CN1173166C - Method and device for measuring double-sided metal waveguide - Google Patents

Abstract

A double-sided metal waveguide measurement method and a device thereof belong to the field of physical measurement. The device is composed of a coupling device, an upper metal film, a thin film layer to be tested, and a lower metal film from top to bottom. The thin film layer to be tested and the upper and lower metal films are double-sided metal waveguide structures, and the upper and lower metal films are the upper and lower covering layers of the waveguide. Light is mainly transmitted in the film layer to be tested. The method is as follows: use vapor deposition, sputtering or other methods to form the device of the present invention on both sides of the film to be tested; select the laser wavelength, incident angle and polarization mode; receive and record the light intensity of the laser beam reflected from the bottom surface of the coupling device, or from the lower layer The light intensity of the laser beam transmitted by the metal film; change the laser incident angle to obtain the light intensity-incident angle curve, find out the resonance angle of the guided mode absorption peak and the width and depth of the corresponding absorption peak, and calculate the refractive index and thickness of the film material . The invention realizes high-precision, large-range, fast and real-time measurement, and the device has simple manufacturing process, low price, easy operation and miniaturization.

Description

Method and device for measuring double-sided metal waveguide

technical field

The invention relates to a measuring method and its device, in particular to a double-sided metal waveguide measuring method and its device, belonging to the field of physical measurement.

Background technique

In the past two decades, with the development of laser technology, especially the development of integrated optoelectronics technology, the measurement of optical properties and thickness of materials and the research and application of optical waveguide characterization technology have made great progress. Among them, the dual-wavelength method has been put into practice, and there are many reports on it. After literature search, it is found that the U.S. Patent No. 5034617, the patent name is: method and device for measuring film thickness and refractive index. This patent proposes a method for measuring optical film thickness. In this method, a certain wavelength λ ₁ is first selected. The laser beam is incident on the substrate material coated with optical film, then observe the reflected light intensity, measure and record the incident angles of the minimum point of reflected light intensity, θ ₁ and θ ₂ , then change the wavelength λ ₂ of the incident laser light, and then Measure an angle θ ₃ where the reflected light intensity is extremely small, and then substitute these five data into the formula to calculate the thickness and refractive index of the film to be tested. This method can measure the optical properties such as the thickness and refractive index of the film, but in this structure, the third angle value is obtained by adjusting the light wavelength of the incident laser, which inevitably brings a certain amount of dispersion, thus Seriously affect the accuracy of the measurement results. Another reported more is a prism coupling measurement structure. The laser is incident on the substrate material coated with optical film through the coupling prism, then observe the reflected light intensity, measure and record the incident angle of the minimum point of reflected light intensity, θ ₁ and θ ₂ , then replace the coupling prism, and measure a The angle θ ₃ at which the reflected light intensity is extremely small, and then these five data are substituted into the formula to calculate the thickness and refractive index of the film to be tested. The advantage of this method is that it avoids the dispersion caused by the dual-wavelength method. However, the distance between the prism and the film to be measured is difficult to adjust accurately, which in turn will have a great impact on the coupling efficiency, resulting in the efficiency of the two couplings. different, thus affecting the accuracy of the measurement results. Moreover, in order to couple the light from the prism to the thin film material, this method requires that the refractive index of the material to be measured should be smaller than that of the coupling prism, which greatly limits the applicable measurement range of this method.

Contents of the invention

Aiming at the deficiencies and defects of the prior art, the present invention provides a double-sided metal waveguide measurement method and its device, which are applicable to lasers of various wavelengths, the measuring instrument is miniaturized, the operation is simple, the manufacturing process is simple, and the price is low. Accurately measure and characterize the thickness, refractive index, birefringence coefficient, anisotropy, etc. of optical materials (including thin films and bulk materials), as well as the transmission loss of optical waveguides and the number of guided mode modes. The thickness of thin film materials is measured from microns Accurate measurements can be achieved from the level of 1 to 1000 mm, and direct coupling can be achieved without coupling devices.

The technical scheme of the present invention is realized in this way, the device of the present invention is made up of coupling device, upper layer metal film, test film layer, lower layer metal film from top to bottom, upper layer metal film, test film layer and lower layer metal film are double-sided The metal waveguide structure, the upper and lower metal films are the upper and lower covering layers of the waveguide, and the light is mainly transmitted in the thin film layer to be tested.

