JPH095210A - Characteristic evaluating apparatus for tree type and star type couplers - Google Patents

Abstract

PURPOSE: To provide a low-cost apparatus capable of automatically executing the characteristic measurement and evaluation of tree type and star type couplers. CONSTITUTION: A light source 1 is coupled to an object to be measured (tree type or star type coupler) 5 via a single-mode fiber(SMF) 2, a branch coupler 3 and a reflection return light branch coupler 4 are provided on the SMF 2, the ends of N fibers 6 and ends of guided fibers of the couplers 3, 4 for branching and guiding the light transmitted through the object 5 to be measured are individually coupled to a photodetector 7 via an optical switch 8, and means for calculating and evaluating the characteristics of the object to be measured from the data detected by the photodetector 7 is coupled to the photodetector 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for evaluating the characteristics of tree-type couplers and star-type couplers using optical fibers or optical waveguides. Such tree and star couplers are essential components in optical distribution systems.

[0002]

2. Description of the Related Art In an optical communication system, especially in a subscriber system in which the number of terminals is remarkably large, a tree type coupler (1 × N coupler) or a star type coupler (2 × N, ...) For distributing light.・ N × N coupler) is very important. The tree-type coupler divides one input into equal N outputs, and the star coupler divides each input from M channels (M = 2 to N) into equal N outputs. It is a thing. Further, in the case of a reverse input, the signal is transmitted to the input end (1 channel in the tree type, M channel in the star type) through a similar distribution process. Such tree-type and star-type couplers are essential parts for optical distribution systems.
It is also a part used in large quantities.

Now, the optical subscriber system is currently under research and development, and it is in the stage of asking for an opportunity for practical use. The factor that hesitates to put it into practical use is the problem of the balance between the cost and the effect of wiring, but it is considered that the effect on the cost is small at this stage. That is, it is necessary to reduce the cost of the parts used in the optical subscriber system as much as possible.

By the way, the tree-type and star-type couplers are manufactured by the one-point fusion method of fibers or the optical waveguide method. The fiber one-point fusion method is one in which fibers are twisted and one point thereof is fused, and cost factors are material cost, processing cost, and evaluation cost. Since this is performed in a small number of products destined for one product, the yield is poor, so that the processing cost and the number of channels are increased, and the evaluation cost is the main factor of the cost increase. In the optical waveguide method, a large number of inexpensive waveguides can be manufactured by using glass or polymer waveguides. However, the adjustment cost required for coupling the waveguide and the input / output fiber, and further, the characteristic evaluation cost is the main factor of the cost increase as the number of channels increases as in the fiber fusion method.

The number of tree type couplers that may be practically used is 1 × 16, and the number of star type couplers is 2 × 3.
There is a problem in that it is too expensive to evaluate such multi-channel characteristics on a channel-by-channel basis in a laboratory-level device.

[0006]

As examples of evaluation items of the coupler, insertion loss (hereinafter referred to as IL) for each channel, which is transmission loss from the input end to the output end, light reflected from the input end is reflected and the input end is reflected. Loss due to returning to
L), IL for each channel by reversing the I / O port
And RL, and crosstalk output (hereinafter directional) to other output ports when input from one of the multi-channel output ports. These are for one wavelength or a large number of wavelengths in the specification range. Needs to be measured and evaluated by changing the polarization state. In this way, it is necessary to measure a large amount of light in order to evaluate the coupler,
For downtime, automation of measurement is necessary.

As a coupler evaluation device, product number C5561-01 is commercially available from Hamamatsu Photonics.
The range of use of this is expandable to 1 × 8 tree type couplers, and IL and spectroscopic evaluation are also possible. However, the spectroscopic evaluation is not always necessary in the production line of tree type and star type couplers. Further, this measuring device does not have the RL measuring function which is a necessary evaluation item. Therefore, the emergence of an automated device that measures and processes evaluation items required on a production line at high speed is strongly desired.

[0008]

A tree-type and star-type coupler characteristic evaluation apparatus according to the present invention connects a light source 1, the light source 1 and an object to be measured 5, and outputs the light emitted from the light source 1 to the light source. A single-mode fiber 2 that guides the object to be measured 5, a first coupler 3 that is provided on the single-mode fiber 2 and branches a part of the light emitted from the light source 1 as reference light, and the single-mode fiber. A second coupler 4, which is provided in the downstream portion of the first coupler 3 of the fiber 2 and branches the reflected return light from the object 5 from the single mode fiber 2, and the light transmitted through the object 5. A fiber group 6 composed of N number of guided fibers, the first and second couplers 3 and 4, and a photodetector 7 for detecting the amount of light passing through the fiber group 6.
An optical switch 8 for individually connecting the first coupler 3, the second coupler 4, and the end of each fiber of the fiber group 6 to the photodetector 7, and the first coupler 3, the second coupler 4 and the fiber group 6, and means for evaluating the performance of the coupler based on the data detected by the photodetector 7.

