Manufacturing method for diffractive optical waveguide

Abstract

A manufacturing method for a diffractive optical waveguide. On one hand, a grating material is printed in a structural region of a working template (401) by means of an inkjet printing technique to form an imprint resist layer, pre-curing treatment is performed on the location of a gap of a spliced sub-template (102) corresponding to a polymer resist layer to form a pre-cured resist layer (202) having a specified hardness, and then after a polymer resist material (203) is aligned with the gap, secondary curing is performed to form a patterned structure of an imprinted grating. On the other hand, a patterned transfer structure is formed on a first substrate (101), such that compared with the prior art, the demolding step or process is reduced, or the surface states of a grating structural region and a non-grating structural region on the surface of the substrate are changed, and thus the surface of the grating structural region and the surface of the non-grating structural region have different bonding forces. By means of the method, the imprint quality is improved, the invisibility of the grating is improved, the thicknesses of the overflowed resist and the remaining resist are controlled, the imprint process and the waveguide performance are improved, and the formed waveguide has more excellent optical performance and higher transparency.

Description

Fabrication method of diffractive optical waveguide TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, and in particular to a fabrication method of diffractive optical waveguide. BACKGROUND

[0002] Nanoimprint technology is a kind of micro-nano processing technology for manufacturing nano-sized structures, and the diffractive optical waveguide using nanoimprint process has become the mainstream product of AR optics. In the prior art, the process of preparing the grating of the diffractive optical waveguide based on the existing nanoimprint process is relatively complex, or the grating structure is easily affected by the complexity of different processes, resulting in low product performance or yield, and thus affecting the optical performance and appearance of the diffractive optical waveguide, which is undesirable for those skilled in the art. SUMMARY

[0003] The present application provides a fabrication method of diffractive optical waveguide to improve the existing nanoimprint process. On the one hand, the grating material is printed to form an imprint glue layer in the structure area of the working template by inkjet printing technology, the gap position of the corresponding splicing sub-plate of the polymer glue layer is first solidified, a pre-solidified glue layer with a certain hardness is formed, and then the polymer glue material is aligned with the gap and the second solidification is performed to form the patterned structure of the imprint grating. On the other hand, a patterned transfer structure is formed on the first substrate, which reduces the demolding step or process compared with the prior art. Or change the surface state of the grating structure area and the non-grating structure area of the substrate, and through the way of surface modification, the surface of the grating structure area and the non-grating structure area has different binding force. Through the above way, the imprint quality is improved, the accuracy of the diffractive grating structure production and the diffraction efficiency are improved, the invisibility of the grating is improved, the thickness of the overflow glue and the residual glue is controlled, the imprint process and the waveguide performance are improved, the formed waveguide has more excellent optical performance, and has higher transparency. BRIEF DESCRIPTION OF DRAWINGS

[0004] Fig. 1~Fig. 16 are schematic diagrams of the fabrication method of the diffractive optical waveguide provided by the present application. DETAILED DESCRIPTION

[0005] In view of the problems pointed out in the background section of the present application, the present application provides a fabrication method of diffractive optical waveguide. A fabrication method of diffractive optical waveguide, as shown in Fig. 1, includes the following steps:

[0006] S1: providing a working template, the working template having at least one structure area and a non-structure area.

[0007] In step S1, the working template is obtained based on the stamping master, or the working template is formed by stamping the master and imposition, and the working template includes at least one structure area to form the grating structure of the diffractive optical waveguide.

[0008] S2: printing a predetermined volume of grating material in the structure area of the working template based on the inkjet printing technology to form a grating material stamping adhesive layer, and obtaining the working template with the grating material stamping adhesive layer.

[0009] In step S2, the grating material stamping adhesive layer is formed by printing a certain amount of grating material in the structure area of the working template through the inkjet printing technology, and no grating material is printed in the non-structure area of the working template, so that the grating material stamping adhesive layer is only formed in the structure area, and the non-structure area is in a vacant state without grating material.

[0010] In the conventional uniform adhesive stamping mode, only the grating material in the structure area is pressed to form the grating structure during stamping, and the grating material in the non-structure area cannot form the required grating structure, so that more than 90% of the grating material in the conventional stamping mode is wasted and cannot form the grating structure, which causes serious waste of grating material and is not conducive to cost control. In the present application, a certain amount of grating material is printed in the specified structure area of the working template to form the stamping adhesive layer, which is different from the uniform adhesive mode in the prior art, changes the area and position relationship of the uniform adhesive in the prior art, and can control the printing of grating material according to the grating structure area, and the non-structure area is not printed to form grating material, which is different from the conventional uniform adhesive mode, and the present application can save more than 90% of the grating material, greatly reduce the product manufacturing cost, and improve the economic benefit.

[0011] In the present embodiment, the printing position in the structure area of the working template can be accurately selected, and the volume of grating material printed in each structure area can be accurately controlled, so as to change the existing stamping mode and reduce the stamping cost.

[0012] In step S2, the predetermined volume of grating material is determined based on the volume of grating material filled in the grating area and the volume of grating material remaining outside the grating area.

[0013] S3: contacting the working template with the grating material stamping adhesive layer in step S2 with the substrate, and performing stamping to completely transfer the structure of the working template to the substrate. In step S3, the working template with the grating material stamping adhesive layer in step S2 is contacted with the substrate, and the stamping is performed by aligning the working template with the mark on the substrate according to the pre-set positioning information.

[0014] S4: curing the stamping adhesive layer in the working template, and removing the working template to obtain the diffractive optical waveguide with the grating structure.

[0015] The present application firstly prints the grating material to form the embossing glue layer by the inkjet printing technology in the structure area of the working template, on the one hand, the grating material is saved compared with the prior art, on the other hand, the grating material is filled in each grating structure area as much as possible by the force during the inkjet printing, especially the different grating tooth root parts, such as the tooth root parts of the tooth shape of the flash or the bevel tooth, so that the grating material is filled more completely, the grating structure shape is transferred more completely during the pattern transfer, and the tooth shape defect and the like caused by the incomplete filling in the prior art can be prevented. The method of the present application can improve the situation.

