Terahertz wave band polaroid with metal wire grids processed on single surface and double surfaces of COC (cycloolefin copolymer) substrate

Abstract

The invention relates to a terahertz wave band polaroid based on metal wire grids processed on one side and two sides of a COC (cycloolefin copolymer) substrate. The COC structure comprises a COC substrate, metal wire grating structures arranged periodically, a polyimide protective film and an OCA transparent optical adhesive layer. According to the invention, an ultraviolet lithography technology is adopted for processing, and the terahertz wave band polarization selection performance is excellent in the 0.1-3THz frequency band. The terahertz wave polarization state control device is suitable for application scenes needing to control the terahertz wave polarization state, such as terahertz imaging, communication and experimental optical systems.

Description

Technical Field

[0001] The present invention belongs to the technical field of terahertz optical devices, and in particular relates to a terahertz band polarizer with metal wire grids processed on one side and both sides of a COC (cyclic olefin copolymer) substrate. Background Art

[0002] Terahertz polarizers have widespread applications in imaging, communications, spectral analysis, and other fields in the terahertz band (0.1-10 THz). As an important optical component, they can be used to manipulate the polarization state of terahertz waves. However, the wavelength of terahertz waves ranges from 30 μm to 3 mm, far longer than visible light (380-760 nm). Traditional optical polarizers, such as polymer-absorbing polarizers, are ineffective for these long wavelengths because their molecular structure is far smaller than the terahertz wavelength and cannot achieve effective polarization separation. Therefore, current terahertz polarizers utilize a single-direction metal wire grid to absorb the parallel electric field component. Existing metal wire grid terahertz polarizers, manufactured using high-precision suspended wire drawing technology, are monopolized by foreign companies and cost over 20,000 RMB per piece, severely limiting the development and widespread adoption of terahertz technology in my country. We have designed and fabricated a terahertz polarizer using a COC (cyclic olefin copolymer) film substrate and a periodic parallel metal wire grid fabricated on its surface using UV photolithography. The manufacturing process of this invention is less complex than similar imported products and is compatible with semiconductor industry processes, making industrialization easier. Its price is significantly lower than imported terahertz-band polarizers, while achieving comparable performance indicators. While maintaining high performance, this invention significantly reduces costs, providing a reliable domestic alternative to polarizers for terahertz research and application, and enhancing the security of my country's supply chain in related industries. Summary of the Invention

[0003] The purpose of the present invention is to provide a terahertz band polarizer with metal wire grids processed on one side and both sides of a COC substrate.

[0004] The terahertz band polarizer of the present invention comprises a COC substrate (2), a periodically arranged metal wire grid structure (1), a polyimide protective film (3), and an OCA transparent optical adhesive layer (4). The metal wire width is 3 to 7 μm, the period is 11 to 18 μm, the metal layer thickness is 100 to 700 nm, and the operating band covers the 0.1-3 THz frequency band. The metal wire grid has a duty cycle of 15% to 50%. In the 0.1-3 THz frequency band, the polarizer has a high extinction ratio (≥20 dB), a high polarization degree (≥99%), and a high transmittance (≥80%). BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 、 Figure 2 、 Figure 3This is a diagram of polarizer performance parameters.

[0006] Figure 4 、 Figure 5 This is a schematic diagram of the structure of a single-sided processed metal wire grid terahertz band polarizer and a side cross-sectional view.

[0007] Figure 6 、 Figure 7 This is a schematic diagram of the structure of a double-sided metal wire grid terahertz band polarizer in a metal structure exposed to air, and a side cross-sectional view.

[0008] Figure 8 、 Figure 9 This is a structural diagram and side cross-sectional view of a double-sided metal wire grid terahertz band polarizer with a polyimide protective layer.

[0009] Figure 10 、 Figure 11 This is a schematic diagram of the structure of the hot-pressed double-sided metal wire grid terahertz band polarizer and a side cross-sectional view.

[0010] Figure 12 、 Figure 13 This is a schematic diagram of the structure of a double-sided metal wire grid terahertz band polarizer bonded with OCA optically transparent adhesive, and a side cross-sectional view.