The coupling device adopts high refractive index prism (n>1.5), grating, coupling waveguide and other devices, or directly couples air without coupling device. The shape of the prism can be equilateral, or isosceles, or cylindrical, or Spherical or other common or special shapes.

The upper metal film and the lower metal film can generally be selected from metals that absorb less at the working wavelength. The metal dielectric constant ε=ε _r +iε _i is related to the working wavelength, and the thickness of the metal film should be strictly controlled so that the incident light and the guide Coupling of waves is most effective. The thickness of the upper metal film is between 20nm-80nm. The thickness of the lower metal film can be determined according to the measurement method. When the reflected light measurement method is used, it should be greater than 100nm; when the transmitted light measurement method is used, it should generally be less than 30nm. The metal type can choose silver, gold, aluminum, copper and other metals with small imaginary part of dielectric constant in the optical frequency range. Generally, the real part of the dielectric constant ε _r ≤ -10, and the imaginary part of the dielectric constant ε _i ≤ 5.0 .

The thickness of the film layer to be tested is between 0.5 μm and 1000 μm. The thickness must ensure that it can carry more than three guided wave resonance modes, and its refractive index is between 1.0 and 2.3. The film layer to be tested is in the transmission layer of the waveguide structure. The wave light is transmitted in the film layer to be tested. Therefore, the refractive index and other properties of the film to be tested will most directly affect the transmission properties of the guided wave light, which effectively improves the measurement efficiency and accuracy.

Based on the above-mentioned measuring device, the method of the present invention realizes the precise measurement of the optical properties and thickness of the film such as the refractive index with a brand-new idea, and can characterize various parameters of the waveguide material. The specific steps are as follows:

Step 1: Form the double-sided metal waveguide structure of the device of the present invention by evaporation, sputtering or other methods on both sides of the film to be tested, and its structure is "coupling device-upper metal film-test film layer-lower metal film" four-tier structure;

The second step: choose the appropriate laser wavelength, incident angle and polarization mode, choose the laser as the light source, the working wavelength can be selected in the visible and infrared frequency range, the laser beam output from the laser is incident on the coupling device, the incident angle is required Multiple resonant absorption peaks can be excited when changing from 0 to 90 degrees, and the polarization mode can be selected according to the measurement requirements, either transverse magnetic wave (TM mode) or transverse electric wave (TE mode);

Step 3: Use a light intensity measuring device on the other side of the coupling device to receive and record the light intensity of the laser beam reflected from the bottom surface of the coupling device, or receive and record the light intensity of the laser beam transmitted from the lower metal film from the direction of the bottom surface;

Step 4: Continuously change the incident angle of the laser in the range of 0 to 90 degrees, and record the reflected (transmitted) light intensity at the same time to form a reflected (transmitted) light intensity-incident angle curve, and find out the value of the guided mode absorption peak on the curve The resonance angle and the corresponding absorption peak width and depth, then, according to the characteristic formula of the double-sided metal waveguide, can be calculated to obtain the precise values of the refractive index and thickness of the thin film material.

The inventive method is further described below:

①Using the ATR (attenuated total reflection) guided mode absorption peak of the double-sided metal waveguide is very sensitive to the optical properties such as the refractive index of the waveguide medium and has a one-to-one correspondence, and the curve of the reflection (transmission) light intensity changing with the laser incident angle , transforming the measurement of optical properties such as film thickness and refractive index and the characterization of waveguide parameters into the measurement of the curve of reflected light intensity versus incident angle;

② Using the ATR guided mode absorption peak of the double-sided metal waveguide is very sensitive to the optical properties such as the refractive index of the waveguide medium and has one-to-one correspondence, the ATR guided mode area is selected as the working area;

③ The working point, that is, the incident angle is selected in the high-order mode area, low-order mode area and surface mode area of the ATR absorption peak, including the case of using multiple operating points in one device to work simultaneously and using transmitted light for measurement;

④Using the characteristics of double-sided metal waveguide TE and TM mode separation, when measuring thin films sensitive to light polarization, only the transverse electric (TE) or transverse magnetic (TM) mode optical signal is used as the incident light, and the other mode Light is used as a reference light, which can realize double-beam measurement, and through the comparison of optical signals, the noise caused by the light source can be effectively eliminated;

⑤Using the characteristic that the double-sided metal waveguide can carry multiple modes (usually more than three), the thickness of the film to be tested can be measured at the same time, thereby improving the measurement accuracy and practicability.

