Red light polarization filter suitable for high-power laser

Abstract

The invention relates to the technical field of optical elements, in particular to a polarization filter with red light suitable for high-power laser. The invention discloses a polarization filter with red light, and discloses a polarization filter with red light with working wave bands of 635 + / -10nm and 915 + / -10nm, the polarization filter with red light comprises a substrate, a main film system and a secondary film system, the main film system is located on the upper side of the substrate, the secondary film system is located on the lower side of the substrate, and the main film system is located on the upper side of the substrate. The main film system comprises 74 high-refractive-index film layers and low-refractive-index film layers which are alternately overlaid outwards from the substrate according to the structure of the main film system, and the secondary film system comprises 6 high-refractive-index film layers and low-refractive-index film layers which are alternately overlaid outwards from the substrate according to the structure of the secondary film system. According to the polarization filter with the red light, natural light with the wavelength of 635 + / -10 nm can be highly transparent, high transmittance of P polarized light with the wavelength of 915 + / -10 nm can be achieved, high reflectivity of S light with the wavelength of 915 + / -10 nm can be achieved, and beam combination is achieved by reflecting and transmitting laser with different wavelengths.

Description

Technical Field

[0001] This application relates to the field of optical element technology, specifically to a red-polarized filter suitable for high-power lasers. Background Technology

[0002] A laser polarizer is an optical element designed based on the polarization characteristics of light. Its core function is to selectively control the polarization state of a laser by precisely modulating the vibration direction of the light wave. It can transmit light with a specific polarization direction (such as linearly polarized or circularly polarized light) while blocking or attenuating light with other polarization directions, thereby purifying or modulating the polarization state of the beam. This characteristic makes laser polarizers an indispensable key component in laser systems, optical experiments, display technology, optical communication, and biomedicine.

[0003] In spectral analysis and related applications, red-polarized filters designed for high-power lasers are particularly important. These filters need to precisely control the polarization state of the red-band laser and effectively suppress stray light to improve system efficiency and stability. However, existing technologies still have significant shortcomings: First, traditional filters have a low laser damage threshold, and in high-power laser environments, the film layer is prone to ablation due to thermal absorption or electric field concentration, making it difficult to meet the requirements for long-term stable operation of industrial-grade kilowatt-level lasers; second, the polarization extinction ratio is limited, and the leakage of unpolarized light is prominent, leading to a decrease in the system's signal-to-noise ratio and alignment accuracy, thus limiting their application potential in high-precision scenarios. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a red-polarized filter suitable for high-power lasers, aiming to improve the laser damage threshold and polarization extinction ratio, while expanding the cutoff wavelength range and enhancing film stability, so as to meet the stringent requirements of industrial-grade high-power laser systems for precise polarization state control and stray light suppression.

