CN117805963A

CN117805963A - Diffraction optical waveguide and display device

Info

Publication number: CN117805963A
Application number: CN202311707601.1A
Authority: CN
Inventors: 宋昱铭; 隋磊; 田克汉
Original assignee: Yuguang Technology Beijing Co ltd
Current assignee: Yuguang Technology Beijing Co ltd
Priority date: 2023-12-12
Filing date: 2023-12-12
Publication date: 2024-04-02

Abstract

The invention discloses a diffraction optical waveguide and a display device. The diffractive optical waveguide includes: the device comprises a waveguide substrate, a coupling grating and a two-dimensional pupil expansion grating; the two-dimensional pupil expansion grating comprises a plurality of optical unit structures which are arranged in an array, wherein each optical unit structure comprises a plurality of sections, and the sections are spliced in sequence along a first direction; the sections shrink in width at the top, middle upper and bottom ends of the optical unit structure along a second direction, and the first direction is perpendicular to the second direction; the total length of the optical unit structure along the first direction is L, the grating period of the coupled grating is d, and the relationship between L and d is as follows: 0.88 xd < L <1.19 xd. The optical unit structure is integrally arranged into a curved trapezoid, and the coupling-out efficiency and the conduction efficiency can be adjusted by adjusting the curved trapezoid structure, so that the structure has high two-side light splitting efficiency and two-side coupling-out efficiency, and particularly, the structure is an excellent structure at the conduction tail end of a two-dimensional grating region.

Description

Diffraction optical waveguide and display device

Technical Field

The present invention relates generally to the field of diffraction-based display technology, and more particularly to a diffractive optical waveguide and a display device.

Background

The diffraction optical waveguide has the advantages of light weight, easy replication, high processing yield and the like, and compared with the array optical waveguide which has low processing yield and difficult mass production of holographic waveguides, the diffraction optical waveguide with the surface relief is an ideal consumer electronic waveguide glasses solution. The diffraction optical waveguide can be generally divided into a one-dimensional mydriatic diffraction optical waveguide and a two-dimensional mydriatic diffraction optical waveguide, wherein the two-dimensional mydriatic diffraction optical waveguide has a two-dimensional grating structure (namely, grating periods exist in two directions) in some gratings of a coupling-out area, and signal light orders transmitted inside the waveguide form four orders from the inside of a medium to an interface, and the four orders comprise: total reflection order, coupling-out order, left-side beam split order, right-side beam split order, as shown in fig. 3, correspond to R (0, 0), R (1, 1), R (-2, 0), respectively; this may act as a two-dimensional pupil expansion, with the black dots representing light coupled out perpendicular to the screen. The two-dimensional mydriatic structure needs to penetrate the whole coupling-out area, which is a relatively large-span area, so that the four parameters are required to have relatively high degrees of freedom, and the aim of high efficiency and good non-uniformity of the whole coupling-out area is fulfilled.

Accordingly, there is a need to provide a diffractive optical waveguide and a display device to at least partially solve the above-mentioned problems.

Disclosure of Invention

In the summary, a series of concepts in a simplified form are introduced, which will be further described in detail in the detailed description. The summary of the invention is not intended to define the key features and essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

To at least partially solve the above problems, a first aspect of the present invention provides a diffractive optical waveguide comprising:

a waveguide substrate;

the coupling-in grating is arranged on the waveguide substrate and is used for coupling light into the waveguide substrate;

a two-dimensional mydriatic grating disposed on a waveguide substrate, the two-dimensional mydriatic grating including a plurality of optical unit structures arranged in an array for expanding light propagating to the waveguide substrate and simultaneously coupling out from the waveguide substrate;

the optical unit structure comprises a plurality of sections, and the sections are spliced in sequence along a first direction;

the sections shrink in width at the top, middle-upper and bottom ends of the optical unit structure, respectively, in a second direction, the first direction being perpendicular to the second direction;

The total length of the optical unit structure along the first direction is L, the grating period of the coupling-in grating is d, and the relationship between L and d is: 0.88 xd < L <1.19 xd.

Optionally, the sections are formed of trapezoids, the trapezoids being either right side up or upside down;

alternatively, the sections are formed by rounded trapezoids, which are either right-angled or inverted;

alternatively, the sections are formed of an approximate trapezoid, which is either right or inverted.

Optionally, the L and the d have the following relationship: 0.95 xd < L <1.15 xd.

Optionally, the optical unit structure includes four sections, which are a first section, a second section, a third section, and a fourth section along the first direction, respectively;

the top width of the first section is W1, the bottom width of the first section and the top width of the second section are W2, the bottom width of the second section and the top width of the third section are W3, the bottom width of the third section and the top width of the fourth section are W4, and the bottom width of the fourth section is W5.

Optionally, the W2, W4, L have the following relationship: (W2+W4)/L is more than or equal to 1.25 and less than or equal to 1.60.

Optionally, the W2, W4, L have the following relationship: (W2+W4)/L is more than or equal to 1.30 and less than or equal to 1.45.

Optionally, the W2, W4, L have the following relationship:

0.90≤W2/W4≤1.40，0.65≤W2/L≤0.85，0.6≤W4/L≤0.7。

optionally, the W2 and the W4 have the following relationship: W2/W4 is more than or equal to 0.95 and less than or equal to 1.20.

Optionally, the W2 and the L have the following relationship: 0.4 XL < W2<1.0 XL.

Optionally, the W1 and the W5 have the following relationship: W1-W5 > 0.2Xmax (W1, W5).

Optionally, the W1, the W2, the W5 have the following relationship:

w5 > 0.1×w1, or, w5 >0.2×w1, or, w1=w5=0;

0.8XW2 > W5, or 0.3XW2 > W5.

Optionally, in the second direction, the height of the first section is L1, the height of the second section is L2, the height of the third section is L3, the height of the fourth section is L4, and the L1, L2, L3, and L4 have the following relationship: (L1+L2)/(L3+L4) is more than or equal to 0.43 and less than or equal to 2.30.

Optionally, the L1, the L2, the L3, the L4 have the following relationship: (L1+L2)/(L3+L4) is more than or equal to 0.50 and less than or equal to 1.50.

Optionally, the whole structure of the optical unit structure is a non-centrosymmetric structure, and W1 is more than or equal to W5;

When (l1+l2)/(l3+l4) =1, w2+.w4;

when w2=w4, w1=w5, l1/(l1+l2) noteql 4/(l3+l4).

