JP2890423B2 - Optical waveguide measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide measuring device capable of evaluating the characteristics of an optical waveguide with high accuracy.

[Summary of the Invention]

The present invention relates to an optical waveguide measuring device, wherein a sample stage,
It has a first and a second prism, and has a sample stage and a first prism.
And a prism pressing means for bringing the sample disposed between the second prism and the second prism into contact with each other, a prism moving means, and a pressing means for pressing the sample from the back surface following the movement of the prism, thereby forming an optical waveguide. The characteristics can be easily and quickly evaluated.

[Conventional technology]

2. Description of the Related Art In recent years, research and development of functional devices using optical waveguides have been active. Conventionally, there has been a strong need for a device which can evaluate the characteristics of these optical waveguides with high accuracy and is easy to use, but there has been no device that is stable and reliable. Moreover, there were no commercially available devices.

In evaluating the characteristics of the waveguide, the refractive index n, the film thickness h, the light absorption α, and the like are measured and calculated.

The measurement is performed by a prism coupling (prism coupler) method using a coupling prism of a laser beam and a waveguide. The prism coupling method, as shown in the principle diagram of FIG. 25,
This is a method in which a prism, that is, a couple-in prism (3) and a couple-out prism (4) are brought into contact with a waveguide sample (2) to be measured on an xyz fine-rotation stage (1) through a gap (gap). Light beam (input beam)
(5) is incident at a specific angle θ near the right-angled corner on the bottom surface of the couple-in prism (3), optical coupling occurs with a specific waveguide mode, and a light beam is introduced into the sample (2).
By adjusting the incident angle θ, an arbitrary guided mode can be excited.
(8) is a polarizer, (9) is a focusing lens, and (10) is a sample stage.

In order to confirm that the guided light has been obtained, the output beam (6) taken out from the couple-out prism (4) is projected on a light receiving element or a screen (7) to detect and confirm. For example, a rutile prism or the like is used for the prisms (3) and (4). Good coupling cannot be obtained unless the gap between the prisms (3) and (4) and the sample (2) is less than half the wavelength. However, a well-adjusted one provides high coupling efficiency. The prism coupling method has the advantage of being able to selectively excite modes with a simple and fairly good coupling efficiency, and is well suited for measuring waveguide characteristics.

[Problems to be solved by the invention]

By the way, the above-mentioned sample (2) and prisms (3) and (4)
It is difficult to delicately adjust the gap between them, and it is difficult to fix them stably and reliably. Actually, it is difficult to say that it is simple. It was difficult to make a highly-evaluable evaluation device.

On the other hand, in the conventional experiment, since the prism and the sample are firmly pressed and fixed to each other on a surface plate or the like in order to improve the contact between the prism and the sample, the incident angle of the measurement laser beam to the couple-in prism can be varied. It was simple such that the surface plate could be rotated as it was (see FIG. 25) or the angle of the laser optical system could be changed. For this reason, a rotating mechanism with high accuracy and high repeatability has been desired.

At the same time, the angle of incidence θ of the laser beam to the couple-in prism was confirmed by a so-called protractor such as an angle scale. Therefore, reading errors and mistakes, individual differences, and lack of reading accuracy (for example, 0.001 ° class) were hardly desired, so that accurate reproducibility as well as uncertainty of the angle setting and troubles were impossible.

In setting the incident position of the optical axis between the laser beam and the couple-in prism (aligning the height (or level) of the incident spot of the laser beam and the couple-in prism parallel to the table surface), setting the initial position and setting the prism It has not been easy to adjust the positions (levels) of each other by spacers or the like in response to a change in size, a change in the laser emission system, or the like. At the same time, it is difficult to finely adjust the optimum position of the prism of the laser beam. Therefore, it is necessary to find an optimum position for smooth and level measurement.

When the angle of incidence of the couple-in prism is variable, the center of rotation in the couple-in prism to keep the coupling always at the right-angled corner at the bottom of the couple-in prism can be measured or measured with a simple moving table. Since the response to the sample size is slow, uncertain and poor in reproducibility, a device with a high-precision mechanism and a precise moving length measuring device has been desired.

Conventionally, the prism and the sample were pressed from the back with screws, for example, to improve the contact between each other.However, without holding the prism and the sample, simply pressing it blindly would cause the prism to rise, slip, or fall. However, the adhesion deteriorates, and the coupling is greatly hindered, such as twisting as the screw is pressed. In addition, measurement reliability and reproducibility are low,
It has been desired to hold a new prism.

In the prism coupling method, it is necessary to adjust the gap between the sample and the prism to obtain a good coupling efficiency.However, conventionally, as described above, the contact between the prism and the sample is simply performed without considering the holding of the prism. Since the screw was pressed and pressed, it was difficult to make fine adjustments to obtain the optimum contact condition, and the gap size could not be controlled. Therefore,
It was difficult to cause only the coupling, and the reproducibility of the evaluation measurement was naturally low. Similarly, when the spring pressure was used for the pressing, the degree of contact was not known, and good results were not obtained. When the pressure is simply applied by a screw or the like, the direction of the pressure is not always perpendicular to the contact surface between the prism and the sample, and this is considered to be a cause of the lifting or falling of the prism. As described above, conventionally, there has been no mechanism or means capable of applying pressure in the direction perpendicular to the contact surface, and there has been no gap adjustment and length measurement means having high reliability and reproducibility. Therefore, the success of the evaluation measurement due to the above-mentioned uncertain holding of the prism and the like, the pressing, and the fine adjustment of the contact gap, etc. is due to the skill and skill of the manual labor, and the workability and productivity are remarkable. It was bad.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an optical waveguide measuring device that can easily, quickly, and accurately evaluate characteristics of an optical waveguide.