[0005] The red-polarized filter suitable for high-power lasers provided in this application adopts the following technical solution: A red-polarized filter suitable for high-power lasers includes a substrate, a primary film system, and a secondary film system. The primary film system is located on one side of the substrate, and the secondary film system is located on the opposite side of the substrate. The film system structure of the red-polarized filter is: LHLHLH|Sub|(LH). 37 The operating wavelengths are 635±10nm and 915±10nm; Wherein, Sub is the substrate, LHLHLH is the submembrane system, and (LH) is the submembrane system. 37 The main film system is H, which is the TA2O5 film layer, and L is the SiO2 film layer. The main membrane system (LH) 37It consists of 74 alternating layers of high-refractive-index and low-refractive-index films stacked from the substrate outwards. The geometric thicknesses of the 1st to 74th layers are as follows: Layer 1 132.41 nm, Layer 2 215.1 nm, Layer 3 175.66 nm, Layer 4 280.66 nm, Layer 5 120.68 nm, Layer 6 168.89 nm, Layer 7 102.79 nm, Layer 8 160.46 nm, Layer 9 92.79 nm, Layer 10 134.56 nm, Layer 11 97.89 nm, Layer 12 153.79 nm, Layer 13 97.24 nm, Layer 14 155.4 nm, Layer 15 96.44 nm, Layer 16 157.07 nm, Layer 17 180.6 ...17 180.66 nm, Layer 180.66 nm, Layer 19 100.66 nm, Layer 10 134.56 nm, Layer 11 97.89 nm, Layer 12 153.79 nm, Layer 13 97.24 nm, Layer 14 155.4 nm, Layer 15 96.44 nm, Layer 16 157.07 nm, Layer 17 180.66 nm, Layer 1 Layer 1: 98.36nm; Layer 18: 162.02nm; Layer 19: 103.03nm; Layer 20: 163.12nm; Layer 21: 98.85nm; Layer 22: 156.42nm; Layer 23: 96.44nm; Layer 24: 155.87nm; Layer 25: 96.94nm; Layer 26: 156.97nm; Layer 27: 97.59nm; Layer 28: 157.74nm; Layer 29: 98.32nm; Layer 30: 159.72nm; Layer 31: 100.22nm; Layer 32: 161.9nm; Layer 33: 99.89nm; Layer 34: 158.96nm; Layer 35: 97.53nm; Layer 36: 158.96nm; Layer 35: 97.53nm; Layer 36: 158.36nm; Layer 37: 97.53nm; Layer 38: 158.96nm; Layer 39: 97.53nm; Layer 30: 98.36nm; Layer 31: 100.22nm; Layer 32: 161.9nm; Layer 33: 99.89nm; Layer 34: 158.96nm; Layer 35: 97.53nm; Layer 36: 158.96nm; Layer 35: 97.53nm; Layer 36: 158.36nm; Layer 37: 97.53nm; Layer 38: 158.36nm; Layer 39: 98.36nm; Layer 30: 98.36nm; 6.52nm, 37th layer 97.09nm, 38th layer 157.3nm, 39th layer 98.38nm, 40th layer 159.16nm, 41st layer 98.94nm, 42nd layer 159.46nm, 43rd layer 99.08nm, 44th layer 160.04nm, 45th layer 99.57nm, 46th layer 159.39nm, 47th layer 98.07nm, 48th layer 156.82nm, 49th layer 96.61nm, 50th layer 155.9nm, 51st layer 96.88nm, 52nd layer 157.44nm, 53rd layer 99.19nm, 54th layer 160.98nm, 55th layer 100.43nm. m, 56th layer 160.43nm, 57th layer 98.87nm, 58th layer 159.2nm, 59th layer 98.25nm, 60th layer 157.85nm, 61st layer 97.32nm, 62nd layer 152.29nm, 63rd layer 93.13nm, 64th layer 141.28nm, 65th layer 94.33nm, 66th layer 162.7nm, 67th layer 101.07nm, 68th layer 164.06nm, 69th layer 112.31nm, 70th layer 292.7nm, 71st layer 190.72nm, 72nd layer 182.59nm, 73rd layer 149.41nm, 74th layer 225.26nm; The subfilm system LHLHLH comprises six alternating layers of high-refractive-index and low-refractive-index films stacked from the substrate outwards. The geometric thicknesses of the first to sixth layers are: layer 1 23.76 nm, layer 2 60.6 nm, layer 3 86.87 nm, layer 4 23.3 nm, layer 5 72.75 nm, and layer 6 160.33 nm.

[0006] Furthermore, the substrate is a quartz substrate.

[0007] Furthermore, the primary film system and the secondary film system are deposited on the substrate by vacuum deposition.

[0008] Furthermore, the TA2O5 film is deposited by vapor deposition using ion beam assisted deposition.

[0009] Furthermore, the SiO2 film is deposited by reactive ion plating using vapor deposition.

[0010] Furthermore, the red-polarized filter suitable for high-power lasers has an average transmittance of more than 98% in the natural light range of 625-645nm.

[0011] Furthermore, the red-polarized filter suitable for high-power lasers has an average transmittance of more than 99% for P-polarized light in the wavelength range of 905-925nm.

[0012] Furthermore, the red-polarized filter suitable for high-power lasers has an S-ray reflectivity greater than 99% in the 905-925nm wavelength range.

[0013] In summary, this application has the following beneficial effects: 1. This application significantly improves the laser damage threshold of the filter by optimizing the film structure and film deposition process, enabling it to withstand long-term operation of industrial-grade kilowatt-level high-power lasers, while enhancing film adhesion and thermal stability, and reducing the risk of ablation caused by heat absorption or electric field concentration. 2. The synergistic design of the primary and secondary film systems in the polarization filter of this application achieves high-precision polarization state control in the 915nm band, while also providing low-energy indication in the 635nm band. The polarization extinction ratio is significantly improved, effectively suppressing unpolarized light leakage, and extending the cutoff wavelength range. The transmittance of natural light is >98% in the 625-645nm range and the transmittance of P-polarized light is >99% in the 905-925nm range, meeting the stringent requirements of high-power laser systems for stray light suppression and polarization state purification. Attached Figure Description

[0014] 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.