Optionally, along the second direction, randomly intercepting a sampling section from the sections, wherein the width of the top end of the sampling section is M1, the width of the bottom end of the sampling section is M2, and the height of the sampling section is H, and the M1, the M2 and the H have the following relations:

0.ltoreq.arctan (((M1-M2)/2)/H.ltoreq.beta.where beta <75 deg..

Optionally, the β has the following relationship: beta <45 deg., alternatively beta <30 deg..

Optionally, corners of the optical unit structure are rounded.

Optionally, in the second direction, a straight line A1 is made through the tangent point of the uppermost end of the optical unit structure, a straight line A2 is made through the widest part of the upper part of the optical unit structure, a straight line A3 is made through the narrowest part of the middle part of the optical unit structure, a straight line A4 is made through the widest part of the middle part of the optical unit structure, and a straight line A5 is made through the tangent point of the lowermost end of the optical unit structure;

the straight line connecting the uppermost tangential point of the optical unit structure and the boundary intersection point of A2 and the optical unit structure is B1, and the included angle between B1 and A1 is alpha 1, wherein alpha 1 is less than or equal to 180 degrees;

the straight line connecting A2 with the boundary intersection point of the optical unit structure and the boundary intersection point of A3 with the optical unit structure is B2, and the included angle between B2 and A2 is alpha 2, and alpha 2 is more than or equal to 30 degrees and less than or equal to 90 degrees;

The straight line connecting the boundary intersection point of A3 and the optical unit structure and the boundary intersection point of A4 and the optical unit structure is B3, and the included angle between B3 and A3 is alpha 3, and the angle between B3 and A3 is more than or equal to 90 degrees and less than or equal to 150 degrees;

the straight line connecting the boundary intersection point of the A4 and the optical unit structure and the tangent point of the lowest end of the optical unit structure is B4, and the included angle between the B4 and the A4 is alpha 4, and the alpha 4 is more than or equal to 20 degrees and less than or equal to 75 degrees.

Optionally, along the second direction, setting the midpoint of the narrowest part of the middle part of the optical unit structures as the center, wherein the connecting lines of the centers of the first optical unit structure, the second optical unit structure and the third optical unit structure adjacent to the oblique rear part respectively form lattice direction lines, the sum of included angles between the two lattice direction lines and the central line of the first optical unit structure is theta, and the included angle between the two lattice direction lines and the central line of the first optical unit structure is more than or equal to 45 degrees and less than or equal to 75 degrees.

Optionally, the θ has the following relationship: θ is 50-70 °, or 55-65 °.

Optionally, the W2, the L, the θ have the following relationship: w2 < 2/3× (d×tan (θ)), L < 1/2× (d×tan (θ)).

Alternatively, the optical unit structure is a bump-like or concave hole-like structure formed on the waveguide substrate.

A second aspect of the present invention provides a display device comprising the diffractive optical waveguide as claimed in any one of the above technical aspects.

Optionally, the display device is a near-eye display device, comprising a lens, the lens comprising the diffractive optical waveguide.

According to the diffraction optical waveguide and the display device, the optical unit structure in the two-dimensional grating is integrally arranged into the curved trapezoid, and the coupling-out efficiency and the conduction efficiency can be adjusted by adjusting the curved trapezoid structure, so that the structure has high two-side light splitting efficiency and high two-side coupling-out efficiency, and particularly, the structure is excellent at the conduction tail end of the two-dimensional grating region.

Drawings

The following drawings of embodiments of the present invention are included as part of the invention. Embodiments of the present invention and their description are shown in the drawings to explain the principles of the invention. In the drawings of which there are shown,

FIG. 1 is a schematic diagram of a prior art optical unit structure;

FIG. 2 is a schematic diagram of a prior art coupling-out grating;

FIG. 3 is a prior art coupled-out grating propagation order diagram;

FIG. 4 is a schematic dimensional view of an optical unit structure according to a preferred embodiment of the present invention;

FIG. 5 is a schematic diagram of the structure of a coupling-out grating according to a preferred embodiment of the present invention;

FIG. 6a is a schematic diagram of the structure of a diffractive optical waveguide according to a preferred embodiment of the present invention;

fig. 6b is a schematic structural view of a display device according to a preferred embodiment of the present invention;

fig. 7 is a schematic structural view of an optical unit structure according to a preferred embodiment of the present invention;

fig. 8 is a schematic structural view of an optical unit structure according to a preferred embodiment of the present invention;

FIG. 9 is a schematic diagram illustrating the dimensions of the sampling area of FIG. 8;

fig. 10 is a schematic structural view of an optical unit structure according to a preferred embodiment of the present invention;

FIG. 11 is a schematic dimensional view of an optical unit structure according to a preferred embodiment of the present invention;

FIG. 12 is a schematic view of a coupling-out grating provided with differently shaped optical cell structures;

FIGS. 13a and 13b are schematic views of optical cell structures provided with differently shaped curved trapezoids;

FIG. 14 is a graph of simulated data of the effect of the parameter L/d on both side splitting x both side out-coupling;

FIGS. 15 a-15 e are simulated data graphs of the effect of different values of L/d on two-sided spectroscopic x two-sided coupling-out for different parameters W1-W5;

FIGS. 16a and 16b are schematic views of optical cell structures provided with differently shaped curved trapezoids;

Fig. 17a is a graph of simulated data of the effect of different values of (w2+w4)/L on two-sided spectroscopic x two-sided coupling out for the parameter L/d=0.875;

fig. 17b is a graph of simulated data of the effect of different values of (w2+w4)/L on two-sided spectroscopic x two-sided coupling out for the parameter L/d=1.000;

fig. 17c is a graph of simulated data of the effect of different values of (w2+w4)/L on two-sided spectroscopic x two-sided coupling out for the parameter L/d=1.125;

FIGS. 18a and 18b are schematic views of optical cell structures provided with differently shaped curved trapezoids;

FIGS. 19 a-19 c are simulated data graphs of the effect of different values of W2/W4 on two-sided spectroscopic x two-sided coupling-out for different parameters L/d;

FIGS. 20a and 20b are schematic views of optical cell structures provided with differently shaped curved trapezoids;

fig. 21 a-21 i are simulated data graphs of the effect of different values of (l1+l2)/(l3+l4) on the two-sided spectroscopic x two-sided coupling-out for different parameters L1, L3.