[Means for solving the problem]

An optical waveguide measuring device according to the present invention includes a sample holder (31), first and second prisms (15) and (16), and includes a sample holder (31) and first and second prisms (15). 15) and (1)
6) The sample of the optical waveguide to be measured (2
6) has prism pressing means (32) for bringing the prisms (15) and (16) into contact with each other.

The sample holder (31), the first and second prisms (15) and (16), and the prism pressing means (32) are mounted on a table (4).
5) Rotation device (17), rotation center positioning adjustment device (18), and prism (15) for setting the height of the laser beam, which are arranged above and below this table (45) to set the incident beam angle
(16) A level adjustment stand (33) for adjusting the position is provided.

Then, a prism moving means (87) is provided to make the distance between the two prisms (15) and (16) variable. Further, pressing means (101A) (101B) for pressing the sample (26) from the back surface to the prisms (15) and (16) following the movement of the prism by the prism moving means (87) are provided. In this case, the pressing means (101A) is attached to the sample holding table (31).
It is desirable to provide a slit (62) through which (101B) is inserted.

[Action]

The sample (26) is held on the sample holder (31), and the prisms (15) and (16) come into contact with the surface of the sample (26) via the prism pressing means (32). At this time, the gap between the sample surface and the prism is adjusted by the prism pressing means (32), and the prisms (15) and (16) are constantly applied and pressed perpendicularly to the sample surface, so that good optical coupling efficiency is obtained. Obtained with good reproducibility.

Further, since the prism moving means (87) is provided, the distance between the two prisms (15) and (16) can be arbitrarily changed, so that the light absorption can be measured.

In addition, the sample (26) in cooperation with the prism pressing means (32)
By pressing from the back surface of the sample via the pressing means (101A) and (101B), a good contact state is obtained even for a small undulation on the sample surface where good contact cannot be obtained just by pressing the prism. Is obtained, and reliable optical coupling becomes possible, and the optical coupling efficiency is further increased.

〔Example〕

Hereinafter, an embodiment of an optical waveguide measuring apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of an optical waveguide measuring device according to the present embodiment. The measuring device main body (11), a laser beam emitting device (12), an optical system (13), and a photodetector (14). And the whole is arranged on a horizontal surface plate.

The measuring apparatus main body (11) will be described in detail in FIG. 2 and the following drawings. The rotating apparatus for setting the incident beam angle to the couple-in prism (15), the couple-out prism (16), and the couple-in prism (15) ( 17), a rotation center position adjusting device (18) and the like. As the couple-in prism (15) and the couple-out prism (16), for example, a rutile prism is used. Laser beam emitting device (1
2) means a plurality of laser irradiation means necessary for measurement, for example, a He-Ne laser (12A) having a wavelength of 1.52 μm, and a He-Ne laser having a wavelength of 1.152 μm.
-Ne laser (12B) and He-N with visible light wavelength 0.6328μm
An e-laser (12C) is provided.

As the optical system (13), since the laser power is as small as 5 mW or less, an Au mirror (19) and wavelength separation mirrors (20) and (21) are used so as to minimize loss. The first wavelength separation mirror (20) has a transmittance of 98.5% for a laser beam having a wavelength of 1.52 μm,
It is composed of a dichroic mirror having a reflectivity of 99% for a laser beam having a wavelength of 1.152 μm.
1) is composed of a dichroic mirror having a transmittance of 98% for a laser beam having a wavelength of 1.152 μm and 1.52 μm and a reflectance of 99% for a laser beam having a wavelength of 0.6328 μm. Laser beam (22A) from each laser irradiation means (12A) (12B) (12C)
(22B) and (22C) pass through the corresponding Au mirror (19) and wavelength separating mirrors (20) and (21), and pass through a Glan-Thompson prism (23) and a pinhole (24) to form a plano-convex lens (25).
And is incident on the sample (26) of the optical waveguide to be measured through the couple-in prism of the measuring device main body (11). Here, as the plano-convex lens (25), a plano-convex lens of f = 250 mm is used in order to make a laser beam having a diameter of 1 mm to 2 mm incident on the sample (26) with a spot diameter of several 100 μm. The output light beam extracted from the couple-out prism (16) is detected by a photodetector (14), for example, a CCD line sensor. In the case of 1.52 μm light, a germanium photodiode is used as a photodetector.

2 to 4 show an example of the measuring device main body (11). In this example, the sample of the optical waveguide to be measured (26)
Sample holding table (31) supporting the sample, 1 in contact with the sample (26)
Gap adjusting device (32) for adjusting the gap between the pair of prisms, ie, couple-in prism (15) and couple-out prism (16), prism (15) (16) and sample (26) [(32A) (32B)] , A level adjustment table (33), a rotation device (17) for rotating in a horizontal plane, a rotation center position adjustment device (18), and the like.

That is, a level adjusting table (33) for supporting the upper part of the apparatus main body is provided on the horizontal platen (34). This level adjustment stand (33)
The laser beams (22A) to (22C) correspond to the laser beam height determined by the laser beam emitting device (12) and the optical system (13) fixed to the other part of the surface plate (34). It has a function to raise and lower the cup-in prism (15) so that it can easily enter the optimum position of the in-prism (15). The guide-supported post (35) fixed to the horizontal surface plate (34) And a slider (36) arranged to be able to move up and down while being guided by the support (35), and a micrometer head (37) for moving the slider (36) up and down. The guide mechanism between the support (35) and the slider (36) is composed of, for example, various so-called linear guides in which rollers or balls are put in a dovetail groove or a V-groove. High precision and smooth slider with little backlash due to this linear guide (36)
Of the micrometer head (3
The micrometer head (37) allows fine adjustment of the slider and thus the prisms (15) and (16) while checking the height of the elevation adjustment by the scale of (7).