[0015] Figure 1 This is a schematic diagram of the structure of a red-polarized filter applicable to high-power lasers according to an embodiment of this application; Figure 2 This is a spectral transmittance curve of a red-polarized filter suitable for high-power lasers according to an embodiment of this application. Detailed Implementation

[0016] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. All reagents and instruments used, unless otherwise specified below, are commercially available products.

[0018] Performance testing The experiment was conducted under constant temperature (23±0.1℃) and constant humidity (50±5%RH) conditions.

[0019] (I) Polarization Extinction Ratio (PER) Test The laser, polarizer, polarizing filter (as described in this embodiment), analyzer, and optical power meter are placed on the optical platform in the order of the optical path. The laser is a distributed feedback laser (DFB) with a wavelength set to 915 nm. All optical components are ensured to be coaxial to avoid stray light interference. The polarizer and analyzer are aligned parallel to their transmission axes, and the optical power meter reading I is recorded. 平行 Rotate the analyzer 90° so that its transmission axis is perpendicular to the polarizer, and record the optical power meter reading I. 垂直 ; Calculate PER: PER = ; (ii) Damage threshold test The damage threshold is defined as the minimum laser energy density at which a material suffers permanent damage (such as surface melting or cracking) under laser irradiation. A "1-on-1" testing method is used, meaning that each test point is irradiated only once, and the laser energy density is gradually increased until damage occurs.

[0020] 1. Test equipment Laser: 1064nm Nd:YAG pulsed laser (pulse width 10ns, repetition rate 10Hz, energy stability <3%). Attenuator: A tunable attenuator used for precise control of laser energy; Energy meter: used to calibrate laser energy density; Beam analyzer: measures beam diameter and calculates energy density; Microscope: Used to observe the morphology of damage.

[0021] 2. Test Procedure The beam analyzer was used to measure the beam diameter D (diameter 1 / e²) of the 1064nm laser on the filter surface, and the beam area A was calculated as A = π(D / 2). 2 Next, the laser energy was adjusted to 1 J / cm² using an attenuator, and the single-pulse energy E was measured using an energy meter to calculate the energy density: Φ = Select 5-10 test points, with an interval of ≥2mm between each point. Start with a low energy density (1J / cm²) and gradually increase the energy density (increase by 10% each time). Irradiate one point at each energy density. Immediately after irradiation, observe the surface morphology with a microscope and record the lowest energy density at which damage occurs. The appearance of melting or cracks on the surface is considered as damage. The damage threshold is the average energy density of the undamaged point and the damaged point.

