Optical substrate with integrated antenna and spectrometer comprising same

Abstract

The invention relates to an optical substrate (1) having an integrated waveguide (2), in which at least one antenna (330) is formed, said at least one antenna being formed from a plurality of nanopores (341, 342, 343), at least one of the nanopores (341, 342, 343) differs from the other nanopores (341, 342, 343) by at least one of its diameter, its pitch from the waveguide (2) in the height direction of the optical substrate (1), and its distance from adjacent nanopores of the same antenna in the longitudinal direction of the optical substrate (1). The invention also relates to a spectrometer (S) integrated with such an optical substrate (1).

Description

Technical Field

[0001] This invention relates to the field of integrated optics, and more particularly, to an optical substrate having an integrated antenna and a spectrometer comprising the optical substrate. Background Technology

[0002] In integrated optics, when it is desired to guide light from a planar guiding structure embedded within an optical component or on its surface to an optical detector outside the optical component, particularly infrared (IR) or camera-type optical detectors, along a direction close to the normal to the optical component's surface, the light naturally diverges from the emission point to the detection point. If several different sources are formed on the surface of the optical component, and it is desired to associate each source with a different pixel or group of pixels of the optical detector, the signals from these different sources will be scattered across several pixels. This causes signals from different sources to be superimposed on a single pixel (or group of pixels) at the optical detector, resulting in crosstalk and a reduced signal-to-noise ratio. This large angular divergence is attributed to the highly divergent source points, which are considered point-like, and to the active region in the optical detector (especially infrared optical detectors), which can be located hundreds of micrometers below the physical surface of the optical detector.

[0003] The first solution to overcome these drawbacks is to isolate the source points. However, this reduces the density of information that can be processed.

[0004] Another solution involves measures to extract light from the waveguide to the optical detector. For example, a Bragg grating (a physical alternation of high / low refractive index regions) can be used placed on the surface of the waveguide. The greater the interaction between the guided mode and the Bragg grating, the stronger the extracted signal. This principle is well-known in integrated optics. Therefore, most solutions for improving the directivity of radiant flux are based on two-dimensional antennas of the surface array type, formed by electron beam exposure, focused ion beam, or polymerization. The following publications disclose such solutions:

[0005] -3D optical YagiUda nanoantenna array,Dregely D. et al., Nat. Communications2, 267(2011),

[0006] -Hybrid nanoantennas for directional emission enhancement,Usak, E. et al., Appl.Phys.Lett.,105,221109(2014),

[0007] -Dielectric antennas-a suitable platform for controlling magneticdipolar emission,Schmidt MK et al., Opt.Express 20,13636-13650(2012),

[0008] -All-dielectric wavelength antenna router with bidirectionalscattering of visible light,Li,J. et al.,Nano Lett,4396-4403(2016),

[0009] -All Integrated Lithium Niobate Standing Wave Fourier TransformElectro-Optic Spectrometer), Loridat et al., Journal of Lightwave Technology, Volume: 36, Issue: 20, Oct. 15 (2018).

[0010] There are three-dimensional single-antenna solutions similar to surface microlenses, which are relatively complex to implement, as described in “Broadband highly directive 3D nanophotonic lenses”, Johlin, E. et al., Nature Communications 9 (2018).

[0011] -Improving the vertical radiation pattern issued from multiple nano-groove scattering centers acting as an antenna for future integrated opticsFourier transform spectrometers in the near IR, Morand et al., Opt Lett. 2019, Feb 1;44(3):542-545.

[0012] However, existing Bragg gratings are implemented only on a surface in a planar manner. Therefore, the extraction power of the grating can only be controlled by controlling the period or the duty cycle of the period.

