Optical module, preparation method of optical module and optical system

Abstract

The embodiment of the invention relates to an optical module, a preparation method thereof and an optical system. The optical module comprises a first functional substrate, a second functional substrate and an electrolyte layer. The first functional substrate includes a first substrate, a first diffraction grating formed on a first surface of the first substrate, and a first electrochromic layer formed on a second surface of the first substrate opposite to the first surface. The second functional substrate comprises a second substrate, a second diffraction grating formed on the third face of the second substrate and a second electrochromic layer formed on the fourth face, opposite to the third face, of the second substrate, and the second face and the fourth face are arranged at intervals in a face-to-face mode. The electrolyte layer is sandwiched between the first electrochromic layer and the second electrochromic layer to form an electrochemical unit. By applying variable voltage to the electrochemical unit, the effective refractive index of the second diffraction grating and the light absorption coefficient of the electrochemical unit can be changed, and then the coupling angle and the light transmittance of the optical module can be dynamically regulated and controlled.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of optics, in particular, to an optical module, a preparation method of the optical module, and an optical system. BACKGROUND

[0002] In an optical system such as an augmented reality (AR) glasses, a traditional optical module has a light adjustment function, and usually adopts a scheme of an optical waveguide sheet and an externally packaged electrochromic device. However, the scheme has the following defects: a large packaging thickness, affecting the wearing comfort and the lightweight design; a large number of alignment times in the process, reducing the production yield; a fixed coupling angle of the grating, which cannot dynamically adjust the optical path; a limited brightness adjustment range, limiting the use scenarios; and a single control mechanism, lacking flexibility in dual regulation of the refractive index and color. SUMMARY

[0003] In view of this, it is necessary to provide an optical module, a preparation method of the optical module, and an optical system to solve at least one of the above technical problems.

[0004] The first aspect of the present application provides an optical module. The optical module includes a first functional substrate, a second functional substrate, and an electrolyte layer. The first functional substrate includes a first substrate, a first diffraction grating formed on a first surface of the first substrate, and a first electrochromic layer formed on a second surface of the first substrate, the first surface and the second surface being opposite. The second functional substrate includes a second substrate, a second diffraction grating formed on a third surface of the second substrate, and a second electrochromic layer formed on a fourth surface of the second substrate, the third surface and the fourth surface being opposite, the second surface and the fourth surface being spaced apart and arranged face to face. The electrolyte layer is interposed between the first electrochromic layer and the second electrochromic layer to form an electrochemical cell. By applying a variable voltage to the electrochemical cell, the effective refractive index of the second diffraction grating and the light absorption coefficient of the electrochemical cell can be changed, and then the coupling angle and the light transmittance of the optical module are dynamically regulated.

[0005] In terms of structure, in the related art optical module, the diffraction grating and the electrochromic layer are designed as independent substrates, while in the optical module of the embodiments of the present application, the diffraction grating and the electrochromic layer are integrated into a double-sided design, in which the first diffraction grating and the first electrochromic layer are independent of each other, the functional layers do not interfere with each other, and the first substrate is shared, the second diffraction grating and the second electrochromic layer are independent of each other, the functional layers do not interfere with each other, and the second substrate is shared. Therefore, the problem of a large thickness and complex packaging of the scheme of externally hanging an electrochromic structure in the traditional optical module is solved, and the optical module is lighter and thinner and has a shorter optical path.

[0006] In terms of function, the coupling angle of the grating in the optical module of the related art is fixed, the light path cannot be dynamically adjusted, and the brightness cannot be changed. However, the optical module of the embodiment of the present application dynamically controls the effective refractive index change of the second diffraction grating and the light absorption coefficient change of the electrochemical cell by using the voltage input of the electrochemical cell, thereby changing the light coupling angle, improving the light coupling efficiency, and actively suppressing stray light to optimize display uniformity and the like.

[0007] In terms of process, the optical module of the related art needs multiple bonding processes, and the process is complex. However, the optical module of the embodiment of the present application is beneficial to reduce the bonding times because the diffraction grating and the electrochromic layer share the substrate.

[0008] In terms of cost, the optical module of the related art needs at least four substrates, and the preparation of each substrate is an independent process, which is high in cost. However, the optical module of the embodiment of the present application is beneficial to reduce the material cost and the process cost because the number of substrates is reduced, the bonding times are reduced, and the process is simplified.

[0009] The second aspect of the present application provides a preparation method of an optical module, which comprises: providing a first functional substrate integrated with a first diffraction grating and a first electrochromic layer; providing a second functional substrate integrated with a second diffraction grating and a second electrochromic layer; and assembling the first functional substrate and the second functional substrate through alignment and bonding process, and forming an electrolyte layer between the first functional substrate and the second functional substrate to form an electrochemical cell.

