AMPLITUDE AND PHASE MODULATING USING OPTICAL ELEMENT

Abstract

Method of operating an optical element, the optical element comprising a. a cover having a first surface and a second surface, b. a support, and c. a means; wherein: - the cover is orientated with the first surface directed towards the support; - a part of the first surface is attached to the support; - a spatial arrangement of the cover as seen in a cross section of the cover defines a cover contour profile; - the means is arranged to move the cover from a first cover contour profile to a further cover contour profile which is different from the first cover contour profile; wherein the optical element further comprises a substrate on a side of the support opposite the cover, a cavity being defined between the cover and the substrate, with a cavity height defined as a distance from the substrate to the cover, characterized in that the method is characterized by: - based on a desired phase response for the optical element and a desired amplitude response, control the means to cause the optical element to exhibit a response corresponding to the desired phase response and the desired amplitude response.

Description

The current application relates to an optical element comprising, a cover having a rst surface and a second surface, a support, and ameans. The cover is orientated with the rst surface directed towards the support, a part ofthe rst surface is attached to the support, a spatial arrangement ofthe cover as seen in a cross section ofthe cover denes a cover contour prole, and the means is arranged to move the cover from a rst cover contour prole to a further cover contourprole which is different from the rst cover contour prole. An optical element is known from e.g.WO 2021 / 032752 Al andWO 2018 / 228671 Al. This document discloses optical devices ofspecic interest. The working principle is thatwhen a cover is provided that has some desired optical behaviour, e.g. reecting light, transmitting only some light, etc. the interaction ofincident light can be changed by changing the cover contour prole. To facilitate the cover changing shape to facilitate changing the optical behaviour ofthe optical device, the cover is made relatively thin, in terms ofWO 2021 / 032752 Al 2-dimensional. As an example, a single graphene layer cover is presented, with a coating on top to obtain desirable optical characteristic. Since the optical device is very small, they can be used to act like a pixel in a larger collection of similar devices. Control of scattering, reection and / or interference behaviour can be used to turn a pixel on or offand / or vary its colour. This way, images can be generated and / or manipulated. Several principles ofoperation are available with such optical devices.A rst operational principle is shown in gures lA lC, which correspond to gures 9 11 ofWO 2021 / 032752 Al. These gures show respectively an optical device with a at cover, a convex cover, and a concave cover. Light incident on the at cover (g. 1A) is reected as ifhitting a smooth and straight surface, i.e. parallel incident rays remain parallel after reection. As such, specular reection takes place at the cover. In the convex and concave positions ofthe cover, parallel incident rays are no longer parallel after reection, thus causing diffuse reection. By changing the shape ofthe cover, it is thus possible to alternate between specular and diffuse reection. To suit this rst operational principle, the cover is sufciently reective towards the incident light. In this example, the light is incident on the second surface, whichmay also be called the outside ofthe optical device. Figures 2A 2C, which correspond to gures 12 14ofWO 2021 / 032752 Al, show a second operational principle. Reference is rst made to the substrate which spans the support on an opposite side ofthe cover, in order to dene a cavity between the cover and the substrate. The substrate is partly reective and partly transmissive. The cover is relatively reecting. Light incident on the substrate is thus partly transmitted and partly reected. The transmitted light reects on the rst surface ofthe cover, i.e. coming from the inside, and is transmitted back through the substrate, where it interferes with the light reected by the substrate. Depending on the wavelength ofthe light and the distance between the cover and the substrate, the interaction can be constructive or destructive. Since that distance changes when the cover changes shape, the interferometric characteristics ofthe optical device can be changed. Figures 4 and 5 show even otherways ofusing the changing cover contour prole. In the case ofgure 4, an optical element is shown with a substrate 106 that is relatively reective. The cover 101 in this case is relatively absorbing. Nevertheless, ofan incoming lightbeam 601, at least some lightmay be transmitted towards the substrate 106 as transmitted lightbeam 603. This reects back viathe substrate 106 as reected light 604. Due to interference ofthe transmitted lightbeam 603 and the reected light 604, a pattern ofnodes and antinodes is present. The cover 101 can then be moved, e.g. by changing its cover contour prole or its position with respect to the support, to place the cover at an antinode for absorbing the light, or at a node for not or absorbing less the light. Accordingly, the exiting light 605 can be present in less ormore intensity by controlling the cover. This principle is called interferometric absorption. Figure 5 shows the principle ofinterferometric reection, similar to g. 2, but with light 601 incident the cover. In this case, light is partially transmitted through the cover 101, and reected at the substrate 604, which for that purpose is reective. The cover 101 reects some light 605, but also transmits some light 603. After reecting 604 from the substrate 106, light passing through the cover 101 again interferes with the reected light 605. By controlling the position or cover contour prole ofthe cover 101, control is possible ofwavelengths oflight that do or do not interfere constructively. In both cases, light transmitted through the covermay actually be refracted. However, since the gures show a specic example oflight incident normal to the cover, the wording transmitting was used. The invention can however be applied, depending on the use-case, to non- normal light also. These principles have been described only briey herein, as the operational principles involved are in themselves known, and have been applied e.g. inWO 2018 / 228671 A1 (see gures 1 and 2). These principles thus show thatby varying the reectance and / or transmittance and / or absorbance ofthe cover and the substrate, and the direction atwhich light is incident (from outside