Reference numerals illustrate:

100: optical unit structure

101: a first trapezoid

102: second trapezoid

103: third trapezoid (V)

104: fourth trapezoid shape

105: fifth trapezoid shape

106: sixth trapezoid shape

107: seventh trapezoid

108: eighth trapezoid

109: ninth trapezoid (L)

110: tenth trapezoid

111: eleventh trapezoid

112: twelfth trapezoid

113: first section

114: second section

115: third section

116: fourth section

117: sampling section

200: two-dimensional pupil-expanding grating

300: lens

400: light machine

500: optical unit structure

600: coupling in grating

700: waveguide substrate

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without one or more of these details. In other instances, well-known features have not been described in detail in order to avoid obscuring the invention.

In the following description, a detailed description will be given for the purpose of thoroughly understanding the present invention. It should be appreciated that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of these exemplary embodiments to those skilled in the art. It will be apparent that embodiments of the invention may be practiced without limitation to the specific details that are familiar to those skilled in the art. Preferred embodiments of the present invention are described in detail below, however, the present invention may have other embodiments in addition to these detailed descriptions.

Ordinal numbers such as "first" and "second" cited in the present invention are merely identifiers and do not have any other meaning, such as a particular order or the like. Also, for example, the term "first component" does not itself connote the presence of "second component" and the term "second component" does not itself connote the presence of "first component".

It should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer" and the like are used in the present invention for illustrative purposes only and are not limiting.

In some embodiments, a trapezoid structured optical cell structure 500 is disclosed, as shown in fig. 1, 2, but has two drawbacks: 1) The trapezoid structure naturally has an acute angle structure, the processing recovery difficulty is high, the waveguide structure is a period of a sub-wavelength structure and is usually only hundreds of nanometers, so that the processing recovery is not good enough, the light splitting performance is deteriorated, and the robustness is not good enough; 2) After the upper bottom and the lower bottom of the traditional trapezoid are fixed and high (the duty ratio is determined after three parameters are determined, and the duty ratio is a variable which mainly affects four orders), the waist structure is fixed, the control freedom degree of the waist structure for the coupling-out efficiency of two sides is insufficient, the coupling-out efficiency b of two sides after light splitting is lower although the light splitting efficiency a is higher, the coupling-out efficiency c=a×b of the whole structure has no obvious advantage, the curved trapezoid can keep the light splitting efficiency a ' higher in the application, and the coupling-out efficiency b ' of two sides can be adjusted, so that the coupling-out efficiency c ' =a ' ×b ' of the whole structure is higher.

The invention discloses a diffraction optical waveguide and a display device.

Exemplary embodiments according to the present invention will now be described in more detail with reference to the accompanying drawings.

As shown in fig. 4, 5, and 6a, in a preferred embodiment, a diffractive optical waveguide includes: a waveguide substrate 700, an incoupling grating 600 and a two-dimensional pupil expansion grating 200;

waveguide substrate 700 may be made of glass, optical plastic, or other optically transmissive material;

the incoupling grating 600 is arranged on the waveguide substrate 700 for coupling light into the waveguide substrate 700; the coupling-in grating 600 may employ a one-dimensional grating;

the two-dimensional mydriatic grating 200 is a coupling-out grating, the two-dimensional mydriatic grating 200 is arranged on the waveguide substrate 700, and the two-dimensional mydriatic grating 200 comprises a plurality of optical unit structures 100 arranged in an array for expanding light propagating to the waveguide substrate 700 and simultaneously coupling out from the waveguide substrate 700;

the optical unit structure 100 includes:

the sections are spliced in sequence along a first direction, and the first direction is the X-axis direction in the figure;

the sections shrink in width at the top, middle-upper and bottom ends of the optical unit structure 100, respectively, along a second direction, which is a Y-axis direction in the figure, the first direction being perpendicular to the second direction;

The total length of the optical unit structure 100 along the first direction is L, the grating period of the coupling grating is d, and the relationship between L and d is: 0.88 xd < L <1.19 xd.

In the diffractive optical waveguide of this embodiment, the optical unit structure is integrally configured as a curved trapezoid, and the coupling-out efficiency and the conduction efficiency can be adjusted by adjusting the curved trapezoid structure, so that the structure has high two-side light splitting efficiency and two-side coupling-out efficiency, and especially, the structure is excellent at the conduction end of the two-dimensional grating region. Compared with the traditional trapezoid structure, the curved trapezoid structure can adjust the structure morphology of the optical unit in a large degree of freedom in a certain duty ratio range, so that a product of large light splitting efficiency and coupling efficiency on two sides is formed, a simulation experiment result can be referred, and meanwhile, the processability is obviously higher than that of a common trapezoid in the prior art.

In one embodiment, as shown in fig. 4, the optical unit structure 100 includes four sections, a first section 113, a second section 114, a third section 115, and a fourth section 116, respectively, along a first direction;

the top width of the first section 113 is W1, the bottom width of the first section 113 and the top width of the second section 114 are W2, the bottom width of the second section 114 and the top width of the third section 115 are W3, the bottom width of the third section 115 and the top width of the fourth section 116 are W4, and the bottom width of the fourth section 116 is W5.

As shown in fig. 4, the total length l=l1+l2+l3+l4 of the optical unit structure 100.

The maximum width of the four sections after being spliced is W2, the length is L=L1+L2+L3+L4, wherein the relation between L and the period d of the coupling grating is L <1.2×d, and the preferable L < d; w2 and L have a relationship of W2<0.7 xl.

Simulation experiment 1:

all simulation experiments in this example used a grating with a refractive index of 1.9 and green light with a wavelength of 532 nm.

Simulation experiments are carried out on the coupling-out gratings shown in fig. 2 and 5, and experimental results are shown in table 1, compared with the optical unit structure of the existing trapezoid structure, the optical unit structure of the curved-edge trapezoid (similar to a calabash) structure can have higher middle coupling-out efficiency and two-side light splitting x two-side coupling-out, almost all reach the order of twice of the existing trapezoid, and the rear end of the whole diffraction optical waveguide can have good coupling-out efficiency, namely, the conduction tail end of a two-dimensional grating area.

TABLE 1 comparison Table of four optical parameters for the prior trapezoidal structures, curved trapezoidal structures of the present application

Structure of the	Intermediate coupling-out efficiency	Intermediate total reflectance	Two-sided splitting x two-sided out coupling	Total reflectance of both sides after light splitting
					Trapezoidal shape	0.00547	0.7267	0.0038	0.7247
Curved trapezoid	0.01189	0.7168	0.0047	0.7077

For the optical unit structure of the traditional trapezoid shown in fig. 1 and fig. 2, the coupling-out efficiency of the left side and the right side after light splitting is lower than that of the curved trapezoid structure, and from the point of view, the curved trapezoid has a large modulation degree of freedom for the whole duty ratio, because the duty ratio is determined by three parameters (upper bottom, lower bottom and high) of the traditional trapezoid, and the curved trapezoid can break through the duty ratio control to obtain the wind-light efficiency of the left side and the right side outside the traditional trapezoid, the coupling-out efficiency of the left side and the right side after light splitting, and the product of the wind-light efficiency and the coupling-out efficiency of the right side outside the traditional trapezoid.