In the device of the present invention, the light source 1 emits light having different wavelength bands from each other by two light emitting means 9 and 10.
And a wavelength coupling coupler 4 for guiding the light output from the light emitting means 9 and 10 to the single mode fiber 2.
1 and each of the light emitting means 9 and 10 can change the output wavelength into two or more kinds.

Further, in the device of the present invention, each of the light emitting means 9 and 10 has a fiber collimator 12 with a Lamipole polarizer 11, a half-wave plate 13, a fiber collimator 14 and the half-wave plate 13 which are sequentially connected. Via polarization control means 40 having means 15 for driving
It is preferably connected to the wavelength coupling coupler 41.

In the device of the present invention, it is preferable that each of the first coupler 3 and the second coupler 4 is a wavelength independent coupler.

Further, in the tree-type and star-type coupler characteristic detecting apparatus of the present invention, each fiber of the fiber group 6 is connected to the output fiber 29 directly connected to the measurement object 5 and connected to each fiber. It is preferably a multimode fiber having a core diameter larger than the mode field diameter of the output fiber 29.

Furthermore, in the tree-type and star-type coupler characteristic detecting device of the present invention, the optical switch 8 comprises:
Terminal 16 of the optical waveguide branched by the first coupler
And the terminal 17 of the optical waveguide branched by the second coupler
And a waveguide terminal 18 of each of the fiber groups 6 arranged and fixed on the circumference 19 at equal intervals.
0, the terminal arranging plate 20 is separated from the terminal arranging plate 20, and is arranged so as to face the terminal arranging plate 20 so as to be rotatable around the central rotation axis 44 and to transmit the light emitted from one of the terminals 16, 17, and 18. Rotating disk 2 having one opening 22 for
1, a collimator lens 23 that faces the opening of the rotating disk and is attached to the inside of the opening to collimate the light emitted from the waveguide terminal into parallel light; the rotating disk 21 and the photodetector 7. The condensing lens 24, which is arranged between the collimator lenses 23, condenses the parallel light emitted from the collimator lens 23 and makes it enter the photodetector 7 as spot light, and the rotation driving means 25 for rotationally driving the rotating disk 21. And a light blocking unit for blocking stray light entering the photodetector.

[0014]

The device of the present invention reduces the cost required for the characteristic evaluation of the tree-type and star-type couplers and enables the cost reduction.

An embodiment of the device of the present invention will be described below.
FIG. 1 is a block diagram for explaining the configuration of an embodiment of the device of the present invention. In FIG. 1, a light source 1 and an object to be measured 5 are optically connected by a single mode fiber 2 (hereinafter referred to as SMF2), and a light guide path formed by this SMF2 is provided with the light emitted from the light source 1. First coupler 3 for collecting a part as reference light (REF)
Is arranged, and about 10% of the light emitted from the light source 1 is branched from the SMF 2 as REF. Further, a second coupler 4 is provided downstream of the first coupler 3, which is a measurement object 5
The reflected return light from is branched from SMF2.

The SMF 2 is output from the optical connector 26, and the emitted light is input to the input fiber 28 of the measuring object 5 via the optical connector 27 facing it. As an example of the measuring object 5, a tree-type coupler having a 1 × 4 waveguide is shown in FIG. in this case,
The input light input to the input fiber 28 is branched into four by the tree-type coupler 5, passes through the output fiber 29, and the light output connectors 30-O ₁ , 30-O ₂ , 30-, respectively.
It is output from O ₃ , 30-O ₄ . These input / output fibers 28 and 29 are usually SMF.

Facing the light emitting connector 30, 4
(Generally N = 1 to 32) light receiving connectors 31-O
_1p, 31-O_2p, 31-O_3p, 31-O_4pIn front of
Connector for writing light 30-O₁~ O_FourConnected to. Receiving
Optical connector 31-O_1p~ O _4pThe transmitted light passing through the
The most stable bond that does not depend on the
To form, an optical fiber coupled to the light receiving connector.
Ibar 6 is the mode field diameter of the output fiber 29.
Multi-mold with core diameter larger than (MFD)
It is preferably fiber (MMF).

