Light beam receiver assembly

Abstract

According to a first aspect of the present invention, there is provided a beam receiver assembly comprising: an optical filter layer; a beam shaping layer; and a substrate having an optical receiver, the optical filter layer and the beam shaping layer being positioned such that the optical receiver receives a light beam that has passed through the optical filter layer and the beam shaping layer, the optical filtering layer is configured to allow the light beam to be transmitted in a working wavelength range of the optical receiver and attenuate other wavelengths; and wherein the beam shaping layer is configured to spatially shape a light amplitude of the beam onto a specific portion of the optical receiver.

Description

Field of the Invention

[0001] The present invention relates to the fields of integrated photonics, target tracking and ranging, data processing, and remote sensing. The present invention discloses a beam receiver assembly having one or more layers and an optical receiver, wherein the one or more layers optimize the incident beam of the optical receiver. Background Art

[0002] The light beams collected / detected by optical receivers may not be optimal (e.g., non-uniform), causing these receivers to be vulnerable to the "blinding effect", or signal loss (due to undetected light beams), or masked by signal noise (due to background or atmospheric optical solar clutter). To address these issues, various design implementations of the optical receivers themselves have been proposed. However, such designs typically require trade-offs. Designing a single structure that simultaneously modifies and receives an incident light beam can be very complex.

[0003] In recent years, there has been an effort to reduce the dependence on a light beam receiver that can simultaneously receive and enhance the light beam characteristics on the same physical structure. An example of such an effort is to simplify the allocation of separate structures on independent but integrated physical structures to separately receive and enhance the light beam characteristics, as described, for example, in "Opt.Comm." Vol. 514, 2022 by Zhang et al. Zhang et al. disclose physically distinct but integrated photon components that separately receive light beams (in the form of photodetectors) and focus the light beams onto a point to improve the response ability of the photodetectors (in the form of metal lenses on the photodetectors). Assuming that the detected optical signal may include background noise (from other transmitted signals and / or optical solar clutter) in addition to the main signal to be detected, the net received signal can consist of a set of multi-wavelength signals (including the main signal), which introduces dispersion to the net received signal. For example, in the case of optical focusing to improve the responsivity, chromatic aberration may occur. This hinders the precise detection of light beams.

[0004] There is a need to provide an improved photonic component to address the above drawbacks. Summary of the Invention

[0005] According to a first aspect, there is provided a beam receiver assembly, comprising: an optical filtering layer; a beam shaping layer; and a substrate having an optical receiver, wherein the optical filtering layer and the beam shaping layer are positioned such that the optical receiver receives a light beam that has passed through the optical filter layer and the beam shaping layer, wherein the optical filtering layer is configured to allow the light beam to transmit within the wavelength range in which the optical receiver operates and attenuate other wavelengths; and wherein the beam shaping layer is configured to spatially shape the optical amplitude of the light beam onto a specific portion of the optical receiver.

[0006] From the above disclosure and the more detailed description of the various embodiments, it will be clear to those skilled in the art that the present invention has made significant progress in the technical aspect of changing the beam characteristics of the incident beam to enhance the detection of the beam by the optical receiver system. Of particular importance in this regard is that the present invention provides the potential for enhanced beam detection that is not affected by dispersion. This can prevent the loss of signal information in the beam, which would otherwise occur due to the presence of blur / streaks on the resulting beam. The additional features and advantages of the various embodiments will be better understood from the detailed description provided below. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A and 1B show two schematic diagrams of a beam receiver assembly having stacked layers;

[0008] Figure 2A and 2B show a table of schematic side views of variations of discrete stacked layers for defining the beam characteristics of a beam;

[0009] Figure 3 show a table of schematic isometric views of stacked layer unit cells;

[0010] Figure 4 is an isometric view including Figure 3 the stacked layers shown for defining the unit cells of the beam characteristics of a beam;

[0011] Figure 5 is by Figure 4 an isometric view of a stack composed of the stacked layers described for defining the beam characteristics of a beam;

[0012] Figure 6 is the transmission of the estimated result of the optical field of an additional embodiment of the photon component in the stack;

[0013] Figure 7 is a table showing the estimated electric field (|E|) distributions along the xz cross-section and the xy cross-section of the stack array unit with and without Figure 1A and 1B the optical filter stack;

[0014] Figure 8 show a table of schematic diagrams of beam filtering and focusing; and beam filtering, expansion, and focusing;

[0015] It should be understood that the drawings are not necessarily to scale and present a somewhat simplified representation of various features illustrating the basic principles of the invention. The specific design features of the beam receiver assembly structure disclosed herein, including, for example, the specific dimensions of the stacked layers, will be determined in part by the particular intended application and the use environment. Certain features of the illustrated embodiments are enlarged or distorted relative to other features to assist in providing a clear understanding. In particular, thin features may be thickened, for example, for clarity of illustration. Specific embodiments

[0016] In the following description, various embodiments are described with reference to the drawings, in which like reference numerals generally refer to like parts in different views. For those skilled in the art, that is, those with knowledge or experience in the technical field, it will be apparent that the beam receiver assembly disclosed herein can have many variations in use and design. The embodiments described below illustrate the general principles of the invention to provide a beam receiver assembly suitable for receiving and optimizing an incident beam for applications adapted to its optical receiver design. Given the benefits of this disclosure, other embodiments suitable for other applications will be apparent to those skilled in the art.