Simulation experiment 2:

TABLE 2 comparison of four optical parameters of the existing optical Unit Structure, the optical Unit Structure of the present application

Structure of the	Intermediate coupling-out efficiency	Intermediate total reflectance	Two-sided splitting x two-sided out coupling	Total reflectance of both sides after light splitting
					Single diamond shape	0.00816	0.8559	0.0010	0.8635
Double diamond shape	0.00334	0.8147	0.0017	0.8338
					Round shape	0.00645	0.7929	0.0020	0.8319
Oval shape	0.00636	0.8209	0.0013	0.8590
					Trapezoidal shape	0.00547	0.7267	0.0038	0.7247
Curved trapezoid	0.01189	0.7168	0.0047	0.7077

The structure of the optical unit for comparison is shown with reference to fig. 12, respectively: round, oval, trapezoidal, double diamond, single diamond, curved Bian Tixing.

As shown in fig. 6b, when the light in the waveguide is transmitted along the arrow and transmitted into the dashed frame, a larger intermediate coupling-out efficiency and a larger two-side beam splitting x two-side coupling are required to realize the high efficiency of the end view field, and the intermediate total reflectance is a less important parameter at this position, and an excessive intermediate total reflectance in the dashed frame region causes energy waste. The total reflectivity of the two sides after light splitting only plays a role in a small range, and can be regarded as a negative index. In summary, the curved trapezoid optical unit structure is a structure with very good optical effect within the range of the dashed line frame, which exceeds the conventional shape.

The optical cell structure 100 in fig. 5 is formed by a certain edge gaussian blur of a curved trapezoid. For micro-nano optical processing, the smoother the curve is, the more beneficial to processing, and the sigma parameter of Gaussian blur is adjusted, so that the edge of the two-dimensional structure can be smoothed to different degrees, and the edge morphology changing from 0nm sigma to 200nm sigma and the finally realized optical effect can be realized.

The formula for Gaussian blur is shown above, where σ is the standard deviation of the normal distribution and σ is less than 200nm, preferably less than 100nm.

In one embodiment, as shown in fig. 7, each section of the optical cell structure 100 is composed of a trapezoid, which is either right side up or upside down. The smaller bottom side of the trapezoid is upward, and the smaller bottom side of the trapezoid is downward. In fig. 7, the optical unit structure 100 includes twelve trapezoids:

the first trapezoid 101 is arranged in the right direction, the second trapezoid 102 is inverted, the third trapezoid 103 is inverted, the fourth trapezoid 104 is inverted, the fifth trapezoid 105 is arranged in the right direction, the sixth trapezoid 106 is arranged in the right direction, the seventh trapezoid 107 is inverted, the eighth trapezoid 108 is inverted, the ninth trapezoid 109 is inverted, the tenth trapezoid 110 is inverted, the eleventh trapezoid 111 is inverted, and the twelfth trapezoid 112 is inverted.

What needs to be stated is: the sixth trapezoid 106 looks like a rectangle, still being a trapezoid, but looks relatively close to a rectangle due to drawing size limitations only.

From practical application, a plurality of curved-edge trapezoid structures can be formed by utilizing multi-trapezoid splicing, and great design freedom is possessed.

In one embodiment, as shown in fig. 5, certain sections of the optical cell structure 100 are formed of rounded trapezoids, either right-angled or inverted. The rounded trapezoids may be rounded at the top two corners, for example, the rounded at the top of the first trapezoid 101, or rounded at the bottom two corners, for example, the rounded at the bottom of the twelfth trapezoid 112, or rounded at all four corners, for example, rounded at all four corners of the first trapezoid 101.

In one embodiment, as shown in fig. 5, certain sections of the optical cell structure 100 are constructed of approximately trapezoids, which are either right or inverted. The approximate trapezoid may be such that both waists of the trapezoid are arc-shaped, e.g. both waists of the fourth trapezoid 104, the fifth trapezoid 105 are arc-shaped.

In one embodiment, L, d has the following relationship: 0.95×d < L <1.15×d, and the corresponding technical effects can be referred to the results of simulation experiments 3 and 4.

In one embodiment, W2 is the maximum width of the section near the top end of the optical unit structure 100, W4 is the maximum width of the section near the middle of the optical unit structure 100, W2, W4, L have the following relationship: the ratio of (W2+W4)/L is more than or equal to 1.25 and less than or equal to 1.60, and the corresponding technical effects can be referred to the results of simulation experiments 5, 6, 7 and 8.

In one embodiment, W2, W4, L have the following relationship: the ratio of (W2+W4)/L is more than or equal to 1.30 and less than or equal to 1.45, and the corresponding technical effects can be referred to the results of simulation experiments 5, 6, 7 and 8.

In one embodiment, W2, W4, L have the following relationship:

W2/W4 is more than or equal to 0.90 and less than or equal to 1.40,0.65, W2/L is more than or equal to 0.85,0.6 and W4/L is more than or equal to 0.7, and the corresponding technical effect can be referred to the result of the simulation experiment 9.

In one embodiment, W2, W4 have the following relationship: W2/W4 is more than or equal to 0.95 and less than or equal to 1.20, and the corresponding technical effect can be referred to the result of the simulation experiment 9.

In one embodiment, W2, L have the following relationship: 0.4 XL < W2<1.0 XL.

In one embodiment, W1, W5 have the following relationship: W1-W5 > 0.2Xmax (W1, W5).

In one embodiment, W1, W2, W5 have the following relationship:

w5 > 0.1×w1, or, w5 >0.2×w1, or, w1=w5=0;

0.8XW2 > W5, or 0.3XW2 > W5.

In one embodiment, in the second direction, the height of the first section 113 is L1, the height of the second section 114 is L2, the height of the third section 115 is L3, and the height of the fourth section 116 is L4, where L1, L2, L3, L4 have the following relationship: the corresponding technical effect can be referred to the result of the simulation experiment 10, wherein (L1+L2)/(L3+L4) is more than or equal to 0.43 and less than or equal to 2.30.

In one embodiment, L1, L2, L3, L4 have the following relationship: the ratio of (L1+L2)/(L3+L4) is more than or equal to 0.50 and less than or equal to 1.50, and the corresponding technical effect can be referred to the result of the simulation experiment 10.

