Ultraviolet laser double-incidence-angle short-wave pass filter

Abstract

The application relates to the field of optical film devices, and particularly discloses a double-incidence-angle short-wave pass filter for ultraviolet laser. The filter comprises a substrate, a filter film and an antireflection film, the filter film and the antireflection film are arranged on two sides of the substrate respectively, the filter film is a 24-layer film system in which a high-refractive-index layer HFO2 film layer and a low-refractive-index layer SIO2 film layer are alternately arranged in sequence, and the filter can realize high transmission of 266 nm short waves and high reflection of 355 nm long waves under the conditions of 0-degree and 45-degree incidence.

Description

Technical Field

[0001] This application relates to the field of optical thin film devices, and in particular to a short-pass filter for ultraviolet lasers with dual incident angles. Background Technology

[0002] In ultraviolet laser systems, it is often necessary to separate short-wavelength (266nm) and long-wavelength (355nm) lasers. For example, 266nm is used for high-precision micromachining, while 355nm is used for rough machining or inspection. Traditional beam splitters are mostly based on normal incidence designs. When incident at a 45° angle, the change in optical path causes a shift in the beam splitting wavelength and a decrease in reflection / transmission efficiency, making it difficult to meet practical integration requirements. Moreover, in the ultraviolet band (especially 266nm), due to high material absorption and film stress mismatch, performance deteriorates sharply at oblique incidence, such as a decrease in emission efficiency at 266nm and 355nm. Summary of the Invention

[0003] In view of this, this application provides a short-pass filter for ultraviolet lasers with dual incident angles, which can achieve high transmission of 266nm short-wavelength and high reflection of 355nm long-wavelength under incident conditions of 0° and 45°.

[0004] To achieve the above objectives, this application employs the following technical solution:

[0005] A short-wavelength pass filter for ultraviolet lasers with dual incident angles, characterized in that it comprises a substrate, a filter film, and an antireflection film, wherein the filter film and the antireflection film are respectively disposed on two sides of the substrate; the filter film is a 24-layer film system consisting of alternating high-refractive-index HFO2 film layers and low-refractive-index SiO2 film layers; the 24-layer film system, from the substrate outwards, consists of:

[0006] The first layer is an HFO2 film with a thickness of 55.65 nm; the second layer is an SiO2 film with a thickness of 61.72 nm.

[0007] The third layer is an HFO2 film with a thickness of 43.96 nm; the fourth layer is an SiO2 film with a thickness of 68.17 nm.

[0008] The fifth layer is an HFO2 film with a thickness of 45.93 nm; the sixth layer is an SiO2 film with a thickness of 54.92 nm.

[0009] The 7th layer is an HFO2 film with a thickness of 50.22 nm; the 8th layer is an SiO2 film with a thickness of 63.68 nm.

[0010] The 9th layer is an HFO2 film with a thickness of 46.38 nm; the 10th layer is an SiO2 film with a thickness of 63.39 nm.

[0011] The 11th layer is an HFO2 film with a thickness of 49.99 nm; the 12th layer is an SiO2 film with a thickness of 52.83 nm.

[0012] The 13th layer is an HFO2 film with a thickness of 47.86 nm; the 14th layer is an SiO2 film with a thickness of 64.24 nm.

[0013] The 15th layer is an HFO2 film with a thickness of 46.22 nm; the 16th layer is an SiO2 film with a thickness of 66.84 nm.

[0014] The 17th layer is an HFO2 film with a thickness of 47.96 nm; the 18th layer is an SiO2 film with a thickness of 57.44 nm.

[0015] The 19th layer is an HFO2 film with a thickness of 46.07 nm; the 20th layer is an SiO2 film with a thickness of 66.09 nm.

[0016] The 21st layer is an HFO2 film with a thickness of 39.98 nm; the 22nd layer is an SiO2 film with a thickness of 61.24 nm.

[0017] The 23rd layer is an HFO2 film with a thickness of 46.38 nm; the 24th layer is an SiO2 film with a thickness of 23.52 nm.

[0018] The present application discloses a short-pass ultraviolet laser filter with dual incident angles. The filter film employs a 24-layer system, and the physical thickness of the high / low refractive index layers is adjusted to ensure high transmission of 266nm short-wavelength laser and high reflectivity of 355nm long-wavelength laser under both normal and oblique incident conditions. Specifically, the 266nm short-wavelength laser transmittance is ≥99.5%, and the 355nm long-wavelength laser reflectivity is ≥99.5%. This solves the problems of low splitting efficiency and incompatibility of traditional filters when used with different incident angles.

[0019] In some embodiments, the antireflective film is a four-layer film system, wherein the four layers are arranged sequentially from the substrate outwards as follows:

[0020] The first layer is an HFO2 film with a thickness of 57.30 nm; the second layer is an SiO2 film with a thickness of 66.74 nm.

[0021] The third layer is an HFO2 film with a thickness of 45.14 nm; the fourth layer is an SiO2 film with a thickness of 34.92 nm.