[0017] This application relates to an integrated photonics device, particularly a beam receiver assembly. The beam receiver assembly has a multi-layer structure that receives an incident beam and changes the beam characteristics of its substrate to receive the resulting beam. The beam assembly can be, for example, part of an optical receiver system used in wireless communication applications.

[0018] The beam receiver assembly has at least the following components: one or more optical modulation layers; and a substrate having an optical receiver. The optical receiver is used to extract data from the signal carried by the incident beam. Thus, the optical receiver includes components such as one or more photodetectors and support infrastructure such as a scatterer array, waveguides, gratings, lens arrays, and optical switches. Alternatively, the optical receiver can be a device that integrates one or more of these components, such as a photodetector with an integrated waveguide.

[0019] Layout of an optical receiver, such as the type of photodetector, uses one or more of a scatterer array, waveguide, grating, lens array, and optical switch; and the relative position of each of them with respect to the photodetector can be designed for the application of the optical receiver system to which the beam receiver assembly belongs. For example, a lidar receiver system can use a free-space avalanche photodetector or a waveguide-integrated avalanche photodetector, in combination with an on-chip waveguide integrated into a scatterer or grating array. While a free-space avalanche photodetector is directly capable of detecting the light field incident on the photodetector, the scatterer array allows the light field in free space to be coupled to an on-chip optical waveguide connected to the avalanche photodetector. The avalanche photodetector allows for highly sensitive detection of the light field when a high reverse bias (i.e., close to the breakdown voltage) is applied. Due to the application of the high voltage, the carriers in the transition region are accelerated, and when the carriers generated by the incident photons collide with the bound electrons, this greatly increases (compared to a conventional photodetector) the number of free electron-hole pairs.

[0020] These layout considerations result in the beam incident on the beam receiver assembly needing to be spatially concentrated on certain parts of the optical receiver, depending on the design of the optical receiver. Another consideration is the operating wavelength range required for the application using the optical receiver system. One or more optical modulation layers have at least one optical filter layer and at least one beam shaping layer, both configured to address the above problems and output a beam optimized for the optical receiver design.

[0021] The optical filter layer provides a wavelength-sensitive transmission function by being configured to allow the transmission of a beam within a predefined wavelength range and attenuate other wavelengths. By setting this predefined wavelength range to the wavelength range in which the optical receiver operates, the beam output by the optical filter layer is optimized for the optical receiver operating environment and also reduces the chromatic dispersion caused by the presence of multiple wavelength signals. In one embodiment, the optical filter layer operates by changing the refractive index in the form of a spatial structure arrangement, the spatial structure arrangement including metals and / or dielectrics, the order of which is greater than, equivalent to, or less than the wavelength of the optical signal passing through the optical filter layer.

[0022] In one embodiment, the beam shaping layer provides a method for spatially focusing a beam by being configured to spatially shape the optical amplitude of the beam onto a specific portion of the optical receiver. This focusing concentrates the output beam into a spot with a significantly smaller width compared to the original width of the incident beam incident on the beam receiver assembly. In other embodiments, the beam shaping layer expands or collimates the beam rather than focusing it. Thus, the beam shaping layer is configured to spatially shape the beam amplitude, and the beam shaping layer allows control of the spatial amplitude distribution of the optical signal collected by the optical receiver, where, depending on the application scenario, the optical receiver can receive a focused, expanded, or collimated beam.

[0023] When the beam propagates through the beam receiver assembly to reach the optical receiver, the optical filtering layer, the beam shaping layer, and the optical receiver position are set such that the optical filtering layer and the beam shaping layer are placed along the path of the beam. Thus, the optical receiver receives the beam that has passed through the optical filtering layer and the beam shaping layer.

[0024] At least one optical filtering layer and at least one beam shaping layer can be implemented as a thin film, a corrugated thin film, and / or a nanostructure, which are located on or integrated into a substrate provided with an optical receiver. The order of these layers may be changed. In one embodiment, the beam shaping layer is disposed between the optical filtering layer and the optical receiver. Then, the beam shaping layer can be disposed on the optical receiver. In another embodiment, the optical filtering layer is disposed between the beam shaping layer and the optical receiver. Then, the optical filtering layer can be disposed on the optical receiver.

[0025] The beam receiver assembly will be described in more detail below with reference to the accompanying drawings.