[0013] Another possibility for fabricating Bragg gratings is to form periodically spaced air nanopores (similar to cylinders) in the material constituting the component. For example, this technique for forming nanopores is described in the following publications:

[0014] -High aspect ratio nanochannel machining using single shotfemtosecond Bessel beams),Bhuyan et al.,Appl.Phys.Lett.97,081102(2010),

[0015] -Single shot high aspect ratio bulk nanostructuring of fused silicausing chirp controlled ultrafast laser Bessel beams,Bhuyan et al.,Appl.Phys.Lett.104,0201107(2014),

[0016] -Spatio-temporal dynamics in nondiffractive Bessel ultrafast lasernanoscale volume structuring, Velpula et al., Las.Photon Rev.2,230(2016),

[0017] -Near-infrared spectro-interferometer using femtosecond laser writtenGLS embedded waveguides and nano-scatterers, Martinn'n et al., Optics Express, Vol. 25, Issue 7, pp. 8386-8397 (2017).

[0018] According to these techniques, a non-diffraction irradiation process is used to photolithographically etch nanopores in an optical substrate including a waveguide using a focused Bessel beam. The focused Bessel beam locally generates sufficiently concentrated energy within the optical substrate to induce localized one-dimensional micro-explosions. Lateral pressure release creates one-dimensional axially uniform cavities, thereby producing extended uniform nanopores (sometimes referred to as Bessel nanopores). Using this technique, two lasers facing each other with the optical substrate located in the middle can be used, or a single laser aligned with the substrate can be used.

[0019] The main advantage of laser lithography for manufacturing elongated nano - pores is that it can cover a sampling length of 1 cm in a very short time (a few seconds) without changing the mask. Additionally, the position of the pores relative to the waveguide can be adjusted. The geometry and length of the nano - pores can be "freely" controlled, but there is a trade - off between length and diameter.

[0020] For example, the fabrication of air nano - pores using laser lithography technology makes it possible to achieve this type of planar array. Similar to the two - dimensional antennas described above, only the period or the duty cycle of the period can be changed to control the extraction power of the array.

[0021] The publication Laser written 3D 3T spectro - interferometer: Study and optimisation of the laser written nano - antenna, Bonduelle et al., SPIE Astronomical Telescopes + Instrumentation, Dec 2020, France. pp.82, <10.1117 / 12.<2562179> describes the extraction of optical flux from a waveguide using nano - pores. Summary of the Invention

[0022] The present invention aims to optimize the extraction of optical flux confined within a waveguide integrated in an optical substrate using a three - dimensional nano - antenna of the air nano - pore type formed by laser lithography, in order to direct said optical flux towards a detector located on the surface of the optical substrate integrating the waveguide.

[0023] Unlike classical lithography techniques which are surface techniques, in fact, using the above - mentioned laser lithography technique, a Bragg grating can be achieved at any depth in the optical substrate integrating the waveguide, especially allowing the protection of diffraction structures and waveguides from surface effects (scratches, dust, etc.). According to the present invention, it is also contemplated to implement diffraction nano - structures by other techniques, for example in a resin deposited above the waveguide: depositing a photosensitive resin on the surface waveguide, then exposing it using a laser, for example a UV laser (simpler than the femtosecond laser of the laser lithography technique), then the photosensitive resin degrades at the exposed places, and then the degraded photosensitive resin is removed with a solvent, thus also forming air nano - pores.

[0024] The method according to the present invention for implementing a three - dimensional nano - antenna (usually with a diameter of 100 nm) using laser lithography or other equivalent techniques is more versatile than the prior art. The result is similar to that achieved by Microlight or tools, such as three - dimensional stacking achieved by two - photon absorption in polymers.

[0025] Therefore, nanoantennas can be formed directly within the waveguide material, without the need for methods like those used in Microlight. In such cases, an additional resin deposition step is required.

[0026] This invention provides a means to obtain additional degrees of freedom. In fact, nanopores can be formed at different heights relative to each other. Thus, the extraction of light flux from the waveguide through these three-dimensional antennas composed of nanopores can be controlled by several parameters: period, duty cycle plus the diameter of the nanopores, the height offset of the periodic nanopores, spacing, or stacking.

[0027] This has the effect of reducing the angular emission cone, thus allowing the flux extracted from the waveguide to be directed to a significantly reduced number of pixels associated with the optical detector. Consequently, the divergence is almost zero, independent of the depth of the active region in the optical detector, and the signal can be measured without crosstalk.