or inside the optical device), it is possible to cause the cover to create a certain interaction with the light, optionally in cooperation with the substrate. The interaction changes when the cover shape changes, i.e. when the cover contour prole changes. The optical device described above has been used successfully to modulate light, but there remains a need to further inuence the range ofpossible modulations. The invention stems in part from the realization that such an optical element can be made more versatile depending on its use. In particular, the applicant has realized that it is possible to control not only the amplitude of light, but also its phase. By providing both amplitude and phase modulation in dependence ofa desired response, the optical element can be used in a variety of applications, amongst which holography. While light with any suitable characteristicmay be used, it is envisioned to use monochromatic light as a source. One such example is coherent light such as light generated by a laser or a laser diode. According to the invention therefore, the optical element described in claim 1 is controlled to exhibit the desired phase and amplitude modulation.WO 2021 / 032752 A1 is silent with regards to controlling the amplitude / phase modulation in dependence ofa desired phase response, and therefore lacks the versatility presented by the method ofclaim 1. There may be multiple ways ofcontrolling the amplitude and phase ofmodulated light. WO 2021 / 032752 A1 already explains some methods ofcontrolling the element, all ofwhich could be used to create a desired response. However, said desired response does not account for phase change. Instead, any modulation inWO 2021 / 032752 A1 inherently has a phase response, but this was nottaken into account, nor achieved in dependence ofa desired phase response. In line with the invention, it is possible to control the cover such that a desired phase response is achieved. Then, it is possible to further control the element to also provide a desired amplitude response. As an example, instead ofremaining in a single position corresponding to the desired phase response, it is possible to move the cover back and forth between that position and another in which the optical element outputs little to no light. Depending on the residence time in these positions (i.e. cover contour proles), the total perceived amplitude oflight output can be changed. This switching between positions is referred to as temporal dithering. As another example, the cover could have optical properties that can be changed. As an example, the covermay be congured to have a changeable absorbance. In such a case, the position ofthe cover could be used to obtain a desired phase, whereas the absorbance could be used to further inuence the amplitude. A non-limiting example ofobtaining such a cover is providing it with a cover that has strain responsive optical properties. For this purpose the cover may be ormay comprise a 2-dimensional material. The covermay be ormay comprise a straintronic material, whichmay be the 2-dimensional material. As yet another example, a cavity may be formed below the cover, optionally by the provision ofa substrate on a side ofthe support away from the cover. Since the cavity may inuence the optical properties ofthe device as a whole, changing the optical properties ofthe cavitymay allow changing the phase or amplitude response, in addition to changing the position or shape ofthe cover. Optical properties ofthe cavity can for instance be changed by changing the composition ofa gas, liquid, or liquid crystal contents ofthe cavity. It is however also possible to change optical properties ofthe substrate instead or in addition. This could be done by providing a straintronic and / or 2-dimensional material at or in the substrate. In particular, a straintronic material could be chosen that changes its refractive index in response to strain. Similarly, the cover and / or the substrate may comprise a material which exhibits changing mechanical properties in response to e.g. temperature changes. Alternatively, a material could be chosen that changes its crystalline structure with temperature. Examples might be suitably chosen mechanical metamaterials, or sold-solid phase change materials. Further, the cover and / or substrate may comprise a material with electrical properties that change in response to an applied torque, for instance a twisted bilayer ofgraphene, or suitably chosen other twistronic material. In general, any material forthe cover and / or substrate with changing properties in response to the application ofa charge may also be used advantageously. Such a material could be a metasurface or could be structured as atunable or photonic metamaterial. Alternatively, a photonic crystal could be used, with its response to an electric eld changing with temperature. These changing properties referred-to above could be used to provide a tunable property of the optical device, which can be tuned independently from the cover contour prole. As such, a larger variation ofresponses can be obtained, including those that allow selecting amplitude and phase responses at least almost independently from each other. In any case, activationmay be done using the means introduced earlier, or using separately provided means for inuencing the cover and / or substrate and / or cavity respectively. Such separately provided means can operate based on any suitable principle (like the means introduced earlier). At this time, it is noted that regardless ofthe actuation method used, given a sufciently small system, any one actuation method will often have some corresponding co-phenomenon in another domain as well. As such, at nano-scale, the actuation method and corresponding co- phenomena usually pair up. Examples ofsuch pairs, whichmay be used in the currently described invention forthe separately provided means as a non-exclusive list ofexamples, are: - Thermo-electrical and electro-thermal actuation, - Thermo-optical and opto-thermal actuation, - Thermo-magnetic and magneto-thermal actuation, - Opto-electrical and electro-optic actuation, and - Magneto-optic and opto-magnetic actuation. At the same time, quantum and superconducting effects may also play a role. Accordingly, use can be made ofsuch effects ifdesired. In addition or as an alternative to affecting the amplitude and phase of light, materials could be chosen (forthe cover and / or substrate and / or cavity) that exhibit a quantum-effect, in order to further change a state ofthe light. Viatemporal dithering, the optical element can be used to account for different sources and / or source strengths and / or sources ofdifferent spectral distributions. Accordingly, it is