Optical engine, device and method

Abstract

An optical engine for infrared (IR) upconversion imaging, wherein the optical engine comprises a metasurface (1) comprising metasurface unit cells (10), each metasurface unit cell (10) featuring a nanoresonator with an asymmetrical protrusion (13).

Description

[0001] Sony Semiconductor Solutions Corporation et al.

[0002] OPTICAL ENGINE, DEVICE AND METHOD

[0003] TECHNICAL FIELD

[0004] The present disclosure generally pertains to the technical field of optical engineering and photonics, specifically focusing on infrared (IR) upconversion imaging.

[0005] TECHNICAL BACKGROUND

[0006] The technical field of optical engineering and photonics involves the study and application of light (photons) and its interaction with various materials and systems. This field encompasses a broad range of technologies including lasers, optics, fiber optics, and photon-based sensing systems.

[0007] Infrared (IR) upconversion imaging involves converting infrared light into visible or short-wave infrared (SWIR) light to create images that are visible to the human eye or detectable by standard imaging sensors. This is particularly useful in applications such as night-vision, thermal imaging, medical diagnostics, and surveillance, where visibility in low-light or through obscurants like fog and smoke is necessary.

[0008] Although there exist techniques for upconversion of Infrared (IR) light, it is generally desirable to improve on existing techniques.

[0009] SUMMARY

[0010] According to a first aspect there is provided an optical engine for infrared (IR) upconversion imaging, wherein the optical engine comprises a metasurface comprising metasurface unit cells, each metasurface unit cell featuring a nanoresonator with an asymmetrical protrusion.

[0011] According to a second aspect there is provided an optical device comprising the optical engine for infrared (IR) upconversion imaging, wherein the optical engine comprises a metasurface comprising metasurface unit cells, each metasurface unit cell featuring a nanoresonator with an asymmetrical protrusion. The optical engine is configured to convert infrared (IR) light into visible or short-wave infrared (SWIR) light, and the optical device includes a detection system for capturing the upconverted light.

[0012] According to another aspect, there is provided a method for upconverting infrared (IR) light to visible or short-wave infrared (SWIR) light, comprising: generating a pump beam using a narrowband light source, generating a signal beam that carries infrared information from a target object, directing the pump beam and the signal beam onto an optical engine that includes Sony Semiconductor Solutions Corporation et al. metasurface unit cells, each unit cell featuring a nanoresonator with an asymmetrical protrusion, and detecting, using an imaging sensor, an upconverted signal beam that has been upconverted by the optical engine to visible or SWIR frequencies.

[0013] Further aspects are set forth in the dependent claims, the drawings and the following description.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Embodiments are explained by way of example with respect to the accompanying drawings, in which:

[0016] Fig. 1 presents a schematic representation of an upconversion device engineered for infrared (IR) imaging applications;

[0017] Fig. 2 illustrates a nonlinear metasurface-based optical engine comprising the upconversion device of Fig. 1, designed for high-quality upconversion of infrared light to visible or short-wave infrared (SWIR) light;

[0018] Fig. 3 is a block diagram illustrating elements and processes involved in the nonlinear metasurface-based optical engine designed for efficient IR upconversion imaging;

[0019] Fig. 4 is a comparative chart representing the performance metrics of various metamaterials used in upconversion processes, specifically focusing on their effectiveness in second harmonic generation (SHG);

[0020] Fig. 5a depicts a schematic view of an embodiment of the metasurface unit cell;

[0021] Fig. 5b is a zoomed in view of the metasurface unit cell from Fig. 5a, whereby the arrows highlight the protrusions lx and ly;

[0022] Fig. 6a is a side view of the unit cell from Figs. 5a and 5b, depicting the substrate 11 and placed on top, 4 unit cells including the metasurface 1;

[0023] Fig. 6b is a top view from the unit cell, wherein P depicts the phase, i.e. the distance between the single unit cells;

[0024] Fig. 7a depicts the measured normalized conversion efficiency of a high-efficiency nonlinear metasurface 1 with asymmetrical design as in the first embodiment, including an Alo.2Gao.8As metasurface with an asymmetrical L-shape configuration;

[0025] Fig. 7b shows the performance of the metasurface 1 across various angles of incidence, specifically within an aperture of f / 19.2; Sony Semiconductor Solutions Corporation et al.

[0026] Fig. 7c depicts the normalized conversion efficiency for a modified version of the high- efficiency nonlinear metasurface 1 described in the first embodiment;

[0027] Fig. 7d illustrates the performance stability of the modified metasurface 1 across a range of incident angles, specifically within an aperture of f / 10;

[0028] Fig. 8a provides a schematic representation of the second embodiment of the high-efficiency nonlinear metasurface 1, including an AlGaAs nanoresonator with high-Q resonances;

[0029] Fig. 8b depicts a side view of the metasurface unit cell from Fig. 8a, providing a detailed perspective of the arrangement and the interaction of components;

[0030] Fig. 9a is a graphical representation that illustrates the normalized conversion efficiency of the second embodiment which is an AlGaAs metasurface 1 on an AlGaO pedestal;

[0031] Fig. 9b is a secondary plot to indicate that the normalized conversion efficiency remains stable for angles within an aperture of f / 5.6;

[0032] Fig. 10 illustrates a block diagram of a method for upconverting infrared (IR) light to visible or short-wave infrared (SWIR) light;

[0033] Fig. 11 shows a block diagram depicting an embodiment of an electronic device, e.g., a wearable device such as smart glasses or the like, that can implement the upconversion process of IR to visible light.

[0034] DETAILED DESCRIPTION OF EMBODIMENTS

[0035] Before a detailed description of the embodiments under reference of Figs. 1 to 11 is given, some general explanations are made.

[0036] The embodiments disclose an optical engine for infrared (IR) upconversion imaging, the optical engine comprising a metasurface featuring metasurface unit cells. Each metasurface unit cell includes a nanoresonator with an asymmetrical protrusion. The optical engine is designed for efficient infrared (IR) upconversion imaging, leveraging high-quality factor resonances to enable low-peak power, continuous-wave laser sources for high-resolution, cost-effective, and stable imaging applications.

[0037] Upconversion is a nonlinear optical process in which lower-energy photons (typically in the infrared or near-infrared spectrum) are absorbed and converted into higher-energy photons (e.g., in the visible or SWIR regime).

[0038] A unit cell is the smallest repeating structural element of the metasurface that retains the overall properties and functionalities of the entire surface. Each unit cell typically consists of a Sony Semiconductor Solutions Corporation et al. nanoresonator, which is a nanostructured element made from materials with specific optical properties, such as high nonlinearity and low optical losses. A nanoresonator is a nanoscale structure designed to confine and manipulate light at specific resonant frequencies, enhancing interactions between light and matter for applications such as sensing, imaging, and nonlinear optical processes.