[0028] Therefore, this invention enables control over the power extracted using a two-dimensional array with a given number of nanopores by controlling the vertical position of the array relative to the waveguide. The angular divergence of the radiation decreases with the number of nanopores or the length of the array. In this case, the period of the nanopores is preferably λ / n, where λ is the wavelength of the signal and n is the refractive index of the substrate in which the waveguide and nanopores are formed.

[0029] To obtain a more uniform shape of vertical radiation, apodization gratings can be used. This apodization can be achieved in two ways: either by controlling the diameter of the nanopores or by vertically shifting the position of the nanopores.

[0030] Finally, when the period of the nanopore is 2 to 3 times λ / n, several radiative Bragg orders exist (i.e., several light radiation directions other than the normal direction). The nanopores can also be distributed horizontally and vertically to reduce the influence of radiation in directions other than the vertical direction.

[0031] Therefore, this invention enables the development of a compact spectrometer without any moving parts, in which the detector is combined with a photon collector waveguide, and characterized by a Bragg grating as the sole relay optics.

[0032] Therefore, the present invention relates to an optical substrate having an integrated waveguide, the optical substrate having a longitudinal direction, a transverse direction and a height direction, and being made of a material with a refractive index of n, the waveguide being formed in the optical substrate according to the longitudinal direction of the optical substrate, and at least one antenna being formed in the optical substrate in the height direction separately from the waveguide, the at least one antenna being configured to diffract an evanescent wave in the height direction of the optical substrate, the evanescent wave being generated by a standing wave generated by injecting an optical signal of wavelength λ into the waveguide on the surface of the waveguide, characterized in that the at least one antenna is formed by several nanopores formed according to the transverse direction of the optical substrate, at least one of the nanopores being different from the other nanopores in at least one of the following: its diameter, its spacing from the waveguide according to the height direction of the optical substrate, and its spacing from adjacent nanopores of the same antenna according to the longitudinal direction of the optical substrate.

[0033] The distribution and / or apodization of the nanopores in the height direction can improve flux extraction from the waveguide to the outside of the substrate. In one embodiment, the at least one antenna includes an odd number of nanopores, preferably between three and five, and more preferably five.

[0034] The width (angular flare) and intensity of the diffraction signal are related to the number of nanopores: more pores result in a more coherent signal, sharper peaks, and less crosstalk. Therefore, signal intensity is directly proportional to the number of pores, while diffraction width is inversely proportional. Increasing the number of pores imposes constraints on repeatability. A trade-off between signal coherence and repeatability is achieved with approximately five nanopores per antenna.

[0035] The at least one antenna may be formed between the waveguide and the detector, in which case the at least one antenna diffracts the evanescent wave away from the waveguide; or the at least one antenna may be formed relative to the waveguide and the detector, in which case the at least one antenna diffracts the evanescent wave toward the waveguide and the detector.

[0036] The standing wave formed in the waveguide by injecting an optical signal with wavelength λ can be obtained by reflecting the light at the end of the waveguide using a mirror, or by injecting from two sources on both sides of the waveguide (so that it is injected from the left and right sides of the waveguide at the same time). This requires pre-dividing the optical flux from the sources to achieve a 50 / 50 distribution, and then splitting the optical path to inject through the two opposite input ends of the waveguide.

[0037] In one embodiment, the diameter of the nanopore decreases symmetrically from the central nanopore to the terminal nanopore of the antenna.

[0038] The variable nanoaperture diameter (apodization) within the same antenna makes it possible to adjust the envelope of the diffracted signal. For example, a larger aperture at the center of the antenna allows for the reduction of side lobes in the signal diffracted by the antenna, thereby improving the extraction quality of the signal diffracted outside the optical substrate, and thus enabling, for example, a shift from a diffracted signal with a generally sinusoidal shape to a Gaussian shape.

[0039] In one embodiment, the nanopores are located in parallel planes along the height direction of the optical substrate.