advantageous ifthe calculation is based in part on the intensity oflight incident the optical element to facilitate said accounting. As an example, when the desired output is a relatively intense colour, e.g. amonochromatic colour, the method could include switching between a rst cover contour prole which results in a high intensity output, and a further cover contour prole which results in a low intensity output. When the incident radiation is relatively strong (that is to say too strong), the residence time ofthe further cover contour prole may be lengthened as compared to the residence time ofthe rst cover contour prole, in comparison with a situation in which the incident radiation is relatively weak, so that a desired intensity output is still achieved. The ratio of residence times can be changed in the other direction for relatively weak incident radiation. Moreover, it is advantageous ifthe calculation is additionally or alternatively based at least in part on a spectral distribution oflight incidentthe optical element. As an example, when the desired output is certain spectral distribution comprising e.g. a combination oftwo colours, the method could include switching between a rst cover contour prole which results in a certain intensity output ofa rst colour ofthe two colours of said certain spectral distribution, and a further cover contour prole which results in another intensity output ofa second colour of said spectral distribution. The ratio ofresidence times denes the desired output in colour and intensity, i.e. denes the spectral distribution that is output on average. When the incident radiation contains radiation ofthe rst colour that is relatively strong (that is to say too strong), the residence time of the further cover contour prole may be lengthened as compared to the residence time ofthe rst cover contour prole, in comparison with a situation in which the incident radiation contains radiation ofthe rst colour that is relatively weak, so that a desired intensity output for that colour is still achieved. The ratio ofresidence times can be changed in the other direction for incident radiation that is relativelyweak for the rst colour. Moreover, it is advantageous ifthe calculation is additionally or alternatively based at least in part on the state ofquantized light incident the optical element. As an example, when the desired output concerns light with a certain light state comprising e.g. a combination oftwo polarization states, two quantum states (i.e., pure / mixed and / or coherent / incoherent states and / or squeeze states) or a combination oflight with different states, the method could include switching between a rst cover contourprole which results in a certain intensity output ofa rst state ofthe two states of said certain quantized light, and a further cover contour prole which results in another intensity output ofa second state of said quantized light. The ratio ofresidence times denes the desired output in state and intensity and / or phase, i.e. denes the light state that is output on average. When the incident radiation contains radiation ofthe rst state that is relatively strong (that is to say too strong), the residence time ofthe further cover contour prole may be lengthened as compared to the residence time ofthe rst cover contour prole, in comparison with a situation in which the incident radiation contains radiation ofthe rst state that is relatively weak, so that a desired intensity output for that state is still achieved. The ratio ofresidence times can be changed in the other direction for incident radiation that is relativelyweak for the rst state. Ofcourse, it is advantageous ifthe calculation is additionally or alternatively based at least in part on a combination ofthe intensity, phase and / or state oflight incident the optical element. As an example, the optical element could receive light from two different sources: oneLED or laser and one correlated or entangled photon-pair source. Such a setup allows for an improved use ofthe cover with two optical channels: one channel for optical transmission ofclassical data as part ofa lasertelecommunication system with the optical element modulating the amplitude and / or phase of light with visible / telecom wavelength, and another channel for secured transmission ofquantum data as part ofa system integrating a quantum communication protocol, such as Quantum Key Distribution and entanglement-based quantum communication, with the optical element modulating the amplitude, phase and / or state ofquantized light. Ofcourse in these situations, a cover and / or substrate and / or cavity could be chosen that affects said quantum state differently upon operation. Therefore, using a combination ofamplitude, phase and / or state oflight incident to the optical element allows for quantum-level security in classical data transmission, ensuring that sensitive information remains protected from eavesdropping, even by future quantum systems. To facilitate control ofboth amplitude and phase, it is advantageous ifthe means comprise rst means and further means. The rst means may be congured to inuence the amplitude of modulated light and the furthermeans being congured to inuence the phase ofmodulated light. Accordingly, light that is modulated by the optical element can be controlled by the two distinguishable means. Ifboth means inuence at least one other aspect ofthe modulated light (i.e. amplitude or phase), itbecomes possible to collectively control phase and amplitude via both the means. In this case, it is useful ifthe rst means and furthermeans are independently controlled.A controllermay for instance be arranged to provide control signals for independent control. The methodmay comprise receiving a desired phase and / or amplitude response. The method in general may be performed by a controller. The same controller can be used for multiple optical elements, so as to create an image using the multiple optical elements, such as a display or holographic display. Other methods exist for controlling phase and amplitude. As an example, the supportmay be expandable, and the furthermeansmay be congured to expand the support. It is noted that for any element that is described as being expandable in this application, and any similarterms used throughout this document, said expansionmay be reversible. As such, the supportmay also be contractible, retractable or collapsible. As the cover is attached to the support, expanding the support will provide different response forthe cover. As such, an independent control method, that is independent from the means changing the cover contour prole, is available. The support can be made expandable for instance by manufacturing it from a piezoelectric