A rotating device (17) for setting the incident angle of the laser beam is provided above the slider (36) of the level adjusting table (33). This rotating device (17) is constructed by supporting the shaft (not shown) of the rotating substrate (39) on the bearing side cylinder (38) with double angular contact ball bearings, thereby achieving high-precision rotation with little backlash. Is possible. A scale (40) is provided on the outer periphery of the rotating substrate (39) to provide a rough guide for setting the incident angle of the laser beam to the couple-in prism (15) or for reading the incident angle. Rotating device (17)
A rotary encoder (for example, optical type) is built in, and a digital display device is connected to the outside to eliminate angle reading errors and errors, etc., so that high accuracy (0.001 （class reading and setting can be performed with good reproducibility) Can be configured.

By the way, regarding the incident beam position of the couple-in prism (15), as shown in FIG. 5A, the incident laser beam (22) always comes near the bottom right angle corner C of the prism (15) to improve the coupling efficiency. It is important to. Therefore, even when the couple-in prism (15) is rotated while being in contact with the sample (26) in order to obtain an arbitrary angle setting of the incident beam, the incident beam always remains in the prism (15).
The rotation center for approaching the corner C at the bottom right angle is as follows.

Enters the prism (15) at an arbitrary angle alpha _1, an angle alpha ₂ enters into the corner C of the laser beam to be refracted, if the refractive index of the prism (15) and _{n 2, n 1 sinα 1 =} n 2 a sin .alpha _2, the laser beam spot diameter of several 100μm by each arbitrary angle alpha ₁ Includes the tangent of the circle. Therefore, in the rutile prism, when the wavelength λ = 1.152 μm, the refractive index n ₂ = 2.7321,
Since a mm-square prism is used, it contacts the prism slope and ▲ ▼ as shown in FIG. 5B. Let the center of the circle of 1.29 be the center of rotation 0. This value varies depending on the size, material, and refractive index of the prism (15), which varies depending on the wavelength of light. Therefore, in this example, the rotation device (17) is used to accurately and easily align the rotation center with the optimum point of the couple-in prism determined by various conditions.
A rotation center position adjusting device (18) is provided above.

The rotation midpoint position adjusting device (18) is provided on a Y movable table (41) movable in the Y direction (gap direction between the prisms (15) and (16) and the sample (26)), and is disposed thereon. X movable in X direction (longitudinal direction of sample (26)) orthogonal to Y direction
A moving table (42), and the Y moving table (41) and the X moving table (4) by micrometer heads (43) and (44), respectively.
It is configured to perform the drive and length measurement of 2).

The Y moving table (41) and the X moving table (42) employ a so-called linear guide mechanism which can move minutely smoothly and does not cause backlash in operation. The micrometer head (4
According to 3) and (44), fine adjustment and fine measurement for reading the rotation center can be performed with high reproducibility.

The sample holder (31) is equipped with a rotation center position adjustment device (1
8) Table (45) integrally mounted on X carriage (42)
Provided above. As shown in FIG. 6, the sample holder (31) has a step (3) supporting the sample (26) vertically and at an appropriate height.
6) having a vertical surface (31a). This vertical surface (31a) supports the sample (26) from the back when the sample (26) is pressed by the prisms (15) and (16) so that the sample (26) is not bent or distorted, and Rigidly formed to ensure pressure contact.

A clamp (79) using a leaf spring is attached to the sample holder (31) in advance, and when the sample (26) is placed on the step (36) of the holder (31), the sample is clamped by the clamp (79). (26) is configured to be retained. Sample (2
According to the shape of 6), the elastic clip (78) is further fitted from the upper end as necessary to hold the sample (26).

The couple-in prism (15) and the couple-out prism (16) each form a right-angled triangle, and the apex opposite to the sample contact surface (46) is cut parallel to the sample contact surface (46) to form a plane (47). Is formed.

The couple-in prism (15) and the couple-out prism (16) are supported on a support (48) on a table (45).
Attached to.

The support (48) is a plane (48a) that supports and pushes the prisms (15) and (16) at the back, and a prism that prevents the prisms (15) and (16) from rising and falling when contacting the sample (26). Support surface (48b) (48c) that provides upper and lower surfaces, prism (1
5) In order to prevent lateral displacement of (16), surfaces (48d) and (48e) surrounding the side surface and the inclined surface of the prism are provided. That is, the prisms (15) and (16) are embedded in the support (48) except for the contact surface (46) with the sample (26). Further, the prisms (15) and (16) are pressed by the set screws (49) from the upper surface of the support (48) to further secure the prism and improve reproducibility.

A support (48) surrounding the entire prism (15) (16)
Is provided with, for example, a slit (50) having a width of 3 mm for inputting and outputting a light beam. The surface of the support (48) in contact with the prism has a black matte color to suppress harmful reflected light and scattered light.

