Reconfigurable optical logic gate based on pcsel and implementation method thereof

Abstract

This application discloses a PCSEL-based reconfigurable optical logic gate and its implementation method. The PCSEL-based reconfigurable optical logic gate includes: a modulated photonic crystal surface-emitting laser capable of generating two light spots; a polarization selection unit for polarization projection of the two light spots; a photodetector unit for receiving the two light spots after polarization projection; and a threshold decision unit for determining the output logic state based on the total output light intensity received by the photodetector unit. The PCSEL-based reconfigurable optical logic gate and its implementation method disclosed in this application effectively reduce the number of light sources, collimating and beam-combining elements, and optical path alignment steps, simplifying the optical path structure and facilitating miniaturization and low-cost packaging. It achieves stable logic output, reduces external polarization modulation and multi-level polarization control structures, improves output stability, reduces structural complexity, and enhances the decision stability and repeatability of the PCSEL-based reconfigurable optical logic gate.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, and in particular to reconfigurable optical logic gates based on PCSEL and their implementation methods. Background Technology

[0002] PCSEL (Photonic Crystal Surface-emitting Laser) utilizes in-plane feedback and vertical radiation coupling in a two-dimensional photonic crystal to achieve surface-emitting laser output. It features high beam quality, ease of integration into two-dimensional arrays, and the ability to control the far-field direction and beam shape through the photonic crystal structure.

[0003] Optical logic gates are core components of optical information processing systems and optical computing units. Traditional optical logic gates often employ a hybrid optoelectronic architecture, primarily based on discrete light source devices and detectors. Typically, two or more side-emitting lasers, vertical-cavity surface-emitting lasers, or external light sources represent the input logic. Multiple optical signals are then coupled to photodetector arrays, comparators, or digital circuits via collimating lenses, beam combiners / splitters, and other optical elements in the spatial optical path to perform AND, OR, XOR, and other logical operations. In this hybrid optoelectronic structure, the processing speed is limited by the bandwidth of the photodetector and the response speed of the subsequent electrical logic circuits, failing to fully utilize the speed advantage of full-domain optical signal processing. Furthermore, multiple discrete optical components and auxiliary driving circuits lead to complex optical path alignment, large system size, high packaging costs, and poor reliability, making it difficult to meet the requirements of on-chip integration and miniaturization applications. Summary of the Invention

[0004] To address one or more of the above problems, this application proposes a reconfigurable optical logic gate based on PCSEL and its implementation method.

[0005] According to one aspect of this application, a reconfigurable optical logic gate based on a PCSEL is provided, comprising: a modulated photonic crystal surface-emitting laser, a polarization selection unit, a photodetector unit, and a threshold decision unit. The modulated photonic crystal surface-emitting laser is capable of generating two light spots. The polarization selection unit is used to perform polarization projection on the two light spots generated by the modulated photonic crystal surface-emitting laser. The photodetector unit is used to receive the two light spots after polarization projection to obtain the total output light intensity. The threshold decision unit is used to determine the output logic state based on the total output light intensity received by the photodetector unit.

[0006] According to another aspect of this application, a method for implementing a PCSEL-based reconfigurable optical logic gate is provided, for implementing any of the above PCSEL-based reconfigurable optical logic gates, including the following steps: S11: A modulated photonic crystal surface-emitting laser forms two light spots under the operating current, denoted as the first light spot and the second light spot; S12: The first and second light spots are polarized and projected through the polarization selection unit to map the polarization state of the two light spots into the output light intensity. S13: The two light spots after polarization projection are received by the same photoelectric detection unit to obtain the total output light intensity. S14: The threshold decision unit determines the output logic state based on the output light intensity after polarization projection and the total output light intensity received by the photoelectric detection unit.

[0007] The reconfigurable optical logic gate based on PCSEL disclosed in this application and its implementation method can achieve the following technical effects: (1) By generating two spatially separated light spots through a modulated photonic crystal surface-emitting laser, the two spatial beams are converted into two logic state channels, which improves the functional reuse of the device, effectively reduces the number of light sources, collimating and beam combining elements and optical path alignment steps, simplifies the optical path structure, and is more conducive to miniaturization and low-cost packaging. (2) The two light spots generated by the modulated photonic crystal surface-emitting laser can have their emission direction, polarization state and relative intensity designed in the photonic crystal layer of the modulated photonic crystal surface-emitting laser. The linear polarization, circular polarization or elliptical polarization state required for the logic state can be directly formed at the light source end. Stable logic output can be achieved through polarization selection unit, photoelectric detection unit and threshold decision unit, reducing external polarization modulation and multi-level polarization control structure, improving output stability and reducing structural complexity; (3) By presetting the threshold in the threshold decision unit and outputting the logic state according to the threshold, the decision stability and repeatability of the reconfigurable optical logic gate are improved; (4) The two light spots generated by the same modulated photonic crystal surface-emitting laser are used as logic inputs, so that the two logic inputs have good consistency in packaging position, thermal environment and driving conditions, which can improve the decision stability of the logic gate under power drift, temperature change and small spot position shift conditions.