[0040] In one embodiment, the nanopores are arranged in a V-shape, with the central nanopore at the tip of the V-shape facing the waveguide. Other nanopores are symmetrically arranged in planes perpendicular to the height direction of the optical substrate according to each branch of the V-shape. These planes are further away from the waveguide as the nanopores they contain are closer to the ends of the branches of the V-shape. The spacing between two adjacent nanopores, when projected onto the plane perpendicular to the height direction of the optical substrate, is equal to λ / n or an integer multiple of λ / n. Within the same antenna, the spacing between each pair of adjacent nanopores can be the same, but the invention is not limited in this respect; the spacing within the same antenna can be different, as long as, when projected onto the plane perpendicular to the height direction of the optical substrate, the spacing separating two adjacent nanopores is equal to λ / n or an integer multiple of λ / n.

[0041] According to one embodiment, the at least one antenna includes five nanopores arranged in a W-shape and disposed in two planes parallel to each other and perpendicular to the height direction of the optical substrate. The first plane includes a central nanopore and two end nanopores. The distance between each end nanopore and the central nanopore in the first plane along the longitudinal direction of the optical substrate is equal to a characteristic distance, which is equal to λ / n or an integer multiple of λ / n. The second plane disposed between the waveguide and the first plane includes two other nanopores spaced apart along the longitudinal direction of the optical substrate by a distance equal to the characteristic distance. The first plane and the second plane are separated by half the characteristic distance along the height direction of the optical substrate.

[0042] The feature distance is preferably equal to λ / n, but it can also be an integer multiple of λ / n.

[0043] In one embodiment, the optical substrate includes a plurality of antennas formed on the same side of the waveguide in the height direction and constituting an antenna array, the antenna array being configured to diffract one or more wavelengths.

[0044] Therefore, the antennas formed in the optical substrate can be formed between the waveguide and the detector in the height direction of the optical substrate, or formed relative to the waveguide and the detector, so that the waveguide is located between the antenna and the detector.

[0045] Another object of the present invention is to provide a spectrometer comprising a light source, an optical substrate as defined above, and a detector, the substrate having two opposing parallel planes along the height direction of the optical substrate, the light source being configured to inject light into a waveguide of the optical substrate, and the detector being arranged facing the plane of the substrate to which light diffracted by at least one antenna is guided.

[0046] Optical injection can be achieved using optical fibers bonded to the substrate facing the waveguide, or using microlenses bonded to the waveguide, or by focusing a beam of light from a light source using a microscope objective or any suitable optical lens assembly.

[0047] In one embodiment, a fluid reservoir is formed on the surface of an optical substrate, on the side of the optical substrate facing the detector, to allow for spectral analysis of light diffracted by the at least one antenna and passing through the reservoir.

[0048] In one embodiment, a microfluidic circuit is formed between the detector and the face of the optical substrate, so as to allow for spectral analysis of light diffracted by the at least one antenna and passing through the microfluidic circuit. Attached Figure Description

[0049] To better illustrate the subject matter of the invention, embodiments will now be described for illustrative and non-limiting purposes with reference to the accompanying drawings.

[0050] In these attached figures:

[0051] Figure 1 This is a cross-sectional view of an optical substrate for an integrated waveguide in the prior art;

[0052] Figure 2 This is a schematic diagram of an existing antenna technology;

[0053] Figure 3 The antenna according to the first embodiment of the present invention is similar to... Figure 2 The view;

[0054] Figure 4 These are curves illustrating the performance differences between an antenna according to the prior art and an antenna according to the first embodiment;

[0055] Figure 5 The antenna according to the second embodiment of the present invention is similar to... Figure 2 The view;

[0056] Figure 6 The antenna according to the third embodiment of the present invention is similar to... Figure 2 The view;

[0057] Figure 7These are curves illustrating the performance differences between an antenna according to the prior art and an antenna according to the third embodiment of the present invention; and

[0058] Figure 8 This is a schematic diagram of a spectrometer according to the present invention, which integrates an antenna according to a fourth embodiment of the present invention. Detailed Implementation

[0059] See Figure 1 As can be seen, an optical substrate 1 with an integrated waveguide, which is a prior art example, is shown.

[0060] exist Figure 1 In the middle, the longitudinal direction of optical substrate 1 is Figure 1 From left to right, the height direction is Figure 1 The direction from top to bottom, and the horizontal direction is perpendicular to. Figure 1 The direction of the plane.