Light output from the waveguide terminal 18 of the fiber 6, the waveguide terminal 16 from the first coupler 3, and the waveguide terminal 17 from the second coupler 17 are individually selected and output by the optical switch 8 to detect light. Guided to vessel 7.

The received light amount data from the waveguide terminals 16, 17 and 18 is input from the photodetector 7 to the arithmetic processing means 32 for arithmetic operation, and as a result thereof, the measurement object 5 (tree type or star type coupler). Means 33 for displaying the characteristic evaluation data of
And recorded by the recording or transmission means 34 or transmitted to another device (for example, a computer).

In FIG. 1, the control means 35 is based on its program or the calculation result of the calculation processing means.
Controls the switch switching sequence of the optical switch 8,
The main wavelength of the light source 1 is switched, the variable wavelength is controlled, and the polarization direction is controlled. Further, the control means 35 also performs low-frequency intensity modulation of the light source, phase detection control of light detection, etc. in order to increase the S / N ratio of detection.

The measurement items and the measurement procedure of the tree-type coupler 5 (measurement target) in one wavelength and one polarization direction by the apparatus of FIG. 1 will be described. The components are forward connected as shown in FIG. The light amount of the reference light branched from the first coupler 3 and output from the waveguide terminal 16 is P _ref
, And when the switch 8 is switched by a command from the control means 35, the amount of light branched from the second coupler 4 and output from the waveguide terminal 17 is shown by P _ret , and when the switch 8 is switched, 6 waveguide end 18
The amount of light output from the device is represented by O _1d , O _2d , O _3d , and O _4d .
From these data, in the arithmetic processing means 32, the forward IL (insertion loss) (IL _1n = O _1d / P _ref , I
L _2n , IL _3n , and IL _4n ) and forward RL (reflection loss) (RL _n = P _ret / P _ref ) are calculated.

Next, in order to obtain the reverse characteristic, the connector 30-O ₁ is connected to I _p of the connector 26,
I of the connector 27, the measurement input terminal connector 30-
Connect to O _1p . Light amount P _ret from waveguide end 17 to R
The L value (RL _1r ) is obtained, and the terminal 30-O ₁ of the waveguide terminal 18 is obtained.
From the amount of light from O _1d seeking _{IL (IL 1r = O 1d /} P ref), the amount of light from the directional D _1n from the remainder of the terminal _{30-O 2 ~O 4 (D} 12 = O 2d / P re f, D 13 = O _3d / P _ref , D ₁₄
= O _4d / P _ref ). Similarly, the connection is changed to obtain the backward characteristic in each of the remaining branch paths of the measurement object, and a data group is obtained.

There is no limitation on how to collect the measurement data, and examples
For example, the insertion loss IL is IL_Nn, IL _NrThe minimum value from
The insertion loss distribution (flatness) is calculated by
And the reflection loss RL of the reflected return light is RL_n, R
L_nrAs the maximum value from
D_nnAs the maximum value of. However, in the above embodiment
Is the branching ratio of couplers 3 and 4 and the coupling effect of the connector.
Corrections such as rate are ignored, and IL, RL,
And D are defined as ratios, not db.

The operation of the above means is repeated for the desired wavelength to obtain the desired data. Similar measurement may be performed on the polarization dependency of the measurement object 5, but the procedure at this time is as follows. First, in the combination of FIG. 1, the polarization control means (to be described later) sets the polarization state (P) in which O _1d becomes maximum. In this polarization state P, the above series of forward measurement is performed, then the polarization state is rotated by 90 degrees, and the same measurement is performed. The difference between these two measured values is the polarization dependent PD value. When performing the backward measurement, the polarization state is adjusted each time the connection is changed.

The components of the measuring apparatus of the present invention will be described below. First, the light source 1 will be described. In the case of communication couplers, it is necessary to evaluate the characteristics of the 1.3 μm band and the 1.55 μm band. Further, in each wavelength band, for example, a 1 × 16 SMF coupler manufactured by Corning Co. is 1269-13.
Numerical guarantees are made in the range of 60 nm and 1430 to 1550 nm. Therefore, it is best to measure at all wavelengths, but this is not always necessary in the production line. For example, it is sufficient to measure only the central wavelength or a total of three wavelengths, the central wavelength and the two wavelengths at both ends. Is. Further, it is desirable that the light source output does not have an element that adversely affects the measurement such as an interference effect. For the above reason, the light source 1 includes a Fabry-Perot semiconductor laser 36 and a wavelength tunable filter 37 in a feedback loop 38 as shown in FIG. 2, and returns a certain amount of light or more from the feedback loop to the laser, a so-called external composite mirror. Use a laser.

