Method for testing optical waveguide

Abstract

The invention provides an optical waveguide testing method, and relates to the field of optical waveguide testing. In the testing method of the optical waveguide, required instruments comprise a laser light source, a microscope objective, a meter, a spectrum analyzer, a coupling device and a prism, a prism coupling method is adopted for testing, a high-refractive-index prism is adopted for prism coupling, and incident light waves and a waveguide mode are subjected to phase matching to achieve waveguide optical excitation. According to the invention, the sensitivity and the precision of optical waveguide testing are improved, tiny optical parameter changes can be measured, an accurate measurement result is provided, rapid measurement can be realized, the testing time can be greatly shortened, the testing can be completed in a short time, the detection process can be detected in real time, the measurement process can be observed and analyzed in real time, and the testing efficiency is improved. Therefore, important data support can be provided for design, manufacturing and performance evaluation of the optical waveguide device.

Description

Technical Field

[0001] The invention relates to the field of optical waveguide testing, and in particular to a method for testing an optical waveguide. Background Art

[0002] The effective refractive index of an optical waveguide is an important parameter for characterizing an optical waveguide. Only when the effective refractive index is known can the propagation constant of the waveguide be calculated, and then other parameters such as the thickness and dielectric constant of the waveguide medium can be calculated according to the dispersion equation of the optical waveguide. Therefore, calculating the thickness and refractive index of the waveguide film by measuring the effective refractive index of the optical waveguide is of great significance to the design of waveguide devices. Traditional optical wave testing generally adopts the m-line method, that is, when the m-line is observed by the naked eye, the angle is recorded and the effective refractive index is calculated. However, due to the large error of the human eye and considering some special cases where the m-line is not easy to be observed, the error of the m-line is sometimes large, making the refractive index result of the optical waveguide inaccurate. Therefore, the present invention proposes a testing method for an optical waveguide, thereby effectively solving the above-mentioned troubles and problems. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] In view of the deficiencies of the prior art, the present invention provides a method for testing an optical waveguide, by bringing a prism into close contact or proximity with the optical waveguide, and utilizing the prism to achieve efficient coupling input of light from a light source to the optical waveguide, and coupling output from the optical waveguide to a detection device, thereby improving the sensitivity and accuracy of the optical waveguide test, being able to measure minute optical parameter changes, and provide accurate measurement results, being able to quickly measure, and greatly reducing the test time, being able to complete the test in a short time, and at the same time being able to perform real-time detection of the detection process, and being able to observe and analyze the measurement process in real time, thereby being able to provide important data support for the design, manufacture and performance evaluation of optical waveguide devices.

[0005] (II) Technical solution

[0006] To achieve the above objectives, the present invention is implemented by the following technical solutions: a method for testing an optical waveguide, the apparatus required for the optical waveguide testing method includes a laser light source, a microscope objective lens, a meter, a spectrum analyzer, a coupling device, and a prism, and the steps of the optical waveguide testing method are:

[0007] S1: Adjust the emission head of the laser light source to a horizontal state so that the laser emitted by the laser and the optical waveguide of the microscope objective are in the same straight line;

[0008] S2: After the adjustment is completed, the laser light source is turned on to emit the laser source, and the laser irradiates the coupling device and refracts onto the glass, and the light is coupled into the glass through the three-dimensional adjustment frame and the optical waveguide stage, and then the three-dimensional adjustment frame and the optical waveguide stage are slowly adjusted to couple the light into the optical waveguide;

[0009] S3: Adjust the light wave stage to observe the amount of light forming the light waveguide in the glass matrix;

[0010] S4: Fix the coupling device and the prism together so that there is an air gap between the film surface of the coupling device and the prism, and observe the refraction angle of the light refracted from the prism into the coupling device by the optical waveguide;

[0011] S5: When the prism is fixed together with the coupling device as output coupling, each mode of the output light corresponds to a different incident angle. The output light is received by the spectrum analyzer, and the graphic lines corresponding to the modes can be observed. When the graphics appear in the corresponding direction, the optical waveguide line image appears with the bright spot as the center in the direction perpendicular to the exit surface. As the distance from the waveguide increases, the curvature becomes slower and the brightness becomes darker.

[0012] Preferably, the testing method of the optical waveguide adopts a prism coupling method for testing, wherein the prism coupling adopts a high refractive index prism to phase-match the incident light wave with the waveguide mode to realize waveguide light excitation.

[0013] Preferably, in the prism coupling test method of the optical waveguide, the refractive index of the glass substrate is n0, the refractive index of the film is n1, the refractive index of the air is n2, the refractive index of the prism is n3, the incident angle of the sawtooth light of the waveguide mode on the upper and lower interfaces of the film is θ, the thickness of the film is h, and the height of the air gap is d, then the propagation constant β of the light beam in the waveguide is:

[0014] β=k z =k1 sinθ.

[0015] Preferably, in the prism coupling test method of the optical waveguide, when the incident angle θ is greater than the critical angle of total reflection When the optical waveguide beam particles penetrate into the film, the waveguide mode is excited to form the input beam.