[0008] (5) By introducing a longitudinal aperture depth distribution associated with the first spatial modulation component and the second spatial modulation component in the photonic crystal supercell, it is possible to compensate or weight the relative radiation coupling intensity of the two logic channels while maintaining the predetermined emission direction and polarization state of the two far-field light spots. Furthermore, the intensity interval between logic states can be increased by designing multi-level aperture depth and aperture bottom position, thereby improving the threshold decision margin. Attached Figure Description

[0009] Figure 1This is a schematic diagram of a reconfigurable optical logic gate based on PCSEL, provided as an embodiment of this application.

[0010] Figure 2 A flowchart illustrating an implementation method of a PCSEL-based reconfigurable optical logic gate according to an embodiment of this application. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only some, not all, embodiments of this invention, and are used merely to explain the invention and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0012] Example 1: Reference manual attached Figure 1 The present invention provides a reconfigurable optical logic gate based on PCSEL, which may include: a modulated photonic crystal surface-emitting laser 1, a polarization selection unit 2, a photodetector unit 3, and a threshold decision unit 4.

[0013] The modulated photonic crystal surface-emitting laser 1 can be configured to generate two beams with predetermined directions, and the two beams can form two spatially separated spots on the far-field projection surface. These two spots formed by the beams emitted by the modulated photonic crystal surface-emitting laser on the far-field projection surface can be denoted as the first spot and the second spot, respectively. The polarization directions of the first spot and the second spot are adjustable. By controlling the polarization directions of the first spot and the second spot, an output of logic state 0 or logic state 1 can be achieved.

[0014] The polarization selection unit 2 can perform polarization projection on the first light spot and the second light spot, so that the polarization state of the two light spots is mapped to the output light intensity.

[0015] The photoelectric detection unit 3 can receive the two light spots after polarization projection and obtain the total output light intensity I. o .

[0016] Threshold decision unit 4 is used to determine the output logic state based on the total output light intensity received by the photoelectric detection unit.

[0017] In an optional embodiment, the modulated photonic crystal surface-emitting laser 1 is provided with a photonic crystal layer, which is disposed on the side of the active layer away from the substrate layer.

[0018] The photonic crystal layer can incorporate two-dimensional periodic structures and modulation structures. The modulation structures can include any one or more of the following: aperture modulation, aperture shape modulation, aperture position modulation, aperture depth modulation, aperture bottom position modulation, supercell modulation, dual-lattice modulation, local defect modulation, refractive index modulation, and current injection region modulation. Therefore, the modulated photonic crystal surface-emitting laser 1 can generate two beams with predetermined directions under operating current, and the light spots formed by these two beams on the far-field projection surface can be spatially separated.

[0019] In an optional embodiment, the photonic crystal layer may include a two-dimensional periodic lattice and a first spatial modulation component and a second spatial modulation component superimposed on the two-dimensional periodic lattice. The first spatial modulation component is used to form a first far-field radiation channel, enabling the modulated photonic crystal surface-emitting laser to form a first light spot on the far-field projection surface. The second spatial modulation component is used to form a second far-field radiation channel, enabling the modulated photonic crystal surface-emitting laser to form a second light spot on the far-field projection surface.

[0020] The first spatial modulation component and the second spatial modulation component can be achieved by different modulation wave vectors, modulation directions, modulation periods, hole displacement vectors, hole diameter variations, hole shape orientations, fill factors, hole depth distributions, hole bottom positions, or local defect distributions.

[0021] Specifically, the photonic crystal layer may include a basic two-dimensional periodic lattice and a supercell structure disposed within the basic two-dimensional periodic lattice. The basic two-dimensional periodic lattice may be a square lattice, and the basic two-dimensional period may be denoted as a. In one embodiment, for a modulated photonic crystal surface-emitting laser with an operating wavelength around 940 nm, the basic period a may be set to 270 nm to 320 nm.

[0022] The supercell structure can be configured to have a first supercell period Ax along a first direction and a second supercell period Ay along a second direction. The first supercell period Ax can refer to having Nx basic two-dimensional periodic lattices along the first direction, and the second supercell period Ay can refer to having Ny basic two-dimensional periodic lattices along the second direction, where at least one of Nx and Ny is greater than 1, and Nx and Ny are integers. The first and second directions are perpendicular to each other.