[0026] According to Figure 1A , a schematic block diagram 100 of a beam receiver assembly 101 is disclosed, which includes at least one optical filtering layer 121 (P≥1) of an optical filtering stack 120 and at least one beam shaping layer 131 (Q≥1) of a beam shaping stack 130 mounted on an optical receiver 110 located on a substrate 140.

[0027] The optical receiver 110 can include a free-space photodetector array, an array of scatterers (e.g., in the form of an optical phased array) seamlessly connected to a waveguide-integrated photodetector, and an array of scatterers combined with a lens and a photoelectric switch (e.g., in the form of a focal plane switch array), which are also seamlessly connected to the waveguide-integrated photodetector. These different components can be integrated onto the same platform, e.g., an optical phased array combined with a waveguide-integrated photodetector.

[0028] Stacks (120 and 130) advantageously provide the ability to adjust the beam characteristics of the beam receiver structure, i.e., the spatial distribution of the optical amplitude. Stacks 120 and 130 can be implemented by a phase mask made of any one of, for example, silicon (Si), polysilicon, silicon nitride (Si3N4), silicon dioxide, germanium (Ge), lithium niobate (Li3NbO3), polymers, III-V compounds (i.e., alloys containing elements from groups III and V of the periodic table), and II-VI compounds (i.e., metal alloys containing elements from groups II and VI of the periodic table).

[0029] Depending on the configuration of the beam receiver assembly 101 selected for the application, there can be any number of stacked layers. However, while Figure 1A an optical filtering stack 120 with multiple optical filtering layers 121 and a beam shaping stack 130 with multiple beam shaping layers 131 are shown, another embodiment (not shown) has a beam receiver assembly with only one optical filtering layer and only one beam shaping layer.

[0030] The stacked layers output a modulated beam 162 that is used for an optical receiver 110 disposed on a substrate 140. The modulated beam 162 is the result of the incident beam 142 being spectrally filtered by the optical filtering stack 120 and spatially shaped by the beam shaping stack 130, since the optical filtering layer 121 and the beam shaping layer 131 are arranged such that the optical receiver 110 receives the beam that has passed through the optical filtering layer 121 and the beam shaping layer 131. The optical receiver 110 can include a structure that induces light scattering (e.g., a grating structure) to co-couple the free-space beam to an on-chip photodetector.

[0031] As Figure 1A shown, the optical filtering stack 120 and the beam shaping stack 130 are vertically stacked together. For example, the first optical filtering layer p = 1 is vertically stacked above the second optical filtering layer p = 2, and the third optical filtering layer p = 3 is stacked above the second optical filtering layer p = 2; while the first beam shaping layer q = 1 is vertically stacked above the second beam shaping layer q = 2, and the third beam shaping layer q = 3 is stacked above the second beam shaping layer q = 2. Figure 1A The implementation of uses an arrangement where the beam shaping layer 131 is disposed between the optical filtering layer 121 and the optical receiver 110. Thus, the first beam shaping layer q = 1 is located above the optical receiver 110, which in turn is located on the chip substrate 140. The optical filtering layer 121, the beam shaping layer 131, and the optical receiver 110 are shown aligned on the chip substrate 140.

[0032] Each optical filtering layer 121 may include thin films of materials interleaved with thin films of different materials. One or more optical filtering layers 121 may have different thicknesses, or they may all have the same thickness. Overall, the optical filtering stack 120 includes a plurality of optical filtering layers 121 made of alternating materials of high and low refractive indices. This composition configures each optical filtering layer 121 to spectrally filter optical signals of specific wavelengths. By selecting an appropriate combination of materials and their respective dimensions, the optical filtering stack 120 can be configured to allow a light beam to transmit within the wavelength range in which the optical receiver 110 operates and attenuate other wavelengths using one or more optical filtering layers 121. According to Figure 6 , the optical filtering stack 120 may have one optical filtering layer 121 configured as 602 that attenuates wavelengths less than 1.2 μm, and another optical filtering layer 121 configured as 604 that attenuates wavelengths between 1.2 μm and 1.4 μm. The output modulated light beam 162 contains optical signals with wavelengths greater than 1.4 μm.

[0033] Each beam shaping layer 131 may include periodically placed unit cells, each unit cell having an optical shaping element with a structure (core / post) having an elliptical, polygonal, or closed Bessel curve cross-section. Thus, each beam shaping layer 131 may have a plurality of optical shaping elements with different cross-sections, spaced apart by a certain distance, as will be discussed in more detail below. These optical shaping elements allow the beam shaping layer 131 to spatially shape the optical amplitude and modify the beam characteristics of the light beam. Such beam characteristics include the spatial distribution of the optical amplitude. Such modulation may also include modulation of the beam spot size, redistribution of the beam for uniform illumination, beam width, field of view of the beam, and is configured to improve the responsivity of the photodetector in the optical receiver 110. By selectively combining appropriate optical shaping elements that affect the beam characteristics, the beam shaping stack 120 can be configured to reduce the aberration (e.g., spherical aberration) of the focused beam, which may be caused by the wavelength-selective transmission and attenuation performed by the optical filtering stack 120. In another configuration, the selected optical shaping elements also contribute to aligning the beam to the optical receiver 100. For example, the beam shaping stack 130 may have one beam shaping layer 131 that spatially aligns the beam to a portion of the optical receiver 110; and another beam shaping layer 131 that spatially focuses the beam to another portion of the optical receiver 110.

