An adjustable laser attenuator

Abstract

The present invention discloses an adjustable laser attenuator, comprising two rectangular prisms made of the same substrate, with their inclined surfaces aligned against each other. Films of varying thickness are applied to one end of the inclined surfaces to control the air gap between them, thereby achieving different attenuation ratios for different wavelengths. By coating the film at one end of the aligned inclined surfaces of the two prisms and then gluing the two prisms together, the film thickness is controlled to control the air gap between them, achieving attenuation in different wavelengths, with attenuation ratios ranging from 1% to 100%.

Description

Technical Field

[0001] The invention relates to an adjustable laser attenuator, belonging to the technical field of laser attenuators. Background Art

[0002] Optical attenuators are devices used to attenuate optical power. They are primarily used in applications such as measuring optical fiber system performance, signal attenuation in short-distance communication systems, and system testing. Optical attenuators are crucial fiber optic passive components that precisely attenuate optical signal energy to the desired level. They are commonly used to absorb or reflect residual optical power, assess system loss, and perform various tests. Currently, a series of optical attenuators are widely used in the optical communications field, bringing convenience to users.

[0003] In optical components, attenuators generally achieve attenuation in a certain band through thin film design. The film layer is very thick, the applicable band is limited, and the production is very difficult. The present invention will greatly reduce the difficulty of film preparation and achieve attenuation effects in different bands. Summary of the Invention

[0004] The present invention provides an adjustable laser attenuator. The thickness of the film layer is used to control the air interval between right-angle prisms to achieve attenuation in different wavebands. The attenuation ratio can be achieved from 1% to 100%.

[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] An adjustable laser attenuator includes two right-angle prisms made of the same substrate, with their oblique surfaces aligned with each other. Film layers of different thicknesses are plated on one end of the oblique surfaces of the right-angle prisms to control the air gap between the two oblique surfaces, thereby achieving different attenuation ratios in different bands.

[0007] For the convenience of preparation, the above film layer can be plated on one of the right-angle prisms.

[0008] The coating thickness of the film layer is determined according to the required attenuation ratio.

[0009] The thickness of the film determines the distance of the air gap, thereby ensuring the attenuation ratio. The width of the film is not limited, as long as it does not affect the use. The preferred film width is 1.5-2.5mm.

[0010] After research, the applicant found that controlling the air gap between the prisms by controlling the thickness of the film layer has a decisive effect on the attenuation ratio of the attenuator. By precisely controlling the thickness of the film layer, the distance of the air gap is controlled, which can greatly improve the stability of the attenuation ratio; thereby, a wide-band attenuation film with a stable attenuation ratio is obtained, which solves the problem that the existing film layer is thick and can only achieve attenuation in a certain band, improves the use effect of the lens, and enhances the customer's use effect.

[0011] For easy control, the spacing between the two rectangular prism oblique surfaces at one end of the non-coated film layer is zero, and the spacing between the two rectangular prism oblique surfaces at one end of the coated film layer is the film layer thickness, so that the air gap between the two rectangular prism oblique surfaces forms a triangular structure.

[0012] In order to facilitate preparation and not affect the coated film, glass plates are glued to both end faces of the two right-angle prisms, that is, the two glass plates and the two right-angle prisms form a whole.

[0013] The above method is to coat a film layer on the area of ​​about 2mm on two right-angle prisms, and then glue the two end faces of the two right-angle prisms with glass plates. The air gap between the right-angle prisms is controlled by the thickness of the film layer to achieve attenuation in different bands, and the attenuation ratio can be achieved from 1% to 100%.

[0014] Different bands include from near ultraviolet to near infrared or mid-to-far infrared.

[0015] The substrate is made of quartz prism or zinc selenide prism with a refractive index of 1 to 3. For the near-ultraviolet to near-infrared band, the right-angle prism is made of fused quartz (or other optical glass); for the mid- and far-infrared band, the right-angle prism is made of zinc selenide (or other infrared materials).