[0023] In one implementation, the values ​​of Nx and Ny can range from 3 to 10. By setting a first supercell period and a second supercell period, the energy bands of the basic two-dimensional periodic lattice are folded in the Brillouin zone corresponding to the supercell structure, and the target folding mode forms a radiation channel that can couple with free space.

[0024] When Ax and Ay are between 3a and 5a, a first and second light spot with a relatively large spatial separation can be formed; when Ax and Ay are between 5a and 10a, a first and second light spot with a relatively small spatial separation can be formed. Therefore, different supercell periods can be selected based on the required spot spacing of the polarization selection unit 2 and the beam collection unit 5 to obtain a first and second light spot with suitable spatial separation.

[0025] When Ax and Ay are too small, the corresponding supercell reciprocal lattice vector increases, and the folded target radiation channel deviates from the predetermined free space propagation conditions. The exit angles of the first and second light spots are too large, which is not conducive to the parameter selection of polarization selection unit 2 and beam collection unit 5. When Ax and Ay are too large, the spatial separation of the two target radiation channels decreases, and the number of folded bands in the supercell increases, making the non-target folded mode close to the target mode. This will cause parasitic light spots and mode competition problems, affecting the realization of reconfigurable optical logic gates.

[0026] The supercell structure may include at least two sets of air holes with positional differences relative to the basic two-dimensional periodic lattice. Air holes can be circular, elliptical, rectangular, irregularly shaped, or bilattice-like. The positional offset of the air hole relative to its corresponding basic lattice point is denoted as d, and the positional offset d can be set to 0.02a~0.20a.

[0027] The supercell structure may include a first air hole group and a second air hole group. The first air hole group and the second air hole group are offset in opposite directions relative to their corresponding basic lattice points. If the offset of the first air hole group is denoted as +d, then the offset of the second air hole group can be denoted as -d.

[0028] When the position offset d is too small, the supercell perturbation is insufficient, and the coupling between the target folding mode and free space is weak, which reduces the out-of-plane output intensity of the first and second beam spots. When the position offset d is too large, the influence of the supercell perturbation on the basic two-dimensional periodic feedback is enhanced, and additional spatial Fourier components are generated, thereby increasing the non-target radiation channels, side lobes and higher-order modes, and reducing the beam quality of the target mode.

[0029] The first and second air hole groups can use the same or nearly the same aperture, aperture shape, and absolute value of positional offset. In this case, the supercell structure forms an approximately symmetrical refractive index distribution about a predetermined direction, and the first and second light spots can achieve approximately balanced output. Approximately balanced output means that the first and second light spots have the same or close output light intensity before entering the polarization selection unit 2.

[0030] The first and second air hole groups can have different positional offsets, apertures, shapes, fill factors, average hole depths, or bottom positions. In this case, the supercell structure forms an asymmetric refractive index distribution, and the first and second light spots have different output coupling strengths. Therefore, the intensity weights corresponding to the two logic inputs can be further adjusted.

[0031] The first air hole group and the second air hole group can adopt the same anisotropic aperture orientation, so that the first light spot and the second light spot can have the same predetermined polarization state; the first air hole group and the second air hole group can adopt different anisotropic aperture orientations, so that the first light spot and the second light spot form different polarization states.

[0032] Therefore, by combining at least two of the parameters among the supercell period, air hole position offset, air hole size, air hole orientation, air hole depth, and distance from the bottom of the hole to the active layer, the modulated photonic crystal surface-emitting laser can directly form a spatially separated first and second spot in the working state, and make the first and second spots have a predetermined emission direction, output intensity relationship, and polarization state.

[0033] When the first air hole group and the second air hole group have the same absolute value of positional offset, the same or approximately the same air hole size, and the same or approximately the same average hole depth, the first light spot and the second light spot are in an approximately balanced output state. At this time, the modulated photonic crystal surface-emitting laser is suitable for the working mode in which the two logic inputs have the same logic weight.

[0034] Assume that the first and second light spots have high transmittance and low transmittance states respectively after passing through polarization selection unit 2. When both the first and second light spots are in the low transmittance state, the total output light intensity is denoted as I. 00 When the first light spot is in a high transmittance state and the second light spot is in a low transmittance state, the total output light intensity is denoted as I. 10 When the first light spot is in a low transmittance state and the second light spot is in a high transmittance state, the total output light intensity is denoted as I. 01 When both the first and second light spots are in a high transmittance state, the total output light intensity is denoted as I. 11 For an approximately balanced output structure, the four input states form the following strength relationship: I 00 01 ≈I 10 11 .

[0035] Therefore, it is possible to I 00 with I 01 Or I 00 with I 10 Set a decision threshold between them, implementing OR logic; it can be done in I 01 ​​with I 11 Or I 10 with I 11 A decision threshold is set between the thresholds to implement AND logic; this can be achieved by adjusting the I values ​​within the intermediate strength range. 01 and I 10 A window decision is made to implement XOR logic. By reversing the aforementioned decision result, NOR logic, NAND logic, and XNOR logic can be further implemented.