Supports (48) corresponding to each prism (15) and (16)
A prism pressing means, that is, a gap adjusting device (32) is provided in connection with each. The gap adjusting device (32) is fixedly disposed on the table (45) perpendicular to the sample holder (31), and is movably engaged with the guide (52). 0.5mm, equivalent to a micrometer head, screwed onto a slider (53) integrated with the container (48) and a precision nut (54) provided on the slider (53)
And a lead screw (55) having a pitch. For a finer feed, a differential screw can be used. For the engagement between the guide portion (52) and the slider (53), a dovetailed groove structure with high precision and smoothness and adjusted to minimize backlash is adopted.
The lead screw (55) is supported by a holder (56) and a flanged bearing (57) that are planted on the guide (52).
The knob (58) and the snap ring (59) are attached. The knob (58) and the holder (56) are provided with a scale and a vernier so that a minute feed amount can be read. Further, a combination of a magnescale or the like and a digital display is also effective as a finer measurement. In order to determine the degree of contact between the prism and the sample in the gap adjustment on the basis of the pressure level, a pressure sensor or the like is provided on the sample holder (31) or the slider (53) and the guide side, and reproducibility is considered. . The gap adjusting device (32) of the couple-in prism (15) and the gap adjusting device (32) of the couple-out prism (16) are symmetrical with respect to the table (4).
5) Attached to upper mounting bases (60) and (61). Here, the mounting base (61) on the couple-out prism (16) side is attached to the table (45) with the elongated hole (62) and the tightening screw (63).
It is attached so that it can be changed in the longitudinal direction of the sample (26) via. This makes it possible to change the spacing between the couple-in prism (15) and the couple-out prism (16) to measure the light absorption α.

On the other hand, a detector (14) for detecting a beam emitted from the couple-out prism (16), for example, a CCD line sensor or a photodiode is arranged on the table (45).
That is, the substrate (65) on which the photodetector (14), for example, a photodiode (in the case shown) is mounted, or the substrate on which the CCD line sensor is mounted is selectively positioned at a position corresponding to the output angle range A of the output beam according to the measurement. It is fixedly attached to the support (64).

The support (64) is supported by a movement adjustment table that moves and adjusts in the height direction, the Y direction, and the Y direction, respectively. That is, (69) is a guide (66), a slider (67) and a lead screw (6
Height adjustment means consisting of 8), (70) is a guide part (71) by a rack or pinion mechanism and a slider (7
The adjustment means in the X direction consisting of 2), (73) is a guide portion (7
4) and a slider (75) in the Y direction. Incidentally, (76) is a shielding portion provided with a slit (77) for shielding light from an unnecessary direction when the CCD line sensor is arranged, and is removed in the case of a photodiode.

In the optical waveguide measuring device having such a configuration, the sample (26) of the optical waveguide to be measured is arranged on the step (36) of the sample holder (31) in contact with the vertical surface (31a). At this time, it is temporarily fixed by the clamp (79). Depending on the shape of the sample (26), the elastic clip (7
Temporarily fixed in 8).

Then, the respective gap adjusting devices (32) are driven to bring the couple-in prism (15) and the couple-out prism (16) into contact with the sample (26). On the other hand, by operating the micrometer head (37) of the level adjustment table (33), the height of the prisms (15) and (16) is adjusted to the height of the laser beam. In addition, rotation center positioning adjustment device (18)
By driving the Y moving table (41) and the X moving table (42), the position of the center of rotation is determined, and by rotating the rotating substrate (39) of the rotating device (17), the couple-in prism (15) is rotated. The angle of incidence of the laser beam on is set.

The above-described optical waveguide measuring device has the following advantages.

The level (height) of the prisms (15) and (16) and the position of the laser beam can be easily adjusted by the level adjustment table (33).
The position of the optimum incident spot on the couple-in prism (15) can be fine-tuned. Also, length measurement becomes possible.

The combination of a high-precision shaft and a bearing of the rotating device (17) enables functional, stable and high-precision measurement.

By combining a rotary encoder and a digital display for reading the rotation angle, it is possible to eliminate reading errors and errors in the incident angle of the measurement beam, to enable highly accurate reading of the incident angle, and to improve its reproducibility.

In the rotation center position adjusting device (18), the fine adjustment and the length measurement of the rotation center position can be smoothly and reliably performed without play by the linear guide mechanism and the micrometer head. Therefore, by the fine adjustment and the length measurement, the incident beam is converted to the bottom right angle corner C of the couple-in prism (15).
The center of rotation that is always kept constant can be accurately set, and the optical coupling efficiency can be improved.

Since the entire back side of the prisms (15) and (16) is firmly fixed by the support (48), the prisms (15) and (16) rise, fall, laterally displace, twist, etc. in contact with the sample (26). Is prevented, and contact accuracy, reproducibility and coupling efficiency are improved.

Always prism (15) with gap adjustment device (32)
Since (16) is pressed and pressed perpendicularly to the surface of the sample (26), good coupling efficiency and reproducibility can be achieved. The reproducibility of the gap adjustment is improved by the graduated knob. Therefore, high-precision characteristics of the optical waveguide (refractive index, thickness,
(E.g., propagation loss).

8 to 13 show other examples of the measuring device. In addition,
2 to FIG. 7 are denoted by the same reference numerals, and redundant description will be omitted. 2 to 4, the prisms (15) and (16) in contact with the sample (26) are used to increase the coupling efficiency between the laser beam and the sample (26), that is, the waveguide. ), And in order to guarantee a reliable connection and high reproducibility without raising, falling, laterally displacing, twisting, etc., each of the prisms (15) and (16) is other than the prism front surface (contact surface with the sample). It is firmly supported by a support (48) that wraps around. That is, the vertical surface (48) supporting and pushing the back of the prism of the support (48)
a) and the surfaces (48b) and (48c) that support the upper and lower surfaces of the prism prevent the prism from floating and falling, and the sides (48d) and (48e) that surround the prism side and slopes cause lateral displacement,
Twist is prevented, and the set screw (49) is clamped from above. By the way, such a solid support (4
In the prisms (15) and (16) supported by 8), a table (45) with high planar accuracy, a sample holder (31) perpendicular to the table, and a holder (31) parallel to the table (45) The prisms (15) and (16) and the support (3) are provided by a slide mechanism of the vertical gap adjusting device (32) and a support (48) having a back surface and a vertical lower surface parallel to the support (31).
When 1) is completely parallel and the sample (26) is parallel, firm support by the support (48) can easily and easily realize coupling with high coupling efficiency. Therefore, the reproducibility is high.