[0022] Example See attached document Figure 1 and attached Figure 2A red-polarized filter suitable for high-power lasers, operating in the wavelength bands of 635±10nm and 915±10nm, comprises a substrate, a main film system, and a secondary film system. The main film system and the secondary film system are located on opposite sides of the substrate. The main film system consists of 74 layers of high-refractive-index and low-refractive-index films alternately stacked from the substrate outwards according to the main film system structure. The main film system structure is as follows: substrate / 132.41nmH, 215.1nmmL, 175.66nmH, 280.66nmmL, 120.68nmH, 168.89nmmL, 102.79nmH, 160.46nmmL, 9 2.79nmH, 134.56nmL, 97.89nmH, 153.79nmL, 97.24nmH, 155.4nmL, 96.44nmH, 157.07nmL, 98.36nmH, 162.02nmL, 103.03nmH, 16 3.12nmL、98.85nmH、156.42nmL、96.44nmH、155.87nmL、96.94nmH、156.97nmL、97.59nmH、157.74nmL、98.32nmH、159.72nmL、10 0.22nmH, 161.9nmL, 99.89nmH, 158.96nmL, 97.53nmH, 156.52nmL, 97.09nmH, 157.3nmL, 98.38nmH, 159.16nmL, 98.94nmH, 159 .46nmL, 99.08nmH, 160.04nmL, 99.57nmH, 159.39nmL, 98.07nmH, 156.82nmL, 96.61nmH, 155.9nmL, 96.88nmH, 157.44nmL, 99.1 9nmH, 160.98nmmL, 100.43nmH, 160.43nmmL, 98.87nmH, 159.2nmmL, 98.25nmH, 157.85nmmL, 97.32nmH, 152.29nmmL, 93.13nmH, 141.28nmmL, 94.33nmH, 162.7nmmL, 101.07nmH, 164.06nmmL, 112.31nmH, 292.7nmmL, 190.72nmH, 182.59nmmL, 149.41nmH, 225.26nmmL / air; The submembrane structure is as follows: substrate / 23.76 nmH, 60.6 nmH, 86.87 nmH, 23.3 nmH, 72.75 nmH, 160.33 nmH / air; Wherein, H is a high refractive index film layer and L is a low refractive index film layer. In this embodiment, H is a TA2O5 film layer and L is a SiO2 film layer. The substrate is selected from Herringbone SUP-313 quartz, which has the characteristics of low expansion coefficient, few impurities, high heat resistance, moisture resistance and excellent chemical stability. The main film system and the secondary film system are deposited on the substrate by vacuum deposition. The TA2O5 film is deposited by ion beam assisted deposition, in which ion beams are introduced to bombard the film surface during evaporation to improve atomic mobility and promote densification. The SiO2 film is deposited by reactive ion plating, in which reactive gas O2 is introduced during sputtering to react the sputtered Si atoms with O2 to generate SiO2, resulting in a dense film with a precisely controllable refractive index. In this embodiment, the provided red-polarized filter suitable for high-power lasers is used. The optical performance of the double-sided coated red-polarized filter is measured using a spectrometer, and its spectral curve is referenced. Figure 2 It can be seen that in the wavelength range of 625-645nm, the average transmittance of natural light is greater than 98%, and in the wavelength range of 905-925nm, the average transmittance of P-polarized light is greater than 99%, and the reflectance of S-polarized light is greater than 99%. Furthermore, at a wavelength of 915nm, this filter exhibits extremely excellent polarization extinction performance, with a polarization extinction ratio as high as >1000:1. This allows the filter to almost completely suppress light components perpendicular to the desired polarization direction, thereby obtaining highly pure polarized light output in laser systems. It has significant application value for some applications with extremely stringent requirements for polarization state. In addition to the aforementioned superior optical performance, this red-polarized filter also possesses excellent resistance to laser damage. Tests have shown that, under conditions of a wavelength of 1064nm, a pulse width of 10ns, and a repetition frequency of 10Hz, its damage threshold reaches >10J / cm². This high damage threshold characteristic indicates that the filter can maintain stable optical performance under continuous irradiation by high-power laser pulses, and will not be damaged or degraded due to excessive laser energy, thus ensuring the reliability and stability of the laser system under high-power operation.

[0023] The above are all modifications that can be made to this embodiment without contributing any inventive step, or solutions that clearly constitute technical teaching, after reading this specification. However, as long as they are within the scope of the claims of this application, they should be protected by patent law.