material, such as PZT. Another option is to use a material that is expandable, e.g. by absorption. In general materials that can change their thickness by absorbing something, such as light, heat, charge, etc. can be used, all ofthese materials being summarized as absorbing materials. As a particular example, a material containing spin crossover particles is mentioned. These particles are described in e.g. Colossal expansion and fast motion in spin-crossover@polymer actuators by Piedrahita- Bello et al. (http: / / dx.doi.org / 10.1039 / d1mh00966d). Anotherway to inuence the optical behaviour besides using the rst means is to change the index ofrefraction ofthe cavity. The cavitymay for this purpose be lled with a gas composition whichmay be altered to change its refractive index. The furthermeansmay therefore be congured to inuence a gas composition in the cavity. Aside from a gas, the cavitymay also be lled by a liquid (mixture) and / or liquid crystals, whichmay have a greater effect on the refractive index. In such a case, the furthermeans may be congured to inuence the respective composition ofthe liquid and / or liquid crystals in the cavity. The optical element described herein can be ofany suitable type, and provide optical behaviourbased on any number ofsuitable principles. As an example, the optical device can operate by reecting light using the cover. For that purpose, it is possible the cover has a relatively large reectance as compared to its transmittance. As an example, the value oftransmittance divided by reectance would be not more than 0.5, preferably notmore than 0.25, more preferably not more than 0.1, most preferably notmore than 0.0 1 . The transmittance, reectance and absorbance dened hereinmay be measured at a wavelength X which varies from 10nm to 3000 um. In one aspect, most preferably 380 to 740 nm. In another aspect, more preferably from 10 nm to 200 nm, most preferably from 13 nm to 193 nm. In another aspect, more preferably from 700nm to 2000 nm, most preferably from 850nm to 1550 nm. In another aspect, more preferably from 30 000nm to 3 000 000 nm. Ofcourse, absorptionmay also be considered. As an example, the optical device can operate by absorbing light using the cover. For that purpose, it is possible the cover has a relatively large absorbance as compared to its reectance. As an example, the value ofreectance divided by absorbance would be notmore than 0.5, preferably notmore than 0.25, more preferably notmore than 0.1, most preferably not more than 0.01. The absorbance and reectance dened above may be measured at a wavelength X which varies from 10nm to 3000 um. In one aspect, most preferably 380 to 740 nm. In another aspect, more preferably from 10nm to 200 nm, most preferably from 13 nm to 193 nm. In another aspect, more preferably from 700 nm to 2000 nm, most preferably from 850nm to 1550 nm. In another aspect, more preferably from 30 000 nm to 3 000 000 nm. The optical elementmay be congured for reecting light incident on the second surface. In that case, the transmittance and reectance may be measured for light incident the second surface. Alternatively, the optical elementmay be congured for reecting light incident on the rst surface, in that case, the transmittance and reectance may be measured for light incident the rst surface. Besides using the cover for reection only or mainly, it is also possible to employ reective interference, taking place mainly between a reected lightbeam at the substrate (or cover) and a refracted lightbeam through the substrate (or the cover) that the cover (or substrate) reects, or absorbing interference, taking place mainly between a reected light bean with the incident lightbeam at the substrate (or cover) and its absorption at the cover (or substrate). An optical element congured for this purpose is called an interferometric optical device. The absorbance ofthe covermay accordingly also be relevant, as explained above. The interference may take place for light incident the second surface, or for light incident the rst surface. In the latter case, a substrate is needed below the cover, as is described further below. The substrate is congured for transmitting a part ofthe light and reecting a part ofthe light. The transmitted light is then reected on the cover, and transmitted back outthrough the surface. The egressing light interferes (constructively or destructively) with the directly reected light. Depending on the position ofthe cover with respect to the substrate, it is possible to change the interference-based behaviour ofthe optical element. Depending on the desired optical behaviour, it is ofcourse possible to use a cover with different ratios ofreectance, transmittance and absorbance, optionally in combination with e.g. a reective, transmissive or absorbing substrate, the terms reective, transmissive or absorbing being dened using the same ranges forthese respective quantities, and / or the same ratios betweenthem as is dened for the cover. In general, the optical properties for the substrate are chosen complimentary to the optical properties ofthe cover. The invention is not limited to any such combination, rather to improving movement ofthe cover using amplitude and phase modulation. Ofcourse, the substrate need not be square or rectangular. The substrates shape in general is not important, it is even possible for a single substrate to span multiple optical elements. More relevantmay be the shape dened within the support, as this denes the shape ofthe optical element in plan view. It is possible this shape is square or rectangular, to create a pixel-like element, but circular optical elements are also envisaged. The inventionmay however be applied to optical elements of all shapes. This is true for all embodiments described herein, whether they do or do not have a substrate. It is noted that for some shapes ofoptical elements, the substrate is rigid and planar, while for others it is possible for it to be exible and / or curved. In such cases, the spacer and cover are adapted to the substrate, in such away that the second surface ofthe cover is approximately parallel to the substrate. In this case, the cover is preferably reective, for instance as expressed in the ratio above. The substrate is not as reective, for example having a ratio oftransmittance divided by reectance ofmore than 0.5, more than 0.75, more than 0.9 or even more than 0.99, or even more than 1, preferably for light incident from a surface ofthe substrate facing away from cover. The opposite direction is also possible, where the cover transmits and reects light, and the substrate reects the transmitted light. In this case, the coverwould be relatively transmissive, for example having a ratio oftransmittance