[0036] When the first and second air hole groups have different positional offsets, different air hole sizes, different average hole depths, different longitudinal volume fill factors, and / or different hole bottom positions, the first and second light spots are in an unbalanced output state, and I... 01 ≠I 10 .

[0037] Therefore, by setting multiple intensity decision intervals, the intermediate states corresponding to the first logical input of the first spot and the second logical input of the second spot can be further distinguished, so that the threshold decision unit 4 can select different logical decision rules according to different intensity intervals, thereby improving the reconfigurable freedom of the logic function.

[0038] In an optional embodiment, in order to enable the longitudinal structure of the photonic crystal in the modulated photonic crystal surface-emitting laser 1 to participate in the parameter setting of two logic channels simultaneously, the air hole depth can be used as a longitudinal modulation degree of freedom independent of the in-plane hole displacement, hole diameter and hole orientation.

[0039] A supercell structure can have at least three different air holes with different depths. The depth of each air hole is determined according to the modulation state of the first spatial modulation component and the second spatial modulation component at the corresponding lattice position. The hole depth distribution of the supercell and the in-plane spatial modulation of the supercell constitute a three-dimensional modulation structure. The in-plane spatial modulation is used to set the emission direction and / or polarization state of the first light spot and the second light spot, and the hole depth distribution is used to adjust the relative output intensity of the first light spot and the second light spot.

[0040] Define the effective thickness of the photonic crystal layer as t PC Each type of air hole with a different depth within the photonic crystal layer is defined as a class of air holes, and the depth of the i-th type of air hole is denoted as h. i Let i be an integer not less than 3, and define the normalized hole depth η. i η i =h i / t PC or η i =h i / a.

[0041] For different air pores in the same supercell structure, the air pores η with the same depth iSimilarly, since there are at least three different air pore depths in the same supercell structure, there can be at least three different values ​​of η in the same supercell structure. i .

[0042] The photonic crystal layer also includes a first air hole group and a second air hole group. The first air hole group can correspond to the first spatial modulation component, and the second air hole group can correspond to the second spatial modulation component. The first air hole group has a first average hole depth h1, and the second air hole group has a second average hole depth h2. The first average hole depth h1 and the second average hole depth h2 are not equal. By adjusting the difference between the first average hole depth h1 and the second average hole depth h2, the relative output coupling strength of the first far-field radiation channel and the second far-field radiation channel can be adjusted.

[0043] Specifically, the first average aperture depth h1 and the second average aperture depth h2 can be set around the common aperture depth h0, where h0 can range from 0.2a to 3a. Therefore, h1 = h0 + Δh and h2 = h0 - Δh. Thus, while keeping the sum of the first and second average aperture depths constant, the difference in longitudinal radiation coupling caused by the two air aperture groups can be adjusted by changing the differential aperture depth Δh, thereby reducing the impact on the overall average longitudinal perturbation of the photonic crystal when adjusting the relative output weights of the two logic channels.

[0044] The depth distribution within the first air hole group can be correlated with the first spatial modulation component, and the depth distribution within the second air hole group can be correlated with the second spatial modulation component. For example, the first air hole group can be used at lattice locations that contribute significantly to the first far-field radiation channel, and the second air hole group can be used at lattice locations that contribute significantly to the second far-field radiation channel. Thus, the in-plane modulation wave vector, hole displacement direction, and hole orientation are used to form two predetermined far-field radiation channels, and the longitudinal hole depth difference is further used to adjust the radiation coupling strength of the two far-field radiation channels, thereby achieving at least partial decoupling between the emission direction, polarization relationship, and logic channel output weights.

[0045] In an optional embodiment, L aperture depths can be set within a supercell structure, where L can be 3 to 8, and each aperture depth repeats periodically with the supercell. Each aperture depth is allocated based on the modulation states of the first and second spatial modulation components at corresponding lattice points. For example, when the two spatial modulation components have positive and negative modulation states respectively, the corresponding lattice points can be divided into four categories and set to at least three aperture depths from h0+Δh1+Δh2, h0+Δh1-Δh2, h0-Δh1+Δh2, and h0-Δh1-Δh2, where Δh1 and Δh2 can range from 0.2a to a, thereby further mapping the two in-plane spatial modulation components into multi-level vertical depth coding.

[0046] In an optional embodiment, the longitudinal volume fill factor F of the i-th type of air hole can be defined. v,i This is used to characterize the volume proportion occupied by the air hole in the effective volume of a photonic crystal corresponding to a basic lattice. For a cross-sectional area A along the depth direction... i (z) air hole, F v,i The expression is as follows: F v,i =[∫A i (z)dz] / (a 2 ·t PC ).