[0016] In step S1, the working template is obtained based on the embossing master. Alternatively, the working template is obtained based on the embossing master and by blocking. In detail, the working template is obtained by the following process flow:

[0017] S11: providing an embossing master, the embossing master having a preset pattern area;

[0018] S12: obtaining an intermediate sub-plate by the embossing master, and obtaining a plurality of blocking sub-plates by the intermediate sub-plate;

[0019] S13: blocking the plurality of blocking sub-plates formed in the above steps on a first substrate in a preset manner to form a blocking master;

[0020] S14: providing a second substrate, uniformly coating a layer of polymer glue material on a surface of the second substrate, and locally solidifying the polymer glue material to form a pre-solidified glue layer;

[0021] S15: using the blocking master in step S13 to emboss the second substrate in step S14, and solidifying to obtain the working template.

[0022] As known by those skilled in the art, when the plurality of blocking sub-plates are blocked on the first substrate in the preset manner in step S13, there is a certain gap between the adjacent blocking sub-plates, as shown in FIG. 2, the blocking master formed by the five blocking sub-plates 102 has a plurality of gaps, as shown in area A (of course, the gap in the figure is only an example and does not represent the real gap), the blocking master is formed by the plurality of blocking sub-plates, and there is a gap between the adjacent blocking sub-plates, or there is a blocking gap at the blocking position, whether between the adjacent blocking sub-plates or between the blocking sub-plate and other areas, even when the blocking sub-plates are formed by high-precision laser cutting and then blocked, the gap still exists, which is difficult to avoid.

[0023] When the working template is formed by means of the embossing mold transfer, the mold transfer template is easy to form a protrusion in the area corresponding to the gap between the plurality of splicing sub-templates, and therefore, directly using the mold transfer template to produce the working template with the protrusion structure will adversely affect the grating pattern transfer effect on the optical wafer. Therefore, how to improve the quality of grating pattern transfer is an urgent problem to be solved by those skilled in the art.

[0024] The pre-cured adhesive layer designed in step S14 is first formed to have a certain hardness or a larger hardness, which can reduce or prevent the protrusion formed in the gap when the working template is formed by using the splicing master template. In step S14, a second substrate is provided, and a layer of polymer adhesive is uniformly coated on one surface of the second substrate. When the polymer adhesive is partially cured to form a pre-cured adhesive layer, the pre-cured adhesive layer corresponds to the gap between the splicing sub-templates in the splicing master template formed in step S13.

[0025] The width of the pre-cured adhesive layer is greater than the width of the gap between adjacent splicing sub-templates, or the width of the pre-cured adhesive layer is greater than the gap between adjacent splicing sub-templates and the gap between the splicing sub-templates and other regions, i.e. the width of the pre-cured adhesive layer is greater than or equal to the width of the gap in the splicing master template. The length of the pre-cured adhesive layer covers the length of the gap in the splicing master template, such as the length of the pre-cured adhesive layer in different regions covering the length of the gap in each region, or corresponding to the length of the gap in multiple regions, so that the pre-cured adhesive layer can at least completely cover the gap. In some embodiments, the width of the gap between adjacent splicing sub-templates is limited to 0.5-1mm, and the width of the pre-cured adhesive layer is limited to 2-3mm.

[0026] As shown in FIG. 3, a layer of polymer adhesive 203 is first uniformly coated on the surface of the second substrate 201, and the polymer adhesive corresponding to the position of the gap of the splicing sub-template is partially cured to form a pre-cured adhesive layer 202 with a certain hardness (as shown by the black area in the figure). The pre-cured adhesive layer divides into several regions, and the pre-cured adhesive layer corresponds to the gap between adjacent splicing sub-templates and the gap between the splicing sub-templates and other regions to completely cover all the gaps. Therefore, the polymer adhesive can be limited in each region defined by the pre-cured adhesive layer when the second substrate is embossed with the first substrate, preventing the polymer adhesive from flowing into different gaps, preventing the overflow of the polymer adhesive at different positions, and forming embossing structures only in the structure region. Therefore, a patterned working template without protrusions is formed, and an embossing working template with better structure is obtained to improve the embossing quality of the working template.

[0027] Further, as shown in FIG. 4, the polymer glue material 203 is locally cured to form a pre-cured glue layer 202 by using a curing mask. The curing mask includes a light-transmitting area 301, and the position of the light-transmitting area on the curing mask at least corresponds to the gap between the adjacent splicing sub-masters or between the splicing sub-masters and other areas. The pre-cured glue layer 202 is formed by curing through exposure.

[0028] In step S14, the local area of the polymer glue material 203 is first cured by using the curing mask to form a pre-cured glue layer 202 with a relatively large hardness. Here, the local area of the polymer glue material 203 corresponds to the gap area between the adjacent splicing sub-masters or between the splicing sub-masters and other areas. When the polymer glue material 203 is imprinted by using the splicing master, the corresponding area of the pre-cured glue layer 202 on the second substrate 201 will not be extruded to form a protruding structure, thereby solving the problem of poor transfer effect and poor transfer quality when the grating structure is transferred by using the splicing master. At the same time, the overflow of the glue during the imprinting process is also prevented, and the imprinting quality of the imprinting area is ensured.

[0029] In step S15, when the second substrate in step S14 is imprinted by using the splicing master, the specific operation is as follows: the gap between the adjacent splicing sub-masters of the splicing master is aligned with the position of the pre-cured glue layer on the second substrate, and after all the gaps are aligned, the second curing and demolding are performed to remove the splicing master, thereby obtaining a working template.

[0030] After the above steps, the working template obtained does not have a protruding structure in the gap area of the splicing master. When the working template is used to imprint the diffractive optical waveguide, the imprinting transfer effect is better, and the optical performance of the waveguide is improved.

[0031] In steps S14-S15, before the global curing of the polymer glue material, the positions of the gaps between the corresponding splicing sub-masters and other areas are preferentially cured to form a pre-cured glue layer with a certain hardness. After the polymer glue material is aligned with the gaps, the second curing is performed to form the patterned structure of the imprinted grating, that is, the different cured layers are formed by two times of curing. This is different from the one-time curing in the prior art. For the existing imprinting process, the imprinting process and the performance of the waveguide are greatly improved, and the optical performance of the formed diffractive optical waveguide is more excellent.