Now, in the measuring apparatus shown in FIGS. 2 to 4, each part is manufactured with a tolerance in shape. Therefore, it can be said that it is relatively difficult to achieve the parallel accuracy of the prisms (15) and (16) and the sample holder (31) by managing and maintaining the final accuracy of assembly as a set of these parts. Also,
If the sample (26) is not parallel in the thickness direction, the prism (15) (16) is constrained by the support (48). Non-parallelism occurs between the prisms (15) and (16) and the sample surface in contact with each other, which reduces the coupling efficiency or disables the coupling. This can be said to be relatively easy. In addition, forcible pressing in this state may damage the prisms (15) and (16) or the sample (26). Therefore, even in such a situation, it is required to support the prism so that the fitting between the prism and the sample surface is improved and the optical coupling is reliably obtained.

In the above example, a slit (50) is provided in a part of the support (48) for the input and output of the measurement laser beam. However, since the prism is almost covered, unnecessary reflection is generated in the prism. And may cause measurement noise.

On the other hand, the light absorption of the optical waveguide is a couple-in prism (1
It can be obtained by detecting the intensity of the couple-out light while gradually changing the interval between 5) and the couple-out prism (16). In the example of FIG. 3, the table (4) of the gap adjusting device (32B) on the couple-out prism (16) side is used.
The mounting hole of the mounting base (61) to 5) is made to be a long hole (62), and the couple-out prism (16) can be moved based on the couple-in prism (15) at the center of rotation. It is fixed. The screw fixing of the mounting table (61) must be re-fixed every time the measuring position is moved. Therefore, the surfaces of the sample holder (31) and the sample (26) adjusted first and the prism (16) are fixed. Parallelism with the surface, the prism (1) with respect to the surface of the sample holder (31) and the sample (26).
6) The optimal vertical position of the support (48) and the gap adjusting device (32) must be readjusted and set for each measurement. Therefore, it is hard to be constant, such as a change in the gap inclination, and the reproducibility of the measurement is not good. In addition, in the case of the measurement using the prism interval as a parameter, it is necessary to adjust each time, which hinders continuous smooth measurement.
Both time and effort are heavy. Further, the distance between the couple-in prism (15) and the couple-out prism (16) is measured with a scale or the like and fixed with screws. However, since the length of the distance is uncertain, the reproducibility of the accuracy of the measurement data may be poor. Therefore, even if the distance is changed, there is a demand for a moving table and a distance measurement in which the parallelism and the verticality of the sample and the prism do not change.

The examples of FIGS. 8 to 13 improve the above points. First, in this example, the system has a degree of freedom (flexibility) in order to correspond to non-parallel in the thickness direction of the sample or non-parallel to the prism contact surface by a gap adjusting device or a support for the sample holder. Interpose elements. Due to this degree of freedom, the prism is rotated by the non-parallel pressing force of the sample or its reaction force with the contact point of each other as a fulcrum or a point of force, and the prism surface and the sample surface are adapted to each other.

FIG. 8 shows an embodiment in which a flexible member is interposed between the support (48) and the prisms (15) and (16) shown in FIG. In this example, a support (48) that wraps the entire rear part of the prisms (15) and (16) except for the contact surface (46) of the sample (26) is formed.
It is formed so as to have a gap of 0.5 mm. On the other hand, the prisms (15) and (16) are fitted into the support (48), respectively, with the entire rear portion of the prism wrapped by a cushion material (81) made of cork material or the like having a thickness of 0.5 mm.

In this way, cushion material (81) is prism (15) (16)
The surface (46) of the prisms (15) and (16) and the surface of the sample (26) are satisfactorily contacted by interposing between the support (48) and the support (48). In the case of FIG. 8, the prism (1
5) Although it can be held firmly against (16), the reaction force received from the entire cushioning material (81) is large and the degree of freedom is relatively small. Also, the cushion material (81) is naturally provided with slits for entering and exiting the measurement beam. However, unnecessary reflection at other locations is also a concern, and fabrication is also difficult.

9 and 10 show another example in which this point is improved.
In this example, as a prism support (48) constituting a part of the gap adjusting device (32), a prism support surface (82a) that is horizontal to the table (45) and perpendicular to the sample holder (31); A support having only the prism pressing surface (82b) parallel to the holding surface of the sample holder (31) is provided. Then, the back pressing surface (82b) and the prism (15) (1
6) Cushion material with good adhesion and parallel to the back of this example. In this example, 0.5 mm thick Si rubber (83) is interposed and prisms (15) and (16) are mounted on support (48). Deploy. In order to further hold the prisms (15) and (16) respectively, a leaf spring clamp (84) made of phosphor bronze is arranged so as to extend over the upper surface of the support (48) and the upper surfaces of the prisms (15) and (16). And one end of the clamp (84) to the upper surface of the support (48) with a set screw (8
Then, the prisms (15) and (16) are relatively lightly pressed by the leaf spring clamps (84). Also,
A positioning piece (86) having a small contact surface of 0.5 to 1.0 mm for a prism set is provided.

In addition, it is conceivable to insert a similar cushion material on the lower support surface (82a), but in this case, there is a fear that a twist may occur due to a component force due to pressure.

In the examples of FIGS. 9 and 10, when the sample is non-parallel, the horizontal and vertical prism tilt adjustment is performed by using a relatively small cushion material (83) and a pressing surface (82b) on the back surface of the prism having a small area. ) Only,
Fits smoothly. At this time, the leaf spring clamp (84)
It keeps track of these swings while keeping the prisms (15) and (16) light and always prevents unnecessary lifting. Further, since rubber is used as the cushion material (83), friction is relatively large and lateral displacement is small. Furthermore, since most of the prisms (15) and (16) are open, the degree of contact with the sample (26) can be observed, so that it is easy to handle such as easy to measure. Further, since the side surfaces of the prisms (15) and (16) are open, unnecessary reflection is reduced, and the quality of measurement is improved. According to this example, defects such as a parallel accuracy of the sample (26), a decrease in the coupling efficiency due to the quality accuracy of the device, a failure in the coupling, and the like are almost eliminated, and the productivity is improved without impairing the positional accuracy.