[0047] Therefore, even if the first and second air hole groups have the same or nearly the same aperture and in-plane shape on the photonic crystal surface, different F values ​​can be obtained by varying the hole depth, sidewall inclination angle, or longitudinal cross-sectional area. v,i And adjust the relative radiative coupling strength of the two logic channels accordingly.

[0048] In an optional embodiment, the distance from the bottom of the air hole to the nearest boundary of the active layer is defined as g. i The first and second air hole groups can have different g1 and g2 values, respectively. One of the first and second air hole groups can terminate inside the photonic crystal layer, while the other can extend to the interface between the photonic crystal layer and the adjacent semiconductor layer or partially enter the adjacent semiconductor layer. Without entering the active region, by setting g1 and g2, the degree of overlap between the corresponding air hole and the longitudinal guided mode can be changed, making the hole bottom position another longitudinally limiting parameter besides the hole depth.

[0049] Taking the optional parameter h as an example for the operating wavelength around 940nm, the air hole depth is... i It can be set to 0.2a to 3a, and the depth difference between different hole depths can be set to 0.05a to 1.0a; when both the first and second air hole groups are confined inside the photonic crystal layer, it can be set to 0.2≤η. i ≤1.0, when at least one of the first and second air hole groups extends into the adjacent semiconductor layer, η i The value can be greater than 1. The above values ​​are used to provide an optional design window. The specific hole depth and hole bottom position can be determined by simulation or calibration based on the longitudinal pattern distribution, the minimum remaining layer thickness allowed by the process, and the target far-field radiation intensity.

[0050] For approximately balanced logic inputs, by setting h1, h2, and F v,1 and F v,2 This ensures that the power ratio RP of the first and second light spots before entering the polarization selection unit is within a predetermined balance tolerance range, for example, 0.8 ≤ RP ≤ 1.25, and also ensures that I 01 with I10 They fall into the same decision interval. For unbalanced logic inputs, RP can be made to deviate from the balance tolerance range by increasing the difference in hole depth, the difference in longitudinal volume fill factor, and / or the difference in hole bottom position, and I can be made to... 01 with I 10 The absolute value of the difference is not less than the preset minimum decision interval ΔI. min This allows for the direct setting of different light intensity weights for two logic inputs using the vertical structure of the photonic crystal.

[0051] In an optional embodiment, the aperture depth distribution and the radiation phase of the non-target spatial Fourier components can be jointly designed so that the target radiation components from different aperture depth levels maintain a predetermined coherent superposition relationship in the first and second far-field radiation channels, while at least one non-target radiation channel exhibits partial cancellation. This allows for the suppression of parasitic spots and background radiation without solely relying on reducing the supercell period or aperture displacement, thereby increasing the decision margin between the total output light intensity corresponding to different logic input states.

[0052] In optional embodiments, the polarization states of the first and second light spots can be designed separately using different modulation regions, modulation directions, modulation displacement vectors, air hole fill factors, local defects, or dual-lattice modulation parameters within the same photonic crystal layer. The first and second spatial modulation components, along with their corresponding hole displacement directions, hole orientations, or bidirectional modulation phases, can be customized according to actual application requirements. The first and second light spots can be configured with the same linear polarization, orthogonal linear polarization, left-handed circular polarization, right-handed circular polarization, or ellipsoidal polarization with different ellipticities.

[0053] The modulated photonic crystal surface-emitting laser 1 can simultaneously control the output beam direction, far-field spot shape, and polarization state within the laser device by adjusting the position of the photonic crystal air hole, modulation direction, modulation period, modulation displacement, double lattice displacement direction, or lattice point spatial modulation method.

[0054] Specifically, when the air hole undergoes periodic position shifts mainly along a fixed direction, a unidirectional position modulation structure for generating specific linearly polarized light spots can be formed; when the air hole undergoes position shifts with a preset phase relationship in two orthogonal directions simultaneously, a bidirectional position modulation structure for generating left-handed or right-handed circularly polarized light spots can be formed; under certain design conditions, the output polarization can be largely independent of the direction of the outgoing beam.

[0055] The modulated photonic crystal surface-emitting laser 1 may further include a waveplate, a liquid crystal polarization modulator, an on-chip polarization rotator, or a drive control unit. This allows for auxiliary adjustment of the polarization state, enabling the modulated photonic crystal surface-emitting laser 1 to output either logic state 1 or logic state 0.