[0032] In some embodiments, in step S2, a predetermined volume of grating material is printed on the structure area of the working template based on the inkjet printing technology to form a grating material imprinting glue layer. It is known that the structure of the diffractive optical waveguide includes a coupling-in area, a coupling-out area, or in some embodiments, a turning area.

[0033] To solve the overflow glue and the imprint residual glue thickness uniformity problems raised in the background section of the present application, the present application defines the printing of a predetermined volume of grating material in different structural areas of the working template based on different grating structures, so as to realize the control of overflow glue and residual glue thickness by precisely controlling the volume of printed grating material in different areas; the predetermined volume of grating material is determined based on the volume of grating material filled in the grating area and the volume of grating material remaining outside the grating area; more specifically, the inkjet-printed grating material in the plurality of different structural areas is defined to satisfy the following relationship:

[0034] The predetermined volume of grating material in each structural area is equal to the sum of the reference grating material volume and the residual grating material volume; for different structural areas, the calculation formula is as follows:

[0035] The predetermined volume of grating material V 耦入 = + (1); in formula (1), f represents the duty cycle of the in-coupling grating structure, h represents the height of the in-coupling grating structure, d represents the diameter of the in-coupling area, x represents the distance of the in-coupling area grating material shrinkage, and t represents the thickness of the in-coupling area residual glue; The predetermined volume of grating material V 转折 = + (2); in formula (2), F1 represents the duty cycle of the turning area grating structure, H1 represents the height of the turning area grating structure, W1 represents the width of the turning area, Y1 represents the distance of the turning area grating material shrinkage, L1 represents the length of the turning area, and T1 represents the thickness of the turning area residual glue. The predetermined volume of grating material V 耦出 = + (3); in formula (3), F2 represents the duty cycle of the out-coupling grating structure, H2 represents the height of the out-coupling grating structure, W2 represents the width of the out-coupling area, Y2 represents the distance of the out-coupling area grating material shrinkage, L2 represents the length of the out-coupling area, and T2 represents the thickness of the out-coupling area residual glue.

[0036] As further more detailed description, as shown in Figure 7, a top view schematic diagram of the coupling-in region, the turning region and the coupling-out region is shown, wherein A represents a top view schematic diagram of the coupling-in region, d represents the diameter of the coupling-in region, i.e. the size of the coupling-in grating region after the imprinting and the inkjet printing, the gray region represents the inkjet printed grating material region in the coupling-in region, and x represents the distance of the inkjet printed grating material in the coupling-in region, i.e. the distance between the formed coupling-in grating structure region and the inkjet printed grating material. B and C shown in Figure 7 represent the top view schematic diagrams of the turning region and the coupling-out region, W1 represents the width of the turning region, L1 represents the length of the turning region, Y1 represents the distance of the inkjet printed grating material in the turning region, W2 represents the width of the coupling-out region, L2 represents the length of the coupling-out region, and Y2 represents the distance of the inkjet printed grating material in the coupling-out region. It is known that in the turning region or the coupling-out region, W1, W2, L1 and L2 can be changed, and even in different regions, Y1 and Y2 are also changed, and different predetermined volumes are defined based on different distances of the inkjet printed grating material. Based on the design, W1, W2, L1 and L2 of different regions are determined according to the gray scale chart during the inkjet printing, and of course, whether W1, W2, L1 and L2 shown in the figure are changed is determined based on the design, and the figure is only an example, but not a limitation of the change trend of W1, W2, L1 and L2.

[0037] Based on the same understanding, H1 in the above formula (2) and H2 in the formula (3) represent the height of the grating structure in the turning region or the coupling-out region, and the value can be changed based on the consideration of the turning and coupling-out efficiency, such as gradually increasing, and the values of H1 and H2 are different at different positions, and therefore, the amount of the inkjet printed grating material in different regions can be determined based on the gray scale chart during the inkjet printing, and the amount of the inkjet printed grating material in different regions is different, and presents a certain regular change.

[0038] By limiting the amount of the inkjet printed grating material in different regions, it is mainly divided into two parts, one part is the reference grating material volume, which is used to determine the required amount of the grating material according to the grating structure, duty cycle, period, height and other grating parameter information in different regions; the second part is the residual grating material volume, which is used to accurately calculate the amount of the overflow glue outside the grating structure region based on the overflow glue during the imprinting and the requirement for the residual grating material during the imprinting; by accurately calculating the reference grating material volume in the grating structure region and the residual grating material volume outside the grating structure region, the overflow glue control and the shape preservation of the grating structure are realized.

[0039] The reference grating material volume in the grating structure region refers to the grating material volume required to completely fill the grating structure from the bottom to the end in the grating structure region; and the residual grating material volume refers to the volume of the residual layer formed outside the grating structure region.

[0040] In combination with Fig. 5, the working template 401 obtained through the foregoing embodiment shows that the working template 401 includes two structures, assuming that the formed working template includes a blazed grating structure region 4011, a straight-tooth grating structure region 4012, and an inclined-tooth grating structure region 4013.

[0041] Fig. 6 is a partial enlarged view of the blazed grating structure region 4011 in the working template 401 of the two structures, which defines a grating region 40112 and a non-grating region 40111. Of course, the same grating region and non-grating region also exist for the straight-tooth grating structure region 4012 and the inclined-tooth grating structure region 4013. Furthermore, the grating region 40112 refers to the region formed from the bottom to the top of the grating, and the grating material is filled in the space region where the grating structure is located from the bottom to the top. The defined reference grating material volume refers to the grating material volume that is exactly required to fill the space region from the bottom to the top of the grating structure. The region outside the grating region 40112 is defined as the non-grating region, which is equivalent to the region outside the grating region. The residual grating material volume refers to the volume of the residual layer formed outside the grating region. Of course, different combinations of grating structures can be included in the same structure region, such as blazed and straight-tooth, straight-tooth and inclined-tooth, and the like. The combinations of multiple grating structures are defined based on different grating designs, and the drawings do not limit the combinations.