[0039] An asymmetrical protrusion in the context of a metasurface unit cell may refer to a structural feature of the nanoresonator that extends unevenly in a horizontal plane parallel to the substrate, thereby introducing asymmetry when viewed from the top. For example, a cross-section of the nanoresonator without the asymmetrical protrusion in the horizontal plane parallel to the substrate has mirror and / or rotational symmetry and introduction of the asymmetry protrusion breaks this asymmetry. In the horizontal plane parallel to the substrate, the area of the asymmetric protrusion is below 10% of the total area of the nanoresonator cross-section. The axes may be orthogonal, and the asymmetrical protrusion may extend along two orthogonal axes of the metasurface. Asymmetry may enhance light-matter interactions, enabling high-quality factor resonances for efficient upconversion of infrared light into visible or short-wave infrared (SWIR) light through nonlinear optical processes. For example, for a resonator having a columnar conformation with a vertical axis perpendicular to the substrate, "protrusion" may refer to the cross-section in a horizontal plane, i.e., the plane parallel to the substrate. Suitable protrusions include, for example, the square, non-equilateral rectangle, circle, soellipse, and L- protrusion (i.e., a square or rectangle with one comer removed). The suitable protrusions mentioned above can have rounded corners.

[0040] According to the embodiments, the unit cell is repeated in a periodic array to form the metasurface. The design and arrangement of these unit cells -allows to achieve desired optical effects, such as high-quality factor resonances, which enhance the interaction between light and the metasurface. By repeating the unit cell in a periodic arrays the metasurface may enable the manipulation of light to achieve high-quality factor resonances and efficient upconversion of infrared light to visible or short-wave infrared (SWIR) light.

[0041] The nanoresonator may have an asymmetrical L-shape. The L-shape inherently provides asymmetry due to its configuration, where one arm of the "L" extends along one axis and the other arm extends along a perpendicular axis. That is, the L-shape design inherently lacks symmetry, meaning the protrusions have different lengths, configurations, or orientations along two axes in a horizontal plane parallel to the substrate. This asymmetrical design allows for tuning the optical properties of the nanoresonator. By having different lengths and orientations Sony Semiconductor Solutions Corporation et al. along the two axes, the L-shaped nanoresonator can more effectively manipulate light at the nanoscale.

[0042] According to the embodiments, the lengths of the protrusions are configured to tune high-quality factor resonances, such that when a pump beam, a signal beam and an upconverted beam interact within the nanoresonator, the signal beam is upconverted to a higher frequency light beam (upconverted beam).

[0043] The metasurface unit cell may include a nanoresonator made of a III-V type semiconductor material. A III-V semiconductor material refers to a compound semiconductor composed of elements from groups III and V of the periodic table. These materials are particularly advantageous due to their superior electronic and optical properties, including high second-order nonlinearity, which provides efficient frequency conversion processes like sum-frequency generation (SFG). III-V semiconductors also exhibit low optical losses and high refractive indices, allowing to enhace light-matter interactions within the metasurface. The ability to engineer these materials at the nanoscale allows for control over the phase, amplitude, and polarization of light of the upconversion process. This makes III-V semiconductors ideal for creating high-quality factor resonances in the metasurface elements, enabling the use of low- peak power, narrowband light sources while maintaining high upconversion efficiency.

[0044] The nanoresonator may be of a different material than the substrate. Using a different material for the nanoresonator than the substrate in a metasurface-based optical engine may allow for optimized optical properties, improved resonance tuning, enhanced mechanical and thermal stability, fabrication flexibility, and overall enhanced device performance for efficient IR upconversion imaging.

[0045] The nanoresonator may be made of AlAs, GaAs, Alo.2Gao.8As, Al(X)Ga(i-X)As, LiNbO3 or GaP. The nanoresonator being made of AlAs, GaAs, Alo.2Gao.8As, Al(X)Ga(i-X)As, LiNbO3 or GaP may allow for high second-order nonlinearity, low optical losses, and high refractive indices, optimizing the efficiency and performance of the IR upconversion process.

[0046] The nanoresonator may be placed on a pedestal. Placing the nanoresonator on a pedestal eliminates the need for a base low refractive index and low optical losses substrate like glass, quartz, AlGaO(X) or SiCh, simplifying fabrication and potentially enhancing optical performance by increasing the refractive index contrast.

[0047] The nanoresonator and the pedestal may be made of different materials. Using different materials for the nanoresonator and the pedestal allows for independent optimization of optical properties and mechanical stability, enhancing the overall performance and efficiency of the metasurface. Sony Semiconductor Solutions Corporation et al.

[0048] The nanoresonator, the pedestal, and the substrate may be made of different materials. Using different materials for the nanoresonator, pedestal, and substrate allows for tailored optimization of each component's optical, mechanical, and thermal properties, leading to enhanced overall performance and efficiency of the metasurface-based optical engine.

[0049] The pedestal may include AlGaO and the substrate on which the pedestal is positioned may include GaAs. Using AlGaO for the pedestal and GaAs for the substrate leverages the low refractive index and low optical losses of AlGaO for enhanced optical interactions, while GaAs provides robust mechanical support and excellent thermal properties, optimizing the performance of the metasurface-based optical engine.

[0050] The high-quality factor resonances can be tuned via asymmetry factor size and shape. The tuning allows for achieving high Q-factor of the resonance and consequent reduction of incident light acceptance angle range width or vice-versa. Typical achievable values for the Q-factors are tens to few thousands and for the incident light acceptance angle range are ± tens of degrees to ± tenths of degrees.

[0051] An acceptance angle range width regarding incident light may be in the range of ± 50 degrees to ± 2 degrees.

[0052] According to embodiments, the signal source emits a signal beam at a wavelength range from 1000 nm to 2500 nm, for example, 1640 nm to 1660 nm, and the pump source may emit a pump beam at a wavelength range of 700 nm to 1500 nm, for example 1280-1325 nm.

[0053] According to embodiments, the metasurface unit cell may have a periodic arrangement with a period in the range of 800 to 1000 nm, preferably 960 nm.

[0054] According to embodiments, the nanoresonator may have a height of 200 to 600 nm, preferably 479 nm.

[0055] The nanoresonator may have similar width on each side of the horizontal plane of the substrate, or the widths on each side of the nanoresonator may be different.

[0056] The length of the protrusions may be in the range of 50 nm to 150 nm, preferably between 77 nm and 110 nm. The protrusions may be configured to tune high-quality factor resonances, for example by adjusting the length of the protrusion. This tuning ensures that when a pump beam, a signal beam and upconverted beam interact effectively within the nanoresonator, the signal beam is efficiently upconverted to a higher frequency light beam (upconverted beam). This upconverted beam is detectable by a visible or short-wave infrared (SWIR) imaging sensor, thereby enhancing the overall efficiency and effectiveness of the upconversion process. Sony Semiconductor Solutions Corporation et al.