[0061] Optical substrate 1 is made of a material with a refractive index of n, and includes an integrated waveguide 2 formed according to the longitudinal direction of optical substrate 1. Waves originate from... Figure 1 The wave enters the integrated waveguide 2 from the left and is reflected by the mirror 2a formed at the right end of the integrated waveguide 2, thereby forming a standing wave with a propagating wave and a reverse propagating wave generated by the mirror 2a inside the integrated waveguide 2. The evanescent wave generated by this standing wave propagates through multiple nanopores 4. Figure 1 The antenna 3 is formed by five nanopores 4 spaced at intervals of λ / n (λ is the wavelength of the light signal injected into the waveguide 2). The waveguide 2 is tubular and extends in the transverse direction of the optical substrate 1.

[0062] like Figure 1 As shown, the term nanopore refers to a nanoscale pore formed within the substrate, specifically within the thickness of the optical substrate 1. Thus, the nanopore is completely surrounded by material, at least in the height and longitudinal directions. The nanopore is not a surface structure or depression formed on the surface of the optical substrate 1. The nanopore can have a circular cross-section in a plane perpendicular to the lateral direction. Each nanopore can be filled with a vacuum, air, or even any material with a refractive index different from that of the optical substrate 1.

[0063] Each nanopore can be made, for example, using a focused laser beam. The focused laser beam is configured to produce micro-explosions, which cause material compression, thereby leading to the formation of the nanopore. By changing the laser power, the refractive index can also be locally altered to obtain a sufficiently large refractive index contrast to produce diffraction (e.g., by locally making the initial material amorphous).

[0064] Alternatively, nanopores can also be created using a two-part substrate: the surface of the first part can be etched before being covered by the second part of the substrate.

[0065] Antenna 3 vertically extracts a portion of the propagating wave by converting the evanescent portion of the propagating wave interacting with nanopore 4 into a vertically radiated wave, thus sampling a point in the propagating wave. The same variation is obtained for the reverse propagating wave. The wave diffracted by antenna 3 is extracted to detector 5, and an optical sensor layer 6 is formed on top of detector 5. The sum of the two waves radiated on optical sensor layer 6 allows for the generation of interference that creates contrast in this case. As a non-limiting example, the detector could be made of InP, and the optical sensor layer 6 in the upper part could be an IngaAs pixel array.

[0066] It should be noted that, Figure 1 In this configuration, an air gap exists between the optical substrate 1 and the detector 5, but this air gap is not necessarily mandatory; the detector 5 can be bonded to the surface of the optical substrate 1. Furthermore, an anti-reflective layer can be provided on the surface of the detector 5 facing the optical substrate 1. Figure 2 It further illustrates Figure 1 Antenna 3 is shown only relative to waveguide 2, and for the sake of readability, details are omitted. Figure 1 The optical substrate 1 and detector 5 are arranged in the same plane along the height direction of the optical substrate. The antenna 3 consists of five nanopores 4 arranged in the same plane along the height direction of the optical substrate. The nanopores 4 of the antenna 3 have the same size and diffuse the evanescent wave of the incident light wave E, which is located in the left part of the integrated waveguide 2 and moves from left to right in the integrated waveguide 2 as shown by the arrow in the waveguide 2, toward the detector. Figure 2 (Not shown in the image).

[0067] Figure 3 The antenna 30 according to the first embodiment of the present invention is similar to... Figure 2 The view shows nanopores 41, 42, and 43 arranged in a V-shape, with the tip of the V-shape formed by nanopore 41 closest to the integrated waveguide 2, and the other nanopores 42 and 43 arranged in the height direction toward the optical substrate 1 of the detector. Figure 3 (Not shown in the text) Extends symmetrically. For example... Figure 3 As shown, antenna 30 includes five nanopores 41, 42, and 43. The first nanopore 41, as shown, forms the tip of a V-shape at a first height relative to the optical waveguide 2. Two nanopores 42, in the same plane, are located at a second height relative to the optical waveguide 2 greater than the first height, and two nanopores 43, also in the same plane, are located at a third height relative to the optical waveguide 2 greater than the second height, forming the ends of the branches of the V-shape formed by antenna 30. Note that the height of the nanopores can be defined as the distance separating the center of the nanopore from the optical waveguide 2. Regardless of their height, all nanopores remain away from the surface of the optical substrate 1 opposite the detector 5.