[0016] For the near ultraviolet to near infrared band, the film layer is a silicon dioxide film layer, and for the mid- and far infrared band, the film layer is a germanium film layer (or other film layer materials). Preferably, the thickness of the silicon dioxide film layer is 30 to 1200 nm; the thickness of the germanium film layer is 60 to 3000 nm.

[0017] The preparation of the above film layer includes the following steps:

[0018] (1) Substrate heating: Before coating, the right-angle prism is baked and heated in a vacuum state to increase the temperature of the right-angle prism. The baking temperature is 300-350°C and the time is 1-1.5 hours.

[0019] (2) Ion beam cleaning: The right-angle prism is cleaned by ion beam. The ion cleaning time is 1 to 15 minutes, the ion beam voltage is 300 to 400 V, and the ion beam current is 300 to 400 A.

[0020] (3) Coating of the film layer on the bevel surface of the prism: According to the air spacing distance simulated in the film system design, the film layer is prepared within the 2mm width range of the bevel surface of the right-angle prism.

[0021] The above method uses specific process conditions such as electron beam evaporation and appropriate baking temperature, adopts a single-sided coating method, and controls the air gap between the right-angle prisms by controlling the thickness of the film layer to achieve attenuation in different bands. The attenuation ratio can be achieved from 1% to 100%. It greatly reduces the difficulty of film preparation and achieves attenuation in a wide band.

[0022] In order to improve the adhesion of the film layer, in step (1), before baking and heating, wipe the substrate with a dust-free cloth dipped in a mixture of environmentally friendly wiping liquid and acetone in a volume ratio of (6-8):1.

[0023] The control of conditions during film preparation is also very critical. The preparation conditions of the film not only affect the properties such as the density of the single film layer, but also affect the consistency of the film thickness.

[0024] In order to improve the density, uniformity and adhesion of the film layer, in step (3), the silicon dioxide film layer is plated as follows: SiO2 film material is placed in a crucible and plated by electron beam evaporation, and the background vacuum is higher than 6.0×10 -3 Pa, and the deposition rate is 1-2nm / s.

[0025] In order to improve the density, uniformity and adhesion of the film layer, in step (3), the germanium film layer is plated: the Ge film material is placed in a crucible and plated by electron beam evaporation, and the background vacuum is higher than 6.0×10 -3 Pa, and the deposition rate is 0.5-1nm / s.

[0026] Background vacuum refers to the vacuum degree achieved by the vacuum pumping system in a certain space during vacuum coating, which just meets the vacuum degree required for the deposition of the plated object (different products have different requirements for background vacuum degree).

[0027] The technologies not mentioned in this invention are all referred to the prior art.

[0028] The present invention provides an adjustable laser attenuator. A film layer is formed on one end of the inclined surfaces of two right-angle prisms that are in contact with each other, and then the two right-angle prisms are glued together. The thickness of the film layer is used to control the air gap between the right-angle prisms to achieve attenuation in different bands. The attenuation ratio can be achieved from 1% to 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of the quartz right-angle prisms after gluing in Example 1 of the present invention;

[0030] Figure 2 Schematic diagram of the air gap between the oblique surfaces of two right-angle prisms in Example 1 of the present invention;

[0031] Figure 3 This is a diagram showing the theoretical effect of the attenuation film on the quartz right-angle prism in Example 1 of the present invention;

[0032] Figure 4 This is a diagram showing the actual thickness measurement of the attenuation film on the quartz right-angle prism in Example 1 of the present invention;

[0033] In the figure, 1 is a right-angle prism, 11 is a film layer, 12 is an air space, and 2 is a glass plate. DETAILED DESCRIPTION

[0034] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0035] The film is prepared on a Guangchi 1350 vacuum chamber coater, using a crystal-controlled control system for film thickness. This coater is equipped with an electron beam single evaporation source, and a diffusion pump ensures stable pumping speed.