In one embodiment, the overall structure of the optical unit structure 100 is a non-centrosymmetric structure, and W1 is greater than or equal to W5;

When (l1+l2)/(l3+l4) =1, w2+.w4;

when w2=w4, w1=w5, l1/(l1+l2) noteql 4/(l3+l4).

In one embodiment, as shown in fig. 8 and 9, a sampling section 117 is randomly cut from the sections along the second direction, the sampling section 117 has a top width M1, a bottom width M2, and a height H, where M1, M2, and H have the following relationship:

0.ltoreq.arctan (((M1-M2)/2)/H.ltoreq.beta.where beta <75 deg..

In one embodiment, β has the following relationship: beta <45 deg., alternatively beta <30 deg..

In one embodiment, corners of the optical cell structure 100 are provided as rounded corners.

In one embodiment, as shown in fig. 10 and 11, in the second direction, a straight line A1 is drawn through the uppermost tangential point of the optical unit structure 100, a straight line A2 is drawn through the upper widest part of the optical unit structure 100, a straight line A3 is drawn through the middle narrowest part of the optical unit structure 100, a straight line A4 is drawn through the middle widest part of the optical unit structure 100, and a straight line A5 is drawn through the lowermost tangential point of the optical unit structure 100;

the straight line connecting the uppermost tangential point of the optical unit structure 100 and the boundary intersection point of A2 and the optical unit structure 100 is B1, and the included angle between B1 and A1 is alpha 1, wherein alpha 1 is less than or equal to 180 degrees;

The straight line connecting the boundary intersection point of A2 and the optical unit structure 100 and the boundary intersection point of A3 and the optical unit structure 100 is B2, and the included angle between B2 and A2 is alpha 2, and alpha 2 is more than or equal to 30 degrees and less than or equal to 90 degrees;

the straight line connecting the boundary intersection point of A3 and the optical unit structure 100 and the boundary intersection point of A4 and the optical unit structure 100 is B3, and the included angle between B3 and A3 is alpha 3, and alpha 3 is more than or equal to 90 degrees and less than or equal to 150 degrees;

the straight line connecting the boundary intersection point of A4 and the optical unit structure 100 and the lowest end tangent point of the optical unit structure 100 is B4, and the included angle between B4 and A4 is alpha 4, and alpha 4 is more than or equal to 20 degrees and less than or equal to 75 degrees.

In one embodiment, as shown in fig. 5, in the second direction, a midpoint of the narrowest portion of the middle of the optical unit structures 100 is set as the center, and the connection lines of the centers of the first optical unit structure 100 and the second optical unit structure 100 and the third optical unit structure 100 adjacent to the diagonally rear side respectively form lattice direction lines, and the sum of the included angles of the two lattice direction lines and the center line of the first optical unit structure 100 is θ, and θ is 45 ° or more and 75 °.

In one embodiment, θ has the following relationship: θ is 50-70 °, or 55-65 °.

In one embodiment, W2, L, θ have the following relationship: w2 < 2/3× (d×tan (θ)), L < 1/2× (d×tan (θ)).

In one embodiment, a two-dimensional pupil expanding grating includes a plurality of optical cell structures 100 arranged in an array along a plane for expanding light propagating to waveguide substrate 700 substantially parallel to the plane in-plane and simultaneously coupling out of waveguide substrate 700.

In one embodiment, the optical unit structure 100 is a bump-like or dimple-like structure formed on the waveguide substrate 700, having a cross-section parallel to a plane, the structural features of the cross-section referencing the structural features of the optical unit structure 100 described above.

An embodiment of the present invention also provides a display device including the diffractive optical waveguide according to any one of the above embodiments.

In one embodiment, as shown in fig. 6b, the display device is a near-eye display device comprising a lens 300, the lens 300 comprising a diffractive optical waveguide.

The display device further comprises a light engine 400, the light engine 400 emitting laser light to the incoupling grating.

Simulation experiment 3: influence of the topography parameters L

As shown in fig. 13a and 13b, simulation tests were performed on seven different L-curved trapezoid optical cell structures.

TABLE 3 comparison Table of four optical parameters of trapezoids with different L curved sides for the optical unit structure of the present application

Structure of the	L/d	Intermediate coupling-out efficiency	Intermediate total reflectance	Two-sided splitting x two-sided out coupling	Total reflectance of both sides after light splitting
						The shape is 1L to [0.2,0.2,0.2 ], 0.4]×400W:[200,310, 220,260,70]	1.0	0.00357682	0.666932674	0.005183599	0.709025596
the shape is 2L and is [0.2,0.2,0.2 ], 0.4]×350W:[200,310, 220,260,70]	0.9	0.01070684	0.670345552	0.004551066	0.707472454
						the appearance is 3L and is [0.2,0.2,0.2 ], 0.4]×320W:[200,310, 220,260,70]	0.8	0.014213356	0.682642461	0.003912704	0.714020537
the shape is 4L and is [0.2,0.2,0.2 ], 0.4]×440W:[200,310, 220,260,70]	1.1	0.000611009	0.676807133	0.005186449	0.716654399
						the appearance is 5L and is [0.2,0.2,0.2 ], 0.4]×480W:[200,310, 220,260,70]	1.2	0.001408169	0.692616521	0.004639834	0.73086955
the appearance is 6L [0.2,0.2,0.2 ], 0.4]×440W:[200,310, 220,260,70]-30	1.1	0.00087413	0.687358781	0.004968534	0.704183643
						the shape of the product is 7L [0.2,0.2,0.2 ], 0.4]×350W:[200,310, 220,260,70]-30	0.9	0.010367487	0.696768794	0.004041958	0.716463137

the most suitable total length of L is given by the relation between L and the coupling grating d in the simulation of the group, namely, when L is equal to d, the effect is best, and if L <0.9×d or L >1.1×d, the effect is obviously deteriorated, and the deterioration cannot be compensated by changing the width of W.

Through simulation test, the morphology 1 is the best result, the L length of the morphology 1 is close to 1 times of the coupling grating period d, and the L of the morphology 1, 2 and 4 is better than 0.9 times to 1.1 times of the coupling grating period d, and the ratio is positioned between 0.85 and 1.25, preferably between 0.95 and 1.1.

Simulation experiment 4: different L/d effects on both side splitting x both side out-coupling

The simulation results are shown in table 4 with reference to fig. 14.