[0068] The spacing between two nanopores can be defined as the distance between the centers of the two nanopores. Figure 3 Two adjacent nanopores 41, 42, and 43 are separated by 2λ / n in the longitudinal direction and by 2λ / n in the height direction. However, the present invention is not limited in this respect. Therefore, if it is to be made larger for size reasons, if the lateral spacing between two pores in the same plane is K*λ / n, where K is a natural integer, then the vertical spacing must be K*2λ / n.

[0069] Figure 4 The shape of the radiation obtained above each antenna is shown. Figure 2 Antenna 3 and Figure 3 The performance differences between antennas 30 in the figure (horizontal axis is wavelength, vertical axis is intensity) are represented by the solid curve. Figure 2 The performance of antenna 3 in the figure, and the dashed curve represents Figure 3 The performance of antenna 30 in the middle. Therefore, Figure 4 The improved extraction cone and reduced secondary peak are shown, thus demonstrating the better performance of antenna 30 in reducing crosstalk between adjacent pixels of the detector located opposite the antenna.

[0070] Figure 5 It is similar to the antenna 130 according to the second embodiment of the present invention. Figure 2 The view shows nanopores 141, 142, and 143 configured in a W-shape, with two nanopores 142 located in a first plane and three nanopores 141 and 143 located in a second plane parallel to the first plane and further away from the waveguide 2 than the first plane. The nanopores 141, 142, and 143 in each plane are spaced λ / n apart, and the two planes are spaced λ / (2n). Each nanopore 142 in the first plane is positioned at the center of the two nanopores 141 and 143 in the second plane in its orthogonal projection onto the waveguide 2. However, as previously stated, the invention is not limited in this respect. Therefore, if it is desired to make it larger for size reasons, if the lateral spacing between two holes in the same plane is K*λ / n, where K is a natural integer, then the vertical spacing must be K*2λ / n.

[0071] Figure 6 The antenna 230 according to the third embodiment of the present invention is similar to... Figure 2 The view shows nanopores 241, 242, and 243 arranged in the same plane at a certain distance from waveguide 2 along the height direction of the substrate.

[0072] The differences between the nanopores 241, 242, and 243 in the antenna 230 of the third embodiment are caused by apodization: the nanopores 241, 242, and 243 have different diameters, with the central nanopore 241 having the largest diameter, the two adjacent nanopores 242 having smaller diameters than the central nanopore 241, and the two end nanopores 243 having even smaller diameters than the nanopores 242.

[0073] Figure 7 The effect of apodization is illustrated in the figure, which shows the shape of the radiation obtained above each antenna (horizontal axis is wavelength, vertical axis is intensity). Specifically, the curves are represented by dots according to... Figure 2 Antenna 3, the light gray curve represents according to Figure 6 The antenna 230 in the third embodiment. Apodization allows for a significant reduction in secondary peaks, thereby further reducing crosstalk effects on adjacent pixels of the detector placed opposite the antenna. Figure 7 The improvement in the extraction cone with increasing number of nanopores in the antenna is also shown (a solid curve for one nanopore corresponds to a very flat extraction cone, a dashed curve for three nanopores corresponds to a more pronounced extraction cone, and the optimal extraction cone is obtained with five nanopores (as shown by the dotted curve), which has a less pronounced extraction cone but attenuates more sidelobes compared to an antenna with five apodization holes without apodization). Generally, because the nanopores are embedded in the optical substrate, symmetry of the optical medium surrounding the nanopores is achieved. Therefore, the flux extracted from the waveguide is symmetrical, which allows for enhanced light flux diffracted towards the pixels, thus improving the signal-to-noise ratio. The combination of multiple nanopores allows for a reduction in the emission cone, thereby enabling the flux extracted from the waveguide to be directed to pixels with a significantly reduced number of associated optical detectors.

