be swept to improve the intensity. A sweep of the duty cycle of the cavity space width and the post thickness indicates that the cavity space width and period (i.e., the sum of the width of one cavity space width and one post) have relevance to the center frequency of the resultant radiation. That is, the center frequency of resonance is generally determined by the post/space period. By sweeping the geometries, at given electron velocity v and current density, while evaluating the characteristic harmonics during each sweep, one can ascertain a predictable design model and equation set for a particular metal layer type and construction. Each of the dimensions mentioned about can be any value in the nanostructure range, i.e., 1 nm to 1 μm. Within such parameters, a series of posts can be constructed that output substantial EMR in the infrared, visible and ultraviolet portions of the spectrum and which can be optimized based on alterations of the geometry, electron velocity and density, and metal/layer type. It should also be possible to generate EMR of longer wavelengths

as well. Unlike a Smith-Purcell device, the resultant radiation from such a structure is intense enough to be visible to the human eye with only 30 nanoamperes of current.

[0051] Using the above-described sweeps, one can also find the point of maximum intensity for given posts. Additional options also exist to widen the bandwidth or even have multiple frequency points on a single device. Such options include irregularly shaped posts and spacing, series arrays of non-uniform periods, asymmetrical post orientation, multiple beam configurations, etc.

[0052] As shown in Figure 3, a beam 130 of charged particles (e.g., electrons, or positively or negatively charged ions) is emitted from a source 140 of charged particles under the control of a data input 145. The beam 130 passes close enough to the resonant structure 11OR to excite a response from the fingers and their associated cavities (or spaces). The source 140 is turned on when an input signal is received that indicates that the resonant structure 11OR is to be excited.

When the input signal indicates that the resonant structure 11OR is not to be excited, the source

140 is turned off.

[0053] The illustrated EMR 150 is intended to denote that, in response to the data input 145 turning on the source 140, a red wavelength is emitted from the resonant structure 11OR. In the illustrated embodiment, the beam 130 passes next to the resonant structure HOR which is shaped like a series of rectangular fingers 115R or posts.

[0054] The resonant structure 11 OR is fabricated utilizing any one of a variety of techniques

(e.g., semiconductor processing-style techniques such as reactive ion etching, wet etching and pulsed plating) that produce small shaped features.

[0055] In response to the beam 130, electromagnetic radiation 150 is emitted there from which can be directed to an exterior of the element 110.

[0056] As shown in Figure 4, a green element IOOG includes a second source 140 providing a second beam 130 in close proximity to a resonant structure HOG having a set of fingers 115G with a spacing 120G, a finger length 125G and a finger height 155G (see Figure 9) which may be different than the spacing 120R, finger length 125G and finger height 155R of the resonant structure 11OR. The finger length 125, finger spacing 120 and finger height 155 may be varied during design time to determine optimal finger lengths 125, finger spacings 120 and finger heights 155to be used in the desired application.

[0057] As shown in Figure 5, a blue element IOOB includes a third source 140 providing a third beam 130 in close proximity to a resonant structure HOB having a set of fingers 115B having a spacing 120B, a finger length 125B and a finger height 155B (see Figure 10) which may be different than the spacing 120R, length 125R and height 155R of the resonant structure HOR and which may be different than the spacing 120G, length 125G and height 155G of the resonant structure HOG.

[0058] The cathode sources of electron beams, as one example of the charged particle beam, are usually best constructed off of the chip or board onto which the conducting structures are constructed. In such a case, we incorporate an off-site cathode with a deflector, diffractor, or switch to direct one or more electron beams to one or more selected rows of the resonant structures. The result is that the same conductive layer can produce multiple light (or other EMR) frequencies by selectively inducing resonance in one of plural resonant structures that exist on the same substrate 105.

[0059] In an embodiment shown in Figure 6A, an element is produced such that plural wavelengths can be produced from a single beam 130. In the embodiment of Figure 6A, two deflectors 160 are provided which can direct the beam towards a desired resonant structure HOG, HOB or 11OR by providing a deflection control voltage on a deflection control terminal 165. One of the two deflectors 160 is charged to make the beam bend in a first direction toward a first resonant structure, and the other of the two deflectors can be charged to make the beam bend in a second direction towards a second resonant structure. Energizing neither of the two deflectors 160 allows the beam 130 to be directed to yet a third of the resonant structures. Deflector plates are known in the art and include, but are not limited to, charged plates to which a voltage differential can be applied and deflectors as are used in cathode-ray tube (CRT) displays.