In the method of the present invention, the characteristics such as the angle, depth and width of the ATR guided mode absorption peak in the double-sided metal waveguide are very sensitive and one-to-one corresponding to the characteristics such as the refractive index and thickness of the film. The precise measurement of the refractive index and thickness of the film is essentially to convert the characteristics of the film’s refractive index and thickness into the parameters of the guided mode absorption peak of the double-sided metal waveguide corresponding to each other, so as to realize the measurement of the film’s refractive index. and accurate measurement of thickness.

Compared with the existing technology of measuring the optical properties and thickness of the film through prism coupling, the present invention has the following advantages:

Large measuring range and high precision. Using this method, the measurement of the refractive index of the film material can reach about 0.5% under the limit condition, and can reach 0.2% or higher under the normal working condition, and the measurement accuracy of the film thickness can reach about 0.3% under the limit condition , the normal working area can reach 0.1% or higher. Compared with the usual prism coupling measurement technology, the measurement range of its thickness can be extended to the order of magnitude from 0.5 micron to 1 mm. If the measurement of the refractive index adopts the air coupling method, it also breaks through the previous limitation that the refractive index of the thin film material should be lower than that of the coupling prism.

The method is simple and the measurement efficiency is high. The measurement of the refractive index and thickness of the film is done in one pass, no further steps are required.

The preparation is simple and the cost is low. Utilizing the characteristics of the double-sided metal waveguide, the coupling device can be omitted, and the air direct coupling method can be used for measurement, which reduces the measurement components and reduces the measurement cost.

The manufactured instrument has the characteristics of miniaturization and easy portability. The devices made according to this technology are small in size, easy to carry and install, and have low requirements on the measurement environment.

Wide range of applications. In the usual measurement methods, many restrictions need to be made on the properties of the film to be measured, which hinders the wide application of the measurement method. However, in this technology, there are not many requirements on the refractive index and thickness of the film, so it can be applied in a wider field.

The measurement cycle is short and real-time monitoring can be realized. The response time of the film thickness and refractive index and other optical property measurement methods mainly depends on the response time of the light intensity detector, so fast and even real-time measurement can be realized.

Films that are sensitive to light polarization can be measured with polarized light. When measuring a thin film sensitive to light polarization, only the transverse electric wave (TE mode) or transverse magnetic wave (TM mode) optical signal can be used as the incident light, and the light of the other mode can be used as the reference light to realize the double-beam measurement. Through the comparison of optical signals, the noise caused by the light source can be effectively eliminated.

The present invention has substantive features and significant progress. The method of the present invention can be widely used in the measurement of optical properties and thickness of various films, the characterization of optical waveguide parameters, etc., especially the two groups of film refractive index and thickness can be simultaneously analyzed. Using this technology, high-precision, large-range, fast and real-time measurement can be achieved, while ensuring that the instrument has high-tech performances such as simple manufacturing process, low price, easy operation, miniaturization, and portability.

Description of drawings

Fig. 1 structural representation of the present invention

Detailed ways

As shown in Figure 1, the device of the present invention consists of a coupling device 1, an upper metal film 2, a thin film layer 3 to be tested, and a lower metal film 4 from top to bottom. It is a double-sided metal waveguide structure, the upper metal film 2 and the lower metal film 4 are the upper and lower covering layers of the waveguide, and the light is mainly transmitted in the thin film layer 3 to be tested.

The coupling device 1 can use high refractive index prisms (n>1.5), gratings, coupling waveguides and other devices, or direct air coupling. A double-sided metal waveguide structure is formed on both sides of the film to be tested by evaporation, sputtering or other methods. The upper metal film 2 and the lower metal film 4 are selected from metals that absorb less at the working wavelength. The metal dielectric constant ε = ε _r + iε _i is related to the working wavelength, and the thickness of the metal film should be strictly controlled to make the coupling of the incident light and the guided wave most effective. The thickness of the upper metal film is between 20nm-80nm. The thickness of the lower metal film is determined according to the measurement method. When the reflected light measurement method is used, it should be greater than 100nm; when the transmitted light measurement method is used, it should generally be less than 30nm. The metal types are silver, gold, aluminum, copper and other metals with small imaginary part of dielectric constant in the optical frequency range, the real part of dielectric constant ε _r ≤ -10, and the imaginary part of dielectric constant ε _i ≤ 5.0.

The thickness of the film layer 3 to be tested is between 0.5 μm and 1000 μm, the thickness must be able to carry more than three guided wave resonance modes, and its refractive index is between 1.0 and 2.3. The film layer 3 to be tested is in the transmission layer of the waveguide structure. The waveguide light is transmitted in the film layer 3 to be tested.