divided by reectance ofmore than 1, for light incident the second surface, so that it is relatively transmissive. Said ratio could for instance be between 1 and 3, such as between 1.5 and 2.5, such as around 2. The absorbance could in this case be relatively high. The substrate would preferably be reective for light incident a surface ofthe substrate facing the cover. The reectance could be dened by a ratio oftransmittance divided by reectance ofnot more than 0.5, preferably notmore than 0.25, more preferably notmore than 0.1, most preferably notmore than 0.01. Unless stated otherwise, transmittance and reectance are measured for light normal to the surface ofthe cover. In case a cover is used that is relatively reective, a value ofabsorbance divided by reectance ofthe cover can be less than 0.5, preferably notmore than 0.25, more preferably not more than 0.1, most preferably notmore than 0.01, for light incident the rst and / or second surface, depending on the desired optical behaviour. It is noted that in all cases, the position and shape ofthe cover inuences how the optical device interacts with incident light. Other operational principles which rely on the change ofthe cover position and shape can however also be applied, and the current invention is thus not limited to either reective or interferometric operational principles. In any case, the invention is not limited solely to a cover with a changing shape or a changing cover. In terms ofclaim 1, this can be realized by dening the spatial arrangement ofthe cover with respect to the support. After all, a cover that has not changed in shape but is at a different position with respect to the support, still has a different spatial arrangement as seen in cross section ofthe cover with respect to the support. As such, depending on the use, changing the position ofthe cover (without changing its shape) or changing the shape ofthe cover, thereby changing partially its position, could be used interchangeably. The covermay comprise a 2-dimensional portion. The 2-dimensional portionmay be an extreme membrane. For the purpose ofthe invention in general however, it is sufcient ifthe 2- dimensional portion is sufciently thin to be deformed and / ormoved using the applicable means. In general, it is not necessary, however possible, that the 2-dimensional portion has favourable optical properties in and of itself. Instead, it is possible to provide the desired optical properties using additional material, such as an additional layer or an amorphous portion ofthe cover, which could be or could comprise a metal or an additive. In that regard, reference is made toWO 2021 / 032752 A1 which explains multiple congurations ofthe cover. The skilled person is readily able to vary e.g. the thickness and material ofthe additional material to arrive at desired optical properties for the cover. In that regard, it is noted the 2-dimensional portionmay function as a carrier, whereas the additional material provides desired optical properties. The 2-dimensional portionmay be as dened in embodiment [39a] ofWO 2021 / 032752 A1. Accordingly, the 2-dimensional portionmay be one ormore ofthe following: a. One ormore selected from the group consisting of: C, BN, P, MoS2, MoSe2 , MoTe2, WS2, WSe2, WTe2, NbS2, NbSe2, NbTe2, TaS2, TaSe2, TaTe2, TiSe2, VSe2, CrS2, CrSe2, B, Ge, Si, Si2BN, Sn, Pb, P, Sb, Bi. The preferred C in this context is one ormore selected from the group consisting of: graphene, one ormore graphitic layers and graphyne, preferably graphene. The preferredBN in this context is h-BN. The preferred P in this context is black phosphorus or phosphorene. The preferredB in this context is borophene. The preferred Ge in this context is germanene. The preferred Si in this context is silicene. The preferred Sn in this context is stanene. The preferred Pb in this context is plumbene. The preferred Sb in this context is antimonene. The preferred Bi in this context is bismuthine, b. One ormore transition metal chalcogenides, each being a transition metal chalcogenide not listed in a., c. One ormore oxides, each being an oxide ofa species listed in a. or b., d. One ormore atomic intercalated variants, each being an atomic intercalated variant ofa species listed in a. or b., e. One ormore physically, chemically, mechanically and / or electromagnetically functionalised derivatives, each being a chemically functionalised derivative ofa species listed in a. or b..A preferred physical functionalisation is perforation or atomic barrage treatment.A preferred mechanical functionalisation is stretching or stressing.A preferred electromagnetic functionalisation is application ofa voltage. In one aspect ofthis embodiment, the 2-dimensional portion is a combination selected from the group consisting of: a., b., c., d., e., a.+b., a.+c., a.+d., a.+e., b.+c., b.+d., b.+e., c.+d., c.+e., d.+e., a.+b.+c., a.+b.+d., a.+b.+e., a.+c.+d., a.+c.+e., a.+d.+e., b.+c.+d., b.+c.+e., b.+d.+e., c.+d.+e., b.+c.+d.+e., a.+c.+d.+e., a.+b.+d.+e., a.+b.+c.+e., a.+b.+c.+d. and a.+b.+c.+d.+e.. Specically, the 2-dimensional portionmay comprise or be graphene or boron nitride or both.A preferred boron nitride is hexagonal boron nitride. Graphene is preferably chemical vapour deposited. Boron nitride is preferably chemical vapour deposited. In one aspect ofthis embodiment, the 2-dimensional portion comprises graphene, preferably is graphene. In one aspect ofthis embodiment, the 2-dimensional portion comprises boron nitride, preferably is boron nitride. As mentioned earlier, the thickness ofthe 2-dimensional portion is relatively small. For instance, 1mm or less, preferably 10 um or less, more preferably 1000nm or less, more preferably 100nm or less, more preferably 50nm or less. In one aspect ofthis embodiment, more preferably 10nm or less, more preferably 5 nm or less, most preferably 1 nm or less. A minimum thicknessmay be dened as 25 pm ormore, preferably 69pm or more, more preferably 100pm or more. In one aspect ofthis embodiment, the thickness is 1 nm ormore, preferably 3 nm ormore, more preferably 5 nm or more, more preferably still 10nm or more. In another aspect ofthis embodiment, the thickness is 15 nm or more, preferably 20nm or more, more preferably 30nm or more. Accordingly, the 2-dimensional portionmay be relatively light per unit area, such as 24 kg / m2 or less, preferably 2.4-10l kg / m2 or less, more preferably 2.4- 102 kg / m2 or less, more preferably 2.4-103 kg / m2 or less, most preferably 1.2- 103 kg / m2 or less.A lower limit on the same weight per unit area is 1.7- 109 kg / m2 or more, preferably 3.4- 108 kg / m2 or more, more preferably 1.8- 107 kg / m2 or more. In one aspect ofthis embodiment, the mean density is 5 - 107 kg / m2 