[0060] While Figure 6 A illustrates a single beam 130 interacting with three resonant structures, in alternate embodiments a larger or smaller number of resonant structures can be utilized in the multi- wavelength element 10OM. For example, utilizing only two resonant structures HOG and 11OB ensures that the beam does not pass over or through a resonant structure as it would when bending toward HOR if the beam 130 were left on. However, in one embodiment, the beam 130 is turned off while the deflector(s) is/are charged to provide the desired deflection and then the beam 130 is turned back on again.

[0061] In yet another embodiment illustrated in Figure 6B, the multi-wavelength structure IOOM of Figure 6 A is modified to utilize a single deflector 160 with sides that can be individually energized such that the beam 130 can be deflected toward the appropriate resonant structure. The multi- wavelength element IOOM of Figure 6C also includes (as can any embodiment described herein) a series of focusing charged particle optical elements 600 in front of the resonant structures 11OR, HOG and HOB.

[0062] In yet another embodiment illustrated in Figure 6D, the multi- wavelength structure IOOM of Figure 6 A is modified to utilize additional deflectors 160 at various points along the path of the beam 130. Additionally, the structure of Figure 6D has been altered to utilize a beam that passes over, rather than next to, the resonant structures 11OR, HOG and HOB. [0063] Alternatively, as shown in Figure 7, rather than utilize parallel deflectors (e.g., as in Figure 6A), a set of at least two deflectors 160a,b may be utilized in series. Each of the deflectors includes a deflection control terminal 165 for controlling whether it should aid in the deflection of the beam 130. For example, with neither of deflectors 160a,b energized, the beam 130 is not deflected, and the resonant structure 11OB is excited. When one of the deflectors 160a,b is energized but not the other, then the beam 130 is deflected towards and excites resonant structure HOG. When both of the deflectors 160a,b are energized, then the beam 130 is deflected towards and excites resonant structure 11OR. The number of resonant structures could be increased by providing greater amounts of beam deflection, either by adding additional deflectors 160 or by providing variable amounts of deflection under the control of the deflection control terminal 165.

[0064] Alternatively, "directors" other than the deflectors 160 can be used to direct/deflect the electron beam 130 emitted from the source 140 toward any one of the resonant structures 110 discussed herein. Directors 160 can include any one or a combination of a deflector 160, a diffractor, and an optical structure (e.g., switch) that generates the necessary fields. [0065] While many of the above embodiments have been discussed with respect to resonant structures having beams 130 passing next to them, such a configuration is not required. Instead, the beam 130 from the source 140 may be passed over top of the resonant structures. Figures 8, 9 and 10 illustrate a variety of finger lengths, spacings and heights to illustrate that a variety of EMR 150 frequencies can be selectively produced according to this embodiment as well.

[0066] Furthermore, as shown in Figure 11, the resonant structures of Figures 8-10 can be modified to utilize a single source 190 which includes a deflector therein. However, as with the embodiments of Figures 6 A-I, the deflectors 160 can be separate from the charged particle source 140 as well without departing from the present invention. As shown in Figure 11, fingers of different spacings and potentially different lengths and heights are provided in close proximity to each other. To activate the resonant structure HOR, the beam 130 is allowed to pass out of the source 190 undeflected. To activate the resonant structure HOB, the beam 130 is deflected after being generated in the source 190. (The third resonant structure for the third wavelength element has been omitted for clarity.)

[0067] While the above elements have been described with reference to resonant structures 110 that have a single resonant structure along any beam trajectory, as shown in Figure 12, it is possible to utilize wavelength elements 200RG that include plural resonant structures in series (e.g., with multiple finger spacings and one or more finger lengths and finger heights per element). In such a configuration, one may obtain a mix of wavelengths if this is desired. At least two resonant structures in series can either be the same type of resonant structure (e.g., all of the type shown in Figure 2A) or may be of different types (e.g., in an exemplary embodiment with three resonant structures, at least one of Figure 2 A, at least one of Figure 2C, at least one of Figure 2H, but none of the others).

