WO2011033339A1

WO2011033339A1 - An electromagnetic radiation switch, and a method of performing a switch function in an electromagnetic radiation propagation path

Info

Publication number: WO2011033339A1
Application number: PCT/IB2009/054102
Authority: WO
Inventors: Benoit Bataillou; David Van Steenwinckel; Radu Surdeanu; Viet Nguyen Hoang; Pascal Bancken
Original assignee: Nxp B.V.
Priority date: 2009-09-18
Filing date: 2009-09-18
Publication date: 2011-03-24

Abstract

An electromagnetic radiation switch (100) for performing a switch function in an electromagnetic radiation propagation path, the electromagnetic radiation switch (100) comprising a substrate (102), a regular arrangement of structures (104) formed on and/or in the substrate (102), wherein at least one of the structures (104) is a phase change material structure (104) changeable between at least two different phase states, and a control unit (106) adapted to control the phase state of the at least one phase change material structure (104) to thereby select one of a plurality of switching states for the electromagnetic radiation propagation path.

Description

AN ELECTOMAGNETIC RADIATION SWITCH, AND A METHOD OF PERFORMING A SWITCH FUNCTION IN AN ELECTROMAGNETIC RADIATION PROPAGATION PATH FIELD OF THE INVENTION

The invention relates to an electromagnetic radiation switch.

Moreover, the invention relates to a method of performing a switch function in an electromagnetic radiation propagation path. BACKGROUND OF THE INVENTION

An optical switch may be denoted as a switch that enables optical signals to be selectively switched from one circuit to another or from one optical system to another.

An optical switch may operate by mechanical means, such as physically shifting an optical fiber to drive one or more alternative fibers, or by electro-optic effects, magneto- optic effects, or other methods. Optical switches, such as those using moving fibers, may be used for alternate routine of an optical transmission path. Optical switches, such as those using electro-optic or magneto-optic effects, may be used to perform logic operations.

EP 1,729,166 A2 discloses a tunable optical filter for modulating the intensity of incident light as the light is transmitted through the tunable optical filter, the tunable optical filter comprising a metal film having a periodic array of sub wavelength-diameter holes provided therein, and a supporting layer, at least a portion of the supporting layer having a selectively variable refractive index, the selectively variable refractive index portion being substantially adjacent to the metal film such that the metal film and the supporting layer comprise a perforated metal film unit, and wherein selective variation of the refractive index of the selectively variable refractive index portion of the supporting layer modulates the intensity of light transmitted through the perforated metal film unit without substantially changing the direction of the light.

US 2006/0078249 Al discloses an optical switch which has a conductor and one or more sub-wavelength apertures. The switch is activated and periodic perturbations are dynamically formed in proximity to the conductor. Photons are directed toward and impinge upon the switch, and a greater amount of light propagates through the sub-wavelength apertures in the activated switch as compared to an inactivated switch. An embodiment involves the dynamic control of light propagation through a sub-wavelength aperture in an optical switch. The dynamic control can be achieved by altering the conductivity (or the complex dielectric constant being the real parameter that matters for plasmon propagation) in the switch, altering the refractive index in the switch, altering the shape of the conducting surface, and/or altering the magnetic permeability of the switch.

However, it may be inconvenient to switch conventional optical switches.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the invention to enable electromagnetic radiation switching in a simple manner.

In order to achieve the object defined above, an electromagnetic radiation switch, and a method of performing a switch function in an electromagnetic radiation propagation path according to the independent claims are provided.

According to an exemplary embodiment of the invention, an electromagnetic radiation switch (for instance an optical or an optoelectronic component) for performing a switch function (for instance for the purpose of wavelength-selective filtering or for controlling an optoelectronic communication system) in an electromagnetic radiation propagation path is provided, the electromagnetic radiation switch comprising a substrate (such as a conductor substrate), a regular arrangement of structures (for instance a periodic array of sub wavelength-diameter spots) formed on and/or in the substrate (for instance embedded in the substrate), wherein at least one of the structures is a phase change material structure changeable between at least two different phase states (which may be different stable solid phases which the phase change material can adopt in the presence of a dedicated trigger for changing the phase state), and a control unit adapted to control (or adjust) the phase state of the at least one phase change material structure to thereby select one of a plurality of switching states for the electromagnetic radiation propagation path.

