552 results about "Superlens" patented technology

A metalens for focusing light is described. The metalens includes a library of elements for varying the propagating phase of the focusing light over at least a 2π radians range, where the library of elements is arranged in a sub-wavelength pattern that defines spacings between the elements. Each spacing exhibiting temperature-dependent spacing changes within a temperature range and each element in the library of elements includes: a refractive index exhibiting a temperature-dependency within the temperature range, a shape exhibiting a temperature-dependency within the temperature range, and a size exhibiting a temperature-dependency within the temperature range. The metalens also includes a phase profile defined by a combination of the refractive index, shape, and size of each element in the library, and the sub-wavelength pattern of the library of elements. The metalens also includes a focal length defined by the phase profile, the focal length exhibiting a temperature-dependency within the temperature range.

The invention discloses a titanium dioxide super-lens large-view-field achromatic imaging method and device, and the method comprises the steps: building a simulation model through a time domain finite difference method, and obtaining the phase amplitude corresponding relation of TiO2 nano-column units under different sizes; and according to a first target function preset by single-wavelength super-diffraction focusing, reversely designing and iteratively optimizing the surface phase of the TiO2 super-lens by using a genetic algorithm to obtain the single-wavelength super-diffraction super-lens. And then, optimizing the genetic algorithm, and reversely designing and optimizing the phase of the single-wavelength super-diffraction super-lens again in combination with a Rayleigh-Sommerfeld diffraction formula and a second target function preset by broadband achromatism to obtain the broadband achromatism super-diffraction super-lens. And finally, point spread functions with different off-axis degrees are optimized by means of an exhaustion algorithm and an angular spectrum theory, and large-view-field achromatic super-diffraction imaging is realized. The invention effectively solves the problems of large aberration, obvious chromatic aberration, limited resolution, difficulty in parameter regulation and control and poor off-axis imaging performance of the traditional optical lens and the existing super lens in large-view-field imaging.

The invention relates to the technical field of semiconductor devices, in particular to an infrared photoelectric detector based on a super lens and a manufacturing method of the infrared photoelectric detector. The infrared photoelectric detector based on the super lens comprises a tube socket, a metal tube cap and a detector chip, the metal tube cap and the tube socket are fixedly connected and form a totally-enclosed packaging structure, the detector chip is packaged between the tube socket and the metal tube cap, a chip electrode of the detector chip is welded with a pin of the tube socket, the super lens is arranged at the top of the metal tube cap, and the super lens is arranged on the top of the metal tube cap. The side wall is a metal tube shell, and the super lens comprises a super lens substrate and super lens units periodically arranged above the super lens substrate. According to the infrared photoelectric detector based on the super lens, the super lens units periodically arranged on the super lens can be utilized, the transmittance of incident light can be improved, the interference effect of reflected light can be restrained, and then the detection rate of the infrared photoelectric detector is improved.

The invention discloses a reflection-transmission mixed extreme ultraviolet collimation illumination system, and relates to the technical field of extreme ultraviolet optics. The system comprises a discharge plasma EUV light source, a multilayer film ellipsoid reflector and a collimating super lens. Wherein the discharge plasma EUV light source is used for generating radiation light in an extreme ultraviolet band; the multi-layer film ellipsoid reflector adopts an ellipsoid design, is plated with a high-reflectivity multi-layer film, is arranged on a transmission line of the discharge plasma EUV light source, and is used for focusing light beams of the light source; and the collimating super lens is arranged behind the focal position of the multi-layer film ellipsoid reflector and is used for collimating the focused light beams to form parallel light beams for Talbot photoetching illumination. The extreme ultraviolet illumination system is compact in structure, high in light beam energy and high in collimation, and the exposure quality in an application scene needing high-collimation extreme ultraviolet light beams is effectively improved.