[0068] Alternatively, as shown in Figure 13, a single charged particle beam 130 (e.g., electron beam) may excite two resonant structures 11OR and 11OG in parallel. As would be appreciated by one of ordinary skill from this disclosure, the wavelengths need not correspond to red and green but may instead be any wavelength pairing utilizing the structure of Figure 13. [0069] It is possible to alter the intensity of emissions from resonant structures using a variety of techniques. For example, the charged particle density making up the beam 130 can be varied to increase or decrease intensity, as needed. Moreover, the speed that the charged particles pass next to or over the resonant structures can be varied to alter intensity as well. [0070] Alternatively, by decreasing the distance between the beam 130 and a resonant structure (without hitting the resonant structure), the intensity of the emission from the resonant structure is increased. In the embodiments of Figures 3-7, this would be achieved by bringing the beam 130 closer to the side of the resonant structure. For Figures 8-10, this would be achieved by

lowering the beam 130. Conversely, by increasing the distance between the beam 130 and a resonant structure, the intensity of the emission from the resonant structure is decreased. [0071] Turning to the structure of Figure 14, it is possible to utilize at least one deflector 160 to vary the amount of coupling between the beam 130 and the resonant structures 110. As illustrated, the beam 130 can be positioned at three different distances away from the resonant structures 110. Thus, as illustrated at least three different intensities are possible for the green resonant structure, and similar intensities would be available for the red and green resonant structures. However, in practice a much larger number of positions (and corresponding intensities) would be used. For example, by specifying an 8-bit color component, one of 256 different positions would be selected for the position of the beam 130 when in proximity to the resonant structure of that color. Since the resonant structures for different may have different responses to the proximity of the beam, the deflectors are preferably controlled by a translation table or circuit that converts the desired intensity to a deflection voltage (either linearly or non- linearly).

[0072] Moreover, as shown in Figure 15, the structure of Figure 13 may be supplemented with at least one deflector 160 which temporarily positions the beam 130 closer to one of the two structures HOR and 11OG as desired. By modifying the path of the beam 130 to become closer to the resonant structures HOR and farther away from the resonant structure 11OG, the intensity of the emitted electromagnetic radiation from resonant structure 11OR is increased and the intensity of the emitted electromagnetic radiation from resonant structure 11OG is decreased. Likewise, the intensity of the emitted electromagnetic radiation from resonant structure 11OR can be decreased and the intensity of the emitted electromagnetic radiation from resonant structure 11OG can be increased by modifying the path of the beam 130 to become closer to the resonant structures HOG and farther away from the resonant structure 11OR. In this way, a multi- resonant structure utilizing beam deflection can act as a color channel mixer. [0073] As shown in Figure 16, a multi-intensity pixel can be produced by providing plural resonant structures, each emitting the same dominant frequency, but with different intensities (e.g., based on different numbers of fingers per structure). As illustrated, the color component is capable of providing five different intensities {off, 25%, 50%, 75% and 100%). Such a structure could be incorporated into a device having multiple multi-intensity elements 100 per color or wavelength.

[0074] The illustrated order of the resonant structures is not required and may be altered. For example, the most frequently used intensities may be placed such that they require lower amounts of deflection, thereby enabling the system to utilize, on average, less power for the deflection.

[0075] As shown in Figure 17A, the intensity can also be controlled using deflectors 160 that are inline with the fingers 115 and which repel the beam 130. By turning on the deflectors at the various locations, the beam 130 will reduce its interactions with later fingers 115 (i.e., fingers to the right in the figure). Thus, as illustrated, the beam can produce six different intensities {off, 20%, 40%, 60%, 80% and 100%} by turning the beam on and off and only using four deflectors, but in practice the number of deflectors can be significantly higher.

[0076] Alternatively, as shown in Figure 17B, a number of deflectors 160 can be used to attract the beam away from its undeflected path in order to change intensity as well. [0077] In addition to the repulsive and attractive deflectors 160 of Figures 17A and 17B which are used to control intensity of multi-intensity resonators, at least one additional repulsive deflector 16Or or at least one additional attractive deflector 160a, can be used to direct the beam 130 away from a resonant structure 110, as shown in Figures 17C and 17D, respectively. By directing the beam 130 before the resonant structure 110 is excited at all, the resonant structure 110 can be turned on and off, not just controlled in intensity, without having to turn off the source 140. Using this technique, the source 140 need not include a separate data input 145. Instead, the data input is simply integrated into the deflection control terminal 165 which controls the amount of deflection that the beam is to undergo, and the beam 130 is left on. [0078] Furthermore, while Figures 17C and 17D illustrate that the beam 130 can be deflected by one deflector 160a,r before reaching the resonant structure 110, it should be understood that multiple deflectors may be used, either serially or in parallel. For example, deflector plates may be provided on both sides of the path of the charged particle beam 130 such that the beam 130 is cooperatively repelled and attracted simultaneously to turn off the resonant structure 110, or the deflector plates are turned off so that the beam 130 can, at least initially, be directed undeflected toward the resonant structure 110.