According to another exemplary embodiment of the invention, a method of performing a switch function in an electromagnetic radiation propagation path is provided, the method comprising providing a regular arrangement of structures formed on and/or in a substrate, wherein at least one of the structures is a phase change material structure changeable between at least two different phase states, and controlling the phase state of the at least one phase change material structure to thereby select one of a plurality of switching states for the electromagnetic radiation propagation path.

The term "electromagnetic radiation switch" may particularly denote a switch that enables electromagnetic radiation signals (particularly signals propagating in the form of photons) to be selectively switched from one circuit to another or from one electromagnetic radiation system to another. Particularly, an optical switch may be denoted as a switch that enables optical signals to be selectively switched from one circuit to another or from one optical system to another.

The term "regular arrangement of structures" may particularly denote that the structures are arranged in accordance with a spatially regular pattern. However, individual ones of the structures, groups of the structures, or all of the structures can be controlled to be converted into a state in which they are different from other ones of the structures regarding at least one physical property (particularly regarding electric conductivity/the complex dielectric constant and/or interaction with electromagnetic radiation), thereby selectively breaking the periodicity or regularity regarding the physical property. Thus, while the geometric regularity may maintain the same, the physical regularity regarding interaction between matter and photons may be changed by switching one or more of the structures to another phase.

The term "phase change structure" may particularly denote a structure which can be switched between at least two phases. Phase change materials can have not only two phases but also more than two phases, for instance crystalline, amorphous, meta-amorphous, meta-crystalline, crystalline with a different lattice orientation, etc. To switch between both phases, an increase of the temperature is required. Very high temperatures with rapid cooling down will result in an amorphous phase, whereas a smaller increase in temperature or slower cooling down leads to a crystalline phase. The increase in temperature may be obtained by applying an electric current pulse (or a light pulse) to the phase change material. A high current density caused by the pulse may lead to a local temperature increase. The phase change structure may be adapted such that one of the two phase states relates to a crystalline phase and the other one of the two phase states relates to an amorphous phase of the phase change structure. Such a material property can be found in chalcogenide materials. A chalcogenide glass may be used which is a glass containing a chalcogenide element (sulphur, selenium or tellurium) as a substantial constituent. Examples for phase change materials are GeSbTe, AglnSbTe, InSe, SbSe, SbTe, InSbSe, InSbTe, GeSbSe, GeSbTeSe or AglnSbSeTe.

According to an exemplary embodiment of the invention, a switch or filter for selectively enabling or disabling transmission of an electromagnetic radiation beam of a specific wavelength or wavelength range is provided which makes a substrate having a regular arrangement of structures provided thereon/therein selectively opaque or transparent for the electromagnetic radiation by switching a phase change material between states of different electrical conductivity or complex dielectric constant, thereby disturbing or not disturbing the regular pattern which prevents or suppresses the excitation of surface plasmons making the system transparent (when plasmons are excited) or non-transparent (when such an excitation is not possible). The provision of one or more phase change material structures for such an electromagnetic radiation switch has the particular advantage that a very fast switching is possible by applying a corresponding heating sequence to the phase change material spots. Furthermore, such a system can be monolithically integrated in microprocessing technology, therefore allowing for a miniaturization of electromagnetic radiation switches or filters.

According to an exemplary embodiment of the invention, a tunable optical switch is provided comprising a dielectric material and a metal surface with an array of holes/apertures that allow a specific range of light wavelengths to be transmitted by surface plasmon resonance, whereby perturbing the periodicity of the holes or changing the material constants of the device, preferably by changing the phase of the dielectric material from amorphous to crystalline, changes the filtering properties of the device. The filtering properties of a surface plasmon resonance (SPR) optical filter is changed by changing the phase of the dielectric material.