The spectrum of the laser 36 is a multimode with a narrow interval determined by the length of the external cavity, and the width is a spectrum that is macroscopically regarded as a single wavelength with low coherence controlled by the filter transmission width. Furthermore, the wavelength can be changed by changing the inclination of the filter. 1.55 μm and 1.3 μm
It has the light emitting means 9 and 10 made of a laser having a center wavelength of, and operates one of them in response to a command from the control means 35. The outputs from both laser emission means 9 and 10 pass through the fiber 39, are combined in the WDM coupler 41, and are output via the SMF 2.

As the light source, it is also possible to use a means for cutting out the used wavelength from the output from the SLD (super luminescent diode) with a variable filter. However, in this case, the output intensity of the cut out wavelength is in the uW order, and the RL measurement light amount of 50 dB or more becomes −80 dBm, which is a difficult state for light amount measurement. On the other hand, it may be amplified by optical AMP, but it is expensive and goes against the purpose of cost reduction. Further, the DFB laser has an excessively narrow spectrum width, which causes interference due to reflection and the like inside the measurement target, and the measured value becomes unstable. Further, this is expensive and has a drawback that the wavelength variable range is narrow.

As shown in FIG. 1, the light emitting means 9,
The polarization control means 40 may be provided between the 10 output fibers and the WDM 41. The polarization control means 40 will be described with reference to FIG. In FIG. 3, fiber 3
A Lamipole polarizer 11 is attached to the 9th end to make linearly polarized light (the polarization state of the laser does not change, so the polarization direction is adjusted to maximize the output. In this way, stable linearly polarized light with a good extinction ratio is generally obtained. ) This is made into a parallel beam by the lens 12. After the parallel beam passes through the half-wave plate 13,
It is condensed by the lens 14 and guided to the SMF 2. In response to a command from the control means 35, the half-wave plate 13 is driven by the drive means 15
To rotate around the optical axis. In this way, the polarization direction according to the above command is obtained.

Next, the first coupler 3 and the second coupler 4 will be described. The first coupler 3 and the second coupler 4 are fiber couplers, and one unused terminal thereof is a reflectionless termination. Regarding the wavelength dependence of these couplers, WIC couplers whose characteristics do not change at wavelengths of 1.3 μm and 1.55 μm are used. The branching ratio of the first coupler 3 is about 10% S
The light is branched from the MF 2 and output as the reference light from the waveguide terminal 16. The second coupler 4 splits the reflected return light from the measurement target 5 to the SMF 2 at a splitting ratio of about 50:50 and outputs it as RET light from the terminal 17. Both of these couplers need to have little polarization dependence.

Next, the optical switch 8 will be described. FIG. 4 shows a sectional view of the optical switch 8. The output end 18 of the fiber 6 for N channels (N is 32) and the R
A total of (N + 2) individual fiber ends at the EF end 16 and the RET end 17 were reinforced by a ferrule 42, and were equally spaced (N + 2) on the circumference 19 (FIG. 1) provided on the terminal placement plate 20. In the through hole 20a of the terminal 16,
The ferrule 42 is fixedly arranged so that the 17 and 18 are on the same surface. A through hole is provided in the center of the plate 20, and a bearing 43 is mounted in the through hole, and a rotary shaft 44 passes through the bearing 43. A rotary disk 21 is arranged so as to be separated from the terminal arrangement plate 20 and face it. This rotating disk 21
A rotation shaft 44 supported by a bearing 43 of the terminal placement plate 20 is attached to the center of the rotation axis 44, and the rotation shaft 44 can rotate around the rotation shaft 44.

The rotating disk 21 is emitted from one of the terminals 16, 17, and 18 on a circumference concentric with the circumference 19 of the terminal placement plate 20 on which the terminals 16, 17, and 18 are located. One opening 2 provided at a position for transmitting light
2, a lens 23 is arranged between the opening 22 and the terminal arrangement plate 20, and the lens 23 is a rotating disk 21.
It is fixed to. A portion of the rotary shaft 44 projecting to the outside of the terminal arrangement plate 20 is connected to an appropriate rotary drive means (for example, a pulse motor mounted via a gear, a belt, etc., not shown), and is rotationally driven. It
Generally, in response to a command from the control means 35, the rotary disk 21 is rotated to move the lens 23 and the opening 22 to the terminal placement plate 2.
It is placed at a position facing one of the terminals 16, 17 or 18 located above 0, and the light output from the terminal is individually selected and received. The output lights from the terminals that are not selected are blocked (shielded) by the disk 21, and these output lights are not transmitted to the photodetector 7. That is, the terminal arrangement plate 20 and the rotary disk 21 function as the optical switch 18.