[0079] The configuration of Figures 17A-D is also intended to be general enough that the resonant structure 110 can be either a vertical structure such that the beam 130 passes over the resonant structure 110 or a horizontal structure such that the beam 130 passes next to the

resonant structure 110. In the vertical configuration, the "off state can be achieved by deflecting the beam 130 above the resonant structure 110 but at a height higher than can excite the resonant structure. In the horizontal configuration, the "off' state can be achieved by deflecting the beam 130 next to the resonant structure 110 but at a distance greater than can excite the resonant structure.

[0080] Alternatively, both the vertical and horizontal resonant structures can be turned "off' by deflecting the beam away from resonant structures in a direction other than the undeflected direction. For example, in the vertical configuration, the resonant structure can be turned off by deflecting the beam left or right so that it no longer passes over top of the resonant structure. Looking at the exemplary structure of Figure 7, the off-state may be selected to be any one of: a deflection between HOB and 11OG, a deflection between HOB and HOR, a deflection to the right of 11OB, and a deflection to the left of 11OR. Similarly, a horizontal resonant structure may be turned off by passing the beam next to the structure but higher than the height of the fingers such that the resonant structure is not excited.

[0081] In yet another embodiment, the deflectors may utilize a combination of horizontal and vertical deflections such that the intensity is controlled by deflecting the beam in a first direction but the on/off state is controlled by deflecting the beam in a second direction. [0082] Figure 18 A illustrates yet another possible embodiment of a varying intensity resonant structure. (The change in heights of the fingers have been over exaggerated for illustrative purposes). As shown in Figure 18 A, a beam 130 is not deflected and interacts with a few fingers to produce a first low intensity output. However, as at least one deflector (not shown) internal to or above the source 190 increases the amount of deflection that the beam undergoes, the beam interacts with an increasing number of fingers and results in a higher intensity output. [0083] Alternatively, as shown in Figure 18B ₅ a number of deflectors can be placed along a path of the beam 130 to push the beam down towards as many additional segments as needed for the specified intensity.

[0084] While deflectors 160 have been illustrated in Figures 17A-18B as being above the resonant structures when the beam 130 passes over the structures, it should be understood that in embodiments where the beam 130 passes next to the structures, the deflectors can instead be next to the resonant structures.

[0085] Figure 19A illustrates an additional possible embodiment of a varying intensity resonant structure according to the present invention. According to the illustrated embodiment, segments shaped as arcs are provided with varying lengths but with a fixed spacing between arcs such that a desired frequency is emitted. (For illustrative purposes, the number of segments has been greatly reduced. In practice, the number of segments would be significantly greater, e.g., utilizing hundreds of segments.) By varying the lengths, the number of segments that are excited by the deflected beam changes with the angle of deflection. Thus, the intensity changes with the angle of deflection as well. For example, a deflection angle of zero excites 100% of the segments. However, at half the maximum angle 50% of the segments are excited. At the maximum angle, the minimum number of segments are excited. Figure 19B provides an alternate structure to the structure of Figure 19A but where a deflection angle of zero excites the minimum number of segments and at the maximum angle, the maximum number of segments are excited

[0086] While the above has been discussed in terms of elements emitting red, green and blue light, the present invention is not so limited. The resonant structures may be utilized to produce a desired wavelength by selecting the appropriate parameters (e.g., beam velocity, finger length, finger period, finger height, duty cycle of finger period, etc.). Moreover, while the above was discussed with respect to three- wavelengths per element, any number (n) of wavelengths can be utilized per element.

[0087] As should be appreciated by those of ordinary skill in the art, the emissions produced by the resonant structures 110 can additionally be directed in a desired direction or otherwise altered using any one or a combination of: mirrors, lenses and filters.

[0088] The resonant structures (e.g., HOR, HOG and HOB) are processed onto a substrate 105 (Figure 3) (such as a semiconductor substrate or a circuit board) and can provide a large number of rows in a real estate area commensurate in size with an electrical pad (e.g., a copper pad). [0089] The resonant structures discussed above may be used for actual visible light production at variable frequencies. Such applications include any light producing application where incandescent, fluorescent, halogen, semiconductor, or other light-producing device is employed. By putting a number of resonant structures of varying geometries onto the same substrate 105, light of virtually any frequency can be realized by aiming an electron beam at selected ones of the rows.