[0010] The preparation method of the optical module of the second aspect of the present application has at least the same advantages as the optical module of the first aspect of the present application, which will not be repeated.

[0011] The third aspect of the present application provides an optical system comprising the optical module of the first aspect of the present application and a control unit. The control unit is electrically connected with the electrochemical cell and is configured to send a variable voltage to the electrochemical cell to cooperatively regulate the effective refractive index and the light absorption coefficient.

[0012] The optical system of the third aspect of the present application has at least the same advantages as the optical module of the first aspect of the present application, which will not be repeated. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a partial cross-sectional structural schematic diagram of the optical module of the related art.

[0014] Figure 2 It is a partial cross-sectional structural schematic diagram of the optical module of the embodiment of the present application.

[0015] Figure 3 FIG. 4 is a schematic diagram of the relationship between the light absorption coefficient and the coupling efficiency according to an embodiment of the present application.

[0016] Figure 4 FIG. 5 is a schematic diagram of the relationship between the refractive index variation and the effective refractive index according to an embodiment of the present application.

[0017] Figure 5 FIG. 6 is a schematic diagram of the relationship between the effective refractive index, the grating period and the coupling angle of the optical module according to an embodiment of the present application.

[0018] Figure 6 FIG. 7 is a diagram of the coupling efficiency distribution corresponding to different grating depths of the second diffraction grating in the optical module according to an embodiment of the present application.

[0019] Figure 7 FIG. 8 is a schematic diagram of the structure of the optical system according to an embodiment of the present application.

[0020] Main element symbol explanation: The following detailed description will further illustrate the present application in combination with the above-mentioned drawings. DETAILED DESCRIPTION

[0021] Figure 1 FIG. 9 is a schematic diagram of the partial cross-sectional structure of the optical module 100' of the related art. The optical module 100' can be applied to a full-color AR glasses to make the AR glasses have light-adjusting or color-changing functions. As shown in FIG. 9, the optical module 100' includes a first layer substrate 1, a second layer substrate 2, a third layer substrate 3, a fourth layer substrate 4, a fifth layer substrate 5, an electrolyte layer 6, a bonding adhesive layer 7, a bonding adhesive layer 8 and a bonding adhesive layer 9. Figure 1

[0022] In use, the external ambient light is incident from the side where the first layer substrate 1 is located. The fifth layer substrate 5 is close to the eye E of a person. Among them, the fourth layer substrate 4 serves as a first piece of light waveguide for realizing the coupling-in of light. The fifth layer substrate 5 serves as a second piece of light waveguide for realizing the coupling-out of light to enter the eye E of the user. The fourth layer substrate 4 and the fifth layer substrate 5 are connected through the bonding adhesive layer 9.

[0023] The third layer substrate 3 is connected with the fourth layer substrate 4 through the bonding adhesive layer 8. The electrolyte layer 6 is arranged between the third layer substrate 3 and the second layer substrate 2. The electrolyte layer 6 can be an electrolyte adhesive layer, and also plays a role of bonding the third layer substrate 3 and the second layer substrate 2. The side of the third layer substrate 3 close to the electrolyte layer 6 is used to form an upper electrochromic layer, and the side of the second layer substrate 2 close to the electrolyte layer is used to form a lower electrochromic layer. The third layer substrate 3 and the second layer substrate 2 and the layers (such as the electrochromic layer, the lower electrochromic layer and the electrolyte layer 6) therebetween together constitute an electrochromic structure. ​

[0024] The first substrate 1 acts as a lens and is connected to the second substrate 2 through the adhesive layer 7.

[0025] The following definitions are along the thickness direction Z of the optical module 100', from the first substrate 1 to the fifth substrate 5, which is the direction from the outside to the inside. That is, the direction of the ambient light is outside, and the direction of the user's eye is inside.

[0026] By Figure 1 It can be seen that the optical module 100' includes at least five substrates, three adhesive layers, and one electrolyte layer, and the overall thickness is large. In addition, in the process, the substrates need to be aligned and bonded between each other, so the five substrates need at least four alignment and bonding processes. Moreover, in the optical module 100', the coupling angle of the grating is fixed, and the brightness cannot be effectively adjusted, and the control mechanism is single.

[0027] It should be noted that Figure 1 The optical module of the full-color AR glasses is taken as an example for illustration. For the optical module of the single-color AR glasses, the difference lies in that it only needs one light waveguide to allow a specific wavelength of light to pass (such as one of red light, green light, or blue light), but it still needs four substrates, three alignment and bonding processes, and still has the problem of single control mechanism.