[0034] Certain (overall) beam characteristics can optionally be modified independently and / or jointly by a plurality of beam shaping layers 131. The beam shaping layers 131 can have the same, similar or different functions to define the desired beam characteristics. As the beam propagates through each layer of the beam shaping stack 130, the characteristics can be modified sequentially. Each beam shaping layer 131 can have various properties, which can be combined in various ways to modulate the beam characteristics. For example, the various dimensions of the beam shaping layer 131, including the height of its core (i.e., the location where the beam shaping element is located), the thickness or diameter of its core, are selected based on the phase shift required to focus the beam to a specific location on the optical receiver 110.

[0035] Figure 1B FIG. 150 is a schematic block diagram of a beam receiver assembly 151 according to another embodiment of the present invention.

[0036] Similar to Figure 1A the beam receiver assembly 101, the beam receiver assembly 151 has an optical filtering stack 120 and a beam shaping stack 130. The optical filtering stack has at least one optical filtering layer 121 (P≥1) and at least one beam shaping layer 131 (Q≥1). However, the order of the optical filtering stack 120 and the beam shaping stack 130 with respect to the optical receiver 110 is different. While Figure 1A the beam shaping layer 131 of the beam receiver assembly 101 is located between its optical filtering layer 121 and its optical receiver 110, Figure 1B the optical filtering layer 121 of the beam receiver assembly 151 is located between its beam shaping layer 131 and the optical receiver 110. The optical filtering stack 120 of the beam receiver assembly 151 is mounted on the optical receiver 110 located on the substrate 140.

[0037] Since Figure 1B the construction of the beam shaping stack 130 and the optical filtering stack 120 of the beam receiver assembly 151 is the same as that of Figure 1A the beam receiver assembly 101, it will not be further elaborated herein.

[0038] Figure 2A and Figure 2B are tables comparing the resulting distributions of the beam on the beam receiver when the stacks are applied jointly and separately.

[0039] In Figure 2A Combination A of FIG. 125, combination A includes an optical filtering stack 120 vertically stacked on top of the optical receiver 110. The width of the beam incident on the optical receiver 110 is comparable to its width when incident on the optical filtering stack 120. The optical filtering stack 120 does not spatially change the amplitude distribution of the beam, but spectrally filters out signals of other wavelengths while allowing only signals in a specific band to pass through.

[0040] In combination B, combination B includes a beam shaping stack 130 (e.g., in the form of a single-layer metal lens) vertically stacked on top of the optical receiver 110. The beam incident on the optical receiver 100 is substantially concentrated in a specific area with an effective width smaller than its width when incident on the beam shaping stack 130. Due to the unequal focal lengths of the metal lens at different optical wavelengths, stray signals outside the wavelength band of interest caused by chromatic aberration easily cause the spot size to be concentrated and amplified.

[0041] In combination C, combination C includes an optical filtering stack 120 vertically stacked on the beam shaping stack 130 and a beam shaping stack 130 vertically stacked on the optical receiver 110. When incident on the beam shaping stack 30, the beam incident on the optical receiver 100 is significantly concentrated at a sharp point with an effective width that is significantly negligible. Compared with no such focusing, this increases the response rate of the photodetector in the optical receiver 110. The optical filtering stack 120 selectively allows signals of a specific wavelength to pass through while filtering out signals of other wavelengths, causing the metal lens to effectively focus the spectrally filtered beam at an equal focal length, thus achieving a clear beam focus on the optical receiver 110.

[0042] In Figure 2B Combination D, combination D includes an optical filtering stack 120 vertically stacked on top of the optical receiver 110. The light field incident on the optical receiver 100 can be approximated as including random rays. The optical filtering stack 120 does not spatially change the amplitude distribution of the beam, but spectrally filters out signals of other wavelengths while only allowing signals of a specific band to pass through. Due to the random illumination, the final light field received by the optical receiver 110 is random in space.

[0043] In combination E, combination E includes a beam shaping stack 130 (e.g., in the form of a single-layer metal lens) vertically stacked on top of the optical receiver 110. The light field (which can be approximated as including random rays) incident on the optical receiver 100 is substantially collimated in a specific area to produce a relatively uniform beam. Due to the presence of stray signals outside the wavelength band of interest caused by dispersion, the generated beam is prone to uneven distribution. Therefore, the final light field received by the optical receiver 110 can include different possibilities of beam distribution.