[0056] Therefore, by setting the structural parameters of the modulated photonic crystal surface-emitting laser 1, the modulated photonic crystal surface-emitting laser 1 can emit two beams with different directions. These two beams can form two spatially separated light spots on the far-field projection surface. The emission direction, far-field spot shape and polarization state of the two beams can be adjusted, that is, the two logic states required by the optical logic gate can be formed at the output end of the modulated photonic crystal surface-emitting laser 1.

[0057] Specifically, the first and second light spots can be linearly polarized light, circularly polarized light, or elliptically polarized light.

[0058] When both the first and second light spots are linearly polarized light, the polarization selection unit 2 can be set as a linear polarizer.

[0059] Taking the first and second light spots as linearly polarized light as an example, assuming that the polarization direction of the first and second light spots is the first direction, the output logic state is 1, and the polarization direction of the first and second light spots is the second direction, the output logic state is 0. Since the first and second directions are orthogonal, the first and second light spots can present four combinations of logic states, namely 00, 01, 10 and 11.

[0060] When the transmission axis of the linear polarizer is parallel to the first direction, the transmission intensity of the first or second light spot after passing through the polarizer is high when the polarization direction of the first or second light spot is the first direction, corresponding to logic state 1. At this time, when the polarization direction of the first or second light spot is the second direction, the transmission intensity of the first or second light spot after passing through the polarizer is low, corresponding to logic state 0.

[0061] When the first and second light spots are circularly polarized or elliptically polarized light, polarization selection unit 2 can be configured as a quarter-wave plate and a linear polarizer. Alternatively, polarization selection unit 2 can employ a circular polarization analyzer. In this case, polarization selection unit 2 can map left-handed circular polarization, right-handed circular polarization, or polarization states with different ellipticities to different transmitted light intensities. Thus, by using circular or elliptical polarization, the logic state is not limited to 0° or 90° linear polarization, thereby improving the coding freedom and resistance to optical path rotation disturbances.

[0062] When the first and second light spots are linearly polarized light, the first and second light spots can complete four logic state combinations at the output end of the modulated photonic crystal surface-emitting laser 1. After the first and second light spots are polarized and projected by the polarization selection unit 2, the light spot corresponding to logic state 1 achieves high intensity transmission, and the light spot corresponding to logic state 0 achieves low intensity transmission. That is, the polarization selection unit 2 maps the logic states represented by the first and second light spots to the output light intensity.

[0063] In an optional embodiment, a beam collecting unit 5 may also be provided between the polarization selection unit 2 and the photoelectric detection unit 3. The beam collecting unit 5 can converge the first and second light spots after polarization projection by the polarization selection unit 2 to the photoelectric detection unit 3. Thus, the transmitted light from the first and second light spots after polarization selection is not divided into detection surfaces, but is received by the same photoelectric detection unit 3.

[0064] In an optional embodiment, the beam collecting unit 5 may be a focusing lens, the parameters of which can be set according to the far-field angles of the first and second light spots and the distance between the two light spots. The parameters of the focusing lens may include numerical aperture, focal length, and receiving aperture.

[0065] The photodetector unit 3 is configured to simultaneously receive two light spots and obtain the total output light intensity. Therefore, the output signal no longer depends on the light intensity distribution in different regions of the photodetector, but rather on the projection of the polarization vectors of the two light spots onto the transmission axis of the polarizer, effectively reducing the dependence of the optical logic gate on the light spot position, the photodetector partition boundaries, and the precise alignment of the optical path.

[0066] The threshold decision unit 4 is pre-set with several thresholds. The threshold decision unit 4 can determine the total output light intensity I collected by the photoelectric detection unit 3. o The logic state is compared with a pre-set threshold, and the final output logic state is determined, i.e., logic state 1 or logic state 0.

[0067] For the OR gate, a first threshold can be set in the threshold decision unit 4. When the output light intensity I... o When the light intensity exceeds the first threshold, it is determined that at least one of the first or second light spots is in logic state 1, that is, at least one of the first or second light spots is in a high-intensity transmission state after passing through the polarization selection unit 2. Logic state 1 is then output. When the total output light intensity I... o When the value is below the first threshold, it is determined that both the first and second light spots are in logic state 0, and logic state 0 is output.

[0068] In an optional embodiment, let the light intensity when a single light spot transmits at high intensity be I. H The light intensity when a single light spot transmits at low intensity is I. L Then the value of the first threshold can be greater than 2I. L And less than I H +I L .

[0069] For the AND gate, a second threshold can be set in threshold decision unit 4, when the output light intensity I... oWhen the light intensity exceeds the second threshold, it is determined that both the first and second light spots are in logic state 1, meaning that both the first and second light spots are in a high-intensity transmission state after passing through the polarization selection unit 2. Therefore, logic state 1 is output, and the total output light intensity I... o When the value is below the second threshold, it is determined that at least one of the first and second light spots is in logic state 0, and logic state 0 is output.