[0028] Figure 2 A partial cross-sectional structure diagram of an optical module 100 according to an embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, the optical module 100 includes a first functional substrate 10, a second functional substrate 20, and an electrolyte layer 30. Figure 2

[0029] The first functional substrate 10 includes a first substrate 11, a first diffraction grating 12 formed on one side of the first substrate 11, and a first electrochromic layer 13 formed on the other side of the first substrate 11. The first substrate 11 includes opposite first and second faces 11a and 11b. The first diffraction grating 12 is formed on the first face 11a of the first substrate 11. The first electrochromic layer 13 is formed on the second face 11b of the first substrate 11.

[0030] The second functional substrate 20 includes a second substrate 21, a second diffraction grating 22 formed on one side of the second substrate 21, and a second electrochromic layer 23 formed on the other side of the second substrate 21. The second substrate 21 includes opposite third and fourth faces 21c and 21d. The second diffraction grating 22 is formed on the third face 21c, and the second electrochromic layer 23 is formed on the fourth face 21d. The second face 11b and the fourth face 21d are spaced apart and face each other.

[0031] ​The electrolyte layer 30 is interposed between the first electrochromic layer 13 and the second electrochromic layer 23 to form an electrochemical cell EC; or in other words, the electrochemical cell EC includes the first electrochromic layer 13, the second electrochromic layer 23, and the electrolyte layer 30.

[0032] In the optical module 100, by applying a variable voltage to the electrochemical cell EC, the effective refractive index of the second diffraction grating 22 can be changed, and then the coupling angle of light is dynamically controlled, and the light absorption coefficient of the electrochemical cell EC is changed, and then the light transmittance of the optical module 100 is dynamically controlled.

[0033] In terms of structure, in the related art optical module 100', the diffraction grating and the electrochromic layer are designed as independent substrates, while in the optical module 100 of the present application, the diffraction grating and the electrochromic layer are integrated into a double-sided design, in which the first diffraction grating 12 and the first electrochromic layer 13 are independent of each other, the functions are layered and do not interfere with each other, and they share the first substrate 11, the second diffraction grating 22 and the second electrochromic layer 23 are independent of each other, the functions are layered and do not interfere with each other, and they share the second substrate 21, thereby solving the problems of large thickness and complex packaging of the traditional optical module 100' with an externally hung electrochromic structure, making the optical module 100 thinner and the optical path shorter.

[0034] In terms of function, in the related art optical module 100', the coupling angle of the grating is fixed, and the light path cannot be dynamically adjusted, and the brightness cannot be changed, while in the optical module 100 of the present application, the voltage input of the electrochemical cell EC is used to dynamically control the change of the effective refractive index of the second diffraction grating 22 and the change of the light absorption coefficient of the electrochemical cell EC, and then the wavelength or coupling angle of light coupling can be changed to improve the effect of light coupling efficiency and actively suppress stray light to optimize display uniformity.

[0035] In terms of process, in the related art optical module 100', multiple bonding processes are required, and the process is complex, while in the optical module 100 of the present application, the diffraction grating and the electrochromic layer share the substrate, thereby reducing the number of bonding times.

[0036] In terms of cost, in the related art optical module 100', at least four substrates are required, and the preparation of each substrate is an independent process, which is costly, while in the optical module 100 of the present application, the number of substrates is reduced, the bonding times are reduced, and the process is simplified, thereby reducing the material cost and the process cost.

[0037] In some embodiments, the first diffraction grating 12 is a Bragg grating for light in-coupling, and the second diffraction grating 22 is a subwavelength relief grating (SRG) for light out-coupling.

[0038] In the above embodiments, different types or hybrid function gratings are used, in which the Bragg grating has high angular selectivity and high wavelength selectivity, and is suitable for in-coupling; the subwavelength relief grating (SRG) has high design freedom and is easy to combine with the electrochromic layer to realize effective refractive index control, and is suitable for out-coupling. In some embodiments, the grating period of the subwavelength relief grating is between 450 nm and 900 nm, the depth is between 50 nm and 200 nm, and the duty cycle (ratio of groove width to period width) is between 0.1 and 0.6. Thus, when the effective refractive index is in the range of 1.6 to 2.3, it is beneficial to realize dynamic regulation of the light coupling angle in the range of 30° to 60°.

[0039] In the above embodiments, the specific geometric parameter range (period, depth, duty cycle) of the subwavelength relief grating is a preferred interval obtained by Rigorous Coupled-Wave Analysis (RCWA) simulation, which is beneficial to ensure that the subwavelength relief grating can maintain high coupling efficiency when the effective refractive index changes, and realizes high-performance dynamic light path regulation.