[0044] In combination F, an optical filtering stack 120 is vertically stacked on a beam shaping stack 130, and the beam shaping stack 130 is vertically stacked on an optical receiver 110. The light field irradiated on the optical receiver 100 (which can be approximated as including random rays) is highly collimated in a specific region to generate a highly uniform beam. The optical filtering stack 120 selectively allows signals of specific wavelengths to pass through while filtering out signals of other wavelengths, and the beam shaping stack 130 effectively collimates the spectrally filtered beam to generate a highly uniform beam on the optical receiver 110. The final light field received by the optical receiver 110 has a consistent beam distribution.

[0045] Figure 2A and Figure 2B both illustrate the advantages of the present invention. The optical filtering stack 120 is structurally combined / stacked with the beam shaping stack 130 to eliminate beam distortion caused by dispersion (e.g., chromatic aberration as described in combination B). In addition to allowing the beam to be focused, the beam enhancement stack 130 can also redefine and modify the spatial amplitude distribution.

[0046] Figure 3 A table showing the unit cell 122 structure of the optical filtering layer 121 of the optical filtering stack 120 and the unit cell 132 structure of the beam shaping layer 131 of the beam shaping stack 130. The core 126 of the optical filtering layer 121 includes a thin film layer surrounded by a lower cladding 125 and an upper cladding 124, and the core 126 extends with a height H 120 from the lower cladding 125 to the upper cladding 124. The lower cladding 125 and the upper cladding 124 form part of each unit cell 122 and can each include one or more photon materials, such as Si, polysilicon, Si3N4, Ge, Li3NbO3, polymers, and III-V compounds. The core 133 of the beam shaping layer 131 includes a column surrounded by a lower cladding 135 and an upper cladding 134, and the core 133 has a height H 130extends from the lower cladding to the upper cladding. The lower cladding 135 and the upper cladding 134 form part of each unit cell 132 and each can similarly include one or more photonic materials such as Si, polysilicon, Si3N4, Ge, Li3NbO3, polymers, and III-V compounds. Each core 133 corresponding to the unit cell array is separated by a uniform distance (forming a symmetric array) and a non-uniform distance. The stack of the optical filtering layers 121 and the stack of the beam shaping layers 131 can be obtained respectively using the upper cladding and the beam shaping stack 130, where the upper cladding is the lower cladding of the next layer of the optical filtering stack 120. That is, adjacent optical filtering layers 121 share a cladding, and adjacent beam shaping layers 131 share a cladding. The cladding acts as a relay between two adjacent layers. In the beam shaping layer 131, the height of each pillar can be uniform, but the thickness and distance between each pillar can vary, for example, by fixing the thickness of the upper cladding, typically from 0.01 μm to 5 μm. Therefore, one or more of these claddings (the lower cladding 125 and the upper cladding 124 for the optical filtering layer 121; and the lower cladding 135 and the upper cladding 134 for the beam shaping layer 131) can have different thicknesses. Such a photonic element with discrete core heights, fixed upper and lower cladding thicknesses is beneficial for the large-scale production of commercially scaled and economically sustainable beam receiver assemblies as they can be conveniently fabricated layer by layer using standard manufacturing techniques.

[0047] The optical filtering stack unit cell core 126 in the unit cell 122 receives an optical input field with an amplitude of a λi whose reflection coefficient is r and is transmitted through the core 126 with a coefficient of t. When the optical filtering layers 121 including the unit cell 122 are put together, the reflected parts of each layer can interfere constructively or destructively, respectively resulting in a low intensity or a high intensity of the net transmitted beam. In the optical filtering layer 121, constructive interference enhances the beam falling within the wavelength range in which the optical receiver 110 operates, while destructive interference attenuates light of other wavelengths.

[0048] On the other hand, the beam shaping layer unit cell 132 receives an optical input field with an amplitude of a. The input optical field a propagates through the unit cell 132, generating an output optical signal ae ikH 130 (by the plane wave approximation), where the wave vector k = 2πn eff / λ0, n eff is the effective refractive index of the pillar structure and λ0 is the wavelength of the optical field. The beam shaping layer 131 is not limited to having cores with two discrete heights (binary cores), but can extend to cores with multiple discrete heights (multi-level cores), cores with continuous height levels forming one or more continuous function curves, or cores without any repeating units.

[0049] Figure 4 is another table related to Figure 3 and shows an isometric schematic view of layer 121 of the optical filter stack 120 and beam shaping layer 131 of the beam shaping stack 130. The optical filter layer 121 and the beam shaping layer 131 respectively include an optical filter layer unit cell 122 and a beam shaping layer unit cell 132. The optical filter layer 121 includes a thin film core 123 surrounded by a lower cladding 125 and an upper cladding 124. The beam shaping layer 131 includes a cylindrical core 136 surrounded by a lower cladding 135 and an upper cladding 134. The distance between adjacent cores of each beam shaping layer unit cell 132 can be arbitrarily selected, and the size (height and diameter / diagonal / thickness) of the beam shaping layer unit cell 132 can be based on the expected phase shift at a specific position on the beam shaping layer 131. Therefore, the size (one or more of height, diameter, and diagonal) of each optical shaping element in the beam shaping layer 131 depends on the focal point required at the position of the optical shaping element.