TABLE 4 parameter scanning for different L/d, different W1 to W5, optical cell structures of the present application

Parameters (parameters)	Optimal parameters/nm	Parameter variation range/nm
			W1	200	20-300
W2	310	240-380
			W3	220	100-240
W4	260	240-380
			W5	70	20-140

As shown in FIG. 14, the coupling into the grating period d is preferably 0.9 times to 1.1 times, and the L/d ratio is positioned 0.85 to 1.25, preferably 0.95 to 1.1, through simulation test.

Reference may be further made to fig. 15 a-15 e, tables 5-9.

FIG. 15a shows the effect of W1 on two-sided spectroscopic x two-sided coupling at different L/d. Five values are selected for L/d in the figure, five different curves are respectively presented, and when L/d adopts different values, the two-side light splitting and the two-side coupling have obvious size difference, and when L/d is 1.1250, the two-side light splitting and the two-side coupling are basically maximum. And as W1 increases, some of the two-sided spectroscopic x two-sided coupling out tends to increase, and some tends to decrease. The parameters employed in fig. 15a are shown in table 5.

TABLE 5 variation of width W1, variation of L/d

Parameters (parameters)	Parameter range
		W1	20nm-300nm
W2	310nm
		W3	220nm
W4	260nm
		W5	70nm
L/d	0.5625-1.3125

FIG. 15b shows the effect of W2 on two-sided spectroscopic x two-sided coupling at different L/d. Five values are selected for L/d in the figure, five different curves are respectively presented, and when L/d adopts different values, the two-side light splitting and the two-side coupling have obvious size difference, and when L/d is 1.1250, the two-side light splitting and the two-side coupling are basically maximum. And with the increase of W2, the coupling out of two sides of the two-sided beam splitting is increased, and the coupling out of two sides is reduced. The parameters employed in fig. 15b are shown in table 6.

TABLE 6 variation of width W2, variation of L/d

Parameters (parameters)	Parameter range
		W1	200nm
W2	240nm-380nm
		W3	220nm
W4	260nm
		W5	70nm
L/d	0.5625-1.3125

FIG. 15c shows the effect of W3 on both side splitting x both side out coupling at different L/d. Five values are selected for L/d in the figure, five different curves are respectively presented, and when L/d adopts different values, the two-side light splitting and the two-side coupling have obvious size difference, and when L/d is 1.1250, the two-side light splitting and the two-side coupling are basically maximum. And as W3 increases, both side splitting x both side out-coupling essentially show an increasing trend. The parameters employed in fig. 15c are shown in table 7.

TABLE 7 variation of width W3, variation of L/d

Parameters (parameters)	Parameter range
		W1	200nm
W2	310nm
		W3	100nm-240nm
W4	260nm
		W5	70nm
L/d	0.5625-1.3125

FIG. 15d shows the effect of W4 on two-sided spectroscopic x two-sided coupling at different L/d. Five values are selected for L/d in the figure, five different curves are respectively presented, and when L/d adopts different values, the two-side light splitting and the two-side coupling have obvious size difference, and when L/d is 1.1250, the two-side light splitting and the two-side coupling are basically maximum. And as W4 increases, both side splitting x both side out-coupling substantially show a decreasing trend. The parameters employed in fig. 15d are shown in table 8.

TABLE 8 variation of width W4, variation of L/d

Parameters (parameters)	Parameter range
		W1	200nm
W2	310nm
		W3	220nm
W4	240nm-380nm
		W5	70nm
L/d	0.5625-1.3125

FIG. 15e shows the effect of W5 on both side splitting x both side out coupling at different L/d. Five values are selected for L/d in the figure, five different curves are respectively presented, and when L/d adopts different values, the two-side light splitting and the two-side coupling have obvious size difference, and when L/d is 1.1250, the two-side light splitting and the two-side coupling are basically maximum. And with the increase of W5, the coupling out of two sides of the light splitting is increased, and the coupling out of two sides is decreased. The parameters employed in fig. 15e are shown in table 9.

TABLE 9 variation of width W5, variation of L/d

Parameters (parameters)	Parameter range
		W1	200nm
W2	310nm
		W3	220nm
W4	220nm
		W5	20nm-140nm
L/d	0.5625-1.3125

Simulation experiment 5: influence of the morphological parameters (W2+W4)/L

The simulation results are shown in table 10 with reference to fig. 16a and 16 b.

The change of the relative relation between the two most main width parameters W2 and W4 of the curved trapezoid two-dimensional structure and L is explored to cause the change of the light effect, the sum of the W2 and W4 is in a range, and the whole light effect is the best, and the range is (W2+W4)/L between 1.25 and 1.6.

Table 10. Optical cell structures l=d, different (w2+w4) parameter influence scans of the present application

Structure of the	(W2+W4)/L	Intermediate coupling-out efficiency	Intermediate total reflectance	Two-sided splitting x two-sided out coupling	Total reflectance of both sides after light splitting
						Morphology 1: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,300,220,260,70]	560/400=1.4	0.003662065	0.666843278	0.005187539	0.707190512
Morphology 2: l is [0.2,0.2,0.2,0.4 ]]×400W:[220,320,240,280,90]	600/400=1.5	0.003240412	0.665083023	0.00517186	0.717866777
						Morphology 3: l is [0.2,0.2,0.2,0.4 ]]×400W:[240,340,260,300,110]	640/400=1.6	0.002702961	0.670654367	0.004944593	0.733336957
Morphology 4: l is [0.2,0.2,0.2,0.4 ]]×400W:[180,280,200,240,50]	520/400=1.3	0.004105746	0.676932156	0.004947796	0.704126779
						Morphology 5: l is [0.2,0.2,0.2,0.4 ]]×400W:[160,260,180,220,30]	480/400=1.2	0.004218197	0.68994724	0.004554562	0.707908049
Morphology 6: l is [0.2,0.2,0.2,0.4 ]]×400W:[120,220,140,180,20]	400/400=1	0.004031229	0.718220802	0.003821486	0.724747443

From simulation results, it can be seen that when L is fixed at the best value, i.e., l=d, (w2+w4)/L varies between 1.25 and 1.6, the two-sided spectroscopic x two-sided coupling exhibits a tendency to become larger and smaller, and the optimal value is between 1.3 and 1.45.

Simulation experiment 6: effects of different L/d, morphological parameters (W2+W4)/L

The simulation results are shown in table 11 with reference to fig. 17 a.

Table 11. Optical cell structures of the present application: effect of different values of (w2+w4)/L on both side-splitting x side-out when L/d=0.875

Parameters (parameters)	Parameter range
		W1	200nm
W2	240nm-380nm
		W3	220nm
W4	240nm-380nm
		W5	70nm
L/D	0.875

Simulation experiment 7: effects of different L/d, morphological parameters (W2+W4)/L

The simulation results are shown in table 12 with reference to fig. 17 b.