[0042] As described above, the grating material volume of each structure region = the reference grating material volume + the residual grating material volume. In combination with Fig. 5 and Fig. 6, the residual grating material shape cross-sectional view shown in the non-grating region 40111 is formed after imprinting. The working template provided by the present application forms an imprint structure on a substrate (the substrate is not shown in the figure), and forms an imprint structure including residual grating material. That is, the grating material in the black thick line frame is defined as the residual volume, that is, the volume of the grating material exposed outside the structure region. For example, the residual volume of the in-coupling grating region is defined as , the residual grating material volume of the turning region is defined as , and the residual grating material volume of the out-coupling grating region is defined as . In the formulas, the physical meanings of each physical quantity are the same as described above. The grating material covering the structure region outside the black thick line frame is defined as the reference grating material volume, that is, the grating material volume required to fill the region from the bottom to the end of the grating structure. In this application, for example, the reference grating material volume of the in-coupling region is defined as , the reference grating material volume of the turning region is defined as , and the reference grating material volume of the out-coupling grating region is defined as , the physical meaning of each physical quantity represented in the formula is the same as the foregoing; thus, by defining the two parts of the reference grating material volume and the residual grating material volume, the reference grating material volume can be accurately calculated to ensure that the grating material is completely filled into each region of the grating structure, especially the root position of the blazed and slanted tooth structure, and the residual grating material volume obtained by calculation can accurately control the volume of the grating material exposed outside the structure region; during the imprinting, based on the known volume of the grating material exposed outside the structure region, the thickness of the residual grating material after imprinting can be controlled by controlling the imprinting force, and the overflow condition and the thickness of the residual glue layer after imprinting are controlled by volume control, which is beneficial to those skilled in the art.

[0043] The present application makes the grating material fill each grating structure region as much as possible by means of the force during inkjet printing, especially the root of different grating teeth such as blazed or slanted teeth, so that the grating material is more completely filled, the grating structure shape is more completely transferred during pattern transfer, and the tooth shape defects caused by incomplete filling in the prior art can be prevented.

[0044] Meanwhile, when forming the working template, the gap position of the splicing sub-plate corresponding to the polymer glue layer is preferentially solidified before the polymer glue material is globally solidified, a pre-solidified glue layer with a certain hardness is formed, and the polymer glue material is aligned with the gap before the second solidification to form the patterned structure of the imprinted grating, that is, different solidified layers are formed by two times of solidification, which is different from the one-time solidification in the prior art, and can greatly improve the imprinting process and the waveguide performance, and the formed diffractive waveguide has more excellent optical performance. Based on the grating structure parameters, the volume of the printed grating material in the coupling-in grating region, the turning or coupling-out grating region is calculated, the printing volume is controlled to be below the picoliter level, and the volume of the printed grating material in different regions is accurately controlled to realize the control of the overflow and residual glue thickness, which has unexpected technical effects.

[0045] In another embodiment, a method for manufacturing a diffractive grating is provided, as shown in FIGS. 8-13, comprising the following steps:

[0046] (1) providing a first substrate and performing surface treatment on any surface of the first substrate; the surface treatment at least includes surface tackiness treatment;

[0047] (2) providing an imprinting master, the imprinting master having a patterned structure to be transferred;

[0048] (3) uniformly forming a first imprinting glue layer on the side surface of the imprinting master having the patterned structure;

[0049] (4) based on the surface treated surface in step (1), the first imprinting glue layer in step (3) is imprinted to form a first imprinting composite layer; and the imprinting master in the first imprinting composite layer is removed to obtain a second substrate with a transferred patterned structure;

[0050] (5) the surface of the second substrate with the transferred patterned structure is surface treated;

[0051] (6) the diffraction grating is formed based on the surface treated second substrate in step (5).

[0052] In step (2), the imprinting master 30 is provided, which has a plurality of patterned structures to be transferred, as shown in FIG. 8.

[0053] In step (3), the first imprinting glue layer 40 is uniformly formed on the side surface of the imprinting master 30 with the patterned structure; the first imprinting glue layer 40 is uniformly coated on the side surface of the imprinting master with the patterned structure; and the thickness of the first imprinting glue layer 40 is greater than the highest height of the patterned structure, so as to uniformly coat the first imprinting glue layer 40 on the surface of the entire imprinting master.

[0054] In step (4), based on the surface treated surface 20 in step (1), the first imprinting glue layer 40 in step (3) is imprinted to form a first imprinting composite layer S1.

[0055] On the basis of the foregoing steps, the imprinting master 30 in the first imprinting composite layer S1 is removed to obtain a second substrate S2 with a transferred patterned structure; the second substrate S2 has an optical structure unit complementary to the imprinting master 30, i.e. the transferred patterned structure; as shown in FIG. 8, the second substrate S2 has a grating unit complementary to the imprinting master 30, and the patterned structure is formed by transferring the imprinting master.

[0056] Further comprising step (5), the surface of the second substrate S2 with the transferred patterned structure is surface treated; the surface treated surface structure 50 is obtained, and the surface treatment method adopted is the same as that in step (1); including adhesion treatment or plasma treatment process.

[0057] In step (6), a diffraction grating is formed based on the second substrate that has been surface-treated in step (5). Specifically, two different embodiments are included. As shown in FIG9, the formation of a diffraction grating based on the second substrate that has been surface-treated in step (5) includes step (61), depositing a second material on the second substrate that has been surface-treated in step (5) to form a second material layer 90, the refractive index of the second material layer 90 being greater than that of the first imprinted adhesive layer 40; step (62), providing a first substrate 70, and uniformly forming a third material layer 100 on any surface of the first substrate 70; bonding the third material layer 100 to a surface of the second material layer 90 facing away from the patterned structure to form a diffraction waveguide; when the diffraction waveguide is in operation, light is transmitted by total internal reflection within the first substrate.

[0058] In this embodiment, the third material layer 100 has an adhesive function, which enables the first substrate 70 to bond better with the second material layer 90, especially by improving the bonding force of the two bonding surfaces through adhesive treatment.