[0074] Although the antenna 3 is shown in the accompanying drawings of various embodiments between the waveguide 2 and the detector 5, without departing from the scope of the invention, the antenna 3 may also be formed in the optical substrate 1 below the waveguide 2, that is, opposite to the detector 5 relative to the waveguide 2.

[0075] It should also be clearly understood that the invention is not limited in its various embodiments regarding the generation of standing waves, and that standing waves can be generated in waveguide 2 in any other way, for example, by injecting signals from two light sources on both sides of waveguide 2 (thus simultaneously injecting from the left and right sides of waveguide 2) in the case where the luminous flux from the light source is pre-divided to obtain a 50 / 50 distribution at the two light sources, and then the optical path is separated to inject signals from the two light sources generated at the two opposite input ends of waveguide 2. See now. Figure 8 As can be seen in the figure, the spectrometer S according to the present invention is shown.

[0076] like Figure 8 As shown, the spectrometer S according to the present invention includes an optical substrate 1, a light source 7 and a signal processing device 8. The optical substrate 1 has an integrated waveguide 2, and the integrated waveguide 2 has a mirror 2a at its end opposite to the light wave input end.

[0077] In the optical substrate 1, an antenna 330 according to the fourth embodiment is formed above the waveguide 2 in the height direction of the optical substrate. The antenna 330 is a combination of the first and third embodiments, namely, it consists of five nanopores 341, 342, and 343 that are V-shaped as in the first embodiment and apodized as in the third embodiment. The central nanopore 341 is the largest diameter nanopore constituting the V-shaped substrate, and the other nanopores 342 and 343 are arranged above it, having smaller diameters as they move away from the waveguide 2. The light signal emitted by the light source 7 into the waveguide 2 generates an evanescent wave by propagating in the waveguide 2. This evanescent wave is guided by the antenna 330 to the detector 5, and in particular to the pixel array schematically represented by layer 6 on the upper part of the detector 5. The generated signal is sent to the signal processing device 8. The signal processing device 8 can be a microprocessor, microcontroller, processor, digital signal processor (DSP), field-programmable gate array (FPGA), application-specific integrated circuit (ASIC), or even a computer with software capable of processing and analyzing the signals emitted by the pixels of layer 6.

[0078] Therefore, the light wave injected into the waveguide 2 by the light source 7 forms an evanescent wave diffracted by the antenna 330, which is captured by the pixel 6 and then processed by the signal processing device 8 to form the spectrometer S. In a variant, a fluid circulation channel 9 can be formed on the surface of the optical substrate 1 and connected to a fluid circulation device ( Figure 7 (not shown in the image) to allow fluid to circulate in channel 9, which will be analyzed by the spectrometer S according to the invention by analyzing the effect of the fluid on the light waves captured by the pixel 6 of detector 5.

[0079] It should be understood that the antennas according to the invention are schematically shown in the accompanying drawings, but their dimensions are not necessarily proportional to the dimensions of the optical substrate 1 or the waveguide 2. Furthermore, according to the invention, it is conceivable that each antenna may have more or fewer nanopores, each optical substrate / spectrometer may have multiple antennas to capture different wavelengths, and the antenna configuration may vary for at least one of the following: the diameter of the nanopores in the same antenna, the spacing between the nanopores and the waveguide along the height direction of the optical substrate, and the spacing between two adjacent nanopores.

Claims

1. An optical substrate (1) having an integrated waveguide (2), the optical substrate (2) having a longitudinal direction, a lateral direction and a height direction, and being made of a material having a refractive index of n, the waveguide (2) being formed in the optical substrate (1) along the longitudinal direction of the optical substrate (1), at least one antenna (30; 130; 230; 330) being formed in the optical substrate (1) diverging from the waveguide (2) in the height direction, the at least one antenna (30; 130; 230; 330) being configured to diffract an evanescent wave in the height direction of the optical substrate (1), the evanescent wave being generated on the surface of the waveguide (2) by a standing wave generated by injecting an optical signal having a wavelength of λ into the waveguide (2), characterized in that The at least one antenna (30; 130; 230; 330) is formed by a plurality of nanoholes (41, 42, 43; 141, 142, 143; 241, 242, 243; 341, 342, 343) formed in the lateral direction of the optical substrate (1), and at least one of the nanoholes (41, 42, 43; 141, 142, 143; 241, 242, 243; 341, 342, 343) is different from other nanoholes (41, 42, 43; 141, 142, 143; 241, 242, 243; 341, 342, 343) in terms of at least one of its diameter, its spacing from the waveguide (2) in the height direction of the optical substrate (1), and its spacing from adjacent nanoholes of the same antenna in the longitudinal direction of the optical substrate (1).