As another example, although not shown, a cushion material is interposed between the sample holding table (31) and the sample (26) to be held. This example is the simplest, but usually a small prism (for example,
(5 mm square), the relatively large sample (26) has a large amount of tilt to adapt to the small non-parallel contact surface that occurs, and the sample is bent, distorted, or damaged if the applied pressure is large. In some cases.

FIG. 11 to FIG. 13 show an improved example of a variable distance adjusting means for variably adjusting the distance between the two prisms (15) and (16), that is, a prism moving means. The prism moving means moves the couple-out prism (16) side with respect to the fixed couple-in prism (15), and moves the sample (26) adjusted in advance and the couple-out prism ( It is configured so that the optimum state of the parallelism of 16) and the perpendicularity of the gap adjusting device with respect to the sample (26) are not changed. For this purpose, on the table (45), the sample holding table (31) (that is, the sample (26)
A prism moving means (87) for adjusting the interval, which is parallel to the longitudinal direction, is provided. The prism moving means (87) has a guide (88) and a slider (89) which are mutually engaged by a groove structure, and a so-called rack (90) is attached to the guide (88), and the slider (89) A pinion (not shown) that engages with the rack (90) is arranged at a portion of the guide, and the slider (89) moves on the guide portion (88) by rotating a knob (91) directly connected to the pinion. It is configured as follows. Of course, the guide portion (88) is parallel to the table (45) and parallel to the longitudinal direction of the sample holder (31). The gap adjusting device (32B) on the couple-out prism (16) side is integrally disposed on the slider (89).

Therefore, by turning (91), the couple-out prism (16) can be moved in parallel with the sample surface, and the gap adjusting device (32B) on the couple-out prism (16) side can be moved at an arbitrary moving position. The degree of perpendicularity to the surface of the sample holder (31) is guaranteed.

Also, a scale (reading scale) is provided on the end surface of the table (45), which is flush with the slider side surface almost in contact with the table (45), and a vernier is provided on the slider (89) side.
It is configured to be able to measure the length of the minute interval movement distance. In order to make this measurement more precise, to take measures against length measurement errors and reading errors, and to improve the efficiency of length measurement, for example, this length measurement is performed using a micro length measuring device such as a magnescale or optical scale and a counter. Combinations of readings are particularly efficient, as are incident angles of rotation.

The examples of FIGS. 8 to 13 have the following advantages.

By interposing a cushion material (81) or (83) between the prisms (15) (16) and the support (48), the sample (26)
Of the prism (15) (16) and the surface of the prism (15) and (16) are well compatible with each other. The defect is eliminated, and the sample (26) is prevented from being damaged, so that a secure connection can be obtained. Therefore, the measurement is facilitated, and the strict accuracy of the apparatus can be relaxed, so that the optical fabrication is facilitated. Further, the production of the parallelism of the sample (26) can be facilitated, or the accuracy range of adopting the measurement sample can be widened. Also, since the support (48) can be formed in an open type,
In this case, observation of the degree of measurement coupling is easy to see, and further, unnecessary reflection is reduced and measurement quality is improved.

By the prism moving means (87), the couple-out prism (16) can be moved relative to the couple-in prism (15), that is, a small gap movement with little play, a parallel movement with the sample surface, and a gap adjustment with respect to the sample. Can be maintained. In particular, the measurement position is released from readjustment of the degree of coupling for each change in interval, thereby improving the reproducibility of measurement. In addition, the measurement time for light absorption measurement and the like can be significantly reduced.

Equipped with length measuring means for minute dimensions of the distance between the couple-in and couple-out prisms, anyone can set the required distance strictly and immediately, improving measurement accuracy and reproducing The efficiency is high and efficient measurement is possible.

14 to 17 show an embodiment of the present invention. In addition,
Parts corresponding to FIGS. 11 to 13 are denoted by the same reference numerals, and redundant description is omitted.

Since the optical coupling efficiency is determined by the degree of contact between the prism and the sample, a certain improvement is obtained by the gap adjusting device and the flexible support. However, more strictly, it is desirable to be able to cope with surface accuracy (irregularity) within the area of the sample corresponding to the prism surface. This embodiment further improves this point.

In FIGS. 14 to 17, on the back side of the sample holding table (31), a sample back pressing device (see FIG. 14) having a push rod (100) for pressing the sample (26) from the back to the prisms (15) and (16). 101) [(101A) (101B)] are provided.

