Polarization conversion integrated system

Abstract

The invention belongs to the technical field of polarization conversion, and particularly relates to a polarization conversion integrated system which comprises a light splitting part located on an incident light source light path, a conversion part arranged on the light path of the first light beam and / or the second light beam and used for transmitting an incident light source and forming a first light beam and a second light beam in a separation mode along different light paths. Light beams with preset properties are formed through conversion. According to the invention, the problems of inherent contradiction between volume and assembly precision, insufficient conversion efficiency and light beam uniformity, narrow working bandwidth and angle tolerance, wide temperature range, weak vibration resistance and the like of the existing PBS array type PCS are solved; and the novel PG / metasurface PCS has the problems of poor material stability, high preparation precision requirement, insufficient active regulation and control performance, insufficient on-chip integration adaptability and the like. Other PCSs also have the common defects of low polarization purity, prominent contradiction between cost and mass production and insufficient adaptability to extreme working conditions, and are difficult to meet the requirements of a high-end optical system and multiple scenes.

Description

Technical Field

[0001] This invention belongs to the field of polarization conversion technology, and specifically relates to an integrated polarization conversion system. Background Technology

[0002] A polarization conversion system (PCS) is a core device that connects an unpolarized light source to a polarization-sensitive system, used to convert unpolarized / mixed polarized light into a specified single polarization state.

[0003] Existing PCS have gradually evolved into PBS array-type PCS, which is an integrated, multifunctional optical system that combines polarization beam splitter arrays with polarization conversion systems. However, it still faces inherent contradictions in size and assembly precision (volume > 5mm, precision required ±1μm, limited compatibility and mass production yield), insufficient conversion efficiency (85%-88%) and beam uniformity, narrow operating bandwidth and angle tolerance, and weak wide temperature range and vibration resistance. In addition, the PCS field has also developed new PG / metasurface-type PCS, which has shifted from the traditional "bulk optics" and "discrete components" to "planar optics", "ultra-thin devices" and "on-chip integration". It has made breakthroughs in volumetric efficiency, but is limited by challenges such as poor material stability, high fabrication precision requirements (<50nm), insufficient active control performance, and insufficient on-chip integration adaptability. Furthermore, all types of PCS have common defects such as low polarization purity, prominent contradiction between cost and mass production, and insufficient adaptability to extreme conditions, making it difficult to meet the needs of high-end optical systems and diverse scenarios.

[0004] Therefore, this invention proposes an integrated polarization conversion system. Summary of the Invention

[0005] The purpose of this invention is to disclose a polarization conversion integrated system that solves the problems of existing PBS array-type PCS, such as the inherent contradiction between volume and assembly precision, insufficient conversion efficiency and beam uniformity, narrow operating bandwidth and angle tolerance, and weak wide temperature range and vibration resistance. It also addresses the problems of novel PG / metasurface-type PCS, such as poor material stability, high fabrication precision requirements, insufficient active control performance, and insufficient on-chip integration adaptability. Other PCS also suffer from common defects such as low polarization purity, prominent contradiction between cost and mass production, and insufficient adaptability to extreme conditions, making it difficult to meet the needs of high-end optical systems and diverse scenarios.

[0006] To achieve the above objectives, the present invention discloses an integrated polarization conversion system, comprising: Incident light source; A beam splitter is located in the optical path of the incident light source; the beam splitter is configured to transmit the incident light source and separate it into a first beam and a second beam along different optical paths; A converter is disposed in the optical path of the first beam and / or the second beam to convert the first beam and / or the second beam into a beam with preset properties.

[0007] As an optional implementation, the beam splitter comprises stacked components: The first optical layer allows the incident light source to be transmitted and forms a refracted light source; The second optical layer further refracts the refracting light source to form the first beam and the second beam; The refractive index of the first optical layer is different from that of the second optical layer.

[0008] As an optional implementation, the refractive index of the second optical layer is better than that of the first optical layer.

[0009] As an optional implementation, the first optical layer includes: An embossed transmission grating is tilted and positioned on the incident surface of the first optical layer.

[0010] As an optional implementation, the relief-type transmission grating is a one-dimensional periodic wire grating with a period of λ and a fringe direction along the length of the first optical layer.

[0011] As an optional implementation, the relief-type transmission grating has a first grating and a second grating arranged in parallel and spaced apart within one cycle; Let λ = d1 + d2 + d3, and d1 > d3, d1 > d2; Wherein, d1 is the width of the first grating; d2 is the interval between the first grating and the second grating; and d3 is the width of the second grating.