In conjunction with the content of the present invention, the following three embodiments are provided:

Embodiment one:

The first step: the coupling device 1 selects a high-refractive-index equilateral triangular prism (n=1.5), adopts the sputtering method to plate a metal film layer on the bottom surface of the prism and the substrate material, and then puts the two film layers together, and in between A thin layer of air is left to form a double-sided metal waveguide structure. The thickness of the upper metal film 2 is 34nm, the film 3 to be tested is air, the actual value of the thickness is 5μm, and the actual value of the refractive index is 1.0 (dielectric coefficient is 1.0). The metal film 4 has a thickness of 300nm, and the metal is gold (ε=-14.4+i1.22 at a wavelength of 690.0nm);

The second step: select the incident laser 5 with a wavelength of 690.0nm, the incident light is a transverse magnetic wave (TM mode), and the incident angle 7 is scanned between 0 and 90 degrees;

Step 3: Receive and measure the light intensity of the laser beam 6 reflected from the bottom surface of the prism on the other side of the prism. The minimum value of the reflected light intensity is the resonant absorption peak, and record the angles of the three adjacent resonant absorption peaks excited. have to:

θ ₁ = 22.83 degrees θ ₂ = 18.22 degrees θ ₃ = 11.63 degrees

Substituting the above data into the characteristic equation of the double-sided metal thin conductor,

2π*sqrt(e ₁ -N ₁ ² )*d/λ＝m*π+2*arctan((e ₁ *sqrt(N ₁ ² -e ₂ ))/(e ₂ *sqrt(e ₁ -N ₁ ² )));

2*π*sqrt(e ₁ -N ₂ ² )*d/λ＝(m+1)*π+2*arctan((e ₁ *sqrt(N ₂ ² -e ₂ ))/(e ₂ *sqrt (e ₁ -N ₂ ² )));

2*π*sqrt(e ₁ -N ₃ ² )*d/λ＝(m+2)*π+2*arctan((e ₁ *sqrt(N ₃ ² -e ₂ ))/(e ₂ *sqrt (e ₁ -N ₃ ² )));

Wherein: N _i =n*sinθ _i , e ₂ =-14.4+1.22i (dielectric coefficient of metal layer), n=1.5 (refractive index of coupling device 1), λ=0.69 (wavelength of incident laser 5), m is The mode order is a positive integer, d is the thickness of the film 3 to be tested, and e ₁ is the dielectric coefficient of the film 3 to be tested.

Solving this system of simultaneous equations, we get:

The deviation between e ₁ =1.0021212 and the true value is 0.2%,

The deviation between d=5.00414133μm and the true value is 0.08%;

m=12.0

The calculation shows that the detection of the dielectric coefficient (the square of the refractive index) of the film 3 sample to be tested can reach an accuracy of 0.2%, and the detection of the film thickness can reach an accuracy of 0.08%.

Embodiment two:

The first step: the coupling device 1 selects a high refractive index equilateral rutile prism (n=2.8), and adopts sputtering method to form a double-sided metal waveguide structure on both sides of the film to be tested. The thickness of the upper metal film 2 is 48nm, and the film to be tested 3 It is lithium niobate, the actual value of the thickness is 0.5 μm, the actual value of the refractive index is 2.22 (dielectric coefficient is 4.9284), and the thickness of the lower metal film 4 is 300 nm. The metal is silver (ε=-12.0+i0.4 at a wavelength of 560.0 nm).

The second step: select the incident laser wavelength 5 to be 560.0nm, the incident light is a transverse magnetic wave (TM mode), and the incident angle 7 is scanned between 0 and 90 degrees;

Step 3: Receive and measure the light intensity of the laser beam 6 reflected from the bottom surface of the prism on the other side of the prism. The minimum value of the reflected light intensity is the resonant absorption peak, and record the angles of the three adjacent resonant absorption peaks excited. have to:

θ ₁ = 48.76 degrees θ ₂ = 38.51 degrees θ ₃ = 19.47 degrees

Substituting the above data into the characteristic equation of the double-sided metal thin conductor,

2π*sqrt(e ₁ -N ₁ ² )*d/λ＝m*π+2*arctan((e ₁ *sqrt(N ₁ ² -e ₂ ))/(e ₂ *sqrt(e ₁ -N ₁ ² )));