[0057] The embodiments also disclose an optical device that comprises the optical engine configured to convert infrared light into visible or short-wave infrared (SWIR) light, and that includes a detection system for capturing the upconverted light. The optical engine in the optical device may enhance visibility in low-light or obscured conditions.

[0058] An implementation of the optical engine in a device like night-vision goggles may involve integrating a metasurface composed of a periodic array of unit cells with asymmetrical nanoresonators, mounted within the device housing. Infrared light from a low-peak power, continuous-wave or ns- pulsed signal laser and a low-peak power, continuous-wave or ns- pulsed pump laser is focused onto the metasurface using precision lenses. The metasurface facilitates nonlinear interactions, such as sum-frequency generation, efficiently converting the infrared light to visible or short-wave infrared (SWIR) light. This upconverted light may be captured by a visible or SWIR imager, processed by an onboard unit to enhance image quality, and displayed on a high-resolution screen or viewfinder. The device may include user controls for adjusting image parameters, providing clear, high-resolution images for applications like surveillance, navigation, and security in low-light or obscured conditions.

[0059] The upconverted light may be directed towards a visible or SWIR imager that acts as the detection system. The visible or SWIR imager may serve as the detection system to capture and convert the upconverted signal into high-resolution images.

[0060] The optical device may further comprise an arrangement of optical components, including lenses and filters, to ensure proper alignment and filtering of the light beams. The optical components such as lenses and filters may for example be arranged to align the light beams ensuring that the desired upconverted light reaches the detection system for accurate imaging.

[0061] The optical device may comprise a low-peak power, continuous-wave or ns- pulsed signal laser and a low-peak power, continuous-wave or ns- pulsed pump laser.

[0062] The optical engine may comprise a low-peak power, continuous-wave or ns- pulsed signal laser and a low-peak power, continuous-wave or ns- pulsed pump laser.

[0063] A pump beam may be generated by a narrowband light source with relatively low-peak power and directed onto the metasurface of the optical engine. The narrowband light source with relatively low-peak power may avoid the need for high-peak power lasers.

[0064] The optical device may be configured for applications including night-vision goggles, thermal imaging cameras, medical diagnostic tools, surveillance systems, or scientific instruments for Sony Semiconductor Solutions Corporation et al. astronomical observations. Devices that may utilize this nonlinear metasurface-based optical engine may include night-vision goggles, which convert infrared light into visible light for enhanced visibility in low-light conditions; thermal imaging cameras for industrial inspection, enabling the detection of heat patterns and anomalies in machinery and infrastructure; medical diagnostic tools, such as infrared endoscopes and imaging systems, which allow for non-invasive visualization of tissues and organs; surveillance systems for security, providing clear images through obscurants like fog and smoke; and scientific instruments for astronomical observations, facilitating the study of celestial objects in the infrared spectrum.

[0065] The embodiments also disclose a method for upconverting infrared (IR) light to visible or shortwave infrared (SWIR) light comprises generating a pump beam using a narrowband light source, generating a signal beam that carries infrared information from a target object, directing the pump beam and the signal beam onto an optical engine that includes metasurface unit cells, each unit cell featuring a nanoresonator with an asymmetrical protrusion, and detecting, using an imaging sensor, an upconverted signal beam that has been upconverted by the optical engine to visible or SWIR frequencies. The method may further comprise all the process steps described above with regard to the optical engine and the optical device.

[0066] Additional process steps that may be comprised by the method may include calibrating the optical components by adjusting the alignment and focus of lenses and filters to ensure precise beam convergence and effective filtering. The method may also involve fine-tuning the dimensions or material properties of the nanoresonators to match the specific wavelengths of the pump and signal beams for optimal upconversion efficiency. Additional spectral filters may be used to isolate the upconverted light from any residual pump or signal beam wavelengths, and adjusting the polarization states of the beams can optimize their interaction within the metasurface. The method may also include capturing and analyzing the upconverted images for specific applications, such as medical diagnostics or surveillance, and implementing techniques to mitigate the effects of environmental factors like temperature fluctuations or vibrations that may affect optical alignment and performance. Integrating the optical engine with existing imaging systems or devices, such as night-vision goggles or thermal cameras, can enhance overall functionality.

[0067] Infrared Upconversion Imaging Using Semiconductor Metasurface Technology

[0068] In the realm of optical engineering and photonics, infrared (IR), upconversion imaging is designed to enhance visibility in environments where light is scarce, by converting infrared light, which is invisible to the human eye, into visible or short-wave infrared (SWIR) light. The Sony Semiconductor Solutions Corporation et al. capability to transform IR light into visible spectra is used in numerous applications ranging from night-vision equipment and thermal imaging to medical diagnostics and surveillance systems.

[0069] Typically, infrared upconversion involves interactions between light and specialized materials that can change the frequency of the incoming IR light to a higher frequency within the visible or SWIR range. This process, known as nonlinear frequency upconversion, allows for the capture of detailed images even under low-light conditions.

[0070] Semiconductor metasurface technology allows for enhancing the efficiency and effectiveness of upconversion systems. Metasurfaces, engineered at the nanoscale, manipulate the properties of light at a subwavelength scale, allowing for precise control over the phase, amplitude, and polarization of light. When applied in upconversion devices, these metasurfaces facilitate the efficient conversion of IR light by interacting with specially tuned light sources to produce visible images from IR emissions.

[0071] In the following, embodiments are described that apply an upconversion device that leverages semiconductor metasurface technology to improve the upconversion process.

[0072] Fig. 1 presents a schematic representation of an upconversion device engineered for infrared (IR) imaging applications. The upconversion device is based on the concept of using a semiconductor metasurface-based optical engine to convert IR light into visible or short-wave infrared (SWIR) light using low-peak intensity coherent sources. At metasurface 1 of the upconversion device, the IR light interacts with the semiconductor material to undergo nonlinear processes. This results in the upconversion of light frequencies. A pump beam 2 from a pump source (not depicted) provides energy that contributes to the nonlinear processes within the metasurface 1. The pump beam 2 may for example be generated by a coherent light source with low peak intensity, reducing the overall power requirements and enhancing the stability of the system. The signal beam 3 from the signal source (not depicted) may be a light beam, which carries the IR information from the object 8 (target) to be imaged. The signal beam 3 interacts with the pump beam 2 within the metasurface 1, leading to the frequency upconversion.