[0012] As an optional implementation, the first grating and the second grating are set at an angle θ with respect to the direction perpendicular to the incident surface of the first optical layer, and the value of the angle θ is in the range of (30°, 90°). The tilt height h between the first grating and the second grating is greater than 1500 nm.

[0013] As an optional implementation, the first beam is refracted P-polarized light; The second beam is a straight S-polarized beam.

[0014] As an optional implementation, the conversion element includes: A half-wave plate is placed in the optical path of the S-polarized light and converts it to output P-polarized light.

[0015] As an optional implementation, the incident light source includes unpolarized light or mixed polarized light.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: First, the polarization conversion integrated system proposed in this invention realizes the conversion between individual P-polarized light and S-polarized light in unpolarized light or mixed polarized light through two parts: a beam splitter and a conversion component. This enables the miniaturization and lightweight design of the PCS, expanding the application range of the PCS. Second, in the polarization conversion integrated system proposed in this invention, the beam splitter achieves the separation of P-polarized light and S-polarized light at different deflection angles through two optical layers and the design of an embossed transmission grating, further simplifying the structure of the beam splitter, realizing the miniaturization and weight reduction of the PCS, and improving the conversion efficiency to over 90%. Third, the specific design of the relief transmission grating on the beam splitter in the polarization conversion integrated system proposed in this invention enhances the diffraction efficiency of P-polarized light at the -1 order, while S-polarized light is emitted directly. Combined with a half-wave plate, polarization conversion is achieved, which improves the efficient selection and control of P-polarized light. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a structural diagram of the polarization conversion integrated system in an embodiment of the present invention; Figure 2 This is an optical path diagram of the polarization conversion integrated system in an embodiment of the present invention; Figure 3 This is a graph showing the relationship between the diffraction efficiency of P-polarized light and the diffraction efficiency of S-polarized light versus wavelength in the polarization conversion integrated system of this invention. Figure 4 This is a diagram showing the optical field distribution of P-polarized light in the polarization conversion integrated system of this invention. Figure 5 This is a diagram showing the optical field distribution of S-polarized light in the polarization conversion integrated system of this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings.

[0021] Combination Figure 1 and Figure 2 As shown, this embodiment proposes a polarization conversion integrated system, including an incident light source, a beam splitter, and a conversion component; the beam splitter is located in the optical path of the incident light source; in this embodiment, the beam splitter is configured to transmit the incident light source and separate into a first beam and a second beam along different optical paths; the conversion component converts the first beam and / or the second beam into a beam with preset properties.

[0022] In a preferred embodiment, the incident light source is unpolarized natural light or mixed-polarized natural light, and the beam formed by conversion is a beam with a preset property of a single polarization state.

[0023] In a preferred embodiment, the beam splitter is made of high-refractive-index glass material to achieve both transmission and refraction of the incident light source.

[0024] In a preferred embodiment, the first beam is refracted P-polarized light and the second beam is direct S-polarized light, which are effectively separated by a beam splitter to simplify the optical path. The conversion element is a standard half-wave plate disposed on the optical path of the S-polarized light to convert the output P-polarized light. Customized polarization conversion can be achieved to adapt to different application requirements, while ensuring the diffraction direction and output optical path of the P-polarized light and the S-polarized light. This facilitates subsequent use and reduces the difficulty of system calibration.

[0025] In this embodiment, the structure and position of the beam splitter and converter are designed to achieve efficient conversion and miniaturization, enabling the PCS to adapt to different application scenarios.

[0026] The beam splitter includes a first optical layer stacked in layers ( Figure 1 The image shows layer n1 and the second optical layer ( Figure 1 (As shown in n2 layer); the first optical layer transmits the incident light source and forms a refracted light source; the second optical layer further refracts the refracted light source to form a first beam and a second beam; the refractive index of the first optical layer is different from that of the second optical layer.

[0027] In a preferred embodiment, both the first optical layer and the second optical layer are made of high-refractive-index glass, with the first optical layer using LASF9 glass. In this embodiment, using two layers of glass avoids the stress, aberrations, or delamination risks associated with bonding multiple components, thus improving the stability and reliability of the beam splitter.

[0028] In a preferred embodiment, the refractive index of the second optical layer is superior to that of the first optical layer. In this embodiment, selecting a second optical layer with a refractive index 0.3 higher than that of the first optical layer further improves the transmission efficiency of the beam splitter for P-polarized and S-polarized light. Figure 3 As shown, it reaches over 90% in the 400-700nm range.