[0022] In some embodiments, the substrate is fused silica or UV-grade CaF₂. 2， The surface roughness of the substrate is <1 nm.

[0023] In some embodiments, the HFO2 film has a refractive index of 2.20 for a short-wavelength laser at 266 nm and a refractive index of 2.05 for a long-wavelength laser at 355 nm; the SiO2 film has a refractive index of 1.48 for a short-wavelength laser at 266 nm and a refractive index of 1.47 for a long-wavelength laser at 355 nm.

[0024] In some embodiments, the filter has a transmittance of ≥99.5% for 266nm short-wavelength laser and a transmittance / reflectance of ≥99.5% for 355nm long-wavelength laser when incident at 0° and 45°.

[0025] As can be seen from the above technical solution, this application has at least the following advantages and positive effects:

[0026] This application discloses a short-pass filter for ultraviolet lasers with dual incident angles, which can achieve high transmission of 266nm short-wavelength and high reflection of 355nm long-wavelength under dual incident conditions of 0° and 45°, and at the same time has high reliability and long-term stability. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of an embodiment of this application;

[0028] Figure 2 This is an optical path diagram of an embodiment of this application;

[0029] Figure 3 This is a spectral diagram of the filter film in the embodiments of this application;

[0030] Figure 4 This is a spectral diagram of the antireflection membrane in an embodiment of this application.

[0031] Labeling explanation: 1. Filter film; 2. Substrate; 3. Anti-reflection film. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the application will be described in further detail below with reference to the accompanying drawings. The terminology used in the embodiments section of this application is only for explaining specific embodiments and is not intended to limit the application.

[0033] See Figures 1 to 4 This application provides a short-pass ultraviolet laser dual-incident-angle filter, comprising a substrate 2, a filter film 1, and an antireflection film 3, wherein the filter film 1 and the antireflection film 3 are respectively disposed on two sides of the substrate 2; the filter film 1 is a 24-layer film system consisting of alternating high-refractive-index HFO2 film layers and low-refractive-index SiO2 film layers; the 24-layer film system, from the substrate 2 outwards, consists of:

[0034] The first layer is an HFO2 film with a thickness of 55.65 nm; the second layer is an SiO2 film with a thickness of 61.72 nm.

[0035] The third layer is an HFO2 film with a thickness of 43.96 nm; the fourth layer is an SiO2 film with a thickness of 68.17 nm.

[0036] The fifth layer is an HFO2 film with a thickness of 45.93 nm; the sixth layer is an SiO2 film with a thickness of 54.92 nm.

[0037] The 7th layer is an HFO2 film with a thickness of 50.22 nm; the 8th layer is an SiO2 film with a thickness of 63.68 nm.

[0038] The 9th layer is an HFO2 film with a thickness of 46.38 nm; the 10th layer is an SiO2 film with a thickness of 63.39 nm.

[0039] The 11th layer is an HFO2 film with a thickness of 49.99 nm; the 12th layer is an SiO2 film with a thickness of 52.83 nm.

[0040] The 13th layer is an HFO2 film with a thickness of 47.86 nm; the 14th layer is an SiO2 film with a thickness of 64.24 nm.

[0041] The 15th layer is an HFO2 film with a thickness of 46.22 nm; the 16th layer is an SiO2 film with a thickness of 66.84 nm.

[0042] The 17th layer is an HFO2 film with a thickness of 47.96 nm; the 18th layer is an SiO2 film with a thickness of 57.44 nm.

[0043] The 19th layer is an HFO2 film with a thickness of 46.07 nm; the 20th layer is an SiO2 film with a thickness of 66.09 nm.

[0044] The 21st layer is an HFO2 film with a thickness of 39.98 nm; the 22nd layer is an SiO2 film with a thickness of 61.24 nm.

[0045] The 23rd layer is an HFO2 film with a thickness of 46.38 nm; the 24th layer is an SiO2 film with a thickness of 23.52 nm.

[0046] This ultraviolet laser dual-incident-angle short-pass filter employs a 24-layer filter system, with adjusted physical thicknesses of high / low refractive index layers to ensure high transmission of 266nm short-wavelength laser and high reflectivity of 355nm long-wavelength laser under both normal and oblique incidence conditions. Specifically, the 266nm short-wavelength laser transmittance is ≥99.5%, and the 355nm long-wavelength laser reflectivity is ≥99.5%. This design solves the problems of low splitting efficiency and incompatibility of traditional filters when used with different incidence angles.

[0047] The antireflective film 3 is a four-layer film system, and the four layers are arranged sequentially from the substrate 2 outwards as follows:

[0048] The first layer is an HFO2 film with a thickness of 57.30 nm; the second layer is an SiO2 film with a thickness of 66.74 nm.

[0049] The third layer is an HFO2 film with a thickness of 45.14 nm; the fourth layer is an SiO2 film with a thickness of 34.92 nm.