[0059] In this embodiment, a second material layer 90 is formed by depositing a second material on the second substrate, wherein the refractive index of the second material is greater than 1.7. The refractive index of the second material layer 90 is greater than the refractive index of the first imprinted adhesive layer 40, in order to meet the optical performance requirements of the diffractive waveguide.

[0060] In this embodiment, after surface treatment of the first substrate, it is imprinted onto an imprinting master with a structured imprinting adhesive, and the structured imprinting adhesive layer is transferred onto the first substrate to form a second substrate. Then, a second material layer (grating material layer) is further formed on the structured imprinting adhesive layer to obtain a diffraction grating. Finally, a third material is used to bond the diffraction grating to the first substrate to form a diffraction waveguide. At this point, the second substrate (the first substrate and the structured imprinting adhesive layer) does not need to be separated from the diffraction grating. The first substrate can be used as a protective cover, and the structured imprinting adhesive layer serves to connect the diffraction grating and the first substrate, while also protecting the diffraction grating structure from damage. This method is simpler and more effective than existing imprinting methods for preparing diffraction gratings.

[0061] In another embodiment, in step (6), the diffraction grating is formed based on the second substrate that has been surface-treated in step (5). The method further includes the steps of: (7) providing a first substrate and uniformly forming a second imprinting adhesive layer on any surface of the first substrate; (8) imprinting the second imprinting adhesive layer from step (7) onto the second substrate with the transfer patterned structure that has been surface-treated in step (5), forming a diffraction grating within the second imprinting adhesive layer to obtain a diffraction waveguide with a diffraction grating; when the diffraction waveguide is in operation, light is transmitted via total internal reflection within the first substrate.

[0062] In detail, as shown in Fig. 10, in step (7), the first substrate 70 is provided, and the second imprinting glue layer 80 is uniformly formed on any surface of the first substrate 70; the thickness of the second imprinting glue layer 80 is greater than the highest height of the patterned structure, so that the surface of the entire first substrate 70 is coated with the second imprinting glue layer 80. The refractive index of the second imprinting glue layer 80 ranges from 1.8 to 2.3, and the refractive index of the second imprinting glue layer 80 is greater than that of the first imprinting glue layer 40. The refractive index of the first substrate 70 ranges from 1.8 to 2.2, and the value should be as close as possible to that of the second imprinting glue layer 80.

[0063] As shown in Fig. 11, step (8) is further included, that is, the second imprinting glue layer 80 in step (7) is imprinted based on the second substrate S2 with the transferred patterned structure which has been surface treated in step (5), to obtain the imprinted second imprinting composite layer S3 as shown in Fig. 12; the diffraction grating is formed in the second imprinting glue layer to obtain the diffraction optical waveguide with the diffraction grating; in the working process of the diffraction optical waveguide, the light is totally reflected and transmitted in the first substrate. As shown in Fig. 12, the second imprinting glue layer 80 is imprinted based on the second substrate S2 formed in step (4).

[0064] Through the above-mentioned process of step (1) to step (8), the second imprinting composite layer S3 with the superimposed structure is obtained, and the diffraction grating structure is formed to obtain the diffraction optical waveguide with the diffraction grating structure; in the working process of the diffraction optical waveguide, the light is totally reflected and transmitted in the first substrate, as shown in Fig. 12. The diffraction grating is obtained by the process, and the diffraction grating with the required patterned structure is formed.

[0065] Compared with the prior art, in the present embodiment, only in step (4), the demolding operation exists when the imprinting master in the first imprinting composite layer is removed, and the demolding step or process is reduced. The required diffraction grating can be formed by one-time demolding and imprinting, and the damage to the grating structure caused by multiple demolding operations in the prior art is avoided. The less demolding process of the present application can better ensure the integrity of the grating structure.

[0066] In another aspect, the present application is prepared by the lamination process of step (8); no lamination process is needed for the final diffraction optical waveguide product, and no multiple cleaning operations as in the prior art are needed, so the preparation process is simpler and more efficient. By providing a stamping glue layer between the stamping master 30 and the surface of the first substrate 70, i.e. including two uniform glue operations, the present application has fewer uniform glue operations than the prior art, and at the same time, the stamping pattern area formed by the first stamping glue layer 40 with a lower refractive index is used to stamp the second stamping glue layer 80 with a higher refractive index, to form a diffraction grating with the required refractive index. In this process, the first stamping glue layer 40 with a lower refractive index can completely fill the diffraction grating structure or the second material layer 90 can completely fill the structure area in the first stamping glue layer 40 and does not need to be demolded, i.e. the first stamping glue layer can play a full lamination role, i.e. the full lamination technical effect of the diffraction optical waveguide can be achieved, to bring higher transparency and invisibility of the grating.

[0067] As shown in FIG. 13, the same process as in the foregoing embodiments is performed to obtain an area including three different grating structures, and also to provide an area provided with at least three different grating structures. The present embodiment provides a diffraction optical waveguide including a first substrate, a second stamping glue layer, a first stamping glue layer and a first base substrate provided in sequence; the first stamping glue layer has a patterned structure, and the patterned structure forms a complementary patterned structure in the second stamping glue layer, and the refractive index of the first stamping glue layer is smaller than that of the second stamping glue layer; the projection area of the first stamping glue layer on the first substrate is not smaller than the projection area of the second stamping glue layer on the first substrate; when the diffraction optical waveguide is in operation, light is totally reflected and transmitted in the first substrate.

[0068] The present application also provides a diffraction optical waveguide including a first substrate, a first stamping glue layer and a first base substrate provided in sequence, and also including a second stamping glue layer or a second material layer; the first stamping glue layer has a patterned structure, and the patterned structure forms a complementary patterned structure in the second stamping glue layer or the second material layer, and the refractive index of the first stamping glue layer is smaller than that of the second stamping glue layer or the second material layer; the projection area of the first stamping glue layer on the first substrate is not smaller than the projection area of the second stamping glue layer or the second material layer on the first substrate; when the diffraction optical waveguide is in operation, light is totally reflected and transmitted in the first substrate.

[0069] Further, the present application provides a grating manufacturing method based on selective stamping of surface modification. The surface modification defined in the present application refers to surface treatment of a local surface area of a diffraction optical waveguide base substrate to improve the surface contact angle, to achieve the purpose of the present application.