[0040] In some embodiments, the first electrochromic layer 13 and the second electrochromic layer 23 form a complementary electrochromic system, the first electrochromic layer 13 includes a first transparent electrode layer 131 and a nickel oxide layer 132 which are sequentially stacked on the second surface 11b, and the second electrochromic layer 23 includes a second transparent electrode layer 231 and a tungsten oxide layer 232 which are sequentially stacked on the fourth surface 21d.

[0041] In the above embodiments, NiO (anodic coloring material) and WO3 (cathodic coloring material) are complementary electrochromic materials with stable performance, fast response speed and high optical contrast. The nickel oxide layer 132 and the tungsten oxide layer 232 work together to realize a large dynamic range of optical performance (effective refractive index and light absorption coefficient) at a lower voltage. The nickel oxide layer 132 and the tungsten oxide layer 232 have the advantages of full solid state and low power consumption.

[0042] In other embodiments, the first electrochromic layer 13 and the second electrochromic layer 23 can also be other materials that can form a complementary electrochromic system, one of which is an anodic coloring material and the other is a cathodic coloring material.

[0043] In some embodiments, the optical module 100 includes a visual area 100A and a frame area 100B adjacent to the visual area 100A. For example, when the optical module 100 is applied to AR glasses, one optical module 100 is provided for each of the left and right eyes of the user. The frame area 100B surrounds the visual area 100A and corresponds to the installation position of the frame of the AR glasses. The visual area 100A of the optical module 100 is not blocked by the frame.

[0044] In some embodiments, the first electrochromic layer 13 further includes a first metal layer 133, and the second electrochromic layer 23 further includes a second metal layer 233. The first metal layer 133 is located between the first transparent electrode layer 131 and the nickel oxide layer 132 and is located in the frame area 100B. The second metal layer 233 is located between the second transparent electrode layer 231 and the tungsten oxide layer 232 and is located in the frame area 100B.

[0045] In some embodiments, the first metal layer 133 is located on the surface of the first transparent electrode layer 131 facing the nickel oxide layer 132, and the second metal layer 233 is located on the surface of the second transparent electrode layer 231 facing the tungsten oxide layer 232.

[0046] It should be noted that the first transparent electrode layer 131 and the second transparent electrode layer 231 are usually indium tin oxide, and the conductivity of the first transparent electrode layer 131 and the second transparent electrode layer 231 is not as good as that of metal. The first transparent electrode layer 131 and the second transparent electrode layer 231 have a certain sheet resistance. When the size of the lens of the AR glasses is large, if only the first transparent electrode layer 131 and the second transparent electrode layer 231 are used to conduct the current for driving the entire lens to change color, the following problems may occur: First, the voltage drop is inconsistent: When the current flows from the electrode contacts at the edge of the lens to the center, the voltage will gradually decrease due to the resistance of transparent materials such as indium tin oxide. This leads to inconsistent actual voltage experienced by areas close to the power source and areas far from the power source (such as the center of the lens).

[0047] Second, the response is uneven: Voltage inconsistency can cause the chemical reaction speed of the electrochromic layer (nickel oxide and tungsten oxide) to be uneven. Ultimately, it visually appears that the lens changes color unevenly, and there may be patches of different colors from the edge to the center, affecting the user experience.

[0048] Third, the response speed is slow: Due to the high resistance of transparent materials such as indium tin oxide, it takes longer to charge / discharge the entire large-area capacitive structure, thereby reducing the switching speed of the glasses from the transparent state to the colored state (or vice versa).

[0049] In the embodiments of the present application, by introducing the first metal layer 133 and the second metal layer 233 (such as copper, silver, aluminum, etc.) with better electrical conductivity than the materials (such as indium tin oxide) of the first transparent electrode layer 131 and the second transparent electrode layer 231, a low-resistance current channel can be constructed, so that the current is first transported to the edges of the lens through the first metal layer 133 and the second metal layer 233, and then applied to the electrochromic layer (nickel oxide layer and tungsten oxide layer) along the thickness direction Z of the optical module 100 through the first transparent electrode layer 131 and the second transparent electrode layer 231. This is conducive to reducing the voltage drop and ensuring that the voltage of the entire visual area 100A is basically uniform, thereby facilitating the realization of fast and uniform color changing effect.

[0050] In addition, since metal is opaque, if the metal layer is arranged corresponding to the visual area 100A, it will block the user's line of sight. The lens of the AR glasses is usually fixed by the frame. The frame area 100B is an area where the lens is blocked by the frame and the user's line of sight cannot pass through. Arranging the first metal layer 133 and the second metal layer 233, which are opaque but have good electrical conductivity, in this "hidden" area can not only play a key role in optimizing the electrical performance, but also completely not affect the light transmittance and clarity of the central visual area 100B.