ormore, preferably 1.5- 106 kg / m2 or more, more preferably 5.4- 106 kg / m2 ormore, more preferably 5.7- 105 kg / m2 or more. Various operational principles forthe means are available, and have been identied throughout the previous paragraphs. It is noted that some operational principlesmay allow exerting a force on the cover only in one direction, whereas for others the same means can be used to exert forces in opposing or even various directions on the cover. In case the operational principle only allows forces in a single direction, furthermeans, whichmay be identical, may be applied on the opposite side ofthe cover, e.g. in a mirrored position with respect to the previously mentioned means, so that collectively control can be exerted in both ormore directions. While above an optical element has been described that has means congured to affect the cover, the inverse is also possible and envisaged. Accordingly, the means may alternatively or additionally be arranged to provide an output that is representative ofthe cover changing from the rst cover contour prole to the further cover contour prole. In this manner, the optical element can be used as a sensor responsive to any phenomenon, not necessarily optical, that changes the cover shape. For instance, incident radiation, pressure, sound waves, an electrical charge, temperature, etc. could all be sensed using suitable means. As an example, an electrode could be used to sense a changing electrical charge, e.g. changing in response to a charged cover moving. Ifa predetermined and externally applied electrical charge is applied to the cover, the electrodes could be used to measure deformation ofthe coverby capacitive means, for instance as a result ofincoming radiation or pressure. An electrode or other type ofsensing means would be necessary to measure the changing electric eld as the charged covermoves. In these circumstances, the element described herein need not be described as an optical element per se. In particular, the means and / or furthermeans may each, independent from one another, comprise any one ormore of: - an optical actuator, such as an optical tweezer or photonic circuitry, - ameans for applying or changing radiation incident on the cover, such as a radiation source. - ameans for inuencing agas pressure acting on the cover, - a speaker or any other sound emitter, - a thermal actuator, operating viathermal expansion, and - an electromagnetic and / or superconducting actuator, for instance operating based on tunneling or eld emission. At this time, it is noted that regardless ofthe actuation method used, given a sufciently small system, any one actuation method will often have some corresponding co-phenomenon in another domain as well. As such, at nano-scale, the actuation method and corresponding co- phenomena usually pair up. Examples ofsuch pairs, whichmay be used in the currently described invention as a non-exclusive list ofexamples, are: - Thermo-electrical and electro-thermal actuation, - Thermo-optical and opto-thermal actuation, - Thermo-magnetic and magneto-thermal actuation, - Opto-electrical and electro-optic actuation, and - Magneto-optic and opto-magnetic actuation. At the same time, quantum and superconducting effects may also play a role. Accordingly, use can be made ofsuch effects ifdesired. It is noted that the index ofrefraction ofthe cavity dened by the cover and the substrate can be ofinuence on the optical behaviour ofthe optical element. The index ofrefraction ofthe cavity can be inuenced by at least partially lling the cavity. To facilitate said lling the cavity may be enclosed by one ormore ofthe support, the cover and the substrate, ormay even be sealed entirely. Ifthe cavity is indeed sealed, it can be lled with a substance. Different llings ofthe cavity can lead to different refractive indices, and thus a different optical behaviour. The cavity may for this purpose be lled with a gas composition. Aside from a gas or gas mixture, the cavity may also be lled by a liquid (mixture) and / or liquid crystals, or even a solid lling, whichmay have a greater effect on the refractive index. Another option would be to instill avacuum inside of the cavity. Denition of, and lling ofthe cavitymay also be done for other reasons than inuencing the index ofreection, i.e. to provide absorption, to provide structure rigidity, or other reasons. Moreover, the substance lling a cavity can be ofinuence on otherthan the optical behaviour ofthe optical element, including but not limited to the mechanical response ofthe cover and the electrical inuence ofthe means.A lled cavity can also be used to exert a pressure on the cover, in order to move it using pressure based means. As a further remark, it is noted that the structure described herein as optical element can be used in a different and novel way as well, regardless ofwhether or not the characterizing portion of the claims is applied. In this novel way ofusing the device, a substrate opposite the cover is necessary, so that a cavity is formed between the cover and the substrate. The device is congured to allow entry ofelectromagnetic radiation, such as (visible) light, into the cavity between the support and the substrate, and to allow egress ofthe same, also between the support and the substrate. In contrast to the principles shown above, in which light interacts by being incident the cover (either from the rst or second surface), the lightnow travels substantially parallel to the cover, through the cavity. In this case, the cavity acts like a waveguide. To form a waveguide, the skilled person is able to choose suitable materials forthe support, the substrate and the material at the covers rst surface and optionally for material to ll the cavity with, so that the light is inuenced by the cover. Suitably chosen characteristics, such as optical characteristics, ofthe cover allow interaction with light passing through the cavity. By changing the contour shape ofthe cover, orby changing its position, the waveguide formed in the cavity can be altered. The changing inuence ofthe cover on waves passing through can be used to modulate the light. It is noted that the cover need not actuallymove or change shape in order to affect the passing light differently. For instance, its strainmay be altered for instilling different optical properties. The invention will be further elucidated with reference to the attached drawings, in which: Figures 1A, 1B and 1C show schematically interaction oflight with an optical element known in the state ofthe art, Figures 2A, 2B and 2C show schematically interference interaction oflight with an optical elementknown in the state ofthe art, Figures 3A and 3B show different congurations ofan optical element, with its