According to an exemplary embodiment of the invention, a central transmissive wavelength is determined by the dielectric constants of the metal and the dielectric. An aim of the phase change is to provide a metal matrix with embedded structures that can have a tunable dielectric constant. When a phase change material (PCM) changes phase, the dielectric constant changes abruptly which perturbates the filter. The filter will not filter anymore in a specific phase, or the central transmissive wavelength will suddenly change. This extinction can be calculated before, allowing to selectively put a filter(s) on/off The speed of phase change is very high. It is possible to tune the central wavelength on both phases by choosing the PCM material. An obtainable filter size is also extremely small. For instance, it is possible to implement 4x4 arrays which may be for example 1 μιη x 1 μιη. Metal layers with holes are easy to process in small dimensions. Holes or apertures for visible wavelength may be above 200 nm diameters, and those can be made with lithography 193nm.

In the following, further exemplary embodiments of the electromagnetic radiation switch will be explained. However, these embodiments also apply to the method.

The electromagnetic radiation switch may be adapted for selectively enabling or disabling transmission of an electromagnetic radiation beam having an assigned wavelength or wavelength range through the electromagnetic radiation switch under control of the control unit. Thus, a wavelength filter may be provided. The transmission wavelength may be defined by the design of the substrate and the structures, including materials, dimensions, symmetry or regularity, etc. An electromagnetic radiation beam which is capable of exciting surface plasmons in the arrangement formed by substrate and structures is transmissive for the system, whereas a wavelength which is not capable of exciting such plasmons is opaque. Therefore, by selectively controlling the phase states of the phase change material structures, the physical properties of the phase change material structures may be changed, allowing to modify the pattern of structures from a point of view of the beam. By individually or mutually adjusting specific phase states of the phase change materials, it is possible to easily adjust different transmission modes of the switch.

Particularly, the electromagnetic radiation switch may be adapted as an optical switch. The term "optical switch" may be denoted as a switch which is operable with optical light, that is light in a wavelength range between 400 nm and 800 nm. However, other embodiments of the invention are also applicable to electromagnetic radiation of other wavelength ranges, for instance with infrared light or with ultraviolet light.

The substrate may be an electrically conductive substrate, particularly a metallic substrate. Especially suitable materials for the substrate are silver, aluminum, copper, and/or gold. Such a metallic substrate is a proper basis for exciting or generating surface plasmons. However, the mentioned metals are only examples. Another choice of a metal is of course possible. For instance, other alloys of different metals also work (an example is rhodium).

The regular arrangement of structures may be a spatially periodic arrangement of structures. Thus, the repetition of the structures may be performed in accordance with a specific rule or protocol which defines the periodicity of the system. Thus, structures are repeated in space, for instance along one or two dimensions. The structures may be matrix- like, hexagonal, etc.

The regular arrangement of structures may be a two-dimensional array of spots. The term "spots" may denote small dots which may be essentially zero-dimensional structures having dimensions below a wavelength of the electromagnetic radiation. The spots may be arranged in a matrix-like manner on the substrate, that is along rows and columns which are perpendicular to one another. Such a regular structure formed on and/or in a metallic substrate is appropriate for exciting surface plasmons. At least a part of the structures may be made of a dielectric material, i.e. of an electrically insulating material. According to one embodiment, a first part of the structures are always dielectric, and a second part of the structures is made of phase change material. In another embodiment, all the structures may be made of a phase change material which may also be brought in a dielectric (i.e. electrically non-conductive or electrically insulating) state. Thus, a dielectric pattern in a metallic matrix may be provided as a basis for the switch functionality.

The at least one phase change material structure may be brought into a first phase in which it has dielectric properties and may be brought into a second phase in which it has electrically conductive properties. When the phase change material is in the dielectric state, it forms part of the dielectric pattern within the metallic substrate. A highly ordered structure is therefore achieved which allows the generation of plasmons. When the phase change material is brought in the second phase in which it has an electrically conductive property, it may form part of the metallic substrate (regarding electric current conduction properties), may therefore disturb the regularity of the pattern, and may prevent the excitation of surface plasmons. In the state in which the excitation of plasmons is possible, the system is transmissive for the electromagnetic radiation, and in a state in which the surface plasmons cannot be excited, the system is opaque for the electromagnetic radiation. Thus, the switch function can be realized on the basis of a corresponding control or regulation of the phase change material.