A near-to-eye display system (1) and AR glasses (3). The near-to-eye display system (1) comprises an optical waveguide module (10), an optical engine module (20) and a metalens assembly (22). A first in-coupling grating region (111) and a first out-coupling grating region (112) are formed in the optical waveguide module (10). The optical engine module (20) comprises a light source assembly (21), which is arranged opposite the first in-coupling grating region (111), and the metalens assembly (22), which is arranged between the light source assembly (21) and the optical waveguide module (10), wherein the light source assembly (21) is used for outputting image optical signals to the metalens assembly (22), the image optical signals comprising at least two types of optical signals of different attributes, and the attributes comprising at least one of a wavelength, an emission angle and an emission position. The metalens assembly (22) comprises a substrate (221) and a metasurface structure (222) on the substrate (221), wherein the metasurface structure (222) is configured to receive the image optical signals and diffract the optical signals to the first in-coupling grating region (111). The optical signals which have the same emission position have the same diffraction angle. Thus, the volume and weight of a lens of the optical engine module (20) are reduced, and the design requirements for high image quality and a large field of view are also met.

The invention discloses a super-lens image restoration method based on fuzzy prior and semantic segmentation. The method comprises the following steps: eliminating an image visual angle displacement error by adopting a feature point automatic registration algorithm; the method comprises the following steps: designing a parallel multi-scale convolution adapter on the basis of an encoder optimized by a pre-trained visual Transform model, and generating encoding features adaptive to the degradation characteristics of a super lens; splicing the degraded image and the semantic segmentation mask into a joint tensor along a channel dimension, and obtaining a prior feature based on a fuzzy prior extraction network; performing spatial feature enhancement on the semantic segmentation mask based on a semantic segmentation graph convolutional network to obtain graph features aligned with the coding features; splicing the coding features, the prior features and the image features along channel dimensions to generate fusion features, and finally outputting a preliminary recovery image; and optimizing the whole model by adopting a staged training strategy, and finally outputting a high-quality recovery graph. According to the method, the physical rationality and detail fidelity of the recovery quality are improved.

The invention relates to a high-efficiency super lens based on refractive index matching and a design method thereof. The super lens comprises a super atom structure layer and a bonding substrate layer on any surface, the difference value between the refractive index of any substrate layer and the average effective refractive index of the super-atomic structure layer is smaller than a preset value; when the super lens is designed, the relation among the average effective refractive index, the impedance and the S parameter of the super-atom structure layer is constructed, the structure parameter of the super-atom structure layer is determined based on the requirement parameter of the super lens, the preset S parameter of the super-atom structure layer is obtained based on electromagnetic simulation, and the average effective refractive index of the super-atom structure layer is calculated. And the substrate layer is used as an expected refractive index matching material and is bonded on one surface or two surfaces of the super-atomic structure layer. According to the invention, the high-efficiency super lens is obtained by using the principle of refractive index matching and processing methods such as large-area bonding, the focusing efficiency of the super lens is greatly improved, the application of the super lens is promoted, and the leap-type upgrading of optical devices in the dimensions of light weight and high performance is realized.

The invention provides a super lens, a super lens structure parameter determination method, device and equipment, optical imaging equipment, a storage medium and a program product. The super lens comprises a plurality of areas. Any region comprises a plurality of nano fins; wherein at least part of the area is used for focusing incident light with different wavelengths. The super lens is divided into a plurality of areas, and each area can form a super lens for focusing incident light with different wavelengths, so that wavelength division multiplexing is realized, and compared with a conventional geometrical optical lens for realizing wavelength division multiplexing, the super lens disclosed by the invention has the advantages of small volume and high integration level.

The invention discloses a design and implementation method of a near-infrared light-splitting super lens, and relates to the technical field of super lenses. The super lens is composed of a rotational symmetric structure, so that polarization insensitivity is achieved, incident broadband light can be dispersed to different positions of the same focal plane according to different wavelengths through ingenious optical design, an effective light splitting effect is achieved, and the polarization insensitivity of the super lens is improved by adjusting geometric parameters and shapes of the super lens nano structure units. The positions of light with different wavelengths on a focal plane can be accurately controlled; in the optimization process, a particle swarm optimization algorithm is adopted to reduce errors, and performance attenuation and optical distortion caused by dispersion can be effectively reduced by adjusting dispersion characteristics and geometric parameters of the nano-structure units, so that the precision and reliability of light splitting are improved, and the light splitting precision is improved. The identification capability of the laser detection system is greatly improved, and integration and miniaturization are realized.