Claims

1. A red-polarizing filter suitable for high-power lasers, comprising a substrate, a primary film system, and a secondary film system, wherein the primary film system is located on one side of the substrate, and the secondary film system is located on the substrate on the opposite side of the primary film system, characterized in that, The film structure of the red-polarized filter is: LHLHLH|Sub|(LH) 37 The operating wavelengths are 635±10nm and 915±10nm; Wherein, Sub is the substrate, LHLHLH is the submembrane system, and (LH) is the submembrane system. 37 The main film system is H, which is the TA2O5 film layer, and L is the SiO2 film layer. The main membrane system (LH) 37 It consists of 74 alternating layers of high-refractive-index and low-refractive-index films stacked from the substrate outwards. The geometric thicknesses of the 1st to 74th layers are as follows: Layer 1 132.41 nm, Layer 2 215.1 nm, Layer 3 175.66 nm, Layer 4 280.66 nm, Layer 5 120.68 nm, Layer 6 168.89 nm, Layer 7 102.79 nm, Layer 8 160.46 nm, Layer 9 92.79 nm, Layer 10 134.56 nm, Layer 11 97.89 nm, Layer 12 153.79 nm, Layer 13 97.24 nm, Layer 14 155.4 nm, Layer 15 96.44 nm, Layer 16 157.07 nm, Layer 17 180.6 ...17 180.66 nm, Layer 180.66 nm, Layer 19 100.66 nm, Layer 10 134.56 nm, Layer 11 97.89 nm, Layer 12 153.79 nm, Layer 13 97.24 nm, Layer 14 155.4 nm, Layer 15 96.44 nm, Layer 16 157.07 nm, Layer 17 180.66 nm, Layer 1 Layer 1: 98.36nm; Layer 18: 162.02nm; Layer 19: 103.03nm; Layer 20: 163.12nm; Layer 21: 98.85nm; Layer 22: 156.42nm; Layer 23: 96.44nm; Layer 24: 155.87nm; Layer 25: 96.94nm; Layer 26: 156.97nm; Layer 27: 97.59nm; Layer 28: 157.74nm; Layer 29: 98.32nm; Layer 30: 159.72nm; Layer 31: 100.22nm; Layer 32: 161.9nm; Layer 33: 99.89nm; Layer 34: 158.96nm; Layer 35: 97.53nm; Layer 36: 158.96nm; Layer 35: 97.53nm; Layer 36: 158.36nm; Layer 37: 97.53nm; Layer 38: 158.96nm; Layer 39: 97.53nm; Layer 30: 98.36nm; Layer 31: 100.22nm; Layer 32: 161.9nm; Layer 33: 99.89nm; Layer 34: 158.96nm; Layer 35: 97.53nm; Layer 36: 158.96nm; Layer 35: 97.53nm; Layer 36: 158.36nm; Layer 37: 97.53nm; Layer 38: 158.36nm; Layer 39: 98.36nm; Layer 30: 98.36nm; 6.52nm, 37th layer 97.09nm, 38th layer 157.3nm, 39th layer 98.38nm, 40th layer 159.16nm, 41st layer 98.94nm, 42nd layer 159.46nm, 43rd layer 99.08nm, 44th layer 160.04nm, 45th layer 99.57nm, 46th layer 159.39nm, 47th layer 98.07nm, 48th layer 156.82nm, 49th layer 96.61nm, 50th layer 155.9nm, 51st layer 96.88nm, 52nd layer 157.44nm, 53rd layer 99.19nm, 54th layer 160.98nm, 55th layer 100.43nm. m, 56th layer 160.43nm, 57th layer 98.87nm, 58th layer 159.2nm, 59th layer 98.25nm, 60th layer 157.85nm, 61st layer 97.32nm, 62nd layer 152.29nm, 63rd layer 93.13nm, 64th layer 141.28nm, 65th layer 94.33nm, 66th layer 162.7nm, 67th layer 101.07nm, 68th layer 164.06nm, 69th layer 112.31nm, 70th layer 292.7nm, 71st layer 190.72nm, 72nd layer 182.59nm, 73rd layer 149.41nm, 74th layer 225.26nm; The subfilm system LHLHLH comprises six alternating layers of high-refractive-index and low-refractive-index films stacked from the substrate outwards. The geometric thicknesses of the first to sixth layers are: layer 1 23.76 nm, layer 2 60.6 nm, layer 3 86.87 nm, layer 4 23.3 nm, layer 5 72.75 nm, and layer 6 160.33 nm.

2. The red-polarized filter suitable for high-power lasers according to claim 1, characterized in that, The substrate is a quartz substrate.

3. The red-polarized filter suitable for high-power lasers according to claim 1, characterized in that, The primary and secondary film systems are deposited on the substrate by vacuum deposition.

4. The red-polarized filter suitable for high-power lasers according to claim 1, characterized in that, The TA2O5 film was deposited by vapor deposition using ion beam assisted deposition.

5. The red-polarized filter suitable for high-power lasers according to claim 1, characterized in that, The SiO2 film was deposited by reactive ion plating.

6. The red-polarized filter suitable for high-power lasers according to claim 1, characterized in that, The red-polarized filter suitable for high-power lasers has an average transmittance of more than 98% in the natural light range of 625-645nm.

7. The red-polarized filter suitable for high-power lasers according to claim 1, characterized in that, The red-polarized filter suitable for high-power lasers has an average transmittance of more than 99% for P-polarized light in the wavelength range of 905-925nm.

8. The red-polarized filter suitable for high-power lasers according to claim 1, characterized in that, The red-polarized filter suitable for high-power lasers has an S-light reflectivity greater than 99% in the 905-925nm wavelength range.

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