[0036] Example 1

[0037] like Figure 1 As shown in the figure, a wide-band attenuator comprises two right-angle prisms of the same base material, with the oblique surfaces of the two right-angle prisms facing each other; a 2mm wide film layer is plated on one end of the right-angle prism oblique surface (the film layer is plated on one of the right-angle prisms) to control the air gap between the two right-angle prism oblique surfaces, thereby achieving different attenuation ratios in different bands. Figure 2 As shown, the spacing between the two rectangular prisms' oblique surfaces on the uncoated side is zero, while the spacing between the two rectangular prisms' oblique surfaces on the coated side is the thickness of the coating, resulting in a triangular structure with air space between the two oblique surfaces. Glass plates are glued to each end of the two rectangular prisms, forming a single unit with the two glass plates and the two rectangular prisms.

[0038] The two right-angle prisms are glued together to achieve the attenuation effect. The incident light spot is 1 mm, the overall length of the prism is 70 mm, the material used for the prism is fused quartz, and the attenuation film on the prism is a silicon dioxide film.

[0039] The preparation method of the film layer includes the following steps:

[0040] (1) Substrate heating: Wipe the substrate with a dust-free cloth dipped in a mixture of environmentally friendly wiping liquid (Foshan Jiajin ECH-CS) and acetone in a volume ratio of 7:1, and bake and heat the substrate in a vacuum state to increase the substrate temperature. The baking temperature is 300°C to 310°C, and the baking time is 1.5 hours;

[0041] (2) Ion beam cleaning: The substrate is cleaned with an ion beam. The ion cleaning time is 2 min, the ion beam voltage is 400 V, and the ion beam current is 400 A.

[0042] (3) Coating of the prism bevel surface film layer: According to the air gap distance simulated in the film system design, the film layer is prepared within the 2mm width of the bevel surface;

[0043] SiO2 film coating: SiO2 film material is placed in a crucible and coated by electron beam evaporation. The background vacuum is higher than 6.0×10 -3 Pa, and the deposition rate is 1.5 nm / s.

[0044] The design target attenuation splitting ratio is 88:12, that is, R = 88% ± 1% @ 1064nm. The actual film thickness is measured using a profilometer, and the film thickness is between 950-980nm to ensure air spacing.

[0045] Figure 3 This is the theoretical effect diagram of the attenuation film on the quartz right-angle prism. Figure 3 It can be seen that the film thickness is between 950 and 980 nm, and the splitting ratio at 1064 nm is 88:12; Figure 4 The actual thickness measurement diagram of the attenuation film on the quartz right-angle prism in Example 1 is shown in FIG. Figure 4 It can be seen that the film thickness is 974nm and the splitting ratio is 88.3:11.7.

[0046] After a large number of scientific research experiments, the inventors found that the above-mentioned adjustable laser attenuator can obtain an attenuation ratio from 1% to 100% by adjusting the film thickness. The relationship between the air gap (film thickness) and the attenuation ratio of this example is shown in Table 1, where D is the air gap (film thickness) and T is the attenuation ratio.

[0047] Table 1 Attenuation table of adjustable laser attenuator in Example 1

[0048]

[0049]

[0050] Comparative Example 1

[0051] The difference from Example 1 is that: under the premise that the substrate is still quartz, the thickness of the film layer is 1010 nm, and the rest are the same as Example 1. The attenuation splitting ratio is 90:10, which does not reach the target attenuation ratio of 88:12.

[0052] Comparative Example 2

[0053] The difference from Example 1 is that: under the premise that the substrate is still quartz, the thickness of the film layer is 860nm, and the rest is the same as Example 1. The attenuation splitting ratio is 85:15, which does not reach the target attenuation ratio of 88:12.

[0054] Example 2

[0055] The material used for the prism is zinc selenide, and the film layer is a germanium film layer. Other details are as in Example 1.

[0056] Ge film coating: The Ge film material is placed in a crucible and plated using electron beam evaporation. The background vacuum is higher than 6.0×10 -3 Pa, and the deposition rate is 0.8 nm / s.