The invention relates to an optical super lens suitable for an extreme environment and a preparation method thereof, and the optical super lens comprises a super lens structure layer located at the center, and moth-eye membrane structure layers, an optical substrate and an optical composite membrane which are symmetrically disposed at two sides of the super lens structure layer. The super-lens structure layer, the moth-eye membrane structure layer and the optical substrate are respectively and independently made of wide-band-gap semi-conductive materials with the thermal conductivity of 50 W / m.K or above, and at least one structure parameter of the moth-eye membrane structure layer in the thickness direction of the optical substrate is modulated so as to complete refractive index transition from the super-lens structure layer to the optical substrate. According to the invention, the problem of efficiency reduction caused by refractive index mismatch is solved, and the optical super lens can work normally under extreme conditions such as high temperature or high power.

The invention relates to full-dielectric adjustable optical tweezers based on a composite phase superlens, and belongs to the technical field of optical tweezers. Two regulation modes of geometric phase and transmission phase are integrated into a dielectric metasurface periodic structure, and a circular lens surface is combined according to a specific mapping and arrangement mode. The super lens can excite two different output electric fields under the input of linearly polarized light due to the regulation and control of a composite phase, and the two electric fields can independently exist under the input of circularly polarized light with opposite chirality. Therefore, by adjusting the polarization type of the incident light source of the super lens, free switching of multiple optical capturing modes of particles in a field can be realized. Compared with the existing optical tweezers, the control mode can be flexibly adjusted on the premise that the structure of the device is not changed, and more diversified particle capturing requirements can be met. The high-flexibility and easy-to-integrate micro-nano structure can provide powerful guarantee for the performance of a compact composite optical capturing device.

The invention discloses a data-driven ultra-wideband achromatic lens hybrid reverse design method, which is characterized in that a data-driven reverse dispersion method is adopted, a reverse dispersion project is executed in a plurality of sub-bands divided by a working band, and spatial multiplexing and global optimization are performed on all unit structures, so that the data-driven ultra-wideband achromatic lens hybrid reverse design is realized. And the ultra-lens overall structure with optimal performance and ultra-wide band continuous achromatism is obtained. Compared with the prior art, the ultra-wideband achromatic lens has end-to-end efficient design capability, can realize excellent ultra-wideband achromatic lens working performance, effectively avoids the dependence of a traditional dispersion engineering method on the dispersion regulation and control capability of the integrated resonance unit, multiplies the working bandwidth on the premise of not sacrificing the performance of the ultra-lens, and improves the working efficiency of the ultra-wideband achromatic lens. And the design precision and efficiency are remarkably improved through a data driving method, a new solution is provided for broadband design of an achromatic device, and the method has good application scenes and prospects.

The invention relates to the technical field of information processing, in particular to the technical field of optical detection, and particularly relates to a two-dimensional material layer number identification method and equipment. A photoelectron chip composed of a semiconductor light source, a 2 * 2 waveguide beam splitter, a grating coupler, an on-chip spectrometer, a super lens and an optical detector is compact in structure and low in cost; a semiconductor light source emits an optical signal, the optical signal sequentially passes through a 2 * 2 waveguide beam splitter, a grating coupler and a super lens and then irradiates a two-dimensional material sample, a displacement table is used for carrying out accurate Z-axis focusing and XY plane scanning, reflection spectrum signals are collected in real time, spectrum characteristics are analyzed through an upper computer to determine layer number information, and finally a layer number distribution diagram is generated. According to the method, rapid, automatic and high-precision identification of the number of layers of the two-dimensional material is realized, and large-range scanning detection is facilitated.

The invention provides a polarization adjustable spin decoupling metasurface based on a perovskite material. The metasurface is characterized in that the metasurface is of a three-layer structure, namely a perovskite and metal pattern layer (1), an intermediate dielectric layer (2) and a reflection bottom layer (3) from top to bottom in sequence. When the perovskite is in a metal state, the designed metasurface can independently adjust left-handed and right-handed circularly polarized light; when the perovskite is in an insulated state, the designed metasurface can independently adjust x and y linear polarized light; by switching the state of the perovskite, the phases of the circularly polarized light and the linearly polarized light can be regulated and controlled at the same time, so that different functions are realized. The optical metasurface designed by the invention has huge potential in a terahertz frequency band, and can be widely applied to beam shaping, holographic imaging, information encryption, super lenses and the like.