[0029] In addition, an inclined relief-type transmission grating is provided on the incident surface of the first optical layer.

[0030] In a preferred embodiment, the relief transmission grating is formed on the incident surface of the first optical layer by etching.

[0031] In a preferred embodiment, the relief-type transmission grating is a one-dimensional periodic wire grating with a period of λ and a fringe direction along the length of the first optical layer.

[0032] In a preferred embodiment, the relief-type transmission grating employs an asymmetric toothed grating structure. For example, within one period, the relief-type transmission grating forms a first grating and a second grating arranged in parallel and spaced intervals; let λ = d1 + d2 + d3, where d1 is greater than d3 and d1 is greater than d2; where d1 is the width of the first grating; d2 is the spacing between the first and second gratings; and d3 is the width of the second grating. In this embodiment, the diffraction intensity of P-polarized light in the -1 order can be specifically enhanced, achieving efficient selection and manipulation of P-polarized light.

[0033] In a preferred embodiment, the tilt angle θ between the first and second gratings of the relief-type transmission grating is greater than 30°; the tilt height h between the first and second gratings is greater than 1500 nm. In this embodiment, the diffraction intensity of P-polarized light in the -1st order can be specifically enhanced, achieving efficient selection and manipulation of P-polarized light.

[0034] In this embodiment, the polarization beam splitting function is achieved by etching an embossed grating on a single piece of LASF9 glass. This integrates the functions of multiple components in a traditional optical system onto the same surface, greatly reducing the system size and complexity. At the same time, it enhances the diffraction efficiency of P-polarized light at the -1st order diffraction, while S-polarized light is emitted directly, ensuring effective conversion of the polarization source.

[0035] In summary, this embodiment proposes an integrated polarization conversion system. By combining an asymmetric grating design on the beam splitter with a high refractive index material, incident natural light is naturally separated into P-beams and S-beams. This eliminates the need for an additional polarization beam splitter, simplifies the optical path, improves the system's integration, and accurately and efficiently captures and converts the target polarized light, thereby improving conversion efficiency and establishing a compact polarization optical system.

[0036] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A polarization conversion integrated system, characterized by, The system comprises: an incident light source; a light splitting member located on the light path of the incident light source, configured to transmit the incident light source and separate the incident light source into a first light beam and a second light beam along different light paths; a conversion member arranged on the light path of the first light beam and / or the second light beam, configured to convert the first light beam and / or the second light beam into a light beam with a preset property.

2. The polarization conversion integrated system of claim 1, wherein, The light splitting member comprises: a first optical layer for transmitting the incident light source and forming a refracted light source; a second optical layer for further refracting the refracted light source to form the first light beam and the second light beam; the refractive index of the first optical layer is different from the refractive index of the second optical layer.

3. The polarization conversion integrated system according to claim 2, wherein: the refractive index of the second optical layer is higher than the refractive index of the first optical layer.

4. The polarization conversion integrated system of claim 3, wherein, The first optical layer comprises: a relief transmission grating obliquely arranged on the incident surface of the first optical layer.

5. The polarization conversion integrated system according to claim 4, wherein: the relief transmission grating is a linear grating with one-dimensional periodicity, the period is λ, and the stripe direction is along the length direction of the first optical layer.

6. The polarization conversion integrated system according to claim 5, wherein: the relief transmission grating forms a first grating and a second grating arranged in parallel and at intervals within one period; λ=d1+d2+d3, d1>d3, and d1>d2; wherein d1 is the width of the first grating, d2 is the interval between the first grating and the second grating, and d3 is the width of the second grating.

7. The polarization conversion integrated system according to claim 6, wherein: the first grating and the second grating are arranged at an inclination angle θ with respect to the direction perpendicular to the incident surface of the first optical layer, and the inclination angle θ is in the range of (30°, 90°); the inclination height h of the first grating and the second grating is greater than 1500 nm.

8. The polarization conversion integrated system according to any one of claims 1-7, wherein: the first light beam is a refracted P-polarized light; the second light beam is a straight S-polarized light.

9. The polarization conversion integrated system of claim 8, wherein, The conversion member comprises: a half-wave plate arranged on the light path of the S-polarized light and configured to convert and output P-polarized light.

10. The polarization conversion integrated system according to claim 9, wherein: the incident light source comprises non-polarized light or mixed polarized light.

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