Table 12. Optical cell structures of the present application: effect of different values of (w2+w4)/L on both side-splitting x side-out when L/d=1.000

Parameters (parameters)	Parameter range
		W1	200nm
W2	240nm-380nm
		W3	220nm
W4	240nm-380nm
		W5	70nm
L/D	1.000

Simulation experiment 8: effects of different L/d, morphological parameters (W2+W4)/L

The simulation results are shown in table 13 with reference to fig. 17 c.

Table 13. Optical cell structures of the present application: effect of different values of (w2+w4)/L on both side-splitting x side-out when L/d=1.125

Parameters (parameters)	Parameter range
		W1	200nm
W2	240nm-380nm
		W3	220nm
W4	240nm-380nm
		W5	70nm
L/D	1.125

Simulation experiment 9: influence of the topographical parameters W2/W4

The simulation results are shown in fig. 18a, 18b, 19a, 19b, 19c, and table 14.

The influence of the relative relation between the two most main width parameters W2 and W4 of the curved trapezoid two-dimensional structure on the light efficiency is explored, and when the range is more than 0.95, the light efficiency is better, and preferably 1.0 to 1.1.

Table 14. Optical cell structures of the present application: influence of the topographical parameters W2/W4

Structure of the	w2/w4	Intermediate coupling-out efficiency	Intermediate total reflectance	Two-sided splitting x two-sided out coupling	Total reflectance of both sides after light splitting
						Morphology 1: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,310,220,260,70]	310/260=1.19	0.00357682	0.666932674	0.005183599	0.709025596
Morphology 2: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,310,220,320,70]	310/320=0.97	0.004522463	0.663496172	0.004950785	0.722408109
						Morphology 3: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,310,220,340,70]	310/340=0.91	0.004997776	0.665615674	0.00476191	0.728069962
Morphology 4: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,270,220,260,70]	270/260=1.04	0.00397463	0.668321161	0.005137585	0.701861203
						Morphology 5: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,270,220,220,70]	270/220=1.23	0.00358692	0.66027349	0.005152263	0.712890128
Morphology 6: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,310,220,260,150]	310/260=1.19	0.001870011	0.663907293	0.00513645	0.714619886
						Morphology 7: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,310,220,260,200]	310/260=1.19	0.00168199	0.66349004	0.004953992	0.722045098
Morphology 8: l is [0.2,0.2,0.2,0.4 ]]×400W:[200,310,220,260,10]	310/260=1.19	0.00660812	0.666909326	0.004977057	0.70808862

As can be seen from the above table, W2/W4 is in a suitable interval when this value is 0.95 to 1.30, preferably 1.0 to 1.1.

As shown in FIGS. 19a, 19b and 19c, the optimum range is determined to be W2/W4 of 0.90-1.40, preferably 0.95-1.20, wherein W2/L is 0.65-0.85, W4/L is 0.6-0.7, and W2 is varied from about 260nm to about 340nm, W4 is varied from about 240nm to about 280nm, W2/W4 is varied from about 0.93 to about 1.41, and L/d is 1.000, and the optimum range is 0.005 or more.

Simulation experiment 10: influence of the topography parameters L

The simulation results are shown in fig. 20a and 20b, fig. 21a to 21i, and table 15.

The influence of the change of the ratio of the curved trapezoid two-dimensional structure (L1+L2)/(L3+L4) on the overall light efficiency is explored, and when the value of (L1+L2)/(L3+L4) is 0.43 to 2.3, the light efficiency is better.

Table 15. Optical cell structures of the present application: influence of the morphological parameters (L1+L2)/(L3+L4)

Structure of the	(L1+L2)/(L3+L4)	Intermediate coupling-out efficiency	Intermediate total reflectance	Two-sided splitting x two-sided out coupling	Total reflectance of both sides after light splitting
						Morphology 1:L [0.2,0.2,0.2,0.4 ]]×400W:[200,310,220,260,70]	0.4/0.6=0.67	0.00357682	0.666932674	0.005183599	0.709025596
Morphology 2:L [0.1,0.2,0.3,0.4 ]]×400W:[200,310,220,260,70]	0.3/0.7=0.43	0.003259076	0.66891571	0.005112082	0.711108252
						Morphology 3:L [0.2,0.3,0.2,0.3 ]]×400W:[200,310,220,260,70]	0.5/0.5=1	0.003242513	0.660828221	0.005184279	0.712232854
Morphology 4:L [0.25,0.35,0.15,0.25 ]]×400W:[200,310,220,260,70]	0.6/0.4=1.5	0.00358692	0.66027349	0.005152263	0.712890128
						Morphology 5:L [0.1,0.1,0.3,0 ].5]×400W:[200,310,220,260,70]	0.2/0.8=0.25	0.008730799	0.685661733	0.004509682	0.710911118
Morphology 6:L [0.3,0.4,0.1,0.2 ]]×400W:[200,310,220,260,70]	0.7/0.3=2.33	0.004265808	0.660857206	0.005064988	0.713890499
						Morphology 7:L [0.3,0.5,0.1,0.1 ]]×400W:[200,310,220,260,70]	0.8/0.2=4	0.005023033	0.66548154	0.004766076	0.719225534

As can be seen from the above table, (L1+L2)/(L3+L4) is in a suitable interval, the ratio is 0.43-2.33, preferably 0.50 to 1.50.

As shown in fig. 21a to 21i, two-dimensional traversals of different (l1+l2)/(l3+l4) are shown, and if the two-side spectroscopic x two-side coupling is 0.0051 or more as a boundary condition, it can be seen from the scan result that only (l1+l2)/(l3+l4) can be achieved at 0.43 to 2.33, and that the two-side spectroscopic x two-side coupling extremum is high at 0.67 and 1.00, and that more extreme conditions can be achieved. Thus, the value of (L1+L2)/(L3+L4) is chosen to be from 0.43 to 2.33, preferably from 0.50 to 1.50.

According to the diffraction optical waveguide and the display device, the optical unit structure in the two-dimensional grating is set to be the curved Bian Tixing, and the coupling-out efficiency and the conduction efficiency can be adjusted by adjusting the curved trapezoid structure, so that the structure has high two-side light splitting efficiency and two-side coupling-out efficiency, and particularly, the structure is excellent at the conduction tail end of the two-dimensional grating region. Compared with the traditional trapezoid structure, the curved trapezoid structure can adjust the structure morphology of the optical unit in a large degree of freedom in a certain duty ratio range, so that a product of large light splitting efficiency and coupling efficiency on two sides is formed, and meanwhile, the processability is obviously higher than that of a common trapezoid in the prior art.

