CN-121186916-B - Diffraction optical waveguide device based on polarization coupling topological structure control

CN121186916BCN 121186916 BCN121186916 BCN 121186916BCN-121186916-B

Abstract

The invention discloses a diffraction optical waveguide device based on polarization coupling topological structure control, which comprises a waveguide medium, a coupling-in grating and a coupling-out grating, wherein a plurality of non-grating areas are added in the coupling-out grating, the plurality of non-grating areas divide the rest grating areas of the coupling-out grating into a one-dimensional array structure or a two-dimensional array structure, the grating areas are used for light diffraction coupling-out, the non-grating areas are used for light total reflection, and the optical waveguide is used for realizing uniform distribution of brightness and color in a full view field. The invention breaks through the limitation of uniformity of efficiency distribution of the polarization holographic element, can realize the function of regulating and controlling the energy of the coupled light on a single optical element while maintaining high diffraction efficiency, and has the advantages of high reliability, operability, low cost, rapidness and the like.

Inventors

WENG YISHI
ZHANG WANCHEN
WANG CHUANG
QIU JINGHAN
ZHAO YICHENG
GU YUCHEN
ZHOU LIANG
LI QINGYU
ZHANG YUNING

Assignees

东南大学

Dates

Publication Date: 20260512
Application Date: 20251124

Claims (4)

1. The diffraction optical waveguide device based on polarization coupling topological structure control comprises a waveguide medium, a coupling-in grating and a coupling-out grating, and is characterized in that a plurality of non-grating areas are added in the coupling-out grating, and divide the rest grating areas of the coupling-out grating into a one-dimensional array structure; the coupling grating is arranged as a composite or single-polarization polarizer holographic grating with the diffraction efficiency ranging from 50% to 95%; the coupling-out grating adopts a polarizer holographic grating; The polarization diffraction characteristic and the diffraction efficiency characteristic of the grating region can be independently regulated and controlled; a plurality of gaps are arranged in the coupling-out grating and used as non-grating areas, the coupling-out grating is divided into a plurality of grating areas with intervals by the plurality of gaps, and the plurality of grating areas with intervals are in a one-dimensional array structure; the width of the gap is 50 nm-1 mm, the width of the gap gradually becomes smaller along the light propagation direction, and the width of the grating area gradually becomes larger; The polarizer holographic grating comprises a liquid crystal solution, wherein the liquid crystal solution is a chiral material.
2. The diffraction optical waveguide device based on polarization coupling topology control of claim 1, wherein the refractive index of the waveguide medium is 1.5-2.2 and the thickness is 0.5-1.2 mm.
3. The diffraction optical waveguide device based on polarization coupling topological structure control comprises a waveguide medium, a coupling-in grating and a coupling-out grating, and is characterized in that a plurality of non-grating areas are added in the coupling-out grating, and divide the rest grating areas of the coupling-out grating into a two-dimensional array structure, wherein each grating area is used for light diffraction coupling-out, and the non-grating areas are used for light total reflection; the coupling grating is arranged as a composite or single-polarization polarizer holographic grating with the diffraction efficiency ranging from 50% to 95%; The polarization diffraction characteristic and the diffraction efficiency characteristic of the grating region can be independently regulated and controlled; a plurality of blank areas are arranged in the coupling grating and used as non-grating areas, the coupling grating is divided into a plurality of grating areas with intervals by the plurality of blank areas, and the plurality of grating areas with intervals are in a two-dimensional array structure; along the light propagation direction, the density of the blank area in the coupling-out grating gradually decreases, and the density of the grating area in the coupling-out grating gradually increases; the grating area adopts a left-handed polarizer holographic grating, a right-handed polarizer holographic grating or a left-handed and right-handed composite polarizer holographic grating; the grating area controls the grating vector direction by coating liquid crystal solutions with different liquid crystal spiral directions.
4. The diffraction optical waveguide device based on polarization coupling topology control of claim 3, wherein the refractive index of the waveguide medium is 1.5-2.2 and the thickness is 0.5-1.2 mm.

Description

Diffraction optical waveguide device based on polarization coupling topological structure control Technical Field The invention relates to a diffraction optical waveguide device based on polarization coupling topological structure control, and belongs to the technical field of optical display. Background In recent years, with the development of near-to-eye display technologies such as Augmented Reality (AR) and head-mounted display (HMD), diffractive optical waveguides have been a growing point of research in the field of optical display due to their advantages such as thinness, and large field of view. The Surface Relief Grating (SRG) forms a surface relief structure through an accurate micro-nano processing technology, so that the diffraction regulation and control of light rays are realized, but the problems of complex processing technology and high cost exist, and the Volume Holographic Grating (VHG) forms a grating by utilizing a volume holographic material to record interference fringes, so that the grating has high diffraction efficiency, and the optical performance of the grating is sensitive to environmental factors. In contrast, the polarizer-volume holographic optical waveguide (PVG) technology combines the advantages of polarized optics and volume holographic technology, and can effectively reduce complexity while ensuring optical performance. The polarizer holographic optical waveguide (PVG) technique disperses incident light to the user's eye through a diffraction grating, where coupling elements play an important role in coupling the image light field into the optical waveguide and coupling the pupil-expanding output. In order to pursue exit pupil continuity and uniformity, the diffraction efficiency of the coupling-out element is usually required to be controlled. The polarizer holographic grating is used as a common optical coupling element, has wide wavelength and angle response bandwidth, simultaneously has polarization sensitivity and high diffraction efficiency, has lower manufacturing cost compared with other optical coupling elements, has high transmittance to external light, and can be dynamically regulated. However, although the diffraction characteristics of the polarizer hologram grating are excellent, the high diffraction efficiency of the grating results in poor brightness uniformity because the light is required to complete exit pupil replication and expansion by total internal reflection after being diffracted into the waveguide by the in-coupling grating. However, the accumulated diffraction light intensity loss can lead to gradual brightness decay, and the brightness uniformity of the full field of view is affected. And the diffraction efficiency can be regulated and controlled to effectively reduce the attenuation and improve the brightness uniformity of the whole field of view. In addition, in color display, diffraction efficiency of light rays with different wavelengths can deviate along with the change of a view field angle due to the limitation of a grating dispersion equation, so that the problem of color unevenness is caused, and the wavelength dependence can be minimized through efficiency regulation and control, so that the color consistency is improved. Therefore, diffraction efficiency is moderately sacrificed to optimize exit pupil continuity and uniformity, consistency of full-view field light intensity and color distribution can be ensured, negative influence of uneven brightness and chromatic aberration on user experience is avoided, and visual comfort and immersion can be remarkably improved in a dynamic scene. In summary, in the existing diffraction waveguide technology, when the light beam is output by multiple total reflections in the waveguide, the light intensity is gradually attenuated, so that the display brightness and color are uneven. Conventional polarizer holographic optical waveguides are difficult to achieve efficient modulation of the coupling-out grating on a single optical element. Disclosure of Invention The invention aims to overcome the defects in the prior art and provide a diffraction optical waveguide device based on polarization coupling topological structure control, so that the display uniformity of the polarizer holographic optical waveguide device is improved. The technical scheme adopted by the invention is as follows: the diffraction optical waveguide device based on polarization coupling topological structure control comprises a waveguide medium, an in-grating and an out-grating. And the coupling grating is divided into a one-dimensional array structure or a two-dimensional array structure by the non-grating areas. The grating region is used for light diffraction coupling out, and the non-grating region is used for light total reflection. The optical waveguide is used for realizing uniform distribution of brightness and color in the whole field of view. Preferably, the coupling-out grating adopts a polarizer holographic grating.