2*π*sqrt(e ₁ -N ₂ ² )*d/λ＝(m+1)*π+2*arctan((e ₁ *sqrt(N ₂ ² -e ₂ ))/(e ₂ *sqrt (e ₁ -N ₂ ² )));

2*π*sqrt(e ₁ -N ₃ ² )*d/λ＝(m+2)*π+2*arctan((e ₁ *sqrt(N ₃ ² -e ₂ ))/(e ₂ *sqrt (e ₁ -N ₃ ² ));

Wherein: N _i =n*sinθ _i , e ₂ =-12.0+0.4i (dielectric coefficient of metal layer), n=2.8 (refractive index of coupling device 1), λ=0.56 (wavelength of incident laser 5), m is The mode order is a positive integer, d is the thickness of the film 3 to be tested, and e ₁ is the dielectric coefficient of the film 3 to be tested.

Solving this system of simultaneous equations, we get:

The deviation between e ₁ =4.93331422 and the true value is 0.1%,

The deviation between d=0.501123276μm and the true value is 0.224%;

m=2.0

The calculation shows that the detection of the dielectric coefficient (the square of the refractive index) of the film 3 sample to be tested can reach an accuracy of 0.1%, and the detection of the film thickness can reach an accuracy of 0.224%.

Embodiment three:

Step 1: This example does not use the coupling device 1, but uses the air direct coupling method to excite the guided mode (n=1.0), and uses the sputtering method to form a double-sided metal waveguide structure on both sides of the film to be tested, and the thickness of the upper metal film 2 34nm, the real value of the thickness of the film 3 to be measured is 1000 μm, the real value of the refractive index is 1.673 (dielectric coefficient is 2.8), the thickness of the lower metal film 4 is 300nm, and the metal adopts gold (ε=-34.5+i under the wavelength of 890.0nm .47).

The second step: select the wavelength of the incident laser 5 to be 890.0nm, the incident light is a transverse magnetic wave (TM mode), and the incident angle 7 is scanned between 0 and 90 degrees;

Step 3: Receive and measure the light intensity of the laser beam 6 reflected from the bottom surface of the prism on the other side of the prism. The minimum value of the reflected light intensity is the resonant absorption peak, because in this example, the thickness of the film 3 to be tested is relatively large , so there are many excited modes, and the distance between adjacent modes is very small, so the first, fourth and seventh modes starting from zero are selected for calculation, and the angles of the three selected resonant absorption peaks are recorded to obtain:

θ ₁ = 5.625 degrees θ ₂ = 4.114 degrees θ ₃ = 1.494 degrees

Substituting the above data into the characteristic equation of the double-sided metal thin conductor,

2π*sqrt(e ₁ -N ₁ ² )*d/λ＝m*π+2*arctan((e ₁ *sqrt(N ₁ ² -e ₂ ))/(e ₂ *sqrt(e ₁ -N ₁ ² )));

2*π*sqrt(e ₁ -N ₂ ² )*d/λ＝(m+3)*π+2*arctan((e ₁ *sqrt(N ₂ ² -e ₂ )/(e ₂ *sqrt( e ₁ -N ₂ ² )));

2*π*sqrt(e ₁ -N ₃ ² )*d/λ＝(m+6)*π+2*arctan((e ₁ *sqrt(N ₃ ² -e ₂ ))/(e ₂ *sqrt (e ₁ -N ₃ ² )));

Where: N _i =n*sinθ _i , e ₂ =-34.5+2.47i (dielectric coefficient of metal layer), n=1.0 (refractive index of air), λ=0.89 (5 wavelengths of incident laser light), m is the mode order Number, is a positive integer, can be very big in this instance, d is the thickness of the film 3 to be measured, and _e1 is the dielectric coefficient of the film 3 to be measured.

Solving this system of simultaneous equations, we get:

The deviation between e ₁ =2.7842007 and the true value is 0.57%,

The deviation between d=997.162568μm and the true value is 0.28%;

m=3732

The calculation shows that the detection of the dielectric coefficient (the square of the refractive index) of the film 3 sample to be tested can reach an accuracy of 0.57%, and the detection of the film thickness can reach an accuracy of 0.28%.