As the push rod (100) for pressing the sample (26) from the back to the optimal point of the prisms (15) and (16), for example,
8 or pushrod tip of the rod having a diameter of 2mm was spherical R ₂ as shown in FIG, the tip of the rod as shown in Figure 19 A and B 12
A push rod having a wedge shape of 0 ° and having a substantially vertical contact surface can be used. The push rod (100) shown in FIG. 18 and having a gentle pressing point as a smooth spherical surface can obtain a concentrated load of contact at the optimum point relatively strictly. Further, the push rod (100) shown in FIGS. 19A and B can obtain a contact line over the entire height of the prism. These push rods (100) are attached to the push rod holder (102) so that they can be exchanged and used depending on the condition of the sample (26). The push rod (100) is fitted into the V-groove formed in the push rod holder (102), and the clamp rod (103) inserted through the through-hole in the push rod (100) and the V-groove is tightened with a nut from the opposite side. Is fixed by The V-groove of the push rod holder (102) is for always keeping the push rod (100) at the height of the center of the prism (laser beam level). The sample back pressing mechanism has the same configuration as the gap adjusting device (32) except for the push rod holder (102). That is, the push rod holder (10
A slider (104) integrally formed with 2) is provided, and the slider (104) extends parallel to the table (5) and perpendicular to the contact surface with the sample (26) and the prisms (15) and (16). It is slidably engaged with the guide portion (105). The engagement between the slider (104) and the guide portion (105) is adjusted smoothly and precisely with a dovetail structure. A precision nut is formed on the slider (104), and a lead screw (107) is screwed into the precision nut. The lead screw (107) is rotatably held by a holder (108) erected on the guide portion (105). (109) is a knob provided at the end of the lead screw (107). Therefore, turning the knob (109) rotates the lead screw (107) to move the slider (104) to the sample (26).
Move in the direction toward. Lead screw (107)
The knob (109) is provided with a scale, the holder (108) is provided with a vernier, and the fine feed amount can be determined by the scale and the vernier.

The sample back pressing devices (101A) and (101B) are provided for the couple-in prism (15) and the couple-out prism (16), respectively. In this case, in order to enable pressing even when the distance between the prisms (15) and (16) is reduced by the prism moving means (87) of the couple-out prism (16), the push rods (100) of each other are used. Each push rod (100) has a corresponding holder (10
2) Mounted on opposite sides. That is, the sample back pressing devices (101A) and (101B) are formed in a symmetrical structure.

Then, the movement adjustment means (110A) (110A) ( 110B) is provided. Here, the couple-in prism (15) is fixed to serve as a reference,
As the first sample back pressing device (101A) corresponding to the couple-in prism (15), it is necessary to adjust the push rod (100) to the optimum position near the right angle corner C on the bottom of the prism with high coupling efficiency. It can be moved. Then, the movement adjusting means (110A) of the first sample back surface pressing device (101A) and the movement adjusting device (110B) of the second sample back surface pressing device (101B) which can follow the couple-out prism (16) whose distance can be varied. Have the same functions as the aforementioned couple-out prism (16) and prism moving means (87), respectively. That is, a common guide section (111) is provided on the table (45) and parallel to the table (45) and parallel to the longitudinal direction of the sample (26), and the guide section (111) has a first and a second sample back surface. Pressing device (101A) and (101
The sliders (112) to which B) are integrally attached are engaged. The guide portion (111) and the slider (112) are formed by a dovetail structure which can slide with high accuracy and certainty. A rack (113) is arranged on the guide portion (111), and a pinion (not shown) that engages with the rack (113) is arranged on each slider (112), and the pinion knob (114) is turned. It is configured to move.
A scale is attached to the end face of the table (45), a vernier is attached to the slider (112), and the prism moving means (87) is attached.
It is made to correspond to the movement of. On the other hand, the sample holder (31) has, for example, a maximum distance between the couple-in prism (15) and the couple-out prism (16).
A long hole (for example, 2.5 mm x 2) through which a push rod (100) of 2 mmφ is inserted
5mm) (62).

In the case of the couple-in prism (15) and couple-out prism (16), as shown in FIG. 20, the respective prisms (15) and (16) and the back (11) of the support (48) are provided.
6) is configured to be flush.

According to the embodiment shown in FIGS. 14 to 17, the sample (26) is pressed against the prisms (15) and (16) from the back by the sample back pressing devices (101A) and (101B), so that the sample ( 26) It is possible to perform reliable optical coupling even for small undulations on the surface, and further increase the coupling efficiency.

Further, the push rod (100) optimal for the measurement can be selectively exchanged by the push rod holder (102), and the measurable condition width of the sample (26) is widened.

The vertical pressing of the sample (26) and the prisms (15) and (16) is guaranteed by the sample back pressing mechanism, and the contact can be easily adjusted to a good contact state without causing lateral displacement and other distortion.

Further, the reproducibility is improved by reading the movement length of the movement adjusting means (110A) (110B).

The sample back pressing device (101A) at any position parallel to the sample (26) by the movement adjusting means (110A) (110B)
Vertical pressing of (101B) is guaranteed, and it is possible to adjust the pressing position to an optimum position where the engagement efficiency with the couple-in prism is high.

The follow-up movement can be similarly performed on the couple-out prism (16) moved by the movement adjusting means (110B).

In addition, the length measuring means can quickly perform the matching and improve the reproducibility.

Furthermore, as shown in FIG. 20, the prisms (15) and (16) and the back (116) of the support (48) are flush, so that the couple-in prism (15), the couple-out prism (16) and the back ( 116) to reduce the distance between the two
Then, by moving the couple-out prism (16), the interval can be changed from 0 to a predetermined distance.

When the input beam and the output beam (130) are as shown in FIG. 23, the sample holder (3) having the long hole (62) is used.
As 1), the end on the output beam side may be formed by bending, or as shown in FIG. 24, a sample holder (31) is made of a rigid material and a long hole (62) is formed in the sample holder ( It may be formed to reach the end on the emission side of 31). By using such a sample holder (31), the emitted beam can be satisfactorily applied to the photodetector (14).

In the above example, the so-called flexible support, in which the prisms (15) and (16) are fitted with the cushion material (81) or (83) that fits well into the sample (26), enables a certain improvement in the coupling efficiency. . However, strictly speaking, when the prism is blended into the sample, the back surface of the prism and the prism support surface of the support unit are inclined with the cushion material in between, so the component force of the vertical pressing force naturally causes the deflection of the cushion material. As a result, it becomes a cause of distortion along with the action of lateral displacement and twist of the prism. In addition, when the cushioning material is sufficiently crushed by the pressing force, the function of the flexible support cannot be exhibited, and the flexible support provided with the cushion is still insufficient.