The control unit may be adapted to control the phase state of the at least one phase change material structure to select one of the plurality of switching states by selectively exciting surface plasmons or by preventing excitation of surface plasmons. Surface plasmons, which may also be denoted as surface plasma polaritons, may be denoted as fluctuations in the electron density at the boundary of two materials, particularly at the boundary of a metal with a dielectric. Plasmons may be considered as collective vibrations of an electron gas or plasma surrounding the atomical lattice side of a metal.

The control unit may be adapted to control the phase state of the at least one phase change material structure to thereby selectively disturb or not disturb the regularity of the arrangement of structures. In a highly regular environment (regarding optical properties of the two-dimensional grating), it is presently believed that the excitation of plasmons is possible, whereas it is presently believed that the excitation of plasmons is not possible when the degree of regularity of the structure (more precisely of its physical properties) becomes too small.

The control unit may be adapted to control the phase state of the at least one phase change material structure to thereby selectively render the substrate and the arrangement of structures opaque or transparent for electromagnetic radiation of a specific wavelength or range of wavelengths.

The electromagnetic radiation switch may further comprise at least one further substrate, at least one further regular arrangement of further structures each further regular arrangement formed on and/or in a respective one of the at least one further substrate, wherein at least one of the further structures is a phase change material structure capable of adopting at least two different phase states. The control unit may be adapted to control the phase state of the at least one further phase change material structure to thereby select one of a plurality of switching states for the electromagnetic radiation propagation path. In such an embodiment, it is possible that various of the above substrate/structure configurations are provided, each adapted for being transmissive or opaque for a specific wavelength or range of wavelength. By combining a plurality of such systems, it is not only possible to provide for a wavelength specific filter, but also for a multicolor filter. For example, it is possible that three substrates are provided parallel or serial in an electromagnetic radiation propagation path to thereby allow the selective transmission or non-transmission of electromagnetic radiation through the respective color filters (for instance red, green and blue).

With a color filter having sufficient accuracy, it may be necessary to control the thicknesses and those may depend on the wavelength to be filtered (for instance Bragg filters). To make a purple filter, for example, a blue and a red filter may be implemented. These two filters will not have the same thickness, and it will be an issue if a flat surface is desired on top of a device, for packaging, etc. For cheap filters without Bragg filtering, those may be made using dyes, which are chemicals, and usually not compatible with clean rooms, or not easy to manipulate, and toxic sometimes. Using surface plasmons, what matters is only the diameters of the holes, the pitch of the array, and the requirement on the thickness is a less severe challenge. A set of R,G and B filters, or any combination, may be made in a single lithographic step (it may be sufficient to draw the filters on the lithographic mask). Hence, using metal layers, it is possible to create a set of filters with one single step. Such a procedure is CMOS compatible, it is a really typical step in the CMOS process, and integrating a million filters is a non issue. The whole filter set may be made by embedding this metal layer into the chosen dielectric. It is possible to integrate many wavelength filters side by side to create a highly integrated color filter instead of a wavelength filter.

The electromagnetic radiation switch may comprise a heat sink thermally coupled to the substrate for removing heat generated when changing the phase state of the at least one phase change material structure by heating. A heater unit may be provided which heats the phase change material dots for changing their phase state. Such a heater may include an electromagnetic radiation heater heating the phase change material by the absorption of electromagnetic radiation. Alternatively, it is also that an ohmic heater is provided, which applies an electric current that - due to ohmic losses - locally heats the phase change material in accordance with a specific characteristic, to thereby selectively change the phase state to a crystalline state or to an amorphous state.

A current pulse or a current signal may generate heat generated in a convertible material to thereby change its phase state and consequently its value of the electrical conductivity or the complex dielectric constant. The applied current pulses may have a certain shape (for instance may have a fast raising edge and a slow falling edge, or may have a raising edge which is curved to the right and a falling edge which is curved to the left) and may be characterized by different parameters (such as current amplitude, pulse duration, etc.). By adjusting the pulse parameters, it is possible to control whether the phase change material is converted into a crystalline phase or is converted into an amorphous phase. Very high temperatures with rapid cooling down may result in an amorphous phase. A smaller increase in temperature or slower cooling down may lead to a crystalline phase.

The aspects defined above and further aspects of the invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to these examples of embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited.