[0073] The upconversion process results in a upconverted visible or SWIR beam 4, which emanates from the metasurface 1. The visible beam 4 represents the upconverted light, now in the visible or SWIR spectrum. The visible beam 4 is detectable by conventional imaging sensors (not depicted). The visible beam 4 carries the image information post-upconversion of the object 8 (target). Light flows through the system starting from the object 8 as a signal beam 3 to the metasurface 1 where it gets upconverted in conjunction with the pump beam 2, resulting in the Sony Semiconductor Solutions Corporation et al. visible beam 4. The object 8 is the target from which the IR signal is originally emitted or reflected. In practical applications, this IR signal may come, for example, from a landscape in night vision applications, body tissues in medical diagnostics, and the like. The visible beam 4 may undergo post-processing and detection by an imaging system (not depicted), resulting in the image 9 of the target.

[0074] The upconverted light as produced by the upconversion device forms a visual representation of the original target, now visible to the human eye or standard imaging sensors (not depicted).

[0075] Fig. 2 illustrates a nonlinear metasurface-based optical engine comprising the upconversion device of Fig. 1, designed for high-efficiency upconversion of infrared light to visible or shortwave infrared (SWIR) light. The optical engine includes the metasurface 1, where the upconversion process occurs. The metasurface 1 may be designed, for example, with high- quality factor resonances to enhance the interaction between the incident light and the metasurface 1, leading to efficient upconversion. A pump beam 2 is from a narrowband light source with relatively low-peak power that provides the necessary energy that leads to the nonlinear upconversion processes within the metasurface 1. A lens 5-1 focuses the initial signal beam 3 on the object 8 which is the target to be imaged. The signal beam 3 interacts with the target 8, resulting in a signal beam 3 that is representative for the object 8 (target). Alternatively, the signal beam 3 may emit from the object 8, or be reflected by the object 8, for example in distance measurements, and the like.

[0076] The signal beam 3 carries the infrared light from the target object 8, and is to be upconverted. The signal beam 3 is focused onto the metasurface 1 using lenses 5-2 and 5-3. In the metasurface 1, upconversion of the signal beam 3 together with the pump beam 2 occurs. From the metasurface 1, a visible beam 4 is emitted. The visible beam 4 represents the visible or SWIR light resulting from the upconversion process and carries the upconverted image information and is focused onto the detector 7 using lens 5-4.

[0077] The optical engine further includes a filter 6, which is arranged before the detector 7. The filter 6 may, for example, ensure, that the visible beam 4 reaches the detector 7 in a manner, that filters out residual pump and signal wavelengths, for example. The detector 7 captures the upconverted visible beam 4 and converts it into an electronic signal that can be processed to produce an image 9 of the target.

[0078] Fig. 3 is a block diagram illustrating elements and processes involved in the nonlinear metasurface-based optical engine designed for efficient IR upconversion imaging. It represents Sony Semiconductor Solutions Corporation et al. the systematic approach taken to optimize the design of the metasurface 1 for high conversion efficiency through the strategic selection of materials and tuning of resonances.

[0079] Block Al represents high SFG Efficiency (SFG = Sum-Frequency Generation) as the output block of the diagram and the overall goal when designing the optical engine. It shows that the combination of high second-order nonlinearity from block A2, effective interaction of pump and signal from block A3, along with high-Q resonances from block A4 and optimal material properties (such as low losses from block A5 and high refractive index from block A6), culminates in high SFG efficiency Al. A high SFG efficiency helps to convert IR light into visible or SWIR light effectively.

[0080] Block A2 represents the selection of materials with high Second Order Nonlinearity. Such materials are essential for enabling strong nonlinear interactions necessary for effective frequency conversion. Block A3 represents the importance of effective interaction of pump and signal and connects to the nonlinearity block A2 and material properties block A4. It illustrates how the chosen materials with their specific properties facilitate a robust interaction between the pump and signal beams. This interaction is critical for the generation of the upconverted light through SFG in the metasurface 1.

[0081] Block A4 relates to material properties, in particular to achieving High-Q Resonances. Emerging from the interaction block A3, this block represents the engineered high-quality factor (High-Q) resonances. These resonances are tuned specifically to the wavelengths of the pump beam 2, the signal beam 3, and the visible beam 4 resulting from SFG. High-Q resonances significantly enhance the efficiency of the light-matter interaction, leading to more effective upconversion processes. High Q resonances as in block 4 may be achieved by the use of materials with low losses as in block A5 and a high refractive index as in block A6. Block A5 represents to choose materials with low optical losses to minimize signal degradation. Block A6 represents to choose a material that also has a high refractive index to enhance the light-matter interaction within the metasurface.

[0082] Fig. 4 is a comparative chart representing the performance metrics of various metamaterials used in upconversion processes, specifically focusing on their effectiveness in second harmonic generation (SHG). The relative peak-normalized SHG signal is plotted against the relative Q resonances for SHG for each material. The x-axis represents the relative Q resonances for SHG, which indicates the quality factor ratio specific to SHG applications. Higher values on this axis suggest better performance in terms of resonance quality and efficiency in SHG processes. The Sony Semiconductor Solutions Corporation et al. y-axis represents the relative peak-normalized SHG signal and gives a measure for the efficiency of SHG normalized to peak performance, with higher values indicating more effective SHG.

[0083] The metamaterials represented are Alo.i8Gao.82As, with SFG (sum frequency generation instead of second harmonic generation) which has a relative peak-normalized SHG at 1,1 *10° a.u. and 0,9* 102a.u. relative Q resonances for SHG. Next thereto, as a comparison, GaAs with SFG shows slightly lower relative peak-normalized SHG and slightly higher relative Q resonances at 102a.u.. GaAs shows a relative peak-normalized SHG 102a.u. and 0.7* 103a.u. relative Q resonances for SHG, indicating good SHG efficiency with a significantly higher quality factor. Also depicted in Fig. 4 is GaAs with a high Q value. It shows almost 103a.u. relative peak- normalized SHG and 0.5* 106a.u. relative Q resonances for SHG, demonstrating high performance in both SHG efficiency and quality factor. Fig. 4 also depicts GaP as a metasurface with a pulsed source. Positioned at 107a.u. relative peak-normalized SHG and 0.2* 106a.u. relative Q resonances for SHG, this combination results in high SHG efficiency, particularly with pulsed source usage. GaP with a CW source shows the highest SHG efficiency at over 108a.u. relative peak-normalized SHG and l. l*106a.u. relative Q resonances for SHG, indicating the top performance in the dataset, especially notable with continuous wave (CW) source usage.

[0084] Note that Fig. 4 does not include the Sony’s high-Q resonance metasurface described in detail herein, but a reference Al GaAs SFG metasurface.

[0085] Simulation tools can be used to design and optimize the metasurface-based optical engine. Finite element method (FEM) simulations can be employed to analyze and visualize the electric fields at the pump (pump beam 2), signal (signal beam 3), and sum-frequency generation (SFG) (visible beam 4) wavelengths, providing valuable insights into the interaction dynamics within the metasurface 1. Furthermore, a comprehensive semi -analytical model can be set up to calculate the conversion efficiency and imaging capabilities of the system. This allows for a evaluation of different design parameters and configurations under various operating conditions. Combined with a global or local optimization algorithm, the simulation tools allow for the inverse design of a nonlinear metasurface for a particular upconversion, imaging, and / or signal processing performance target.