[0051] Therefore, the first metal layer 133 and the second metal layer 233 are ingeniously hidden in the frame area 100B, which is conducive to solving the problem of insufficient electrical conductivity of the first transparent electrode layer 131 and the second transparent electrode layer 231, so as to ensure that the electrochromic function of the AR glasses can respond quickly and uniformly, while not sacrificing the transparency of the visual area 100A.

[0052] In some embodiments, the materials of the first substrate 11 and the second substrate 21 are each selected from at least one of rigid glass, ultra-thin flexible glass (UTG), or plastic.

[0053] In the above embodiments, the materials of the first substrate 11 and the second substrate 21 include rigid (glass), low cost (plastic), and flexible (UTG), etc., which enhances the applicable scenarios (such as curved display) of the optical module 100.

[0054] It should be noted that in the embodiments of the present application, the ultra-thin flexible glass refers to a glass material with a thickness less than or equal to 100 microns.

[0055] In some embodiments, the optical module 100 further comprises an outer lens 40. The outer lens 40 is arranged on the side of the first functional substrate 10 where the first diffraction grating 12 is located. The outer lens 40 has at least one of the following characteristics: having a dioptric adjustment function; the surface has a multi-layer film structure, the multi-layer film structure includes an anti-reflection film and / or an anti-fingerprint film; and is subjected to yellowing inhibition treatment.

[0056] In the above embodiments, the optical module 100 can be combined with vision correction function by the setting of the outer lens 40, and the durability and optical quality (such as anti-fouling and anti-fogging) of the final optical module 100 are improved.

[0057] In some embodiments, the optical module 100 further comprises a bonding adhesive layer 50. The outer lens 40 is bonded to the first surface 11a of the first substrate 11 through the bonding adhesive layer 50. The bonding adhesive layer 50 can be, but is not limited to, an optically transparent adhesive.

[0058] In some embodiments, the optical module 100 is applied in an AR glass, the second functional substrate 20 faces the user's eye E, and the external ambient light is incident from the side where the outer lens 40 is located.

[0059] The following describes how the optical module 100 of the embodiments of the present application implements the application of voltage to dynamically adjust the optical properties, including but not limited to, controlling the coupling angle or coupling efficiency of light by electrically controlling the effective refractive index of the second diffraction grating 22; and suppressing stray light or adjusting the overall light transmittance by electrically controlling the light absorption coefficient of the electrochromic layer.

[0060] According to the optical absorption principle of Beer-Lambert Beer's law, there is the following formula (1): Formula (1).

[0061] In formula (1), η (V, λ) is the light coupling efficiency of wavelength λ under the control of voltage V; η0 (λ) is the reference light coupling efficiency when no voltage is applied; k (V, λ) is the light absorption coefficient of wavelength λ under the control of voltage V, which affects the loss of stray light; L is the effective propagation wavelength of light in the electrochromic layer.

[0062] As can be seen from formula (1), when the light absorption coefficient k is increased by applying voltage V, the exponential term is sharply reduced, and finally the light coupling efficiency η (V, λ) is also reduced, corresponding to the darkening of the optical module; on the contrary, when the light absorption coefficient k is reduced by applying voltage V, the exponential term is sharply increased, and finally the light coupling efficiency η (V, λ) is also increased, corresponding to the brightening of the optical module.

[0063] Therefore, according to formula (1) and Figure 3 It can be known that η0 (λ) = 1, the light absorption coefficient k can be changed in the range of 0 to 0.2 by voltage control, and the corresponding light coupling efficiency η changes from 100% to 0% to adjust the display brightness of the optical module, to suppress the internal and external stray light and improve the display contrast. For example, when k = 0, corresponding to the transparent state of the electrochemical cell, η = 100%, at this time the light coupling efficiency is the highest; when k = 0.2, corresponding to the coloring state of the electrochemical cell, the light coupling efficiency η is reduced.

[0064] According to the waveguide mode theory, there is the following formula (2): Formula (2).

[0065] In formula (2), n eff (V, λ) is the effective refractive index of the waveguide or diffraction grating for wavelength λ under the control of voltage V, which dynamically adjusts the coupling condition; Γ is the overlap factor of the electrochromic layer on the waveguide mode; Δn(V, λ) is the amplitude of change in the refractive index of the material for light of wavelength λ as the voltage V is regulated.