[0070] In an optional embodiment, let the light intensity when a single light spot transmits at high intensity be I. H The light intensity when a single light spot transmits at low intensity is I. L Then the value of the second threshold can be greater than I. H +I L And less than 2I H .

[0071] For NOR and NAND gates, the decision process can be reversed based on the above OR and AND gate decision processes. The specific decision process will not be elaborated here. Specifically, this can be achieved by adding an inverter to the circuit or changing the decision direction of the comparator.

[0072] For the XOR gate, the threshold decision unit 4 can be set with a third threshold and a fourth threshold, where the third threshold is lower than the fourth threshold. When the output light intensity I... o When the light intensity is higher than the third threshold and lower than the fourth threshold, it is determined that only one of the first and second light spots is in logic state 1, that is, only one of the two light spots is in a high-intensity transmission state after passing through the polarization selection unit 2, and logic state 1 is output; when the output light intensity I o When the light intensity is below the third threshold, it is determined that both the first and second light spots are in logic state 0, and the output light intensity I... o When the light intensity exceeds the fourth threshold, it is determined that both the first and second light spots are in logic state 1, that is, when the total output light intensity I... o If the value is below the third threshold or above the fourth threshold, the output logic state is 0.

[0073] In an optional embodiment, let the light intensity when a single light spot transmits at high intensity be I. H The light intensity when a single light spot transmits at low intensity is I. L Then the value of the third threshold can be greater than 2I. L And less than I H +I L The fourth threshold can be greater than I. H +I L And less than 2I H Furthermore, the third threshold is less than the fourth threshold.

[0074] For the XNOR gate, the decision process of the XOR gate described above can be reversed to achieve the desired result. The specific decision process will not be described in detail here.

[0075] The reconfigurable optical logic gate based on PCSEL disclosed in this application uses two spatially separated light spots output from the same modulated photonic crystal surface-emitting laser as two logic input channels. The logic state of the light spots is encoded in their polarization states. Then, the two light spots are uniformly polarized and projected by the same polarization selection unit, mapping the logic state to light intensity. The two light spots after polarization projection are received by the same photodetector unit. Finally, the threshold judgment unit determines the output logic state based on the total output light intensity received by the photodetector unit, ultimately realizing six basic logic gates: OR gate, AND gate, NOR gate, NAND gate, XOR gate, and XNOR gate.

[0076] The reconfigurable optical logic gate based on PCSEL disclosed in this application can achieve the following technical effects: (1) By generating two spatially separated light spots through a modulated photonic crystal surface-emitting laser, the two spatial beams are converted into two logic state channels, which improves the functional reuse of the device, effectively reduces the number of light sources, collimating and beam combining elements and optical path alignment steps, simplifies the optical path structure, and is more conducive to miniaturization and low-cost packaging. (2) The two light spots generated by the modulated photonic crystal surface-emitting laser can have their emission direction, polarization state and relative intensity designed in the photonic crystal layer of the modulated photonic crystal surface-emitting laser. The linear polarization, circular polarization or elliptical polarization state required for the logic state can be directly formed at the light source end. Stable logic output can be achieved through polarization selection unit, photoelectric detection unit and threshold decision unit, reducing external polarization modulation and multi-level polarization control structure, improving output stability and reducing structural complexity; (3) By presetting the threshold in the threshold decision unit and outputting the logic state according to the threshold, the decision stability and repeatability of the reconfigurable optical logic gate are improved; (4) The two light spots generated by the same modulated photonic crystal surface-emitting laser are used as logic inputs, so that the two logic inputs have good consistency in packaging position, thermal environment and driving conditions, which can improve the decision stability of the logic gate under power drift, temperature change and small spot position shift conditions.

[0077] (5) By introducing a longitudinal aperture depth distribution associated with the first spatial modulation component and the second spatial modulation component in the photonic crystal supercell, it is possible to compensate or weight the relative radiation coupling intensity of the two logic channels while maintaining the predetermined emission direction and polarization relationship of the two far-field light spots. Furthermore, the intensity interval between logic states can be increased by designing multi-level aperture depth and aperture bottom position, thereby improving the threshold decision margin.

[0078] Example 2: Reference manual attached Figure 2 The present invention also provides a method for implementing a PCSEL-based reconfigurable optical logic gate, applicable to any PCSEL-based reconfigurable optical logic gate in the above embodiments, comprising the following steps: S11: A modulated photonic crystal surface-emitting laser forms two light spots under the operating current, denoted as the first light spot and the second light spot; S12: The first and second light spots are polarized and projected through the polarization selection unit to map the polarization state of the two light spots into the output light intensity. S13: The two light spots after polarization projection are received by the same photoelectric detection unit to obtain the total output light intensity. S14: The threshold decision unit determines the output logic state based on the output light intensity after polarization projection and the total output light intensity received by the photoelectric detection unit.