[0086] To ensure the practical applicability of the optical engine, flexibility is provided to consider specific application requirements. This includes the ability to tailor the spectral range, select appropriate detectors 7, and utilize specific light sources for pump beams 2 and signal beams 3. For example, the optical engine can be optimized for operation in the short-wave infrared (SWIR) range using nanosecond (ns) laser sources, such as SWIR lasers with specific Sony Semiconductor Solutions Corporation et al. wavelengths. The detector 7 can be chosen, such as the SONY IMX264, to ensure compatibility and efficient detection of the upconverted light.

[0087] To optimize the design parameters of the metasurface 1 for the best upconversion imaging performance, a design optimization method can be employed. A Figure of Merit (FoM) can be defined, which quantifies the overall performance of the system. The FoM can be calculated based on relevant parameters, such as the normalized conversion efficiency for normal incidence of the signal beam 3. By coupling the design optimization method with the nonlinear metasurface simulation tools, the optimal parameters of the metasurface 1 can be determined to achieve the highest FoM and, consequently, the best upconversion imaging performance.

[0088] Bayesian optimization is one of the global optimization algorithms that can be utilized to efficiently search for the optimal parameters of the metasurface 1. By iteratively evaluating different parameter combinations and updating the search based on the performance results, the algorithm can converge towards the optimal solution. This reduces the need for manual parameter tuning and maximizing the efficiency and effectiveness of the upconversion imaging system.

[0089] Enhanced IR Upconversion Imaging Using Asymmetrical L-Shaped Nanoresonator Metasurfaces

[0090] [1st Embodiment]

[0091] The embodiments described below disclose a nonlinear metasurface-based optical engine designed for efficient infrared (IR) upconversion imaging. The optical engine addresses the challenges of traditional upconversion devices, such as the need for high-peak power light sources, by utilizing advanced metasurface elements with high-quality factor resonances. These resonances enable the use of low-peak power, narrowband light sources while maintaining high upconversion efficiency, thus offering a cost-effective, compact, and stable solution.

[0092] A component of the optical engine as in the embodiments disclosed herein, is a metasurface unit cell, including a nanoresonator, which may be made from a III-V type semiconductor, for example, the nanoresonator may be made of Alo.2Gao.8As.

[0093] The nanoresonator may be placed on a substrate, with varying configurations. The nanoresonator design includes, for example, an asymmetrical L-shape, which is critical for enabling and tuning the high-quality (high-Q) factor resonances. The high-Q resonances may significantly enhance light-matter interaction, thereby increasing the intensity of light within the nonlinear material and improving the efficiency of the upconversion process. Sony Semiconductor Solutions Corporation et al.

[0094] In an embodiment of the present disclosure, the metasurface unit cell comprises a superstrate of air, a substrate of silicon dioxide (SiCh), and a nanoresonator of Alo.2Gao.8As. The dimensions of the nanoresonator and the periodic arrangement of the unit cells are meticulously calculated to optimize conversion efficiency. When illuminated by narrowband light sources with relatively low-peak power, the metasurface's high-quality factor resonances are excited, leading to efficient upconversion of the incident IR light to higher frequency light. The resulting upconverted light falls within the detection range of commercially available visible or short-wave infrared (SWIR) imagers.

[0095] Fig. 5a depicts a schematic view of an embodiment of the metasurface unit cell. The superstrate surrounding the metasurface unit cell 10 in this embodiment is air. The unit cell 10 includes the metasurface 1, which is a nanoresonator made from a metamaterial that is placed on top of the substrate 11, which is made of SiCh in this embodiment. The substrate 11 supports the metasurface 1 and influences the optical properties of the metasurface 1. The metamaterial is a nanoresonator, composed of Alo.2Gao.8As, and represents the active element of the metasurface 1. It has an asymmetrical L-shape, which is important for its optical response and interaction with incident light. The height of the nanoresonator is 479 nm and has a width Dx in the x-direction of 562 nm and a width Dy in the y direction of 325 nm. The nanoresonator is shaped with protrusions 13, with the dimensions lx and ly, which are 77 to 110 nm in length, according to this embodiment. The protrusions 13 introduce spatial asymmetry to the metasurface unit cell 10. The period P for the periodic arrangement of the unit cells 10 that make up the metasurface 1 on the substrate 11 is set at 960 nm in this embodiment and may be used to tune the phase and amplitude modulation properties of the metasurface 1.

[0096] Fig. 5b is a zoomed-in view of the metasurface unit cell from Fig. 5a, whereby the arrows highlight the protrusion 13. The protrusion 13 has the dimensions lx and ly. These dimensions are critical for tuning the high-quality factor resonances necessary for efficient upconversion. The protrusions may have the same or different lengths, allowing for further optimization of the optical properties of the nanoresonator.

[0097] Fig. 6a is a side view from four of the single unit cells 10 from Fig. 5a and Fig. 5b, depicting the substrate 11 and placed on top, 4 unit cells 10 including the metasurface 1. The unit cells 10 have a predetermined height hd.

[0098] Fig. 6b is a top view from four of the single unit cells 10 from Fig. 5a and Fig. 5b, wherein P depicts the phase, i.e. the distance between the single unit cells 10. The parameters Dx and Dy Sony Semiconductor Solutions Corporation et al. depict the overall length or width of the unit cell 10. The parameters lx and ly relate to the protrusion 13, which lead to an L-shape of the nanoresonator.

[0099] In the embodiments of the present disclosure, the optical engine may combine a source signal, for example a NIR-signal, which can be understood as the signal beam 3 in Figs. 1 and 2, with a pump signal, such as the pump beam 2 from Figs. 1 and 2, for example from narrowband lasers, to achieve upconversion through sum-frequency generation (SFG), resulting in the visible light beam 4. The interaction of the signals in the metasurface 1 results in upconverted light, which is then directed towards a visible or SWIR imager 7 for detection. The optical engine may be included in a system that further includes an optimized arrangement of optical components, such as lenses (5-1, 5-2, 5-3, 5-4) and filters 6, for example to filter out residual, signal and pump wavelengths, to ensure proper alignment and filtering of the light beams (2, 3, 4).

[0100] According to the embodiments of the present disclosure, the optical engine may use high-quality factor resonances to achieve efficient upconversion with continuous-wave (CW) lasers, offering advantages in terms of cost, stability, and safety over traditional high-peak power pulsed lasers. The result is a robust, versatile, and efficient optical engine capable of producing high-quality, high-resolution upconverted images, suitable for a wide range of IR imaging applications.