[0070] A selective stamping method based on surface modification, as shown in FIGS. 14-1 and 14-2, includes:

[0071] Step (1): providing a substrate 100, depositing a first blocking layer 200 on any surface of the substrate 100, the first blocking layer 200 having at least one window area, at least one patterned area corresponding to the shape and position of the grating structure area; the substrate having a grating structure area and a non-grating structure area.

[0072] In step (1), the substrate 100 can be a silicon substrate, a glass substrate, a germanium substrate, gallium arsenide, SiC, TiO2, etc. metal substrate, or a flexible substrate such as a resin polymer; the first blocking layer 200 has at least one window area A, as shown in Figure 14-1; of course, the first blocking layer can include two window areas, each corresponding to the coupling-in area and the coupling-out area of the diffractive optical waveguide, or also including a turning area, etc.

[0073] Further, the plurality of window areas of the first blocking layer correspond to the grating structure area, and the shapes and positions of the two are matched with each other; that is, each window area matches the shape of the corresponding grating structure area to realize the subsequent process operation.

[0074] In step (1), the purpose of setting the first blocking layer is to block the contact between the adhesion layer and the local surface of the substrate in the subsequent step of setting the adhesion layer 300, and to reduce the contact force and contact area between the two. The thickness of the first blocking layer is not more than 100 μm, such as 10~50 μm, 50~80 μm, 80~100 μm.

[0075] Step (2): spin-coating an adhesion material on at least the surface of the window area of the first blocking layer to form a uniform adhesion layer 300; the thickness of the adhesion layer is not more than 20 nm. As shown in Figure 14-1, spin-coating an adhesion material on at least the surface of the window area of the first blocking layer, including spin-coating an adhesion material such as adhesion glue on the surface of the first blocking layer and the surface of the plurality of window areas, and uniformly coating to form a uniform adhesion layer. The adhesion layer serves to improve the adhesion of the substrate surface, improve the bonding force between the high-refractive index stamping glue and the substrate, ensure that the high-refractive index stamping glue is not peeled off by the subsequent process, and improve the contact force.

[0076] Step (3): removing the first blocking layer by physical peeling to completely expose the surface of the substrate below the first blocking layer. In this step, the blocking layer is removed by a physical peeling process, which aims to provide process surface space for the subsequent process of adding the release layer 500, and to remove part of the excess adhesion layer.

[0077] Step (4): depositing a second barrier layer 400 on the surface of the adhesion layer 300, the material of the second barrier layer is different from that of the first barrier layer. The thickness of the second barrier layer is not more than 30 μm. Due to the presence of the adhesion layer on the surface of the substrate, the second barrier layer will preferentially deposit in the adhesion layer area, forming a layer of the second barrier layer, while other areas will not deposit the second barrier layer due to the absence of the adhesion layer; the thickness of the second barrier layer is not more than 30 μm. Of course, if the second barrier layer 400 is deposited in the non-grating structure area, it can also be removed by conventional physical means. In step (4), the second barrier layer serves to protect the adhesion layer to avoid the adhesion layer from being affected and failing. The material of the second barrier layer is different from that of the first barrier layer.

[0078] Step (5): depositing an anti-adhesion layer 500 on the entire surface of the substrate in step (4); the thickness of the anti-adhesion layer is not more than 15 nm. An anti-adhesion layer with a thickness of not more than 15 nm is deposited on the entire surface of the substrate after step (4) by physical vapor deposition. The purpose is to reduce the adhesion of the exposed surface area of the substrate, i.e. to reduce the adhesion of the non-grating structure area, to increase the surface contact angle of the non-grating structure area, to reduce the bonding force between the high-bending imprinting glue in this area and the substrate surface, and to ensure that the high-bending imprinting glue can be peeled off by the following process, so as to realize the surface treatment of the non-grating structure area of the substrate. The surface contact angle of the anti-adhesion layer is not less than 109°. So that the surface of the anti-adhesion layer has good hydrophobicity, liquid or impurities are not easy to deposit on the surface, and the cleanliness of the substrate surface can be better protected.

[0079] Step (6): removing the second barrier layer 400 so that the adhesion layer on the surface of the substrate is completely exposed. In this step, the purpose of removing the second barrier layer is to completely expose the adhesion layer on the surface of the substrate so that the high-bending imprinting glue can be in contact with the adhesion layer as much as possible in the later process, so as to enhance the bonding force between the high-bending imprinting glue and the substrate and improve the bonding strength.

[0080] Step (7): spin coating high-bending imprinting glue on the entire surface of the substrate, the thickness of the high-bending imprinting glue meets the imprinting requirements of the preset diffraction grating; and performing an imprinting process. In this step, based on the existing spin coating process, a layer of high-bending imprinting glue 600 is spin coated on the surface of the substrate to form a high-bending imprinting glue layer 600 of the diffraction grating, and an imprinting process is performed to form a diffraction grating.

[0081] Step (8): After curing, the high-refractive embossing glue is peeled off by physical demolding to expose the surface of the substrate between the at least grating structure regions, and an embossed product is obtained, as shown in FIG. 14-2. In this step, after the high-refractive embossing glue is cured, the high-refractive embossing glue in the non-grating structure region is peeled off by physical demolding, such as manual demolding, mechanical demolding, etc., so that only the embossed diffraction grating structure in the grating structure region is left on the surface of the substrate through the effect of the tackifying layer, as shown in FIG. 14-2. By setting a thin film on the surface of the high-refractive embossing glue, the thin film is removed, and the high-refractive embossing glue in the non-grating structure region with poor adhesion on the surface of the substrate is peeled off. However, the diffraction grating structure in the grating structure region is not affected due to the strong bonding force of the tackifying layer, and the diffraction grating structure in the grating structure region is left on the tackifying layer of the substrate, thereby obtaining an embossed diffraction grating product. Of course, based on the bonding force of the anti-adhesion layer, the anti-adhesion layer in the non-grating structure region is also peeled off when the high-refractive embossing glue is peeled off, and a structure in which only the grating structure is retained in the grating structure region and the surface of the substrate in other structure regions is exposed, as shown in FIG. 15, is also within the scope of protection of the present application.