The utility model discloses a visible light optical system and a visible light optical lens. The visible light optical system comprises a first aspheric lens, a second aspheric lens, a super lens, a third aspheric lens, a fourth aspheric lens, a fifth aspheric lens and a sixth aspheric lens. The focal powers of the first aspheric lens, the super lens and the fifth aspheric lens are positive; the object side surface and the image side surface of the first aspheric lens are convex towards the object side; the object side surface and the image side surface of the second aspheric lens are convex towards the object side; the super lens comprises a substrate and a micro-nano structure, wherein the micro-nano structure is arranged on the object side surface and / or the image side surface of the substrate; the focal power of the fourth aspheric lens and the sixth aspheric lens is negative; the image side surface of the fifth aspheric lens protrudes towards the image side; wherein the sixth aspheric lens has the maximum focal power among the lenses with negative focal power. The visible light optical system provided by the utility model is relatively excellent in imaging quality, and the visible light optical system is relatively small in size.

The invention relates to an optical super lens with high focusing efficiency and a preparation method thereof. The optical super lens comprises a pair of optical substrates, antireflection films arranged on the surfaces of one sides of the optical substrates, moth-eye films arranged on the surfaces of the other sides of the optical substrates in a protruding mode, and a plurality of nano dielectric cylinders arranged between the pair of moth-eye films and made of high-refractive-index materials. At least one structural parameter of the plurality of nano dielectric cylinders in the length direction of the optical substrate is modulated to meet phase distribution of 2 pi, and at least one structural parameter of the moth eye mask in the thickness direction of the optical substrate is modulated to complete refractive index transition from the plurality of nano dielectric cylinders to the optical substrate. According to the invention, the problem of transmittance reduction caused by refractive index mismatch in a traditional optical super lens is solved, and the focusing efficiency of the optical super lens is effectively improved on the basis of not influencing the original phase distribution.

The invention relates to the technical field of super-lens packaging, in particular to a super-lens LED packaging structure, a super-lens LED lamp panel and a backlight system. According to the technical scheme, the LED lamp comprises an LED support, an LED wafer and a super lens, a metal electrical connection frame is arranged in the LED support, and a mounting step is arranged on the top of the LED support; the LED wafer is fixed in the LED bracket; and the super lens is fixed on the mounting step through packaging glue. According to the invention, the ultra-thin design is realized by integrally packaging the super lens and the LED wafer, the light is accurately regulated and controlled by using the microstructure on the surface of the super lens, the light spot uniformity is improved, the LED consumption and the dependence on the optical film are obviously reduced, the system adaptability is enhanced by the flexible layout of the driving chip, and the reliability is improved and the service life is prolonged by the closed packaging structure. The ultrathin performance, the optical performance, the cost and the reliability are comprehensively optimized, and an innovative solution is provided for a backlight system with high cost performance and high performance.

The invention discloses a super-lens design method based on etching uniformity compensation and an optimization system thereof. The super-lens design method specifically comprises the following steps: S1, etching a wafer and establishing an etching rate space distribution model; S2, designing layout partitions and distributing compensation coefficients; s3, pre-compensating the size of the nano structure; s4, generating a final mask and executing etching; according to the method, the space size pre-compensation of the nano structure is actively performed in the mask design stage, and the phase deviation caused by non-uniform etching depth is counteracted by using the change of the effective refractive index of the nano unit, so that the high-performance super lens is obtained under the non-ideal process condition, and the limitation of the process physical limit is broken through.

The utility model relates to the technical field of super-structure lenses, and particularly discloses a fully-integrated polarization imaging device based on a polarization beam splitting super-lens. The fully-integrated polarization imaging device based on the polarization beam splitting superlens comprises a nanopillar array, a transparent medium substrate and an image sensor, a nanorod array is arranged on one side surface of the transparent medium substrate; the image sensor is arranged on the other side, far away from the nanorod array, of the transparent medium substrate; the image sensor is provided with at least two pixel areas; the light beams output from the nano-pillar array pass through the transparent medium substrate and then are split and focused to the pixel area. According to the utility model, the nanorod array, the transparent medium substrate and the image sensor are integrated together, so that the interference of an external light path is reduced, the imaging stability and reliability are improved, the structure is compact, and the size is small. The nanorod array can accurately control polarization and phase of light, high-resolution imaging is achieved, and the problems that an existing polarization system is low in integration degree, large in size and low in resolution are solved.