[0016] Preferably, in the prism coupling test method of the optical waveguide, when the incident angle θ is equal to the propagation constant β of the light wave in the waveguide, the coupling phenomenon occurs, and the refractive index and thickness calculation formula of the waveguide are:

[0017] (2π / λ0)(cosθ)hn3+ψ 10 +ψ 12 =mπ

[0018] (ψ 10 and ψ12 is the air-film and film-substrate surface phase displacement).

[0019] Preferably, in the prism coupling test method of the optical waveguide, the intensity of the incident light beam should not be too weak or too strong. If the light beam is too weak, the brightness of the transmission line is too low, and if the light beam is too strong, the response of the spectrum analyzer may be saturated, affecting the fitting accuracy.

[0020] Preferably, in the prism coupling test method of the optical waveguide, the laser light source probe should not be too close to the waveguide, and the laser light source is wrapped with black cloth except for the lens to reduce interference from reflected light.

[0021] Preferably, in the prism coupling test method of the optical waveguide, near the coupling point between the prism and the waveguide, since the scattered light is particularly strong, this part needs to be covered with a black paper strip.

[0022] Working principle: In the prism coupling detection method of the optical waveguide, it is first necessary to measure the bottom angle θ0 of the prism. Secondly, after the light beam reaches the specified angle on the incident surface of the prism, the reflected light of the incident light on the incident surface of the prism strictly coincides with the small hole, and the initial incident angle of the incident light beam is determined. The synchronization angle of the three adjacent guided modes is measured on the spectrum of the spectrum analyzer, so as to measure the angle position θ. The propagation constants of the four adjacent guided modes n0, n1, n2, and n3 are substituted into the calculation formula of the refractive index and thickness of the waveguide to solve the thickness and refractive index of the film.

[0023] (III) Beneficial effects

[0024] The present invention provides a method for testing an optical waveguide, which has the following beneficial effects:

[0025] The invention provides a test method for an optical waveguide. The optical waveguide test adopts a prism coupling test method. Compared with a traditional m-line observation test method, the prism coupling test method uses a prism to closely contact or approach an optical waveguide, and uses the prism to realize efficient coupling input of light from a light source to an optical waveguide, and coupling output from the optical waveguide to a detection device, thereby improving the sensitivity and accuracy of the optical waveguide test, being able to measure tiny optical parameter changes and provide accurate measurement results, being able to quickly measure, and greatly reducing the test time, being able to complete the test in a short time, and being able to perform real-time detection on the detection process, being able to observe and analyze the measurement process in real time, thereby being able to provide important data support for the design, manufacture and performance evaluation of optical waveguide devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a refraction principle diagram of the prism coupling test method of the optical waveguide test method of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the description of this application, it should be noted that the terms used here are only for describing specific implementations, and are not intended to limit the exemplary implementations according to the present application. For ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and devices known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and devices should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0028] Embodiment 1:

[0029] 2. If Figure 1 As shown, an embodiment of the present invention provides a method for testing an optical waveguide. The instrument required for the optical waveguide testing method includes a laser light source, a microscope objective lens, a meter, a spectrum analyzer, a coupling device, and a prism. The steps of the optical waveguide testing method are as follows:

[0030] S1: Adjust the emission head of the laser light source to a horizontal state so that the laser emitted by the laser and the optical waveguide of the microscope objective are in the same straight line;

[0031] S2: After the adjustment is completed, the laser light source is turned on to emit the laser source, and the laser irradiates the coupling device and refracts onto the glass, and the light is coupled into the glass through the three-dimensional adjustment frame and the optical waveguide stage, and then the three-dimensional adjustment frame and the optical waveguide stage are slowly adjusted to couple the light into the optical waveguide;

[0032] S3: Adjust the light wave stage to observe the amount of light forming the light waveguide in the glass matrix;

[0033] S4: Fix the coupling device and the prism together so that there is an air gap between the film surface of the coupling device and the prism, and observe the refraction angle of the light refracted from the prism into the coupling device by the optical waveguide;

[0034] S5: When the prism is fixed together with the coupling device as output coupling, each mode of the output light corresponds to a different incident angle. The output light is received by the spectrum analyzer, and the graphic lines corresponding to the modes can be observed. When the graphics appear in the corresponding direction, the optical waveguide line image appears with the bright spot as the center in the direction perpendicular to the exit surface. As the distance from the waveguide increases, the curvature becomes slower and the brightness becomes darker.

[0035] The test method of the optical waveguide adopts the prism coupling method for testing. The prism coupling adopts a high refractive index prism to phase-match the incident light wave with the waveguide mode to realize waveguide light excitation. The refractive index of the glass substrate is n0, the refractive index of the film is n1, the refractive index of the air is n2, and the refractive index of the prism is n3. The incident angle of the sawtooth light of the waveguide mode on the upper and lower interfaces of the film is θ, the thickness of the film is h, and the height of the air gap is d. Then the propagation constant β of the light beam in the waveguide is:

[0036] β=k z =k1 sinθ

[0037] When the incident angle θ is greater than the critical angle of total reflection When the optical waveguide beam particles penetrate into the film, the waveguide mode is excited to form an input beam. When the incident angle θ is equal to the propagation constant β of the light wave in the waveguide, coupling occurs. The refractive index and thickness of the waveguide are calculated as follows:

[0038] (2π / λ0)(cosθ)hn3+ψ 10 +ψ 12 =mπ

[0039] (ψ 10 and ψ 12 is the air-film and film-substrate surface phase displacement).