[0011] Among them, 1. Periodic metal wire grid structure; 2. COC substrate; 3. Polyimide protective layer; 4. OCA optically transparent adhesive layer. DETAILED DESCRIPTION

[0012] Example 1: Used between terahertz light source and detector

[0013] In this embodiment, the polarizer of the present invention can be used to control the polarization direction of the incident or detected terahertz wave, thereby enabling research on polarization-sensitive samples.

[0014] Operation: Mount the terahertz polarizer on an angle-adjustable bracket; place it in the light path, in front of the sample, or in front of the detector; select the ideal polarization direction, such as 0° or 90°, by rotating the polarizer; compare the experimental signals under different polarization orientations to analyze the anisotropy or polarization properties of the sample.

[0015] Example 2: Terahertz imaging and security inspection applications

[0016] In this embodiment, the polarization state selection performance of the polarizer of the present invention can be used to eliminate background reflection, improve the detection contrast of specific substances (such as explosives / drugs), and improve imaging quality.

[0017] Operation method: Install a polarizer in front of the terahertz irradiation source or probe to make the irradiated light or received light have strong linear polarization characteristics; change the polarization angle and compare the imaging effects in different directions to enhance the hidden features of the object being measured, such as the identification of metal and powder under clothing.

[0018] Example 3: Polarization Multiplexing Communication System

[0019] In this embodiment, the polarizer of the present invention can be used to transmit two independent data streams with orthogonal polarizations at the same carrier frequency, thereby effectively improving system capacity and spectrum utilization.

[0020] Operation method: Construct two sets of transmitting end channels, A and B. After each is modulated, they are combined and sent through two polarizers installed in different directions. Polarizers in corresponding directions are installed on the receiving end to physically isolate the A and B channels. If real-time switching or matching is required, an electric rotating platform is used to adjust the polarizers.

[0021] Example 4: Secure Communication and Key Distribution

[0022] Polarization state, as a physical security measure, can support terahertz physical layer encryption and key distribution solutions. In this embodiment, the polarizers of the present invention are used by both communicating parties to synchronize and periodically / randomly adjust the polarizer orientation, making it difficult for external parties to detect and decipher it. This, combined with polarization random encoding, enhances physical layer security. At the operational level, the polarizers are adapted with servo motors to achieve rapid angle changes.

Claims

1. A single-sided and double-sided processed metal wire grid terahertz band polarizer based on COC (cyclic olefin copolymer) substrate, characterized in that include: Transparent COC substrate (1), periodically arranged metal wire grid structure (2), metal materials including all conductivity 10 7 Inert metals that are solid at room temperature and have a S / m (Siemens per meter) or above, and corrosion-resistant metals that can produce an oxide film include (gold, silver, copper, rhodium, iridium, ruthenium, osmium, platinum, palladium, aluminum, tungsten, titanium, chromium, nickel, zinc, tin, beryllium, and molybdenum).

2. The terahertz band polarizer according to claim 1, characterized in that: The metal wire grid has a duty cycle of 15%-50%, a line width of 3-7 μm, a period of 10-18 μm, a metal layer thickness of 100-700 nm, and an operating band covering a frequency band of 0.1-3 THz.

3. A terahertz polarizer according to any one of claims 1 to 2, characterized in that The metal wire grid structure is grown on the front side of the COC substrate, and there is no structure on the back side.

4. A terahertz band polarizer according to any one of claims 1 to 2, characterized in that There is a metal wire grid structure on both sides of the COC substrate; A 10-50 μm polyimide layer (3) is spin-coated on the front structure.

5. A terahertz band polarizer according to any one of claims 1 to 2, characterized in that Two single-sided metal wire grid polarizers as claimed in claim 3 are used to heat press the back surfaces thereof to form a polarizer with a double-sided metal wire grid structure.

6. A terahertz band polarizer according to any one of claims 1 to 2, characterized in that An OCA (optically clear adhesive) layer (4) is sandwiched between two unstructured back surfaces of the single-sided metal wire grid polarizers as claimed in claim 3.

7. A terahertz band polarizer according to any one of claims 1 to 2, characterized in that There are metal wire grid structures on both sides of the single-layer COC substrate, and the surface of the structure is exposed to the air without a protective layer.

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