A lens system having reduced physical size. The lens system includes multiple metalenses, lenses with metasurfaces, that integrate the lens and the free space and compress them into multiple layers of metasurfaces, significantly reducing the overall volume and weight of the imaging system while increasing its efficiency. The lens system also provides for tools that can accurately model 3D multilayer metasurfaces, carry out inverse design to find the optimal and fault-tolerant structure, fabricate the metasurfaces with multi-project wafer service, assemble them with a 3D-printed holder, and characterize the performance of the resulting ultra-compact imaging system.

The embodiment of the invention provides a light beam combining system and a laser system, and the light beam combining system comprises a super lens array which comprises a plurality of super lens structures; the super-surface array comprises a plurality of super-surface structures, the number of the super-surface structures is the same as that of the super-lens structures, and each super-lens structure and one super-surface structure form a light path branch; and the light path beam combining structure is used for combining the light of the plurality of light path branches into one light beam and outputting the light beam. By means of the light beam combining system, continuous phase regulation and control can be achieved, and the light beam combining effect is achieved.

According to the metasurface device for snapshot type high dynamic range imaging and the imaging system and method thereof provided by the invention, the dynamic range of a camera can be improved by integrating a plurality of superlenses with different transmittances on a single metasurface; the polarization-independent metasurface is designed by using a pure phase modulation principle, so that the system stability is greatly improved; compared with other backlight imaging methods, the method has the advantages of high integration level, single measurement and space and time cost saving, and has a certain reference effect on development of ultra-compact imaging equipment and improvement of dynamic range imaging capability.

The invention belongs to the technical field of micro-nano optics. The invention provides a multi-focus off-axis super lens of a visible light wave band. The multi-focus off-axis super lens comprises a plurality of groups of off-axis single-focus sub super lens assemblies which are circularly arranged, wherein each group of off-axis single-focus sub super lens assemblies comprises a plurality of off-axis single-focus sub super lenses which are concentrically and annularly distributed; wherein the off-axis single-focus sub-super-lens comprises a micro-structure unit and a substrate unit, the micro-structure unit comprises a plurality of micro-structure columns which are uniformly arranged, and one end of each micro-structure column is arranged on the substrate unit. According to the embodiment of the invention, on the basis of a geometric phase modulation principle, through reasonable phase design and microstructure arrangement, the off-axis single-focus sub-super-lens has a designed focus position; through spatial multiplexing of the micro-structures of the multiple off-axis single-focus sub-super-lenses, one super-lens has the phase characteristics of the multiple off-axis single-focus sub-super-lenses, and the functions of the multiple off-axis single-focus sub-super-lenses are achieved on one super-lens.

The invention provides a liquid crystal optical phased array imaging system and a design method thereof, and belongs to the technical field of liquid crystal optical phased arrays. The system comprises a camera, a lens, a beam splitter prism, a liquid crystal spatial light modulator, a super lens and a computer, and is suitable for a visible light band. Non-mechanical light beam deflection is achieved through the liquid crystal spatial light modulator, angle amplification and dispersion compensation functions are achieved in combination with the super lens, and the problems that a traditional mechanical light beam deflection technology is large in size and short in service life are solved, and the problems that an existing liquid crystal optical phased array is small in angle range and imaging aliasing is caused by dispersion are solved; the superlens adopts a three-layer nanostructure unit stacking design, the upper layer is a dispersion compensation structure, the lower layer is an angle amplification structure, and large-angle imaging and efficient spectrum utilization are realized through phase modulation; the invention has the advantages of compact structure, small volume, low cost, high stability and the like, and is suitable for the fields of laser radar, space optical communication, infrared tracking and the like.

The invention relates to the technical field of image processing, and discloses an infrared super-lens image quality enhancement method based on fusion of double-path decoding and physical perception prompt, which comprises the following steps: S1, generating a physical parameter prompt, acquiring geometric and optical characteristic parameters of an infrared super-lens, and converting the parameters into textualized prompt vectors; s2, constructing a data set; s3, cross-modal feature coding and fusion are carried out; and S4, carrying out double-path decoding and reconstruction. According to the infrared super-lens image quality enhancement method based on the fusion of the two-way decoding and the physical perception prompt, by introducing physical parameter prompt and cross-modal feature fusion, the imaging physical prior of an infrared super-lens is effectively fused into a network, so that a model can understand a degradation source and imaging constraints; and deep collaboration of visual information and physical attributes is realized in a feature extraction process. The design not only enhances the adaptability of the model to a complex imaging system, but also improves the interpretability and robustness of an enhancement result.