cover in different positions, Figures 4 and 5 show schematically an optical element for different interferometric effects, and Figure 6 shows schematically in perspective view anotherway ofusing the optical element. Figure 1A shows interaction oflight with ofa at cover 101, which is supported by supports 104. The parallel rays 601 and 602 are both deected by the same angle and remain parallel after interaction with the cover 101. This constitutes specular reection. Figure 1B shows interaction oflight with a convex cover. Due to the rounded convex cover contour prole, a rst ray 601 is deected by almost 180° and the second ray 602 is only deected by a small angle. The rays 601 and 602 are no longer parallel after reection at the cover. This constitutes diffuse reection. Figure 1C shows interaction oflight with a concave cover. Due to the rounded concave cover contour prole, a rst ray 601 is deected by an angle less than 90° and the second ray 602 is deected by almost 180°. The rays 601 and 602 are no longer parallel after reection at the cover. This constitutes diffuse reection. Figure 2A shows interference interaction with a at cover. Aside from the supports 104, a substrate 106 is also present in this example ofthe state ofthe art, which lies on the bottom ofthe optical element. The support 104, cover 101 and substrate 106 dene a cavity having a depth 205. The substrate 106 is transmissive and absorbing to an extent and the cover 101 is reective, such that an incoming ray 601 undergoes interference which is dependent on the depth 205. Figure 2B shows interference interaction with a convex cover. The cover 101 ofthe optical element ofgure 12 has been deformed into a convex shape (cover contour prole). This was brought aboutby ameans pushing the cover 101 upwards. This increases the depth 205 and the interference behaviour ofincoming light 601 is altered. Figure 2C shows interference interaction with a concave cover. The cover 101 ofthe optical element ofgure 12 has been deformed into a concave shape (cover contour prole). This was brought about by the means pushing the cover 101 downwards. This decreases the depth 205 and the interference behaviour ofincoming light 601 is altered. Now rst referring to gures 4 and 5, it is noted that depending on the optical properties of the cover 101 and the substrate 106, different operational principles are also usable for inuencing incident light. Figure 4 for instance, shows an optical element similar to that ofgures 1 and 2, but with a cover 101 that is relatively absorbing, and a substrate 106 that that is relatively reective. As a result, incident light 601 transmitted 602 through the cover 101 interacts with light reected 604 from the substrate to form a pattern ofnodes and antinodes. The cover can be controlled by means (not shown) to be placed at or away from anode or antinode, to accordingly absorb strongly or less strongly light, so that the intensity ofexiting light 605 can be controlled. In gure 5 a cover 101 is present that is both transmissive and reective, and a substrate that is reective. Accordingly, use can be made ofinterferometric reection, similar to gures 2A 2C, however now the optical element is congured for light incident the cover 101. Otherwise, the optical elementmay be identical to that described above. Figures 3A and 3B show an optical element 99 with a support 4 and a cover 1. The cover 1 is attached to the support 4 as described in claim 1.A substrate 6 is present, with ameans 7 to control the cover contour prole. A controller 12 is attached to the means 7 to power it. Although the means in this case are shown as an electrode, othertypes ofmeans 7 are not excluded. The support 4 also includes an expandable portion 18, so that the support 4 is expandable. The expandable portion can be expanded using furthermeans which are not shown, and could be controlled by e.g. the same controller. In gure 3A, the cover 1 is shown intwo positions, each with its 0an resulting optical response in terms ofamplitude A1, A2 and phase (91, (92. In gure 3B, the support 4 is expanded using the expandable portions 18. Accordingly, a different structure denes the optical properties ofthe optical element. As a result, the means 7 can be used to control the cover to provide an amplitude response A1, A2 similar or identical to that with unexpanded portions 18 in gure 3A, but which willnow have a different phase @3, (94. Accordingly, it is clear that at least to some extent, amplitude and phase can be controlled independently, which can be used to provide a wider range ofoptical responses using the optical element. Finally, reference is made to gure 6, which shows a perspective view ofa device, such as an optical element, similar to that described herein. Like before, the device has a substrate 106 and support 104, which in this case are monolithic. The support 104 denes a cavity C that is of longitudinal shape in this example. Cover 101 held by the support 104 spans the cavity C. Materials for the support 104, the substrate 106, the material at the covers rst surface and material with which the cavity C is lled are chosen so that the cavity C acts as a waveguide. Incidentwaves 601, such as light, can therefore pass through from one side to another, and egress as exited light 602. Viameans 107, in this case presented on top ofthe support 104, although not strictly necessary, the cover 101 can be moved, or its cover contour prole changed. As a result, the cover 101 at least locally inuences the light passing through the cavity C in order to modulate it. It is noted thatterms like preferably, generally and typically are not utilized herein to limit the scope ofthe claims or to imply that certain features are critical, essential, or even important to the structure or function ofthe claims. Rather, these terms are merely intended to highlight alternative or additional features thatmay ormay not be utilized in a particular embodiment ofthe present disclosure. Likewise, for the purposes ofdescribing and dening the present disclosure, it is noted that the terms substantially and approximately and their variants are utilized herein to represent the inherent degree ofuncertainty thatmay be attributed to any quantitative comparison, value, measurement or other representation, as well as to represent the degree by which a quantitative representationmay vary without resulting in a change in the basic function ofthe subject matter at issue. While certain representative embodiments and details have been shown for purposes of illustrating the present disclosure, it will be apparent to those skilled in the art that various changes may be made without departing from the scope ofthe disclosure, which is dened in the appended claims.