Fig. 1 illustrates an electromagnetic radiation switch according to an exemplary embodiment of the invention.

Fig. 2 is a diagram showing a transmitted field/aperture size correlation for a hole array which can be implemented according to an exemplary embodiment of the invention.

Fig. 3 shows an optical switch in a configuration as a tunable wavelength selective filter according to an exemplary embodiment of the invention. Fig. 4 is a diagram illustrating a pitch of an array in dependence of a center of peak wavelength of a system according to an exemplary embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

The illustration in the drawing is schematical. In different drawings, similar or identical elements are provided with the same reference signs.

In the following, referring to Fig. 1, an optical switch 100 for performing a switch function in an electromagnetic radiation propagation path according to an exemplary embodiment of the invention will be explained.

Fig. 1 shows a scenario in which a visible light beam 108 of a specific wavelength propagates through a source optical fiber 120, transmits the optical switch 100 and is coupled into a destination optical fiber 130. The present operation mode of the optical switch 100 determines whether the optical beam 108 can pass the switch 100, or not.

The optical switch 100 comprises a first metal substrate 102 in which a plurality of phase change material spots 104 are embedded in a regular pattern. Each of the phase change material spots 104 is capable of adopting a crystalline state in which the material is metallically conductive, and can adopt an amorphous state, in which the material is electrically insulating.

An ohmic heater 140 is provided and electrically coupled to the spots 104 for applying heat to the phase change material spots 104 to bring them into a desired phase state.

A control unit 106 (such as a microprocessor or a central processing unit, CPU) is provided to control the phase state of the phase change material dots 104 to thereby select an opaque or a transparent switching state of the switch portion 102, 104. Namely, when the structure 104 is electrically conductive, it will not have different electric conductivity properties or complex dielectric constant properties as compared to the metallic matrix 102, and the light beam 108 will not be able to excite surface plasmon resonances in the layer 102, 104. In contrast to this, when the control unit 106 has controlled the heater 140 to heat the phase change material dots 104 in accordance with a heating sequence so that they are brought into an amorphous state, they will form a dielectric pattern having an ordered structure within the metallic substrate 102, allowing the electromagnetic radiation beam 108 to excite surface plasmon resonances in the grating-like structure 102, 104. In the latter scenario, the light beam 108 may pass the switch portion 102, 104, whereas in the former scenario the light beam 108 cannot pass the switch portion 102, 104 and will be reflected. Fig. 1 further shows an input/output unit 150, which is bidirectionally coupled to the control unit 106. Via the input/output unit 150, a user may input control commands to the control unit 106, for instance via buttons, a keypad, or a joystick. It is also possible that the control unit 106 reports to the user, via a display unit of the input/output unit 150, the present switch state of the optical switch 100.

Fig. 1 further shows another switch part 110, 112 which is formed by a metallic matrix 110 and a regular pattern of phase change material spots 112. When the materials 110, 102 are selected differently, when the materials 104, 112 are selected differently, and when the geometric properties (such as a pitch, dimensions or the like) of the switch parts 102, 104 and 110, 112 are selected differently, the transmission wavelength of the second filter part 110, 112 is different than the transmission wavelength of the first filter part 102, 104. Thus, the filter 100 shown in Fig. 1 only allows transmission of the optical beam 108 when the wavelength of the optical beam 108 fits with the transmission properties of both filter parts 102, 104 and 110, 112.

Each of the filter parts 104, 112 is embedded between respective protection layers 160.

Furthermore, each of the metallic matrixes 102, 110 are coupled with a cooling fin 114 for transporting away ohmic heat generated during programming the present state of the phase change material 104, 112.

Fig. 2 shows a diagram 200 having an abscissa 202 along which a wavelength is plotted. Along an ordinate 204, a relative intensity is plotted. Fig. 2 shows that a system similar as the system in Fig. 1 can serve as a wavelength selective filter.

Referring to Fig. 2 light is collected at 550nm (for this design) on twice the surface of the holes. Changing the dielectric constant of the metal or of the dielectric will shift the resonance or prevent it (and light will be reflected). The reflection spectrum is the opposite.