[0082] In combination with FIG. 16, compared with the prior art, the diffraction waveguide with embossed grating structure shown in (1) of FIG. 16 can form the embossed structure shown in (2) and (3) of FIG. 16 after the surface modification embossing process of the present application. In step (8), the high-refractive embossing glue is peeled off by physical demolding to expose the surface of the substrate between the at least grating structure regions, including the embodiment shown in (2) of FIG. 16, in which only the surface of the substrate between the grating structure regions is exposed; and the embodiment shown in (3) of FIG. 16, in which all the surfaces of the substrate except the grating structure regions are exposed, i.e., only the grating structure is retained in the grating structure region, and the surface of the substrate in other structure regions is exposed. Such a structure is beneficial to improving the imaging effect of the waveguide.

[0083] In the present embodiment, the first barrier layer, the second barrier layer, the anti-adhesion layer, the tackifying layer, etc. are set by multiple depositions to change the surface states of the grating structure region and the non-grating structure region of the substrate, so that the surfaces of the grating structure region and the non-grating structure region have different bonding forces, the surface modification of the non-grating structure region and the grating structure region is realized, and then the embossing glue layer with different surface bonding force states is peeled off or retained, thereby improving the embossing quality of the entire embossed product. The peeling off of the high-refractive embossing glue in the non-grating structure region can be realized. Through the process of the present embodiment, on the one hand, the surface parallelism of the product after embossing in the non-grating structure region can be ensured; on the other hand, the problems such as environmental particle adsorption, internal glue pollution and scratching in micro-nano processing can be avoided, and the integrity of the surface of the substrate is protected as much as possible.

[0084] Further, in some other embodiments, in step (8), the anti-sticking layer in the non-grating structure area is also peeled off simultaneously when the high-bending imprint glue is peeled off, as shown in Fig. 16, so that only the imprint structure is reserved in the grating structure area, and the anti-sticking layer in the non-grating structure area is peeled off, forming a diffractive optical waveguide with different structures, as shown in (2) and (3) in Fig. 16, that is, two product categories with different substrates can be obtained according to the actual product requirements, and this is within the technical scope of the present application.

[0085] The above detailed description does not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of fabricating a diffractive optical waveguide, characterized by, The method comprises the following steps: S1: providing a working template, the working template having at least one structure area and a non-structure area; S2: printing a predetermined volume of grating material in at least one structure area of the working template based on an inkjet printing technology, no grating material being printed in the non-structure area, forming a grating material imprinting glue layer, and obtaining the working template with the grating material imprinting glue layer; the predetermined volume of grating material is determined based on a grating material volume filled in a grating area and a residual grating material volume outside the grating area; S3: contacting the working template with the grating material imprinting glue layer in step S2 with a substrate and performing imprinting, and transferring the structure of the working template to the substrate completely; S4: curing the imprinting glue layer in the working template, and removing the working template, and obtaining the diffractive optical waveguide with the grating structure.

2. The method for fabricating a diffractive optical waveguide according to claim 1, characterized in that, In the step S2, a predetermined volume of grating material is printed in at least one structure area of the working template, and the predetermined volume of grating material printed in each structure area is equal to the sum of a reference grating material volume and a residual grating material volume. The reference grating material volume is defined as the grating material volume filled in the grating area, and the residual grating material volume is defined as the volume of the residual layer formed outside the grating area.

3. The method for fabricating a diffractive optical waveguide according to claim 2, characterized in that, The volume of the reference grating material in the coupled region within the structural region is limited to [a certain value]. The volume of the residual grating material within the coupling region is defined as follows: The volume of the reference grating material in the transition region within the structural region is limited to [a certain value]. The volume of the reference grating material in the coupled region within the structural region is defined as follows: The volume of the residual grating material within the transition region is limited to The volume of the residual grating material within the coupling region is defined as follows: ; In the formula, f represents the duty cycle of the in-coupling grating structure, h represents the height of the in-coupling grating structure, d represents the diameter of the in-coupling area, x represents the in-drawing distance of the grating material in the in-coupling area, t represents the thickness of the residual glue in the in-coupling area; F1 represents the duty cycle of the grating structure in the turning area, H1 represents the height of the grating structure in the turning area, W1 represents the width of the turning area, Y1 represents the in-drawing distance of the grating material in the turning area, L1 represents the length of the turning area, and T1 represents the thickness of the residual glue in the turning area; F2 represents the duty cycle of the grating structure in the out-coupling area, H2 represents the height of the grating structure in the out-coupling area, W2 represents the width of the out-coupling area, Y2 represents the in-drawing distance of the grating material in the out-coupling area, L2 represents the length of the out-coupling area, and T2 represents the thickness of the residual glue in the out-coupling area.

4. A method for fabricating a diffractive optical waveguide according to claim 1 or 2, characterized in that, The working template is obtained through the following steps: S11: providing an imprinting master, the imprinting master having a preset pattern area; S12: obtaining an intermediate sub-master through the imprinting master, and obtaining a plurality of spliced sub-masters through the intermediate sub-master; S13: splicing the plurality of spliced sub-masters formed in the above steps on a first substrate in a preset manner to form a spliced master; S14: providing a second substrate, uniformly coating a layer of polymer glue material on one surface of the second substrate, and forming a pre-cured glue layer by locally curing the polymer glue material; S15: using the spliced master in step S13 to imprint the second substrate in step S14, and curing to obtain a working template.

5. The method for fabricating a diffractive optical waveguide according to claim 4, characterized in that, The pre-cured glue layer formed in the step S14 corresponds to the gaps in the spliced master formed in the step S13 one by one, and the gaps include the gaps between the plurality of spliced sub-masters and the gaps between the spliced sub-masters and other areas.

6. The method for fabricating a diffractive optical waveguide according to claim 5, characterized in that, The width of the pre-cured adhesive layer is greater than or equal to the width of the gap in the splicing master; and the length of the pre-cured adhesive layer is at least completely covers the length of the gap in the splicing master.