The invention discloses a visible light optical system and a visible light optical lens. The visible light optical system comprises a super lens, a first aspheric lens, a second aspheric lens, a third aspheric lens and a fourth aspheric lens. The first aspheric lens, the second aspheric lens, the third aspheric lens and the fourth aspheric lens are sequentially arranged from the object side to the image side along the optical axis. The focal power of the super lens is positive; the focal power of the first aspheric lens is positive, and the object side surface and the image side surface of the first aspheric lens both protrude towards the object side; the focal power of the second aspheric lens is negative, and the object side surface and the image side surface of the second aspheric lens both protrude towards the image side; the focal power of the third aspheric lens is positive, the object side face and the image side face of the third aspheric lens both protrude towards the image side, and the focal power of the fourth aspheric lens is negative. According to the visible light optical system, the super lens is combined with the traditional refraction lens, so that the visible light optical system has the advantages of low cost, small size and excellent imaging quality.

The invention relates to a visible light lens, a camera module and terminal equipment, and belongs to the technical field of optical imaging, and the visible light lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are sequentially arranged from an object plane to an image plane along an optical axis; the first lens, the second lens and the fifth lens are lenses with negative focal power, the third lens, the fourth lens, the sixth lens and the seventh lens are lenses with positive focal power, and the fourth lens is a metasurface lens; the object side surfaces of the first lens, the third lens and the seventh lens are convex surfaces, the object side surfaces of the second lens and the sixth lens are concave surfaces, and the object side surfaces and the image side surfaces are spherical surfaces; the object side surface of the fourth lens has microstructure arrangement, and the image side surface is a plane; the object side surface of the fifth lens is a plane, and the object side surface and the image side surface are spherical surfaces. According to the invention, the technical scheme of folding and super mixing is adopted, and the large-aperture optical system is realized by six traditional glass material lenses and one super lens.

The invention discloses a super-lens element atomic structure reverse design method and electronic equipment, and relates to the field of super-lens element atomic structure design. The method comprises the following steps: extracting modal features of element atom structure images and phase spectrum data through a differential perception fusion module, and generating structure image side information and phase spectrum side information; on the basis, asymmetric association representation is constructed, a prompt factor is generated, and a prompt guide fusion feature is formed; and fusing asymmetric correlation representation, prompting and guiding fusion features, element atom structure images and phase spectrum data, generating cross-modal fusion features, and relieving alignment difficulty caused by modal isomerism. Then, semantic modeling and structure enhancement are carried out through a structure difference perception module, and enhanced fusion representation is obtained; and finally reconstructing the dimension and rearranging the space through a feature rearrangement inversion module, and synchronously outputting a predicted element atom structure image and phase spectrum data thereof, thereby realizing bimodal joint generation.

The invention provides an achromatic superlens design method and device, and the method comprises the steps: carrying out the light field simulation of a target metasurface, and obtaining a simulation light field; the target metasurface is a plane where the pattern of the super lens is located; performing iterative optimization on the target metasurface according to the simulation light field and a preset target function, and taking the metasurface corresponding to the minimum preset target function as a final design pattern of the achromatic superlens; the preset objective function is irrelevant to the light wavelength and is used for representing the deviation between the simulation light field and the ideal light field; the ideal light field is related to the polar angle of the target metasurface in space, it is ensured that the super lens can achieve the characteristic that the focal length is not changed under different wavelengths, the high-quality achromatic effect is achieved, and the design efficiency and precision of the super lens are improved.

A display device includes: an image projector including an image forming device and a meta-lens module and configured to output image light formed by the image forming device; and a meta-waveguide configured to transfer the image light output from the image projector, to an observer's field of view, the meta-waveguide including waveguide element configured to totally reflect light inside, an input coupler including a plurality of first nanostructures forming a first phase gradient in a first direction and configured to couple the image light from the image projector to an inside of the waveguide element, and an output coupler including a plurality of second nanostructures forming a second phase gradient in a second direction different from the first direction and configured to output the light coupled to the inside of the waveguide element by the input coupler, to an outside of the waveguide element.