[0040] In the prism coupling test method of the optical waveguide, the intensity of the incident light beam should not be too weak or too strong. If the light beam is too weak, the brightness of the transmission line is too low. If the light beam is too strong, the response of the spectrum analyzer may be saturated, affecting the fitting accuracy. The laser light source probe should not be too close to the waveguide. The laser light source is wrapped with black cloth except for the lens to reduce the interference of reflected light. Near the coupling point between the prism and the waveguide, since the scattered light is particularly strong, this part needs to be covered with a black paper strip. In the prism coupling detection method of the optical waveguide, first, the bottom angle θ0 of the prism needs to be measured. Secondly, after the light beam reaches the specified angle on the incident surface of the prism, the reflected light of the incident light on the incident surface of the prism strictly coincides with the small hole, and the initial incident angle of the incident light beam is determined. The synchronization angle of the three adjacent guided modes is measured on the spectrum of the spectrum analyzer, so as to measure the angle position θ. Substituting the propagation constants of the four adjacent guided modes n0, n1, n2, and n3 into the calculation formula of the refractive index and thickness of the waveguide, the thickness and refractive index of the film can be solved.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for testing an optical waveguide, characterized in that: The optical waveguide testing method requires instruments including a laser light source, a microscope objective lens, a meter, a spectrum analyzer, a coupling device, and a prism. The steps of the optical waveguide testing method are as follows: S1: Adjust the emission head of the laser light source to a horizontal state so that the laser emitted by the laser and the optical waveguide of the microscope objective are in the same straight line; S2: After the adjustment is completed, the laser light source is turned on to emit the laser source, and the laser irradiates the coupling device and refracts onto the glass, and the light is coupled into the glass through the three-dimensional adjustment frame and the optical waveguide stage, and then the three-dimensional adjustment frame and the optical waveguide stage are slowly adjusted to couple the light into the optical waveguide; S3: Adjust the light wave stage to observe the amount of light forming the light waveguide in the glass matrix; S4: Fix the coupling device and the prism together so that there is an air gap between the film surface of the coupling device and the prism, and observe the refraction angle of the light refracted from the prism into the coupling device by the optical waveguide; S5: When the prism is fixed together with the coupling device as output coupling, each mode of the output light corresponds to a different incident angle. The output light is received by the spectrum analyzer, and the graphic lines corresponding to the modes can be observed. When the graphics appear in the corresponding direction, the optical waveguide line image appears with the bright spot as the center in the direction perpendicular to the exit surface. As the distance from the waveguide increases, the curvature becomes slower and the brightness becomes darker.

2. The optical waveguide testing method according to claim 1, characterized in that: The testing method of the optical waveguide adopts the prism coupling method for testing. The prism coupling adopts a high refractive index prism to phase-match the incident light wave with the waveguide mode to realize waveguide light excitation.

3. The optical waveguide testing method according to claim 1, characterized in that: In the prism coupling test method of the optical waveguide, the refractive index of the glass substrate is n0, the refractive index of the film is n1, the refractive index of the air is n2, and the refractive index of the prism is n3. The incident angle of the sawtooth light of the waveguide mode on the upper and lower interfaces of the film is θ, the thickness of the film is h, and the height of the air gap is d. Then the propagation constant β of the light beam in the waveguide is: β=k z =k1sinθ.

4. The optical waveguide testing method according to claim 1, characterized in that: In the prism coupling test method of the optical waveguide, when the incident angle θ is greater than the critical angle of total reflection When the optical waveguide beam particles penetrate into the film, the waveguide mode is excited to form the input beam.

5. The optical waveguide testing method according to claim 1, characterized in that: In the prism coupling test method of the optical waveguide, when the incident angle θ is equal to the propagation constant β of the light wave in the waveguide, the coupling phenomenon occurs. The refractive index and thickness calculation formula of the waveguide are: (2π / λ0)(cosθ)hn3+ψ 10 +ψ 12 =mπ (ψ 10 and ψ 12 is the air-film and film-substrate surface phase displacement).

6. The optical waveguide testing method according to claim 1, characterized in that: In the prism coupling test method of the optical waveguide, the intensity of the incident light beam should not be too weak or too strong. If the light beam is too weak, the brightness of the transmission line is too low, and if the light beam is too strong, the response of the spectrum analyzer may be saturated, affecting the fitting accuracy.

7. The optical waveguide testing method according to claim 1, characterized in that: In the prism coupling test method of the optical waveguide, the laser light source probe should not be too close to the waveguide, and the laser light source is wrapped with black cloth except for the lens to reduce the interference of reflected light.

8. The optical waveguide testing method according to claim 1, characterized in that: In the prism coupling test method of the optical waveguide, near the coupling point between the prism and the waveguide, the scattered light is particularly strong, so this part needs to be covered with a black paper strip.

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