[0057] After a large number of scientific research experiments, the inventors found that the above-mentioned adjustable laser attenuator can obtain an attenuation ratio from 1% to 100% by adjusting the film thickness. The relationship between the air gap (film thickness) and the attenuation ratio of this example is shown in Table 1, where D is the air gap (film thickness) and T is the attenuation ratio.

[0058] Table 2 Attenuation table of adjustable laser attenuator in Example 2

[0059]

[0060]

[0061] In order to ensure the reliability of optical components, environmental tests were carried out on samples according to usage requirements:

[0062] Adhesion test: A 1-inch wide 3M special tape was placed close to the coating surface, and then quickly pulled up in the vertical direction of the film surface, and repeatedly pulled 20 times. The film layers of Examples 1 and 2 did not peel off.

[0063] Wet heat test: After immersion in water at 50°C for 48 hours, the films of Examples 1 and 2 showed no changes, and no peeling or shedding occurred.

[0064] High temperature resistance verification: After the temperature was raised to 300°C and baked for 12 hours and then returned to room temperature, the film layers of Examples 1 and 2 did not show any changes, and there was no peeling or falling off.

Claims

1. An adjustable laser attenuator, characterized in that: The invention comprises two right-angle prisms made of the same substrate, with the oblique surfaces of the two right-angle prisms facing each other. A film layer of different thickness is plated on one end of the oblique surface of the right-angle prism to control the air gap between the two oblique surfaces of the right-angle prism, thereby achieving different attenuation ratios in different bands. At the end without the film coating, the distance between the two right-angle prism oblique surfaces is zero; at the end with the film coating, the distance between the two right-angle prism oblique surfaces is the film thickness; so that the air gap between the two right-angle prism oblique surfaces forms a triangular structure; Glass plates are glued to both end faces of the two right-angle prisms; the film width is 1.5~2.5mm; For the near-ultraviolet to near-infrared bands, the material used for the right-angle prism is fused quartz; for the mid- and far-infrared bands, the material used for the right-angle prism is zinc selenide; For the near ultraviolet to near infrared band, the film layer is a silicon dioxide film layer, and for the mid- and far-infrared band, the film layer is a germanium film layer; The thickness of the silicon dioxide film layer is 30~1200nm; the thickness of the germanium film layer is 60~3000nm.

2. The adjustable laser attenuator according to claim 1, wherein: The preparation of the film layer includes the following steps: (1) Substrate heating: Before coating, the right-angle prism is baked and heated in a vacuum state to increase the temperature of the right-angle prism. The baking temperature is 300~350℃ and the time is 1~1.5h; (2) Ion beam cleaning: Ion beam cleaning is performed on the right-angle prism. The ion cleaning time is 1 to 15 minutes, the ion beam voltage is 300 to 400 V, and the ion beam current is 300 to 400 A. (3) Coating of the film layer on the bevel surface of the prism: According to the air spacing distance simulated in the film system design, the film layer is prepared within the width range of 1.5~2.5mm on the bevel surface of the right-angle prism.

3. The adjustable laser attenuator according to claim 2, wherein: In step (1), before baking and heating, wipe the substrate with a dust-free cloth dipped in a mixture of environmentally friendly wiping liquid and acetone in a volume ratio of (6-8):

1.

4. The adjustable laser attenuator according to claim 2 or 3, wherein: In step (3), the silicon dioxide film is deposited by placing the SiO2 film material in a crucible and depositing it by electron beam evaporation, with a background vacuum higher than 6.0×10 -3 Pa, and the deposition rate is 1-2nm / s.

5. The adjustable laser attenuator according to claim 2 or 3, characterized in that: In step (3), the germanium film is plated: the Ge film material is placed in a crucible and plated by electron beam evaporation, and the background vacuum is higher than 6.0×10 -3 Pa, and the deposition rate is 0.5-1nm / s.

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