On the other hand, certain measurement conditions (for example, temperature, etc.)
When adding a sample, push rod (11
In some cases, it is inappropriate to provide the through-hole (62) of (0), and it is not possible to press with the push rod (100) from the back of the sample. In this case, a support is required that has a mechanism that allows the prism to fit well on the sample surface and that is hardly affected by the component force of the pressing force, and that can concentrate the load on the optimum position of the pressing.

FIG. 21 and FIG. 22 show an embodiment in which such a point is improved.

In this example, a support (48) supporting the couple-in / out prisms (15) and (16), respectively, is attached to the gap adjusting device and is horizontal to the table (45) and vertical to the sample holding part (31). Prism supporting surface (120a) and prism pressing surface (120b) almost parallel to sample holder (31)
And a relatively small-diameter spherical projection is provided at a position corresponding to a predetermined position of the prism back pressing surface (120b), that is, substantially at the center of the pressing plane (47) of the prism back, or A so-called spherical portion (121) for fixing a relatively small diameter metal ball is provided.

In each case, since the back of the prism is directly pressed, the surface accuracy of the spherical surface needs to be high. In the embodiment, a high-precision steel ball (121A) having a diameter of 1 to 2 mm is embedded in the recess (122) of the back pressing surface (120b), and the head is protruded by 0.25 mm. Reference numeral (123) denotes a through hole. When the steel ball (121A) is bonded and fixed, for example, a needle or the like is inserted into the through hole (123) to control the protrusion dimension of the steel ball (121A). Alternatively, when replacing the steel ball (121A), the steel ball (121A) can be removed by inserting a needle or the like into the through hole (123).
Pressing the back surface of the prism with the spherical surface in this way corrects the non-parallelism of the contact between the prisms (15) and (16) and the surface of the sample (26), and performs a tilting motion using the contact point with the spherical surface as a fulcrum. Make

In addition, a thin leaf spring clamp (84) is provided at the upper end of the support (18) to hold the prism, and the prisms (15) and (16) are pressed relatively lightly, and a prism set is set on the side of the support (48). The same positioning piece (86) is provided. Thus, the flexible holding mechanism does not adversely affect the movement of contact between the prisms (15) and (16) and the sample (26), and provides a safe holding mechanism for the movement of the gap adjusting device (32).

Thus, by pressing substantially the center of the pressing plane (47) on the back of the prism, stable, reliable, and optimal optical coupling can be achieved.

Since the pressing surface of the prism support (48) is a metal spherical surface, even if a sufficient pressing force is applied to the prisms (15) and (16), the metal ball (121A) will not be crushed, and a large pressing force will be applied. Even prism (15) (16)
The function to follow 6) can be fully demonstrated. Therefore, when adding certain measurement conditions (for example, temperature, etc.) to the sample (26), it is inappropriate to provide a long hole (62) through the push rod in the sample holder (31) and the push rod from the back Even when the pressing cannot be performed, the prisms (15) and (16) can be adapted to the sample surface well. Further, since the support (48) is configured as a so-called open type in which the side surfaces of the prism are released, it is easy to observe the state of optical coupling. Further, measurement quality is improved with less unnecessary reflection.

〔The invention's effect〕

According to the above-described device of the present invention, the characteristics (refractive index, thickness, propagation loss, etc.) of the optical waveguide can be easily, quickly, and accurately evaluated. Therefore, the present invention can be suitably applied to the evaluation of the characteristics of an optical waveguide required for the development of a functional device using the optical waveguide.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an optical waveguide measuring device according to the present invention, FIG. 2, FIG. 3, and FIG. 4 are front views, plan views, and side views of essential parts of an example of a measuring device main body. 5A and 5B are explanatory views showing the relationship between a prism and an incident beam, FIG. 6 is a perspective view showing an example of a sample holder, and FIGS. 7A and B are cross sections as viewed from a plane showing an example of a prism holder. FIG. 8 is a cross-sectional view as viewed from a plane showing another example of the prism support. FIGS. 9 and 10 are plan and side views showing still another example of the prism support. 11, FIG. 12 and FIG. 13 are front views of main parts showing another example of the measuring device main body,
Plan view and side view, FIG. 14, FIG. 15, FIG. 16 and FIG. 17 are front view, plan view, rear view and side view of a main part showing an example of the measuring apparatus main body according to the present invention. FIG. 19 is a front view showing an example of a push rod, FIGS. 19A and B are plan views and front views showing other examples of the push rod, FIG. 20 is a plan view showing still another example of the prism support, and FIG. And FIG. 22 is a side view and a plan view showing still another example of the prism holder, FIGS. 23 and 24 are sectional views and a front view showing another example of the sample holder, respectively, and FIG. 25 is a prism coupling method. FIG. (11) is a measuring device main body, (12) is a laser beam emitting device, (13) is an optical system, (14) is a photodetector, (15) and (16)
Is a prism, (26) is an optical waveguide sample, (31) is a sample holder, (32) is a gap adjustment device, (48) is a prism holder, (87) is prism moving means, (101A) and (101B) are This is a sample back pressing device.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01M 11/00 G02B 6/34

Claims (2)

(57) [Claims] 1. A sample holder, first and second prisms, and prism pressing means for bringing a sample disposed between the sample holder and the first and second prisms into contact with each other. An optical waveguide measuring device comprising: a prism moving unit; and a pressing unit that follows the movement of the prism and presses the sample against the prism from the back surface. 2. The optical waveguide measuring device according to claim 1, wherein the sample holding table has a slit through which the pressing means is inserted.