[0050] The distance between adjacent cores of the beam shaping layer unit cell 132 can be the same or can vary. The height of the beam shaping layer unit cell 132 can be between 0.01 μm and 10 μm, the diameter or cross-section of the core part of the beam shaping layer unit cell 132 can be between 0.01 μm and 3 μm, and the periodic distance between adjacent layer unit cells 132 can be arranged in a square lattice between 0.01 μm and 3 μm. A lattice refers to a regular arrangement of the beam shaping layer unit cells 132, for example, a triangular, square, or hexagonal two-dimensional lattice arrangement of the beam shaping layer unit cells. Therefore, the optical shaping elements in the beam shaping layer 131 can be arranged in the lattice according to one of the following arrangements: triangular, square, or hexagonal. Advantageously, at least one optical filter layer 121 can be vertically stacked above at least one beam shaping layer 131; and at least one beam shaping layer 131 can be stacked above the optical receiver 110, as Figure 1A shown.

[0051] The optical phase shift at each periodic lattice point is a function of the size of the beam shaping layer unit cell 132. In the Figure 4 example shown, the beam shaping layer unit cell core has a cylindrical column structure. The beam shaping layer unit cell 132 can be a discrete (binary) phase mask with a cylindrical column structure having a height H 130 introducing the required phase shift. Alternatively, the beam shaping layer unit cell 132 can be multi-layered, or can have a continuous spatial height. The cylindrical column structure 133 shown in the figure has an elongated top surface 137 and side walls 138 extending downward from the top surface. The refractive index of the cylindrical column structure can be greater than or less than the surrounding cladding, that is, for each beam shaping layer 131, the cladding has a refractive index different from that of its core. In Figure 3In this case, the beam shaping layer cell 132 introduces an optical phase shift based on its binary thickness structure. The different optical phase shifts (added together) caused by the respective beam shaping layer cells 132 at different points on the beam shaping layer 131 enable the beam reaching the optical receiver 110 to be carefully customized according to specific requirements.

[0052] In one embodiment, the binary thickness structure of the core 136 of the beam shaping layer cell 132 is a cylindrical column structure with a thickness of 0.4 μm (uniform discrete). The cylindrical column structure is surrounded by the upper cladding 134 and the lower cladding 135 in the cell 132. The beam shaping layer cell 132 receives an optical input field with an amplitude of a. The input optical field a propagates through the cell 132, generating an output optical signal ae ikH (by plane wave approximation), where the wave vector k = 2πn eff / λ0, n eff is the effective refractive index of the column structure, and λ0 is the wavelength of the optical field.

[0053] Figure 5 is related to Figure 3 and Figure 4 Another table shows an isometric schematic diagram of the optical filtering stack 120 and the beam shaping stack 130. The core 123 of the optical filtering stack 120 including the thin film is alternately interleaved with the claddings (124 and 125). The core 133 of the beam shaping stack 130 including the cylindrical columns is periodically placed. The optical phase shift at each periodic lattice point of the layer 131 represented by the cell shown by Figure 3 can be caused by modifying k (which is a function of n eff and / or modifying H 130 . In one example, n effVaries with the diagonal or diameter D of the pillar structure. Advantageously, such pillar structures (constituting the core) can be produced using standard manufacturing techniques such as lithography and deposition and include photonic materials such as Si, polysilicon, Si3N4, Ge, Li3NbO3, polymers, III-V compounds. According to one embodiment, the height of each pillar in the stacked layer cell is fixed based on layer-based deposition or etching processes in conventional semiconductor manufacturing. Advantageously, for the beam shaping layer cell 132, the diameter of the pillar structure is a determining factor in introducing an optical phase shift. For example, for a polysilicon cylindrical pillar with a thickness of 0.4 μm, surrounded by a silica upper and lower cladding in a cell with a periodic distance of 0.75 μm between adjacent cells, a diameter from 0 to 0.75 μm (i.e., 0 to 1 times the periodic distance between adjacent cells) causes a monotonically increasing phase shift from 0 to 2π. Thus, the desired optical phase shift at any arbitrary point on the phase mask can be designed according to the relationship between the diameter and the optical phase shift induced by the diameter. Similarly, for a metalens, the phase distribution of the beam is transformed based on modulo 2π arithmetic, which means that the radius of the pillar structure in the cell varies periodically.