[0090] Figure 20 shows a series of resonant posts that have been fabricated to act as segments in a test structure. As can be seen, segments can be fabricated having various dimensions. [0091] The above discussion has been provided assuming an idealized set of conditions - i.e., that each resonant structure emits electromagnetic radiation having a single frequency. However, in practice the resonant structures each emit EMR at a dominant frequency and at least one "noise" or undesired frequency. By selecting dimensions of the segments (e.g., by selecting proper spacing between resonant structures and lengths of the structures) such that the intensities of the noise frequencies are kept sufficiently low, an element 100 can be created that is applicable to the desired application or field of use. However, in some applications, it is also possible to factor in the estimate intensity of the noise from the various resonant structures and correct for it when selecting the number of resonant structures of each color to turn on and at what intensity. For example, if red, green and blue resonant structures HOR, HOG and 10OB, respectively, were known to emit (1) 10% green and 10% blue, (2) 10% red and 10% blue and (3) 10% red and 10% green, respectively, then a grey output at a selected level (level _s ) could be achieved by requesting each resonant structure output levels /(1+0.1+0.1) or level _s /1.2.

[0092] Additional details about the manufacture and use of such resonant structures are provided in the above-referenced co-pending applications, the contents of which are incorporated herein by reference.

[0093] The structures of the present invention may include a multi-pin structure. In one embodiment, two pins are used where the voltage between them is indicative of what frequency band, if any, should be emitted, but at a common intensity. In another embodiment, the frequency is selected on one pair of pins and the intensity is selected on another pair of pins (potentially sharing a common ground pin with the first pair). In a more digital configuration, commands may be sent to the device (1) to turn the transmission of EMR on and off, (2) to set the frequency to be emitted and/or (3) to set the intensity of the EMR to be emitted. A controller (not shown) receives the corresponding voltage(s) or commands on the pins and controls the director to select the appropriate resonant structure and optionally to produce the requested intensity.

[0094] As shown in Figure 21 A, the resonant structures described herein can be used as part of an optical interconnect system that allows various integrated circuits to communicate with each

other. The integrated circuits to be combined with the resonant structures described herein can be any type of integrated circuit that needs to communicate with another integrated circuit. Non- limiting examples include: microprocessors, communications controllers, ASICs, programmable logic devices (e.g., FPGAs, GALs, PALs), memories, peripheral controllers, audio and/or video codecs, etc. Signals generated by a first integrated circuit can be optically output to a second integrated circuit. Alternatively, or in addition, signals generated by the second integrated circuit or a third integrated circuit can be optically received by the first integrated circuit. For example, a microprocessor that has calculated a value may utilize the optical communications described herein to optically send a result to a memory or to optically output a value to a communications controller. Alternatively, the microprocessor may optically request a value from a memory and may optically receive the result from the memory with which the processor was communicating. [0095] In the illustrated embodiment, substrates 2100 have mounted thereon integrated circuits 2110 which include respective optical communications sections 2120. Each optical communications section 2120 includes at least one transmitter and/or at least one receiver. Such transmitters may include at least one resonant structure 110 as described herein. Such receivers may include a receiver for receiving optical emissions from at least one resonant structure 110 as described herein or from other devices emitting EMR at the same frequency as resonant structures described herein. Such receivers include, but are not limited to, a receiver as described in co-pending U.S. Application No. _/__, [Atty. Docket 2549-0068], entitled "Resonant

Detector For Optical Signals," filed on even date herewith, as well as receivers such as photo- diodes. Substrates 2100 optionally may include, mounted thereon or mounted in between, at least one optical directing element 2130 such as a mirror, a lens, or a prism. Similarly, transmitters other than resonant structures also may be used in conjunction with or as a replacement for transmitters using resonant structures described herein. [0096] As shown in Figure 2 IA, an optical emission from the optical communications section 2120 of a first integrated circuit 2110 can (1) be transmitted directly to an optical communications section 2120 on an opposite substrate 2100 or (2) be reflected off or otherwise directed by an optical directing element 2130 to an optical communications section 2120 on the same substrate 2100 or on a different (e.g., opposite) substrate 2100. Each of the optical communications sections 2120 can transmit on the same frequency or can transmit on one of plural frequencies. For example, all optical communications sections 2120 could transmit at the

same frequency (e.g., an infrared, visible or ultraviolet frequency), but such a configuration could cause "collisions" (as that term is used in Ethernet-style communications) between any two integrated circuits transmitting at the same time. Those of ordinary skill in the art would understand that collision-detection and "back-off' can be used to determine a time at which to retransmit the message after a collision.