[0066] From formula (2), we can see that by applying voltage V, the refractive index Δn(V, λ) can be changed to linearly change the effective refractive index n eff .

[0067] Combining formula (2) and Figure 4 It can be seen that when Δn(V,λ)=+0.3, corresponding to the transparent state of the electrochemical unit, the effective refractive index n eff Increased to 2.3; when Δn(V,λ)=-0.3, corresponding to the coloration state of the electrochemical unit, the effective refractive index n eff Coming to 1.7.

[0068] According to the grating coupling formula, the following formula (3) is obtained: Formula (3).

[0069] In formula (3), n eff is the effective refractive index; n0 is the refractive index of air, assuming n0 is 1; θ is the coupling angle; m is the grating order, usually m=±1; λ is the coupling wavelength; Λ is the grating period.

[0070] From formula (3), we can see that if n0,λ,Λ,m are fixed. Changing the effective refractive index n eff When the voltage V changes, the coupling angle θ will change accordingly. According to formula (2), the change of the voltage V will cause the effective refractive index n eff Therefore, combining formula (2) and formula (3), it can be seen that by changing the voltage V, the coupling angle θ can be dynamically adjusted at a fixed incident wavelength.

[0071] Table 1 shows the relationship between the state, voltage, effective refractive index, coupling angle and light absorption coefficient of the electrochemical cell at a wavelength of 940 nm.

[0072] Table 1 Combined with reference formula (3), Figure 5 From Table 1, we can see that: taking the SRG grating period of 700nm as an example, in the colored state (neff =1.7, voltage is -2V) to transparent state (n eff =2.1, voltage is +2V), the coupling angle changes from 15° to approximately 45°, which means that when the voltage changes in the range of -2V to 2V, the dynamic range of the coupling angle is approximately 30°.

[0073] Figure 6 RCWA simulation results, where the yellow area represents the area with higher coupling efficiency.

[0074] Figure 6 The corresponding grating depth in (a) is 100 nm; Figure 6 The corresponding grating depth in (b) is 130 nm; Figure 6 The corresponding grating depth in Figure (c) is 160nm.

[0075] Depend on Figure 6 As shown in Figure (a), when the grating depth is 100nm, the corresponding area with higher coupling efficiency is roughly the area with a grating period of 680nm to 720nm and a duty cycle of 0.5 to 0.6, and the maximum optical coupling efficiency is 67.5%.

[0076] Depend on Figure 6 As shown in Figure (b), when the grating depth is 130nm, the corresponding area with higher coupling efficiency is roughly the area with a grating period of 680nm to 730nm and a duty cycle of 0.55±0.05, and the maximum optical coupling efficiency is 96%.

[0077] Depend on Figure 6 As shown in Figure (c), when the grating depth is 160nm, the corresponding area with higher coupling efficiency is roughly the area with a grating period of 650nm to 750nm and a duty cycle of 0.5 to 0.6, and the maximum optical coupling efficiency is 67.5%.

[0078] The present application also provides a method for preparing an optical module. The method for preparing the optical module includes the following steps S10 and S30. According to different requirements, the order of certain steps or sub-steps of the method for preparing the optical module can be changed, and certain steps or sub-steps can be omitted or combined. In addition, the method for preparing the optical module is the optical module described in any of the above embodiments. Figure 2 Understand the preparation method of the optical module.

[0079] Step S10: providing a first functional substrate, wherein the first functional substrate is integrated with a first diffraction grating and a first electrochromic layer.

[0080] In some embodiments, step S10 comprises forming the first diffraction grating 12 on the first surface 11a of the first substrate 11 and forming the first electrochromic layer 13 on the second surface 11b of the first substrate 11, the first surface 11a being opposite to the second surface 11b.

[0081] In some embodiments, the first diffraction grating 12 can be formed by, but not limited to, nanoimprinting or etching.

[0082] In some embodiments, the first electrochromic layer 13 can be formed by, but not limited to, plating.

[0083] In step S10, the first diffraction grating 12 and the first electrochromic layer 13 are integrated in the first functional substrate 10, which is advantageous in reducing the number of substrates and the number of alignment and bonding times, improving the yield and efficiency of the process, and reducing the manufacturing cost, as compared to forming the first diffraction grating and the first electrochromic layer on different substrates respectively and then aligning and bonding the different substrates.

[0084] Step S20: providing a second functional substrate, the second functional substrate integrating a second diffraction grating and a second electrochromic layer. In some embodiments, referring to Figure 2 , step S20 comprises forming the second diffraction grating 22 on the third surface 21c of the second substrate 21 and forming the second electrochromic layer 23 on the fourth surface 21d of the second substrate 21, the fourth surface 21d being opposite to the third surface 21c.