The processes, steps described in all the preferred embodiments described above are examples only. Unless adverse effects occur, various processing operations may be performed in an order different from that of the above-described flow. The step sequence of the above-mentioned flow can also be added, combined or deleted according to the actual requirement.

In understanding the scope of the present invention, the term "comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. This concept also applies to words having similar meanings such as the terms "including", "having" and their derivatives.

The terms "attached" or "attached" as used herein include: a construction in which an element is directly secured to another element by directly securing the element to the other element; a configuration for indirectly securing an element to another element by securing the element to an intermediate member, which in turn is secured to the other element; and the construction in which one element is integral with another element, i.e., one element is substantially part of the other element. The definition also applies to words having similar meanings such as the terms, "connected," "coupled," "mounted," "adhered," "secured" and their derivatives. Finally, terms of degree such as "substantially", "about" and "approximately" as used herein mean a deviation of the modified term such that the end result is not significantly changed.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting of the invention. Features described herein in one embodiment may be applied to another embodiment alone or in combination with other features unless the features are not applicable or otherwise indicated in the other embodiment.

The present invention has been described in terms of the above embodiments, but it should be understood that the above embodiments are for purposes of illustration and description only and are not intended to limit the invention to the embodiments described. In addition, it will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that many variations and modifications may be made in accordance with the teachings of the present invention, which fall within the scope of the claimed invention.

Claims

1. A diffractive optical waveguide, comprising:

a waveguide substrate;

a coupling-in grating disposed on the waveguide substrate for coupling light into the waveguide substrate;

A two-dimensional mydriatic grating disposed on the waveguide substrate, the two-dimensional mydriatic grating including a plurality of optical unit structures arranged in an array for expanding light propagating to the waveguide substrate and simultaneously coupling out from the waveguide substrate;

2. The diffractive optical waveguide according to claim 1, characterized in that the segments are constituted by trapezoids, which are either right or inverted;

3. The diffractive optical waveguide according to claim 1, wherein L, d have the following relationship: 0.95 xd < L <1.15 xd.

4. The diffractive optical waveguide according to claim 1, characterized in that the optical unit structure comprises four of the sections, a first section, a second section, a third section and a fourth section, respectively, along the first direction;

5. The diffractive optical waveguide according to claim 4, characterized in that W2, W4, L have the following relation: (W2+W4)/L is more than or equal to 1.25 and less than or equal to 1.60.

6. The diffractive optical waveguide according to claim 4, characterized in that W2, W4, L have the following relation: (W2+W4)/L is more than or equal to 1.30 and less than or equal to 1.45.

7. The diffractive optical waveguide according to claim 4, characterized in that W2, W4, L have the following relation:

0.90≤W2/W4≤1.40，0.65≤W2/L≤0.85，0.6≤W4/L≤0.7。

8. the diffractive optical waveguide according to claim 7, wherein W2 and W4 have the following relationship: W2/W4 is more than or equal to 0.95 and less than or equal to 1.20.

9. The diffractive optical waveguide according to claim 4, wherein W2 and L have the following relationship: 0.4 XL < W2<1.0 XL.

10. The diffractive optical waveguide according to claim 4, characterized in that W1, W5 have the following relation: W1-W5 > 0.2Xmax (W1, W5).

11. The diffractive optical waveguide according to claim 4, characterized in that W1, W2, W5 have the following relation:

w5 > 0.1×w1, or, w5 >0.2×w1, or, w1=w5=0;

0.8XW2 > W5, or 0.3XW2 > W5.

12. The diffractive optical waveguide according to claim 4, characterized in that in the second direction the height of the first section is L1, the height of the second section is L2, the height of the third section is L3, the height of the fourth section is L4, the L1, L2, L3, L4 have the following relation: (L1+L2)/(L3+L4) is more than or equal to 0.43 and less than or equal to 2.30.

13. The diffractive optical waveguide according to claim 12, characterized in that said L1, said L2, said L3, said L4 have the following relation: (L1+L2)/(L3+L4) is more than or equal to 0.50 and less than or equal to 1.50.

14. The diffractive optical waveguide according to claim 12, wherein the overall structure of the optical unit structure is a non-centrosymmetric structure, and W1 is equal to or greater than W5;

When (l1+l2)/(l3+l4) =1, w2+.w4;

when w2=w4, w1=w5, l1/(l1+l2) noteql 4/(l3+l4).

15. The diffractive optical waveguide according to claim 2, characterized in that along said second direction a sampling section is randomly cut out from said sections, said sampling section having a top width M1, a bottom width M2 and a height H, said M1, said M2 and said H having the following relation:

0.ltoreq.arctan (((M1-M2)/2)/H.ltoreq.beta.where beta <75 deg..

16. The diffractive optical waveguide according to claim 15, characterized in that said β has the following relation: beta <45 deg., alternatively beta <30 deg..

17. The diffractive optical waveguide according to claim 1, characterized in that corners of the optical element structure are provided as rounded corners.

18. The diffractive optical waveguide according to any one of claims 1 to 17, characterized in that a straight line A1 is made through the uppermost tangential point of the optical unit structure, a straight line A2 is made through the upper widest part of the optical unit structure, a straight line A3 is made through the middle narrowest part of the optical unit structure, a straight line A4 is made through the middle widest part of the optical unit structure, and a straight line A5 is made through the lowermost tangential point of the optical unit structure in the second direction;

19. A diffractive optical waveguide according to claim 1, characterized in that in the second direction, a midpoint of the narrowest part of the middle of the optical unit structures is set as a center, and the connection lines of the centers of the second and third optical unit structures respectively adjacent to the obliquely rear side of the first optical unit structure form lattice direction lines, and the sum of the two lattice direction lines and the center line of the first optical unit structure is θ, and θ is 45 ° or less and 75 °.

20. The diffractive optical waveguide according to claim 19, characterized in that θ has the following relationship: θ is 50-70 °, or 55-65 °.

21. The diffractive optical waveguide according to claim 19, characterized in that W2, L, θ have the following relation: w2 < 2/3× (d×tan (θ)), L < 1/2× (d×tan (θ)).

22. The diffractive optical waveguide according to claim 1, wherein the optical unit structure is a bump-like or a pit-like structure formed on the waveguide substrate.

23. A display device comprising a diffractive optical waveguide according to any one of claims 1-22.

24. The display device of claim 23, wherein the display device is a near-eye display device comprising a lens comprising the diffractive optical waveguide.