[0054] In known optical receivers, the signal amplitude of the incident beam may be very weak, resulting in signal loss. These problems can be solved by vertically integrating a beam shaping layer 131 above the optical receiver 110 to define and modify the spatial distribution of the optical amplitude of the beam, i.e., spatially focusing the beam onto the point of interest on the optical receiver 110. Due to the spatial focusing of the beam shaping stack 130, the incident photon flux at the point of interest increases. This results in an increase in the absorbed optical field from the beam to generate more electron-hole pairs, e.g., which increases the responsivity (the ratio of current to optical power) of the photodetector on the optical receiver 110. The beam shaping layer 131 is designed for beam focusing such that the optical phase of each horizontally adjacent beam shaping layer cell 132 is shifted: where, For line focusing, For point focusing; x and y (i.e., perpendicular to x) are distances corresponding to Δr.

[0055] In known optical receivers integrated with a beam focusing structure, due to the presence of optical signals of different wavelengths, the beam focused onto the optical receiver, e.g., a free space photodetector, is prone to an increase in beam width. Such aberration is particularly evident in an environment where there are optical signals from various different sources, and / or when the main signal to be detected is suppressed after passing through free space, thus increasing the signal-to-noise ratio. These problems can be solved by vertically integrating an optical filtering stack 120 above the beam focusing layer 131 and the optical receiver 110 (as Figure 1AIt is solved by (as shown), to filter signals of other wavelengths spectrally and allow the main signal of interest at a specific wavelength to pass through. Due to the spectral selectivity of the optical filter stack 120, the light beam incident on the beam focusing layer 131 includes signals at a specific wavelength. Therefore, the final light beam from the beam focusing layer 131 can be guided to certain spatial points of interest "achromatically", thereby increasing the responsivity of the free-space photodetector on the optical receiver 110. The improvement in the photoelectric conversion efficiency directly indicates the improvement in the detection sensitivity, which is desirable for many light beam detection applications including lidar and free-space transceivers.

[0056] Figure 6 The time-domain finite-difference (FDTD) numerical simulation results of the vertically stacked optical filter using the optical filter stack on the optical receiver are shown. The numerically simulated optical filter stack 600 has defined parameters. For example, in configuration 602, ten 100-nm-thick polycrystalline silicon thin film layers are alternately interleaved with 250-nm-thick silicon dioxide (SiO2) thin film layers (i.e., a spatial period of 0.35 μm) to filter the optical signal in wavelength range A. In configuration 604, ten 100-nm-high polycrystalline silicon thin layers are alternately interwoven with 305-nm-thick silicon dioxide (SiO2) thin film layers (i.e., a spatial period of 0.405 μm) for filtering the optical signal in wavelength range B. Different layer configurations can be stacked to combine the filtered signal ranges (optical wavelength ranges A and B in configuration 606). The optical filter stack 600 is provided with air in the region outside the upper cladding SiO2 upper cladding. The directivity of the light beam to the optical filter stack is 14.5°. The periodic change of the refractive index in the optical filter stack 600 results in a spectral stopband (negligible light transmittance) centered at a wavelength of ∼550 nm with a stopband spectral width of ∼250 nm. By modifying the materials and structural dimensions of the optical filter stack, other variations of the center stopband wavelength and the stopband spectral width can be achieved. Multiple groups of layers forming optical filter stacks with various stopband properties (e.g., different stopband wavelengths) can be combined in various ways to provide a net range of the stopband center wavelength and the stopband spectral width.

[0057] Figure 7 It is a table of the estimated electric field amplitude (|E|) distribution of the additional array units of the beam shaping stack 130 along the xz cross-section and the xy cross-section in the case of having the optical filter stack 120 at 702 and not having the optical filter stack 120 at 704, respectively.

[0058] In Example 702, the numerical simulation metal lens array cells forming the beam shaping stack 120 have defined parameters. For example, a 0.5-μm thick cylindrical columnar polysilicon structure serves as a phase mask cell with a pitch d = 0.65 μm, and the radius ranges from (0.275 to 0.475) x d, representing a 2π phase shift. Each layer is also covered with 0.25-μm thick silicon dioxide (between the cell cores), and there is air in the area outside the upper cladding cover layer. The beam directivity to the optical filtering stack 120 is 14.5°. The focal length of the metal lens array at 1.55 μm is approximately 4.5 μm, with the center at a distance Δx = 1 μm and Δy = 0 from the center of the array cell. In Configuration 704 without the optical filtering stack 120, an optical signal with a wavelength ranging from 1.0 μm to 1.6 μm is incident on the beam shaping stack 130 for beam focusing. At these wavelengths, the focal length of the metal lens array varies from ~4.5 μm to ~7.5 μm, which results in an enlarged focused area at a certain distance (here 4.5 μm) from the beam shaping stack 130.