[0097] Instead of using a single frequency for all communications, each integrated circuit could be assigned its own, unique receiver frequency. In such a configuration, collisions would only occur when transmitters attempted to transmit to the same integrated circuit at the same time. This would require, however, that each integrated circuit be equipped with as many transmitters as there are receiver frequencies. This is straightforward to accomplish by using a multi-color emitter such as disclosed with reference to Figures 6A-6C and other similar structures. [0098] In yet another configuration, each integrated circuit could be assigned its own transmitter frequency such that no collisions would occur while transmitting. This would require, however, that each integrated circuit be equipped with as many receivers as there are transmitter frequencies. This would allow non-blocking communication between the various integrated circuits in the same optical "backplane." Likewise, each circuit can be assigned multiple unique transmitter frequencies such that it can transmit in parallel to multiple receivers simultaneously. Alternatively, the multiple unique frequencies can be utilized to enable sending more than one bit at a time. For example, a first communications section can include a red- emitting and a green-emitting resonant structure where neither on represents the bits "00", where only red on represents the bits "01", where only green on represents the bits "10," and where both red and green on represents "11." This multi-bit transmission can be scaled to additional bits so that a communications section can transmit n-bits simultaneously, (a) as one bit at a time on n-separate channels, (b) as n-bits at a time on a single channel, or (c) as p bits at a time on q channels such that pxq=n.

[0099] A backplane may also be segmented into plural parts using filters 2140. Filters 2140 allow certain frequencies to remain confined within a particular segment of the backplane. For example, filters 2140 can filter light of a first frequency such that it does not pass further along the backplane. However, the filters 2140 can allow light of a second frequency to pass through them. This would allow some communications (e.g., at the first frequency) to be local-only

communications while other communications (e.g., at the second frequency) to be global communications with integrated circuits 2110 outside of a segment.

[0100] Such a communications structure is preferable in some configurations where the same cell or processor is repeated as part of a parallel processing system, but where each cell or processor still needs to communicate globally. One such a configuration can be used between a first set of circuits (e.g., on a first substrate) acting as distributed, parallel processors, and a second set of circuits (e.g., on a second substrate) acting as local and global memories. In such a case, the local memories and their corresponding processors would be separated from each other by optical filters. Thus, each processor could transmit to its corresponding memory on the same frequency without interfering with neighboring processors because of the filters. However, each processor could still communicate with the global memory using a second frequency which is not blocked by the filter. The second frequency of each processor can be the same for all processors or can be processor-specific.

[0101] Preferably, when multiple frequencies are used, the characteristics of the resonant structures are selected such that emissions by a resonant structure of non-predominant frequencies is kept sufficiently low on frequencies which are a predominant frequency for another resonant structure that correct message transmission and receipt is achieved. [0102] As shown in Figure 2 IB, instead of the planar configuration of the interconnections of Figure 21 A, it is also possible to interconnect integrated circuits in non-planar configurations such as three-dimensional configurations. Figure 2 IB illustrates a cubic configuration where three integrated circuits 2110 and their associated optical communications sections 2120 face an interior of a cube. In such a configuration, optionally using optical directing elements (not shown), integrated circuits 2110 may communicate between each other without the need to be physically connected by signal wires.

[0103] While the above communication was discussed with respect to a single level of local and global communications, it should be appreciated that multiple levels of communications groupings can be utilized according to the present invention as well. As seen in Figure 21 C, groups of integrated circuits in the hierarchy are separated or isolated from each by filters 2140. All circuits communicating in an interior of filter 2140R can communicate with each other using a first frequency (indicated as red (R)) without interfering with any other group of circuits since all groups of circuits are isolated by a corresponding filter 2140R. Similarly, all circuits

communicating in an interior of filter 2140G can communicate with each other using the same second frequency (indicated as green (G)) without interfering with any other group of circuits inside a different filter 2140R. Similarly, all circuits communicating in an interior of filter 2140B can communicate with each other using the same second frequency (indicated as blue (B)) without interfering with any other group of circuits inside a different filter 2140B. Lastly, all illustrated circuits can communicate globally using a fourth frequency (indicated as violet (V)) without interfering with any other circuits outside of the filter 2140V. Alternatively, filters can be eliminated by tuning the receiving resonant structures to the specific desired wavelengths. [0104] While certain configurations of structures have been illustrated for the purposes of presenting the basic structures of the present invention, one of ordinary skill in the art will appreciate that other variations are possible which would still fall within the scope of the appended claims.