[0101] Figs. 7a to 7d depict the upconversion results, i.e. the normalized conversion efficiency for the first embodiment, depending on the wavelength of the signal and the theta signal, i.e. the angle of incidence. Also, Figs. 7a and 7b, compared to Figs. 7c and 7d give differences in the effect of the size of the protrusion (i.e. the level of asymmetry).

[0102] Fig. 7a depicts the simulated normalized conversion efficiency of a high-efficiency nonlinear metasurface 1 with asymmetrical design as in the first embodiment, including an Alo.2Gao.8As metasurface with an asymmetrical L-shape configuration. The chart plots the normalized conversion efficiency, measured in inverse watts (1 / W), against the signal wavelength in nanometers (nm). The metasurface 1, configured with parameters such as height hd of 479 nm, widths Dx of 562 nm, and Dy of 325 nm, exhibits a peak normalized conversion efficiency of 2.4 1 / W at the signal wavelength of 1658 nm. The efficiency measurement is conducted under normal incidence, indicating that the incoming signal light is perpendicular to the metasurface, simplifying interaction dynamics. The signal polarization is set at 40°, affecting how the electric field of the signal light interacts with the metasurface 1. The pump polarization is aligned at 0°, optimized to enhance the interaction for upconversion. The pump wavelength for the pump beam 2 used in this setup is 1534 nm, providing the necessary energy for facilitating the sum- Sony Semiconductor Solutions Corporation et al. frequency generation process, leading to an SFG wavelength of 797 nm (i.e. the visible beam 4). An achieved normalized conversion efficiency may be 107times higher than the reference.

[0103] Fig. 7b shows the performance of the metasurface 1 across various angles of incidence, specifically within an aperture of f / 19.2. This graphical representation plots the normalized conversion efficiency against the theta signal, which has a robust performance in angles from -2 to +2 degrees. The stability of the normalized conversion efficiency within this range demonstrates that the metasurface 1 maintains a high efficiency even when the incident angles vary slightly.

[0104] Fig. 7c depicts the normalized conversion efficiency for a modified version of the high- efficiency nonlinear metasurface 1 described in the first embodiment. This modified example has the asymmetrical L-shaped nanoresonator with adjusted protrusion sizes, specifically lx and ly set to 110 nm each. Fig. 7c shows the normalized conversion efficiency, measured in inverse watts (1 / W), against the signal wavelength, measured in nanometers (nm). The metasurface 1, has a height hd of 479 nm and widths Dx of 562 nm and Dy of 325 nm, and achieves a peak normalized conversion efficiency of 1.55*10-11 / W at the signal wavelength of 1658 nm. The measurement is conducted under normal incidence conditions, ensuring that the incoming signal light remains perpendicular to the metasurface 1, simplifying the interaction dynamics. Signal polarization remains set at 40°, and pump polarization at 0°, with a pump wavelength of 1534 nm to facilitate sum-frequency generation, leading to an SFG wavelength (i.e. a visible beam 4) of 797 nm. The size of the protrusions lx and ly and thus the asymmetry of the unit cell can significantly affect the conversion efficiency.

[0105] Fig. 7d illustrates the performance stability of the modified metasurface 1 across a range of incident angles, specifically within an aperture of f / 10. This graphical representation plots the normalized conversion efficiency against the theta signal, showcasing robust performance across angles from -2 to +3 degrees. The stability of the normalized conversion efficiency within this wider range compared to Fig. 7b indicates that the metasurface 1 continues to maintain high efficiency with the larger protrusions of lx and ly at 110 nm, also at a higher angular tolerance.

[0106] [2nd Embodiment]

[0107] In another embodiment, the metasurface design may include a pedestal structure to further enhance the control over the resonant properties. The pedestal structure elevates the nanoresonator, allowing for more precise tuning of the high-quality factor resonances and improving mechanical stability. This design maintains high conversion efficiency across a range of incident angles, making it suitable for practical imaging applications. Sony Semiconductor Solutions Corporation et al.

[0108] In the second embodiment of the nonlinear metasurface-based optical engine, the design incorporates an array of unit cells each with an optimized AlGaAs nanoresonator mounted on an AlGaO pedestal, which itself is placed on a GaAs substrate.

[0109] Fig. 8a provides a schematic representation of the second embodiment of the high-efficiency nonlinear metasurface 1, including an array of AlGaAs nanoresonators supporting high-Q resonances. This design showcases an asymmetrical L-shaped nanoresonator mounted on a pedestal 12. The superstate surrounding the unit cell is air, and the metasurface 1 is positioned atop a substrate 11, which is made of GaAs in this embodiment. The substrate 11 supports the entire metasurface 1 including the pedestal 12, made of AlGaO.

[0110] The nanoresonator as the active element of the metasurface 1, has a height (hd) of 397 nm. It is characterized by its dimensions Dx and Dy, which are 202 nm and 508 nm respectively. The asymmetrical L-shape is further defined by protrusions lx and ly, measuring 307 nm and 268 nm respectively, introducing further spatial asymmetry, compared to the first embodiment that enhances the optical interactions. The period P of the unit cells across the metasurface 1 in this embodiment is set at 1000 nm, thereby tuning the phase and amplitude modulation properties of the metasurface 1.

[0111] This design achieves a normalized conversion efficiency that is 104times higher than the reference. The signal wavelength (Xsignai) for the signal beam 3 in this setup is 1648 nm, while the pump wavelength (XpUmp) for the pump beam 2 is set at 1325 nm, leading to a sum-frequency generation (SFG) wavelength of 735 nm for the visible beam 4. The configuration benefits from the high-Q resonances of the metasurface 1, made possible by the precise material and structural choices, including the pedestal 12 which enhances the stability and does not require transfer to a different substrate 11 for fabrication.

[0112] Fig. 8b depicts a side view of the metasurface unit cell 10 from Fig. 8a, providing a detailed perspective of the arrangement and the interaction of components. The substrate 11 (GaAs) forms the base layer upon which the pedestal 12 (AlGaO) is mounted. The pedestal 12 elevates the nanoresonator, which represents the metasurface 1, enhancing its exposure and interaction with incident light. The nanoresonator's height (hd) in this embodiment is 397 nm, the widths Dx and Dy, are 202 nm and 508 nm respectively.

[0113] The protrusions 13 lx and ly (not shown in this embodiment) extend from the main body of the nanoresonator and are different in size in this embodiment (i.e. lx is 307 nm, ly is 304 nm)., contributing to the asymmetry of the unit cell. Sony Semiconductor Solutions Corporation et al.