[0059] The beam shaping stack 130 may include beam shaping layers with the same and / or different functions to simultaneously achieve the same, similar, or different functions for modifying beam characteristics. For example, the beam shaping stack 130 may include beam shaping layers with beam focusing and beam expanding functions combined in various ways, as Figure 8 shown. Both the beam expanding layer 831 and the beam focusing layer 861 of the beam shaping stack 130 can advantageously be made of a metal lens array, with array cells as Figure 5 shown, and the estimated electric field amplitude (|E|) distribution as Figure 7 shown.

[0060] The beam expanding layer 831 including metal array cells expands the width of the beam incident on this layer. This causes the net width of the beam to increase from w1 to w2 after passing through the beam focusing layer 861, and the widened beam is less spatially concentrated. Thus, the devices disclosed herein are scalable and provide flexibility in vertically integrating beam shaping layers on the optical receiver 110, and use discretized phase shift cells (i.e., beam shaping layer cells) to modify the beam characteristics of the optical receiver 110. Different stacked layers with the same, similar, or different functions can be used by vertically integrating them above the optical receiver 110, thereby achieving multifunctional layers (feature integration) on a single integration platform.

[0061] In addition, the optical receiver 110 with vertically stacked layers is very compact and fully integrated on the substrate 140. The beam shaping stack 130 can also have its position precisely set through chip design without any mechanical position setting, making the system more stable and less prone to mechanical errors. The optical receiver 110 is also cost-effective because the platform is fully integrated on the chip and additional stacked layers can be conveniently added using the same manufacturing steps. This convenience in manufacturing additional stacked layers enables mass production of such devices, thereby improving cost-effectiveness.

[0062] It will be apparent from the foregoing disclosure and the detailed description of certain embodiments that various modifications, additions, and other alternative embodiments can be made without departing from the true scope and spirit of the invention. The embodiments discussed were chosen and described in order to best illustrate the principles of the invention and its practical application, thereby enabling one of ordinary skill in the art to utilize the invention in various embodiments and make various modifications suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

1. A beam receiver assembly, comprising: An optical filter layer; A beam shaping layer; And A substrate having an optical receiver, wherein the optical filter layer and the beam shaping layer are positioned such that the optical receiver receives a beam that has passed through the optical filter layer and the beam shaping layer, Wherein the optical filter layer is configured to allow the beam to be transmitted within the wavelength range in which the optical receiver operates and attenuate other wavelengths; and Wherein the beam shaping layer is configured to spatially shape the optical amplitude of the beam onto a specific portion of the optical receiver.

2. The beam receiver assembly according to claim 1, wherein The beam shaping layer is disposed between the optical filter layer and the optical receiver.

3. The beam receiver assembly according to claim 1, characterized in that, The optical filter layer is disposed between the beam shaping layer and the optical receiver.

4. The beam receiver assembly according to any one of the preceding claims, further comprising a plurality of filter layers.

5. The beam receiver assembly according to claim 4, wherein The plurality of filter layers alternate between materials of high refractive index and low refractive index.

6. The beam receiver assembly according to claim 4 or 5, characterized in that One or more of the filter layers have different thicknesses.

7. The beam receiver assembly according to any one of claims 4 to 6, characterized in that Adjacent ones of the filter layers share a cladding.

8. The beam receiver assembly according to claim 7, wherein The cladding has a refractive index different from the core of each adjacent filter layer.

9. The beam receiver assembly according to claim 7 or 8, characterized in that, One or more of the claddings have different thicknesses.

10. The beam receiver assembly according to any one of the preceding claims, characterized in that, The optical filter layer enhances the beam falling within the wavelength range in which the optical receiver operates.

11. The beam receiver assembly according to any one of the preceding claims, further comprising a plurality of the beam shaping layers.

12. The beam receiver assembly according to any one of the preceding claims, characterized in that, The beam shaping layer includes an optical shaping element having one or more of the following cross-sections: elliptical, polygonal, or a closed Bessel curve.

13. The beam receiver assembly according to claim 12, wherein, The optical shaping elements are arranged in a lattice according to one of the following arrangements: triangular, square, or hexagonal.

14. The beam receiver assembly according to claim 12 or 13, characterized in that, The size of each optical shaping element depends on the focal point required at the location of the optical shaping element.

15. The beam receiver assembly according to claim 14, characterized in that, One or more lenses have different sizes, including one or more of height, diameter, and diagonal.

16. The beam receiver assembly according to any one of claims 11 to 15, characterized in that, Adjacent ones of the beam shaping layers share the cladding.

17. The beam receiver assembly according to claim 16, wherein, The cladding has a refractive index different from the core of each adjacent beam shaping layer.

18. The beam receiver assembly according to claim 16 or 17, characterized in that, One or more of the claddings have different thicknesses.

19. The beam receiver assembly according to any one of the preceding claims, characterized in that, The optical receiver includes one or more of the following: a free space photodetector array, a scatterer array, a waveguide integrated photodetector, a lens array, a photoelectric switch array, and a grating.

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