Fig. 2 relates to the case of a square array. A hexagonal array would only show one peak. Thus, the type of array may change the spectrum, so Fig. 2 is just one example. This can be calculated (as mentioned above).

Fig. 3 shows an optical switch system 300 according to another exemplary embodiment of the invention in different views and operation modes.

In the embodiment of Fig. 3, a cross-sectional view of the optical switch system 300 is shown. Furthermore, a plan view of the optical switch system 300 is shown in a first operation state 310 in which a transmission of a specific wavelength is possible ("transparent" mode) and in a scenario denoted with reference numeral 320 in which the wavelength is reflected ("mirror" mode).

As can be taken from Fig. 3, only a part of the spots are made of phase change material 104, as shown in the image 310 in which the phase change material is in the amorphous phase, thereby behaving in a similar manner as permanently dielectric spots 302. Thus, in Fig. 1 (diameter of the spots 104, 302 « λ, period around λ), a periodic array of dielectric structures 104, 302 is provided, thereby allowing plasmon resonances to be excited by an optical beam 108, so that a corresponding wavelength can be transmitted.

In the scenario according to reference numeral 320, the phase change material

104 is brought to a crystalline phase in which it is low ohmic and is equivalent to the metal layer 102 in which it is embedded. Thus, the periodicity of the array is broken by the metallic phase change spots 104, so that no or a shifted resonance is monitored, and the corresponding wavelength λ of the light beam 108 is reflected.

Fig. 3 shows the principle of switching on and off the filter 300. This solution is only an example, any change in dielectric constant, thickness, bend radius or n,k values may perturbate the resonance. Regarding heat resistance, under constant illumination the heat can be removed using a heatsink on the sides, which will have good thermal contact with a metal layer.

Fig. 4 shows a diagram 400 having an ordinate 404 along which a pitch of the array of Fig. 3 is plotted. Along an abscissa 402, a center of a peak wavelength is plotted. Thus, Fig. 4 shows the filter characteristics of the arrangement of Fig. 3.

According to an exemplary embodiment of the invention, a plasmon tunable optical switch is provided. A principle of a corresponding filter is to selectively switch on/off a light filter. Embodiments of the invention are based on surface plasmon resonances (SPR) which happen when light hits a metal/dielectric interface. When the metal surface presents corrugations or holes or hole arrays with a specific pitch/hole size, light can be reemitted/filtered. When perturbating this periodicity or the material constants of all or part of the array, the filtering properties will change. If the wavelength is outside the "transparent bandwidth" the layer will act like a mirror. Embodiments of the invention are based on switching a resonance off and on. A corresponding array may have two main properties: light filtering and light collection.

Regarding filtering properties, outside the filtering range, the material (metal) is opaque and the longer wavelengths will be reflected back (this may serve as an IR protection).

Fig. 4 shows a center of a peak wavelength (abscissa 402), wherein a pitch of the array is plotted along an ordinate 404. It is possible to tune the maximum transmission peak by changing the pitch of the array. This can be extended to IR and RF wavelengths.

Fig. 3 and Fig. 4 show the ease of selection of the bandwidth for a detector.

The width of the peak can change over 30% on all the wavelength range, for Al, for perfect arrays. It is possible to enlarge the peak by perturbing the periodicity of the array(arrays with less holes/row, moving a few holes)

The array can be made using standard CMOS technologies and lithography 193nm (for up to visible range hole sizes). The array has a high speed of operation. In the case the switching is made using phase change material, the speed of operation is the speed of a phase change in a very small volume of material. This is limited by the choice of material. For Ge, Sb Te alloys, this is in the nanosecond range. Regarding material choice, plasmonic resonance can be demonstrated (non exhaustive list) on Ag, Al, Cu, Au. The material constants define the "quality" of the effect and the maximal wavelength range. The dielectric choice can be (non exhaustive) Si3N4, Si02, air, vacuum. Additionally or alternatively to a phase change material, it is possible to use any kind of way to change the dielectric constant or break the periodicity (ferro, pyro, piezo electrical). The disclosed design may comprise a metal layer embedded into a transparent substrate. The holes filled with phase change material are contacted on top and bottom, or a stripe of this material can be deposited on top of the array. Many other geometries are possible as well.