[0114] Fig. 9a is a graphical representation that illustrates the normalized conversion efficiency of the second embodiment which is an AlGaAs metasurface 1 on an AlGaO pedestal 12. The normalized conversion efficiency (measured in inverse watts, 1 / W) is depicted on the y-axis against the signal wavelength (measured in nanometers, nm) on the x-axis. The metasurface 1 from the second embodiment is characterized by high-quality factor resonances, resulting in a normalized conversion efficiency of 10'31 / W at a signal wavelength of 1650 nm. This peak indicates the optimal wavelength for upconversion under the given conditions.

[0115] The efficiency measurement is taken at normal incidence, which means the incoming signal light is perpendicular to the metasurface 1, simplifying the interaction dynamics. Signal polarization (i.e. the polarization of the signal beam 3) is set at 45°, which affects how the electric field of the signal light interacts with the metasurface 1. Pump polarization (i.e. the polarization of the pump beam 2) is also set at 45°, aligning with the signal polarization to optimize the interaction for upconversion. The wavelength of the pump beam is set to 1325 nm in this embodiment, providing the necessary (additional) energy for facilitating the upconversion process through sum-frequency generation or similar nonlinear optical processes.

[0116] Fig. 9b is a secondary plot to indicate that the normalized conversion efficiency remains stable for angles within an aperture of f / 5.6. This stability suggests that the metasurface 1 maintains high efficiency across a reasonable range of incident angles, enhancing its applicability in practical devices.

[0117] Fig. 10 is a block diagram illustrating a method for upconverting infrared (IR) light to visible or short-wave infrared (SWIR) light. In step SI, a pump beam 2 is generated using a narrowband light source. This pump beam 2 provides energy for the upconversion process. In step S2, a signal beam 3 is generated, which carries infrared information from a target object 8. This signal beam 3 represents the IR light that needs to be upconverted. In step S3, the pump beam 2 and the signal beam 3 are directed onto an optical engine. The optical engine includes metasurface unit cells 10, each featuring a nanoresonator with an asymmetrical protrusion 13. The interaction between these beams within the nanoresonator enhances the light-matter interaction, facilitating the upconversion process. In step S4, an imaging sensor 7 is used to detect the upconverted signal beam. This signal beam, now at visible or SWIR frequencies as visible beam 4, is captured by the imaging sensor 7, allowing for the creation of a visual representation or an image 9 of the target object 8.

[0118] Implementation Sony Semiconductor Solutions Corporation et al.

[0119] Fig. 11 shows a block diagram depicting an embodiment of an electronic device, e.g., a wearable device such as smart glasses or the like, that can implement the upconversion engine or process of IR to visible light. The electronic device 1100 comprises a CPU 1501 as the processor. The electronic device 1100 further comprises a GPU 1506 that is connected to the processor. The electronic device 1100 also includes an Ethernet interface 1504, which acts as an interface for data communication with external devices, such as additional sensors or imaging systems. The electronic device 1100 further comprises a user interface 1505 that may present, e.g., via a display screen, the upconverted images to the user.

[0120] The electronic device 1100 further comprises a data storage 1502 and a data memory 1503 (here a RAM). The data memory 1503 is arranged to temporarily store or cache data or computer instructions for processing by the processor. The data storage 1502 is arranged as a long-term storage, e.g., for recording upconverted images or other relevant data. The data storage 1502 and the data memory 1503 may comprise computing instructions that implement the processes described above, such as the upconversion process of IR to visible light.

[0121] The electronic device 1100 includes an optical engine 1106, configured to convert infrared light into visible or short-wave infrared (SWIR) light. The optical engine 1106 comprises metasurface unit cells 10, each featuring a nanoresonator with an asymmetrical protrusion 13, designed for efficient upconversion. Additionally, the electronic device 1100 comprises an arrangement of optical components, including lenses 5-1, 5-2, 5-3, 5-4 and filters 6, to ensure alignment and filtering of the light beams 2, 3, 4. A pump beam 2 is generated by a narrowband light source with relatively low-peak power and directed onto the metasurface 1 of the optical engine.

[0122] The computing instructions may further implement various functionalities, such as processing the upconverted images, enhancing image quality, and providing real-time feedback to the user. These functionalities may include applications like night-vision, thermal imaging, or augmented reality (AR), leveraging the upconversion process to provide enhanced visibility and imaging capabilities.

[0123] It should be noted that the description above is only an example configuration. Alternative configurations may be implemented with additional or other sensors, storage devices, interfaces, or the like.

[0124] The electronic device 1100 may be a wearable device, such as smart glasses, head-mounted displays (HMDs), earphones, or other types of smart wearable devices, designed for applications including night-vision goggles, thermal imaging cameras, medical diagnostic tools, surveillance systems, or scientific instruments for astronomical observations. Sony Semiconductor Solutions Corporation et al.

[0125] Note that the present technology can also be configured as described below:

[0126] (1)

[0127] An optical engine for infrared (IR) upconversion imaging, wherein the optical engine comprises a metasurface (1) comprising metasurface unit cells (10), each metasurface unit cell (10) featuring a nanoresonator with an asymmetrical protrusion (13).

[0128] (2)

[0129] The optical engine of (1), wherein the unit cell (10) is repeated in a periodic array to form the metasurface (1).

[0130] (3)

[0131] The optical engine of (1), wherein the nanoresonator has an asymmetrical L-shape.

[0132] (4)

[0133] The optical engine of (1), wherein the lengths of the protrusion (13) are configured to tune high- quality factor resonances, such that when a pump beam (2) and a signal beam (3) interact within the nanoresonator, the signal beam (3) is upconverted to a higher frequency light visible beam

[0134] (4).

[0135] (5)

[0136] The optical engine of (1), wherein the metasurface unit cell (10) includes a nanoresonator made of a III-V type semiconductor material.

[0137] (6)

[0138] The optical engine of (1), wherein the nanoresonator is of a different material than the substrate (H).

[0139] (7)

[0140] The optical engine of (5), wherein the nanoresonator is made of AlGaAs, LiNbO3, or AlGaO, in particular Al(X)Ga(i-X)As and more in particular Alo.2Gao.8As.

[0141] (8)

[0142] The optical engine according to (1), wherein the nanoresonator is placed on a pedestal (12).

[0143] (9)

[0144] The optical engine according to (8), wherein the nanoresonator and the pedestal (12) are made of different materials. Sony Semiconductor Solutions Corporation et al.

[0145] (10)

[0146] The optical engine according to (8), wherein the nanoresonator, the pedestal (12) and the substrate (11) are made of different materials.

[0147] (H)

[0148] The optical engine according to (10), wherein the pedestal (12) includes AlGaO and the substrate

[0149] (11) includes GaAs.

[0150] (12)

[0151] The optical engine of (1), wherein the high-quality factor resonances are insensitive to the angle of incidence of the light within an angular range from ± 50 degrees to ± 2 degrees.