2. The optical substrate (1) according to claim 1, characterized in that The at least one antenna (30; 130; 230; 330) comprises an odd number of nanoholes, preferably between 3 and 5 nanoholes, more preferably 5 nanoholes.

3. The optical substrate (1) according to claim 2, characterized in that The diameters of the nanopores (141, 142, 143; 341, 342, 343) decrease symmetrically from the central nanopore (141; 341) to the end nanopores (142, 143; 342, 343) of the antenna (130; 330).

4. The optical substrate (1) according to any one of claims 1 to 3, characterized in that The nanopores (41, 42, 43; 141, 142, 143; 341, 342, 343) are located in planes parallel to the height direction of the optical substrate (1).

5. An optical substrate (1) according to claim 4 as appended to claim 2 or claim 3, characterized in that The nanopores (41, 42, 43; 341, 342, 343) have a V-shaped arrangement, the central nanopore (41; 341) constituting the tip of the V-shape is opposite to the waveguide (2), and the other nanopores (42, 43; 342, 343) are symmetrically arranged in planes perpendicular to the height direction of the optical substrate (1) according to each branch of the V-shape, and these planes are farther away from the waveguide (2) as the nanopores (42, 43; 342, 343) they contain are closer to the ends of the branches of the V-shape, and the spacing between two adjacent nanopores is equal to λ / n or an integer multiple of λ / n when projected onto a plane perpendicular to the height direction of the optical substrate (1).

6. An optical substrate (1) according to claim 4 as appended to claim 2 or claim 3, characterized in that The at least one antenna (130) comprises five nanoholes (141, 142, 143), the five nanoholes (141, 142, 143) are arranged in a W shape, and are arranged in two planes parallel to each other and perpendicular to the height direction of the optical substrate (1), the first plane comprises a central nanohole (141) and two terminal nanoholes (143), the distance between each terminal nanohole (143) and the central nanohole (141) in the first plane along the longitudinal direction of the optical substrate (1) is equal to a characteristic distance, and the characteristic distance is equal to λ / n or an integer multiple of λ / n, the second plane arranged between the waveguide (2) and the first plane comprises two other nanoholes (142) spaced apart by a distance equal to the characteristic distance along the longitudinal direction of the optical substrate (1), and the first plane and the second plane are spaced apart by a distance equal to half of the characteristic distance along the height direction of the optical substrate (1).

7. The optical substrate (1) according to any one of claims 1 to 6, characterized in that The optical substrate (1) includes a plurality of antennas formed on the same side of the waveguide (2) in the height direction and constituting an antenna array, wherein the antenna array is configured to diffract one or more wavelengths.

8. A spectrometer (S), comprising a light source (7), an optical substrate (1) according to one of claims 1 to 7, and a detector (5), wherein the optical substrate (1) has two opposite parallel planes in the height direction of the optical substrate (1), the light source (7) is configured to inject light into the waveguide (2) of the optical substrate (1), and the detector (5) is arranged to face the plane of the optical substrate (1) to which the light diffracted by the at least one antenna (30; 130; 230; 330) is guided.

9. The spectrometer (S) according to claim 8, characterized in that A fluid reservoir (9) is formed on the surface of the optical substrate (1), on the plane of the optical substrate (1) facing the detector (5), so as to allow spectrometric analysis of light diffracted by the at least one antenna (330) and passing through the reservoir (9).

10. The spectrometer (S) according to claim 8 or 9, characterized in that A microfluidic circuit is formed between a plane of the optical substrate (1) facing the detector (5) and the detector (5) to allow spectrometric analysis of light diffracted by the at least one antenna (330) and passing through the microfluidic circuit.

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