7. A method of fabricating a diffractive optical waveguide as claimed in claim 5 or 6, wherein, The polymer adhesive material in step S14 is subjected to local curing treatment by using a curing mask plate, and the curing mask plate comprises a light-transmitting area, and the positions of the light-transmitting area on the curing mask plate correspond to the gaps in the splicing master one by one.

8. A method of fabricating a diffraction grating, characterized by, The method comprises the following steps: (1) providing a first substrate and performing surface treatment on any surface of the first substrate; (2) providing an imprint master, the imprint master having a patterned structure to be transferred; (3) uniformly forming a first imprint adhesive layer on the side surface of the imprint master having the patterned structure; (4) imprinting the first imprint adhesive layer in step (3) based on the surface of step (1) that has been subjected to surface treatment to form a first imprint composite layer; and removing the imprint master in the first imprint composite layer to obtain a second substrate having a transferred patterned structure; (5) performing surface treatment on the surface of the second substrate having the transferred patterned structure; (6) forming the diffraction grating based on the second substrate that has been subjected to surface treatment in step (5).

9. The method of claim 8, wherein the step of forming the diffraction grating is performed by a method selected from the group consisting of: a holographic method, a lithographic method, a mechanical method, and a combination thereof. In detail, in step (6), the diffraction grating is formed by depositing a second material layer on the second substrate based on the second substrate that has been subjected to surface treatment in step (5).

10. The method of claim 9, wherein the step of forming the diffraction grating is performed by a method selected from the group consisting of: a holographic method, a photolithographic method, a mechanical method, and a combination thereof. In step (6), the method further comprises providing a first substrate and uniformly forming a third material layer on any surface of the first substrate; and combining the third material layer to a surface of the second material layer away from the patterned structure to form a diffraction optical waveguide. In operation, light is totally reflected and transmitted in the first substrate.

11. The method of claim 8, wherein the step of forming the diffraction grating is performed by a method selected from the group consisting of: a holographic method, a lithographic method, a mechanical method, and a combination thereof. In detail, in step (6), the diffraction optical waveguide is formed by providing a first substrate and uniformly forming a second imprint adhesive layer on any surface of the first substrate; and imprinting the second imprint adhesive layer based on the second substrate that has been subjected to surface treatment in step (5) and having the transferred patterned structure to form the diffraction grating in the second imprint adhesive layer to obtain a diffraction optical waveguide with the diffraction grating. In operation, light is totally reflected and transmitted in the first substrate.

12. The method of claim 11, wherein the method further comprises: The refractive index of the second imprint adhesive layer is greater than the refractive index of the first imprint adhesive layer; and the refractive index of the second imprint adhesive layer ranges from 1.8 to 2.

3.

13. The method of claim 10, wherein the method further comprises: The refractive index of the second material layer is greater than the refractive index of the first imprint adhesive layer; and the refractive index of the second material layer is greater than 1.

7.

14. The method of claim 11, wherein the method further comprises: The diffraction optical waveguide comprises a first substrate, a first imprinting glue layer and a first base which are sequentially stacked, and further comprises a second imprinting glue layer or a second material layer; the first imprinting glue layer has a patterned structure, and the patterned structure forms a complementary patterned structure in the second imprinting glue layer or the second material layer, and the refractive index of the first imprinting glue layer is smaller than the refractive index of the second imprinting glue layer or the second material layer; the projection area of the first imprinting glue layer on the first substrate is not less than the projection area of the second imprinting glue layer or the second material layer on the first substrate; in operation, light is totally reflected in the first substrate.

15. A method of fabricating a diffraction grating, characterized by, The method comprises the following steps: Step (1): providing a base having a grating structure region and a non-grating structure region, depositing a first barrier layer on any surface of the base, the first barrier layer having at least one window region, the at least one window region being adapted to the shape and position corresponding to the grating structure region; Step (2): spin-coating a tackiness-improving material on the surface of the window region of the first barrier layer to form a uniform tackiness-improving layer; Step (3): removing the first barrier layer by physical peeling to completely expose the surface of the base under the first barrier layer; Step (4): depositing a second barrier layer on the surface of the tackiness-improving layer, the second barrier layer being different from the first barrier layer in material; Step (5): depositing an anti-adhesion layer on the entire surface of the base in step (4); Step (6): removing the second barrier layer to completely expose the tackiness-improving layer on the surface of the base; Step (7): spin-coating a high-refraction imprinting glue on the entire surface of the base, the thickness of the high-refraction imprinting glue satisfying the imprinting requirement of a preset diffraction grating, and performing an imprinting process; Step (8): after solidification, peeling off the high-refraction imprinting glue by physical demolding to expose the surface of the base between at least the grating structure regions, thereby obtaining an imprinting product.

16. The method of claim 15, wherein the method further comprises: The thickness of the first barrier layer is not greater than 100 μm, the thickness of the tackiness-improving layer is not greater than 20 nm, the thickness of the second barrier layer is not greater than 30 μm, and the thickness of the anti-adhesion layer is not greater than 15 nm.

17. The method of claim 15, wherein the method further comprises: In step (5), the anti-adhesion layer is deposited on the entire surface of the base in step (4) to reduce the adhesion of the non-grating structure region and increase the surface contact angle of the non-grating structure region; the surface contact angle of the anti-adhesion layer is not less than 109°.

18. The method of claim 15, wherein the method further comprises: In step (6), the second barrier layer is removed to completely expose the tackiness-improving layer on the surface of the base, so that the high-refraction imprinting glue is in complete contact with the tackiness-improving layer to enhance the bonding force between the high-refraction imprinting glue and the base.

19. A surface modification based directed pressure printing method according to claim 15 or 17, wherein, In step (8), specifically, only the surface of the base between the grating structure regions is exposed, or all the surface of the base except the grating structure regions is exposed.

20. A surface modification based directed pressure printing method according to claim 15 or 17, wherein, In step (8), in detail, the high-refractive imprint glue of the non-grating structure region of the substrate surface with poor adhesion is peeled off by physical demolding, and the grating structure region is left on the adhesion layer of the substrate due to the strong binding force of the adhesion layer, and a diffraction grating product is obtained.

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