[0085] In some embodiments, the second diffraction grating 22 can be formed by, but not limited to, nanoimprinting or etching.

[0086] In some embodiments, the second electrochromic layer 23 can be formed by, but not limited to, plating.

[0087] In step S20, the second diffraction grating 22 and the second electrochromic layer 23 are integrated in the second functional substrate 20, which is advantageous in reducing the number of substrates and the number of alignment and bonding times, improving the yield and efficiency of the process, and reducing the manufacturing cost, as compared to forming the second diffraction grating and the second electrochromic layer on different substrates respectively and then aligning and bonding the different substrates.

[0088] Step S30: assembling the first functional substrate and the second functional substrate by an alignment and bonding process, and forming an electrolyte layer between the first functional substrate and the second functional substrate to form an electrochemical unit.

[0089] In some embodiments, referring to Figure 2The step S30 includes: through the aligning and bonding process, the second surface 11b of the first substrate 11 and the fourth surface 21d of the second substrate 21 are arranged in a spaced and face-to-face manner, and then the electrolyte layer 30 is formed between the first electrochromic layer 13 and the second electrochromic layer 23.

[0090] In the preparation method of the optical module, in the step S10, the first diffraction grating and the first electrochromic layer share the first substrate, and in the step S20, the second diffraction grating and the second electrochromic layer share the second substrate, so that the preparation method can form the optical module through a single aligning and bonding process. Thus, the multiple aligning and bonding steps in the traditional preparation method of the optical module are simplified into one step, which greatly simplifies the process flow, improves the production yield and efficiency, and reduces the manufacturing cost.

[0091] In some embodiments, the preparation method of the optical module further includes attaching an outer lens to the side of the first diffraction grating of the first functional substrate. In this case, the number of substrates in the optical module does not exceed three (the first substrate, the second substrate and the outer lens), and the bonding process between two substrates does not exceed twice (the first functional substrate is bonded with the second functional substrate once, and the outer lens is bonded with the first functional substrate once). Compared with the traditional preparation method of the optical module, the number of aligning and bonding processes is reduced, and the production efficiency is improved. Figure 1 As shown in the optical module 100' shown in , the thickness of two layers of substrates and two layers of bonding glue is reduced, and the process of twice aligning and bonding is reduced, so that the thickness of the optical module is reduced, the production process is simplified, and the manufacturing cost is reduced.

[0092] The embodiments of the present application also provide an optical system. The optical system includes the optical module of any one of the above embodiments and a control unit (not shown in the figure). The control unit is electrically connected with the electrochemical unit and is configured to send a variable voltage to the electrochemical unit to cooperatively regulate the effective refractive index and the light absorption coefficient.

[0093] In some embodiments, as shown in Figure 7 , the optical system 1000 is an AR glass. The AR glass includes the optical module 100 of any one of the above embodiments and a frame 200. The number of the optical modules 100 is two. The two optical modules 100 are installed on the frame 200. When a user wears the AR glass, the left and right eyes of the user correspond to one optical module 100 respectively.

[0094] Please refer to Figure 2 and Figure 7 , the visual area 100A of the optical module 100 is exposed at the frame 200, and the frame area 100B corresponds to the installation on the frame 200. After the user wears the AR glass, the second functional substrate 20 is closer to the eyes E of the user than the first functional substrate 10.

[0095] In some embodiments, the optical system is an augmented reality or virtual reality display system, and the optical system further comprises an image source, and the optical module is disposed in an optical path of the image source for coupling and directing image light emitted by the image source to an eye of an observer and adjusting transmittance of ambient light in the optical module.

[0096] In some embodiments, the optical system is a Time-of-Flight (ToF) system or a Light Detection and Ranging (LiDAR) system (also known as optical radar system), and the optical system further comprises a light source and a sensor, and the optical module is disposed in an exit light path of the light source and / or an entrance light path of the sensor for angle scanning of a light beam emitted by the light source and / or adjusting light intensity entering the sensor. The light source can be, but is not limited to, a laser light source.

[0097] In some embodiments, the optical system is an adjustable optical filter, and the control unit is configured to adjust the overall intensity of light transmitted through the optical module by adjusting the variable voltage to selectively diffract light of a specific wavelength or incident angle.

[0098] In some embodiments, the optical system is a smart window or a dimmable glass, and the optical module constitutes at least a portion of the smart window or the dimmable glass for controlling light transmittance of ambient light penetrating through the at least a portion and / or changing a propagation direction of light penetrating through the at least a portion.

[0099] In some embodiments, in the smart window or the dimmable glass, dynamic adjustment of the light absorption coefficient k can be used to adjust the light transmittance of the glass in a large area, thereby achieving energy saving and privacy protection.