Claims (3)

1. A double-sided metal waveguide measuring device, characterized in that it adopts a high refractive index prism n>1.5, a grating and a coupling waveguide device, or directly couples air as the coupling device (1); Metals, such as silver, gold, aluminum, copper, and metals with a small imaginary part of the dielectric constant in the optical frequency range, the real part of the dielectric constant ε _r ≤ -10, and the imaginary part of the dielectric constant ε _i ≤ 5.0 to produce The upper metal film (2) and the lower metal film (4), and the thickness of the upper metal film (2) is between 20nm and 80nm, and the thickness of the lower metal film (4) is determined according to the measurement method. When the reflected light measurement method is used, greater than 100nm, and less than 30nm when the transmitted light measurement method is used; the thickness of the film layer (3) to be measured is between 0.5 μm and 1000 μm, and the thickness must carry more than three guided wave resonance modes, and its refractive index is between 1.0 and 2.3 Between; the measuring device consists of a coupling device (1), an upper metal film (2), a thin film to be tested (3) and a lower metal film (4) from top to bottom, wherein the upper metal film (2), the thin film to be tested The layer (3) and the lower metal film (4) are double-sided metal waveguide structures, the upper metal film (2) and the lower metal film (4) are the upper and lower covering layers of the waveguide, and the film layer (3) to be tested is in the transmission of the waveguide structure. layer, the guided light is transmitted in the film layer (3) to be tested. 2. A double-sided metal waveguide measurement method, characterized in that the specific steps are as follows: Step 1: Use evaporation and sputtering methods on both sides of the film to be tested to form a double-sided metal waveguide structure: use a high refractive index prism n>1.5, a grating and a coupling waveguide device, or perform air direct coupling as a coupling device (1 ); use metals that absorb less at the working wavelength, such as silver, gold, aluminum, copper, metals with a small imaginary part of the dielectric constant in the optical frequency range, and the real part of the dielectric constant ε _r ≤ -10, the dielectric constant The imaginary part of the electrical constant ε _r ≤ 5.0 to make the upper metal film (2) and the lower metal film (4), and the thickness of the upper metal film (2) is between 20nm and 80nm, the thickness of the lower metal film (4) according to the measurement The method is determined, when the reflected light measurement method is used, it is greater than 100nm, and when the transmitted light measurement method is used, it is less than 30nm; the thickness of the film layer (3) to be measured is between 0.5μm and 1000μm, and the thickness must bear more than three guided wave resonances Mode, whose refractive index is between 1.0 and 2.3; the measuring device consists of a coupling device (1), an upper metal film (2), a thin film layer to be measured (3), and a lower metal film (4) from top to bottom, wherein, The upper metal film (2), the film layer to be tested (3) and the lower metal film (4) are double-sided metal waveguide structures, the upper metal film (2) and the lower metal film (4) are the upper and lower covering layers of the waveguide, and the metal film to be tested The thin film layer (3) is in the transmission layer of the waveguide structure, and the guided wave light is transmitted in the thin film layer (3) to be tested; The second step: choose the appropriate laser wavelength, incident angle and polarization mode, use laser as the light source, the working wavelength can be selected in the visible and infrared light frequency range, the laser beam (5) output from the laser (8) with a certain incident The angle (7) is incident on the coupling device (1), the incident angle (7) excites multiple resonant absorption peaks, and the polarization mode is incident in TM mode or incident in TE mode; Step 3: Use the light intensity measuring device (9) on the other side of the coupling device to receive and record the light intensity of the laser beam (6) reflected from the bottom surface of the coupling device, or receive and record the light intensity transmitted from the lower metal film from the direction of the bottom surface laser beam intensity; Step 4: Continuously change the laser incident angle (7) within the range of 0 to 90 degrees, and record its reflection and transmission light intensity at the same time to form a reflection and transmission light intensity-incident angle curve, and find the resonance of the guided mode absorption peak on the curve Angles and corresponding absorption peak widths and depths are calculated to obtain accurate values of the refractive index and thickness of the thin film material. 3. The double-sided metal waveguide measurement method according to claim 2, characterized in that the method of the present invention is further described as follows: Transform the measurement of film thickness and refractive index optical properties and the characterization of waveguide parameters into the measurement of the curve of reflected light intensity versus incident angle; Select the attenuated total reflection guided mode area as the working area; The working point, that is, the incident angle (7) is selected in the high-order mode area, low-order mode area and surface mode area of the attenuated total reflection absorption peak, including the case of using multiple operating points to work simultaneously in a device and using transmitted light for measurement; When measuring thin films sensitive to light polarization, only the transverse electric TE or transverse magnetic TM mode optical signal is used as the incident light, and the other mode of light is used as the reference light to realize double-beam measurement; The double-sided metal waveguide carries multiple modes, and the thickness and refractive index of the film (3) to be tested are measured simultaneously.