[0079] Other content that is the same as in the embodiments will not be repeated here.

[0080] The above description is only an optional implementation of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A reconfigurable optical logic gate based on PCSEL, characterized in that, include: Modulated photonic crystal surface-emitting laser, polarization selection unit, photoelectric detection unit, and threshold decision unit. The modulated photonic crystal surface-emitting laser can generate two light spots; The polarization selection unit is used to perform polarization projection on the two light spots generated by the modulated photonic crystal surface-emitting laser. The photoelectric detection unit is used to receive two light spots after polarization projection to obtain the total output light intensity. The threshold decision unit is used to determine the output logic state based on the total output light intensity received by the photoelectric detection unit.

2. The reconfigurable optical logic gate based on PCSEL according to claim 1, characterized in that, The modulated photonic crystal surface-emitting laser is provided with a photonic crystal layer, which is disposed on the side of the active layer away from the substrate layer.

3. The reconfigurable optical logic gate based on PCSEL according to claim 2, characterized in that, The photonic crystal layer includes a two-dimensional periodic lattice and a first spatial modulation component and a second spatial modulation component superimposed on the two-dimensional periodic lattice. The first spatial modulation component is used to form a first far-field radiation channel, enabling the modulated photonic crystal surface-emitting laser to form a first light spot on the far-field projection surface. The second spatial modulation component is used to form a second far-field radiation channel, enabling the modulated photonic crystal surface-emitting laser to form a second light spot on the far-field projection surface.

4. The reconfigurable optical logic gate based on PCSEL according to claim 3, characterized in that, The first spatial modulation component and the second spatial modulation component are respectively adopted by at least one of aperture modulation, aperture shape modulation, aperture position modulation, aperture depth modulation, aperture bottom position modulation, supercell modulation, double lattice modulation, local defect modulation, refractive index modulation or current injection region modulation.

5. The PCSEL-based reconfigurable optical logic gate according to claim 3 or 4, characterized in that, The photonic crystal layer includes a first air hole group and a second air hole group. The first air hole group corresponds to the first spatial modulation component, and the second air hole group corresponds to the second spatial modulation component. The first air hole group has a first average hole depth, and the second air hole group has a second average hole depth. The first average hole depth and the second average hole depth are not equal. By adjusting the difference between the first average hole depth and the second average hole depth, the relative output coupling strength of the first far-field radiation channel and the second far-field radiation channel can be adjusted.

6. The reconfigurable optical logic gate based on PCSEL according to claim 5, characterized in that, A supercell structure has at least three types of air holes with different depths. The depth of each air hole is determined according to the modulation state of the first spatial modulation component and the second spatial modulation component at the corresponding lattice position. The depth distribution of the supercell and the in-plane spatial modulation of the supercell constitute a three-dimensional modulation structure. The in-plane spatial modulation is used to set the emission direction and / or polarization state of the first light spot and the second light spot. The depth distribution is used to adjust the relative output intensity of the first light spot and the second light spot.

7. The reconfigurable optical logic gate based on PCSEL according to claim 3, characterized in that, The polarization states of the first light spot and the second light spot are determined by the first spatial modulation component and the second spatial modulation component, respectively. The polarization states of the first light spot and the second light spot are set by setting at least one of the modulation direction, aperture displacement direction, aperture orientation, fill factor, local defect or dual-lattice modulation parameters of the first spatial modulation component and the second spatial modulation component, respectively.

8. The reconfigurable optical logic gate based on PCSEL according to claim 1, characterized in that, A beam collecting unit is also provided between the polarization selection unit and the photoelectric detection unit. The beam collecting unit is used to converge the light spot after polarization projection by the polarization selection unit to the photoelectric detection unit.

9. The reconfigurable optical logic gate based on PCSEL according to claim 1, characterized in that, The threshold decision unit can make decisions on six basic logic gates: OR gate, AND gate, NOR gate, NAND gate, XOR gate, and XNOR gate.

10. A method for implementing reconfigurable optical logic gates based on PCSEL, characterized in that, The reconfigurable optical logic gate based on PCSEL according to any one of claims 1-9 includes: S11: A modulated photonic crystal surface-emitting laser forms two light spots under the operating current, denoted as the first light spot and the second light spot; S12: The first and second light spots are polarized and projected through the polarization selection unit to map the polarization state of the two light spots into the output light intensity. S13: The two light spots after polarization projection are received by the same photoelectric detection unit to obtain the total output light intensity. S14: The threshold decision unit determines the output logic state based on the output light intensity after polarization projection and the total output light intensity received by the photoelectric detection unit.

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