[0100] The above embodiments are only used to illustrate the technical solutions of the present application and not to limit the present application. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application.

Claims

1. An optical module, characterized in that: include: A first functional substrate comprising a first substrate, a first diffraction grating formed on a first surface of the first substrate, and a first electrochromic layer formed on a second surface of the first substrate, wherein the first surface is opposite to the second surface; a second functional substrate comprising a second substrate, a second diffraction grating formed on a third surface of the second substrate, and a second electrochromic layer formed on a fourth surface of the second substrate, wherein the third surface is opposite to the fourth surface, and the second surface is spaced apart from and face to face with the fourth surface; as well as an electrolyte layer sandwiched between the first electrochromic layer and the second electrochromic layer to form an electrochemical unit; By applying a variable voltage to the electrochemical unit, the effective refractive index of the second diffraction grating and the light absorption coefficient of the electrochemical unit can be changed, thereby dynamically adjusting the coupling angle and transmittance of the optical module.

2. The optical module according to claim 1, wherein: The first diffraction grating is a Bragg grating for light coupling in, and the second diffraction grating is a sub-wavelength relief grating for light coupling out.

3. The optical module according to claim 2, wherein: The grating period of the sub-wavelength relief grating is between 450 nm and 900 nm, the depth is between 50 nm and 200 nm, and the duty cycle is between 0.1 and 0.

6.

4. The optical module according to claim 1, wherein: The first electrochromic layer and the second electrochromic layer form a complementary electrochromic system. The first electrochromic layer includes a nickel oxide layer, and the second electrochromic layer includes a tungsten oxide layer.

5. The optical module according to claim 1, wherein: The materials of the first substrate and the second substrate are each selected from at least one of rigid glass, ultra-thin flexible glass, and plastic.

6. The optical module according to any one of claims 1 to 5, wherein: The optical module further includes an outer lens, which is disposed on a side of the first functional substrate where the first diffraction grating is located; the outer lens has at least one of the following features: With diopter adjustment function; The surface has a multi-layer film structure, wherein the multi-layer film structure includes an anti-reflection film and / or an anti-fingerprint film; Treated to inhibit yellowing.

7. A method for preparing an optical module, characterized in that: include: Providing a first functional substrate, wherein the first functional substrate is integrated with a first diffraction grating and a first electrochromic layer; Providing a second functional substrate, wherein the second functional substrate is integrated with a second diffraction grating and a second electrochromic layer; as well as The first functional substrate and the second functional substrate are assembled through alignment and lamination processes, and an electrolyte layer is formed between the first functional substrate and the second functional substrate to form an electrochemical unit.

8. The method for preparing an optical module according to claim 7, wherein: Providing the first functional substrate includes: forming the first diffraction grating on a first surface of the first substrate, and forming the first electrochromic layer on a second surface of the first substrate, wherein the first surface is opposite to the second surface; Providing the second functional substrate includes: forming the second diffraction grating on the third surface of the second substrate, and forming the second electrochromic layer on the fourth surface of the second substrate, wherein the third surface is opposite to the fourth surface; Assembling the first functional substrate and the second functional substrate includes: arranging the second surface of the first substrate and the fourth surface of the second substrate face to face with each other, and forming the electrolyte layer between the first electrochromic layer and the second electrochromic layer.

9. An optical system, characterized in that: include: The optical module according to any one of claims 1 to 6; as well as A control unit is electrically connected to the electrochemical cell and configured to send the variable voltage to the electrochemical cell to coordinately regulate the effective refractive index and the light absorption coefficient.

10. The optical system according to claim 9, wherein The optical system is an augmented reality or virtual reality display system, and the optical system further includes an image source. The optical module is arranged in the optical path of the image source, and is used to couple the image light emitted by the image source and guide it to the observer's eyes, and adjust the transmittance of ambient light in the optical module; or, The optical system is a time-of-flight system or an optical radar system, and further comprises a light source and a sensor. The optical module is disposed in an outgoing light path of the light source and / or an incident light path of the sensor, and is configured to perform angular scanning on the light beam emitted by the light source and / or adjust the intensity of the light entering the sensor. or, The optical system is a tunable optical filter, and the control unit is configured to control the variable voltage so that the optical module selectively diffracts light of a specific wavelength or incident angle and adjusts the overall intensity of light transmitted through the optical module; or, The optical system is a dimming glass, and the optical module constitutes at least a part of the dimming glass, and is used to control the transmittance of ambient light penetrating the at least part and / or change the propagation direction of the light penetrating the at least part.

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