[0152] (13)

[0153] The optical engine of (1), wherein the signal source emits the signal beam (3) at a wavelength range from 1640 nm to 1660 nm, and the pump source emits the pump beam (2) at a wavelength range ofl280 nm tol325 nm.

[0154] (14)

[0155] The optical engine of (1), wherein the metasurface unit cell (10) has a periodic arrangement with a period (P) in the range of 800 to 1000 nm, preferably 960 nm.

[0156] (15)

[0157] The optical engine of (1), wherein the nanoresonator has a height of 200 to 600 nm, preferably 479 nm.

[0158] (16)

[0159] The optical engine of (1), wherein the nanoresonator has the similar width on each side of the horizontal plane of the substrate 11, or wherein the widths on each side of the nanoresonator are different.

[0160] (17)

[0161] The optical engine of (1), wherein the length of the protrusion (13) is in the range of 50 nm to 150 nm, preferably between 77 nm and 110 nm.

[0162] (18)

[0163] An optical device (1100) comprising the optical engine of (1), wherein the optical engine is configured to convert infrared light into visible or short-wave infrared (SWIR) light, and the optical device includes a detection system (7) for capturing the upconverted light. Sony Semiconductor Solutions Corporation et al.

[0164] (19)

[0165] The device (1100) of (18), wherein the upconverted light is directed towards a visible or SWIR imager that acts as the detection system.

[0166] (20)

[0167] The optical device (1100) of (18), further comprising an arrangement of optical components, including lenses (5-1, 5-2, 5-3, 5-4) and filters (6), to ensure alignment and filtering of the light beams (2, 3, 4).

[0168] (21)

[0169] The optical device (1100) of any of (15) to (20), wherein a pump beam (2) is generated by a narrowband light source with relatively low-peak power and directed onto the metasurface (1) of the optical engine.

[0170] (22)

[0171] The optical device (1100) of (15) wherein the optical device is configured for applications including night-vision goggles, thermal imaging cameras, medical diagnostic tools, surveillance systems, or scientific instruments for astronomical observations.

[0172] (23)

[0173] A method for upconverting infrared (IR) light to visible or short-wave infrared (SWIR) light, comprising: generating a pump beam (2) using a narrowband light source, generating a signal beam (3) that carries infrared information from a target object, directing the pump beam (2) and the signal beam (3) onto an optical engine that includes metasurface unit cells (10), each unit cell featuring a nanoresonator with an asymmetrical protrusion (13), and detecting, using an imaging sensor (7), an upconverted signal beam (4) that has been upconverted by the optical engine to visible or SWIR frequencies.

[0174] REFERENCE SIGNS LIST

[0175] 1 Metasurface

[0176] 2 Pump beam

[0177] 3 Signal beam Sony Semiconductor Solutions Corporation et al.

[0178] VIS beam

[0179] 5-1, 5-2, 5-3, 5-4 Lens

[0180] 6 Filter

[0181] 7 Detector 8 Object (Target)

[0182] 9 Image (Target)

[0183] 10 Metasurface unit cell

[0184] 11 Substrate

[0185] 12 Pedestal 13 Protrusion

Claims

Sony Semiconductor Solutions Corporation et al.CLAIMS1. An optical engine for infrared (IR) upconversion imaging, wherein the optical engine comprises a metasurface comprising metasurface unit cells, each metasurface unit cell featuring a nanoresonator with an asymmetrical protrusion.

2. The optical engine of claim 1, wherein the unit cell is repeated in a periodic array to form the metasurface.

3. The optical engine of claim 1, wherein the nanoresonator has an asymmetrical L-shape.

4. The optical engine of claim 1, wherein the lengths of the protrusion are configured to tune high-quality factor resonances, such that when a pump beam and a signal beam interact within the nanoresonator, the signal beam is upconverted to a higher frequency light visible beam.

5. The optical engine of claim 1, wherein the metasurface unit cell includes a nanoresonator made of a III-V type semiconductor material.

6. The optical engine of claim 1, wherein the nanoresonator is of a different material than the substrate.

7. The optical engine of claim 5, wherein the nanoresonator is made of AlGaAs, LiNbO3, or AlGaO, in particular Al(X)Ga(i-X)As and more in particular Alo.2Gao.8As.

8. The optical engine according to claim 1, wherein the nanoresonator is placed on a pedestal.

9. The optical engine according to claim 8, wherein the nanoresonator and the pedestal are made of different materials.

10. The optical engine according to claim 8, wherein the nanoresonator, the pedestal and the substrate are made of different materials.

11. The optical engine according to claim 10, wherein the pedestal includes AlGaO and the substrate includes GaAs.

12. The optical engine of claim 1, wherein the high-quality factor resonances are insensitive to the angle of incidence of the light within an angular range from ± 50 degrees to ± 2 degrees.

13. The optical engine of claim 1, wherein the signal source emits the signal beam at a wavelength range from 1640 nm to 1660 nm, and the pump source emits the pump beam at a wavelength range of 1280 nm to 1325 nm.Sony Semiconductor Solutions Corporation et al.

14. The optical engine of claim 1, wherein the metasurface unit cell has a periodic arrangement with a period in the range of 800 to 1000 nm, preferably 960 nm.

15. The optical engine of claim 1, wherein the nanoresonator has a height of 200 to 600 nm, preferably 479 nm.

16. The optical engine of claim 1, wherein the nanoresonator has the similar width on each side of the horizontal plane of the substrate 11, or wherein the widths on each side of the nanoresonator are different.

17. The optical engine of claim 1, wherein the length of the protrusion is in the range of 50 nm to 150 nm, preferably between 77 nm and 110 nm.

18. An optical device comprising the optical engine of claim 1, wherein the optical engine is configured to convert infrared light into visible or short-wave infrared (SWIR) light, and the optical device includes a detection system for capturing the upconverted light.

19. The device of claim 18, wherein the upconverted light is directed towards a visible or SWIR imager that acts as the detection system.

20. The optical device of claim 18, further comprising an arrangement of optical components, including lenses and filters, to ensure alignment and filtering of the light beams.

21. The optical device of any of previous claims 15 to 20, wherein a pump beam is generated by a narrowband light source with relatively low-peak power and directed onto the metasurface of the optical engine.

22. The optical device of claim 15 wherein the optical device is configured for applications including night-vision goggles, thermal imaging cameras, medical diagnostic tools, surveillance systems, or scientific instruments for astronomical observations.

23. A method for upconverting infrared (IR) light to visible or short-wave infrared (SWIR) light, comprising: generating a pump beam using a narrowband light source, generating a signal beam that carries infrared information from a target object, directing the pump beam and the signal beam onto an optical engine that includes metasurface unit cells, each unit cell featuring a nanoresonator with an asymmetrical protrusion, and detecting, using an imaging sensor, an upconverted signal beam that has been upconverted by the optical engine to visible or SWIR frequencies.

Images