Finally, it should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims. In the claims, any reference signs placed in parentheses shall not be construed as limiting the claims. The word "comprising" and "comprises", and the like, does not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. The singular reference of an element does not exclude the plural reference of such elements and vice-versa. In a device claim enumerating several means, several of these means may be embodied by one and the same item of software or hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:

1. An electromagnetic radiation switch (100) for performing a switch function in an electromagnetic radiation propagation path, the electromagnetic radiation switch (100) comprising

a substrate (102);

a regular arrangement of structures (104) formed on and/or in the substrate (102), wherein at least one of the structures (104) is a phase change material structure (104) changeable between at least two different phase states;

a control unit (106) adapted to control the phase state of the at least one phase change material structure (104) to thereby select one of a plurality of switching states for the electromagnetic radiation propagation path.

2. The electromagnetic radiation switch (100) according to claim 1, adapted for selectively enabling or disabling transmission of an electromagnetic radiation beam (108), having an assigned wavelength or wavelength range, through the electromagnetic radiation switch (100) under control of the control unit (106).

3. The electromagnetic radiation switch (100) according to claim 1, adapted as an optical switch.

4. The electromagnetic radiation switch (100) according to claim 1, wherein the substrate (102) is an electrically conductive substrate, particularly is a metallic substrate, more particularly is made of one material of the group consisting of silver, aluminum, copper, and gold.

5. The electromagnetic radiation switch (100) according to claim 1, wherein the regular arrangement of structures (104) is a spatially periodic arrangement of structures (104).

6. The electromagnetic radiation switch (100) according to claim 1, wherein the regular arrangement of structures (104) is a two-dimensional array of spots.

7. The electromagnetic radiation switch (100) according to claim 1, wherein at least a part of the structures (104) is made of a dielectric material.

8. The electromagnetic radiation switch (100) according to claim 1, wherein the at least one phase change material structure (104) has dielectric properties in one of the at least two states and has electrically conductive properties in another one of the at least two states.

9. The electromagnetic radiation switch (100) according to claim 1, wherein the at least one phase change material structure (104) can be in a crystalline phase or can be in an amorphous phase.

10. The electromagnetic radiation switch (100) according to claim 1, wherein the control unit (106) is adapted to control the phase state of the at least one phase change material structure (104) to select one of the plurality of switching states by selectively exciting surface plasmon resonances or by preventing excitation of surface plasmon resonances.

11. The electromagnetic radiation switch (100) according to claim 1, wherein the control unit (106) is adapted to control the phase state of the at least one phase change material structure (104) to thereby selectively disturb or not disturb the regularity of the arrangement of structures (104).

12. The electromagnetic radiation switch (100) according to claim 1, wherein the control unit (106) is adapted to control the phase state of the at least one phase change material structure (104) to thereby render the substrate (102) and the arrangement of structures (104) selectively opaque or transparent for electromagnetic radiation (108) of a specific wavelength or range of wavelengths.

13. The electromagnetic radiation switch (100) according to claim 1, further comprising:

at least one further substrate (110);

at least one further regular arrangement of further structures (112), each further regular arrangement formed on and/or in a respective one of the at least one further substrate (110), wherein at least one of the further structures (112) is a phase change material structure (112) changeable between at least two different phase states; wherein the control unit (106) is adapted to control the phase state of the at least one further phase change material structure (112) to thereby select one of a plurality of switching states for the electromagnetic radiation propagation path.

14. The electromagnetic radiation switch (100) according to claim 13, wherein transmission wavelengths of electromagnetic radiation (108) are different for the different substrates (102, 110).

15. The electromagnetic radiation switch (100) according to claim 1, comprising a heat sink (114) thermally coupled to the substrate (102, 110) for removing heat generated when changing the phase state of the at least one phase change material structure (104, 112) by heating.

16. A method of performing a switch function in an electromagnetic radiation propagation path, the method comprising

providing a regular arrangement of structures (104) formed on and/or in a substrate (102), wherein at least one of the structures (104) is a phase change material structure (104) changeable between at least two different phase states;

controlling the phase state of the at least one phase change material structure (104) to thereby select one of a plurality of switching states for the electromagnetic radiation propagation path.