The lens 23 of the rotating disk 21 is connected to the terminals 16,
The output light from 17 or 18 is converted into a parallel light flux and transmitted through the opening 22. This transmitted light beam is transmitted through the large-diameter lens 2
The light enters the peripheral portion of 4 and is focused on the photodetector 7 located at the focal point of the lens 24. The large-diameter lens 24 is attached to the light shielding tube 25, and the photodetector 7 is attached to the light shielding tube 25.
Is disposed on the light shielding plate 51 forming the bottom of the.

In FIG. 1, the MMF (multimode fiber) 6 between the waveguide end 18 and the connector 31 is, for example, GI50 (NA: 0.2) for 1.3 μm,
If the focal length of the lens 23 is, for example, 2 mm, the diameter of the parallel light beam is about 1 mm, so the diameter of the opening 22 is about 2 mm, and the pitch of the through holes 20a on the circumference 19 of the terminal arrangement plate 20 is set to be the same. Assuming 5 mm and N = 32, the diameter of the circumference 19 is 5
If the focal length of the lens 24 is about 100 mm, the diameter of the light spot on the photodetector 7 will be 50 μm and the incident angle will be 12 degrees.

As the photodetector 7, an InGaAs PIN photodiode having excellent wavelength sensitivity is preferably used, and the diameter of its light receiving surface may be about 1 mm. These values are practically reasonable values. Terminal placement board 20
The space from to the photodetector 7 is relatively large and is easily affected by stray light. For this reason, this space should
The a and the light shielding plate 51 prevent the invasion of the stray light of the light shielding.

In FIG. 4, the light guide terminals 16, 17, 1 are shown.
8 is arranged on the concentric circles, these are arranged on the concentric double circles 19, 47 of the terminal arrangement plate 20 as shown in FIGS. 5 (a) and 5 (b). It may be placed at. That is, the reflection-returning optical waveguide terminal 17, which is strongly affected by stray light, is arranged on the small diameter circle 47, and the other terminal 1
6 and 18 are arranged on the large-diameter circumference 19 and the large-diameter circumference 19
A light-shielding cylinder 50 is provided between the small diameter circle 47 and the small diameter circle 47.
By doing so, the stray light from the terminals 16 and 18 is transmitted to the terminal 1
It is possible to prevent the light from entering when measuring the light amount of No. 7.

In the above case, FIG. 5B (rotating disk 21,
As shown in the large diameter lens 24 (FIG. 4) side of the terminal placement plate 20, that is, an explanatory view seen from the right side of the drawing, the rotating disk 21 faces the terminals 16 and 19 on the large diameter circle 19. The opening 22 and the lens 23 are arranged, and the opening 49 and the lens 4 facing the terminal 17 are provided on the circle 47 having a small diameter circle 47.
8 are arranged. The lens 48, the opening 49, and the lens 24 (not shown in FIG. 5) are the lens 23, the opening 22, and the lens shown in FIG. 4 with respect to the return light (RET light) output from the terminal 17. Similar to 24, return light can be incident on the photodetector 7 (not shown). However, when there is a possibility that stray light may enter through the opening 22 during the measurement of the amount of return light, the light shielding plate 52 is opposed to the opening 22 as shown in FIG. 5B. As described above, the rotary disc 21 and the large-diameter lens 24 are arranged between the rotary disc 21 and the large-diameter lens 24.

FIG. 6 shows another mode of the optical switch 8. In FIG. 6, the fiber terminals 16, 17, 18
Are arranged in a straight line on the fixed base 57 so that the end faces thereof are on one plane, the collimator lens 54 is arranged on the movable base 54 movable along the end face of the terminal, and the movable base 54 is set to a predetermined size. After moving to the position, the collimator lens 54 receives the output light from the predetermined terminal and converts it into a parallel light beam,
The light is emitted to the mirror 55, the parallel light flux is reflected by the mirror 55 at a predetermined angle (right angle), the light is condensed by the lens 53 on the fixed base 57, and the light is received by the photodetector.
The movable table 54 moves the collimator lens 54 to a position where the output light from a desired terminal is received.