[0050] The substrate 2 is fused silica, with a transmittance of >85% at 266nm / 355nm when incident at 45°, or ultraviolet-grade CaF2, wherein the surface roughness of the substrate 2 is <1nm, which is used to ensure the adhesion of the film layer.

[0051] The HFO2 film has a refractive index of 2.20 for a short wavelength laser at 266 nm and a refractive index of 2.05 for a long wavelength laser at 355 nm; the SiO2 film has a refractive index of 1.48 for a short wavelength laser at 266 nm and a refractive index of 1.47 for a long wavelength laser at 355 nm.

[0052] The filter has a transmittance of ≥99.5% for 266nm short-wavelength laser and a transmittance and reflectance of ≥99.5% for 355nm long-wavelength laser when incident at 0° and 45°.

[0053] See Figure 3 The optical performance parameters of the filter film shown in the spectrum are as follows: the thick line represents 45° incident light, with visible R 99.6% @ 355nm and T 99.7% @ 266nm; the thin line represents 0° incident light, with visible R 99.6% @ 355nm and T 99.9% @ 266nm.

[0054] See Figure 4 The optical performance indicators of the antireflection film in this embodiment are as follows, as shown in the spectrum: the thick line represents 45° incident light, with a visible R of 0.4% at 266nm; the thin line represents 0° incident light, with a visible R of 0.23% at 266nm.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them; although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A short-pass filter for ultraviolet laser with dual incident angles, characterized in that: The system includes a substrate (2), a filter film (1), and an antireflection film (3), wherein the filter film (1) and the antireflection film (3) are respectively disposed on two sides of the substrate (2); the filter film (1) is a 24-layer film system consisting of alternating high-refractive-index HFO2 film layer and low-refractive-index SiO2 film layer; the 24-layer film system consists of the following layers from the substrate (2) outwards: The first layer is an HFO2 film with a thickness of 55.65 nm; the second layer is an SiO2 film with a thickness of 61.72 nm. The third layer is an HFO2 film with a thickness of 43.96 nm; the fourth layer is an SiO2 film with a thickness of 68.17 nm. The fifth layer is an HFO2 film with a thickness of 45.93 nm; the sixth layer is an SiO2 film with a thickness of 54.92 nm. The 7th layer is an HFO2 film with a thickness of 50.22 nm; the 8th layer is an SiO2 film with a thickness of 63.68 nm. The 9th layer is an HFO2 film with a thickness of 46.38 nm; the 10th layer is an SiO2 film with a thickness of 63.39 nm. The 11th layer is an HFO2 film with a thickness of 49.99 nm; the 12th layer is an SiO2 film with a thickness of 52.83 nm. The 13th layer is an HFO2 film with a thickness of 47.86 nm; the 14th layer is an SiO2 film with a thickness of 64.24 nm. The 15th layer is an HFO2 film with a thickness of 46.22 nm; the 16th layer is an SiO2 film with a thickness of 66.84 nm. The 17th layer is an HFO2 film with a thickness of 47.96 nm; the 18th layer is an SiO2 film with a thickness of 57.44 nm. The 19th layer is an HFO2 film with a thickness of 46.07 nm; the 20th layer is an SiO2 film with a thickness of 66.09 nm. The 21st layer is an HFO2 film with a thickness of 39.98 nm; the 22nd layer is an SiO2 film with a thickness of 61.24 nm. The 23rd layer is an HFO2 film with a thickness of 46.38 nm; the 24th layer is an SiO2 film with a thickness of 23.52 nm.

2. The ultraviolet laser dual-incident-angle short-wavelength pass filter according to claim 1, characterized in that: The antireflective film (3) is a four-layer film system, and the four layers are arranged sequentially from the substrate (2) outwards as follows: The first layer is an HFO2 film with a thickness of 57.30 nm; the second layer is an SiO2 film with a thickness of 66.74 nm. The third layer is an HFO2 film with a thickness of 45.14 nm; the fourth layer is an SiO2 film with a thickness of 34.92 nm.

3. The ultraviolet laser dual-incident-angle short-wavelength pass filter according to claim 1, characterized in that: The substrate (2) is fused silica or ultraviolet-grade CaF₂. 2， The surface roughness of the substrate (2) is <1nm.

4. The ultraviolet laser dual-incident-angle short-wave pass filter according to claim 1, characterized in that: The HFO2 film has a refractive index of 2.20 for a short wavelength laser at 266 nm and a refractive index of 2.05 for a long wavelength laser at 355 nm; the SiO2 film has a refractive index of 1.48 for a short wavelength laser at 266 nm and a refractive index of 1.47 for a long wavelength laser at 355 nm.

5. The ultraviolet laser dual-incident-angle short-wave pass filter according to claim 1, characterized in that: The filter has a transmittance of ≥99.5% for 266nm short-wavelength laser and a transmittance and reflectance of ≥99.5% for 355nm long-wavelength laser when incident at 0° and 45°.

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