Claims

1. Procedure for operating an optical element, where the optical element comprises: a. a covering with a first and a second surface, b. a support, and c. a means, whereby: - the cover is oriented with the first surface facing the support; - a part of the first surface is attached to the support, - a spatial arrangement of the deck considered in a cross-section of the cover defines a cover contour profile, - the device is designed to move the cover from a first covering- contour profile to a further cover contour profile that differs from the first cover contour profile, where the optical element further comprises a substrate on one side of the support opposite the cover, whereby a cavity is defined between the cover and the substrate, with a cavity height defined as the distance from the substrate to the cover, with the characteristic that the working method is characterized by: - it, based on a desired phase response for the optical element and a desired amplitude response, controlling the means to make the optical element respond show corresponding to the desired phase response and the desired amplitude response.

2. Method of working according to the previous conclusion, where the plea is a first plea and a further means includes, where the first means is configured to the amplitude of to influence modulated light and the further means is configured to the phase of the to influence modulated light.

3. Procedure in accordance with the previous conclusion, regarding the first ground and the further ground be controlled independently.

4. Procedure in accordance with one of the preceding claims, comprising the receipt of a desired phase response and a desired amplitude response, whereby the method may possibly be further includes receiving a desired go-length response.

5. Method in accordance with one of the preceding claims, where the support is expandable, and the further means is configured to expand the support.

6. Method in accordance with one of the preceding claims, whereby the covering and / or the exhibits modifiable properties of the substrate and / or cavity, such as optical or mechanical properties, and where the method involves changing these properties.

7. Method for manufacturing an optical element in accordance with the previous claim, where the covering and / or the substrate comprises a material that is configured to its to change optical properties, for example by applying stretch to a material whose refractive index changes with strain, and where the method involves changing the includes optical properties of the cover and / or the substrate.

8. Method for manufacturing an optical element in accordance with claims 6 7, where the covering and / or the substrate comprises a material that is configured for its mechanical to change properties, for example by applying temperature to a mechanical metamaterial or a material whose crystalline structure changes with temperature, and where the method involves changing the mechanical properties of the cover and / or the material includes.

9. Method for manufacturing an optical element in accordance with claims 6 8, where the covering and / or the substrate comprises a material that is configured to its electrical to change properties, for example by applying a torque to a part of the crystalline structure of a material whose electronic behavior changes with angle of rotation, and where the method involves adjusting the electrical properties of the cover and / or the substrate includes.

10. Method for manufacturing an optical element in accordance with claims 6 9, where the covering and / or the substrate comprises a material that is configured to any of to change its properties, for example by applying a charge to a material that has meta-surfaces or that is structured as an adaptable / photonic metamaterial or photonic crystal whose response to electric and magnetic fields changes with temperature, and where the method involves changing such properties.

11. Method for manufacturing an optical element in accordance with claims 6 1O, where the cavity is filled with a substance whose refractive index can be changed, for example by changing a gas composition in the cavity, and where the method involves changing the refractive index of the cavity.

12. Method for manufacturing an optical element in accordance with claims 6 11, where the covering and / or the substrate comprises a material that is configured to the light condition of to change the modulated light, possibly to a specific polarization state, a certain quantum state or a combination of different states.

13. Procedure for operating an optical element according to the previous conclusion, comprising receiving a desired light condition response.

14. Use of an optical element according to the previous conclusion, for communicating with Modulated light that is protected.

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