In another mode of the optical switch 8,
Both fiber ends to be coupled may be moved by means such as electromagnetic solenoids, which are fiber / fiber coupled.

1 to 6, the tree-type coupler (1
Although the case where the object of measurement is xN) has been described, this measuring means can also be applied to a star-type coupler (NxN (N ≧ 2)). That is, in this case, the measurement operation may be repeated for each input channel.

[0040]

The apparatus of the present invention makes it possible to automatically evaluate the characteristics of tree-type and star-type couplers, and reduce the cost required for the characteristic evaluation.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an example of a tree-type and star-type coupler characteristic evaluation device of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of an example of a light source used in the device of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of an example of a polarization control device used as a light source of the device of the present invention.

FIG. 4 is an explanatory cross-sectional view showing the configuration of an example of an optical switch used in the device of the present invention.

5 (a) is a sectional explanatory view showing the configuration of another example of the optical switch 4 used in the device of the present invention, and FIG. 5 (b) is
The plane explanatory view of the above-mentioned optical switch.

FIG. 6 is an explanatory plan view showing the configuration of still another example of the optical switch used in the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... SMF 3 ... 1st coupler 4 ... 2nd coupler 5 ... Measuring object 6 ... MMF 7 ... Photodetector 8 ... Optical switch 9,10 ... Light emitting means 11 ... Lamipole polarizer 12 ... Lens 13 ... Half Wave plate 14 ... Lens 15 ... Half-wave plate driving means 16, 17, 18 ... Waveguide terminal 19 ... Circumference 20 ... Terminal arrangement plate 20a ... Through hole 21 ... Rotating disk 22 ... Opening 23 ... Lens 24 ... Large diameter lens 25, 25a ... Shading cylinder 26, 27 ... Connector 28, 29 ... Fiber 30, 31 ... Connector 32 ... Arithmetic processing means 33 ... Display means 34 ... Recording / transfer means 35 ... Control means 36 ... Fabry-Perot semiconductor laser diode 37 ... Wavelength Variable filter 38 ... Feedback loop 39 ... Fiber 40 ... Polarization control means 41 ... Wavelength coupling coupler 42 ... Ferrule 43 ... Bearing 44 ... Axis 47 ... small diameter circumference 48 ... lens 49 ... opening 50 ... shielding cylinder 51, 52 ... light shielding plate 53 ... condenser lens 54 ... carriage 55 ... mirror 56 ... collimator lens 57 ... fixing base

Claims (6)

[Claims] 1. A light source 1, a single mode fiber 2 that connects the light source 1 and a measurement object 5 and guides light emitted from the light source 1 to the measurement object 5, and a single mode fiber 2. A first coupler 3 which is provided above and splits a part of the light emitted from the light source 1 as reference light; and the first coupler 3 of the single mode fiber 2.
A second coupler 4 which is provided in the downstream portion of the target 5 and branches the reflected return light from the object 5 from the single mode fiber 2, and N fibers which guide the light transmitted through the object 5. A fiber group 6, the first and second couplers 3, 4 and a photodetector 7 for detecting the amount of light passing through the fiber group 6, the first coupler 3, a second coupler 4, and the fiber group 6 The data detected by the photodetector 7 by being guided from the optical switch 8 that individually connects the ends of the respective fibers to the photodetector 7, the first coupler 3, the second coupler 4 and the fiber group 6. And a means for evaluating the physical properties of the measurement object based on the above, and a characteristic evaluation device for tree-type and star-type couplers. 2. The light source 1 includes two light emitting means 9 and 10 for emitting lights having different wavelength bands from each other, and the light emitting means 9 and 10.
A wavelength coupling coupler 41 for guiding the light output from the optical fiber 10 to the single mode fiber 2, and each of the light emitting means 9 and 10 can change its output wavelength into two or more types. The device according to. 3. Each of the light emitting means 9 and 10 has a fiber collimator 12 with a lamipole polarizer 11, a half-wave plate 13 and a fiber collimator 1 which are sequentially connected.
4, and the wavelength coupling coupler 4 via polarization control means 40 having means 15 for driving the half-wave plate 13.
The device of claim 2, wherein the device is coupled to 1. 4. The device according to claim 1, wherein each of the first coupler 3 and the second coupler 4 is a wavelength independent coupler. 5. Each fiber of the fiber group 6 comprises:
Output fiber 29 directly connected to the measurement object 5
The device of claim 1, wherein the device is a multimode fiber having a core diameter greater than the mode field diameter of the output fiber 29 coupled to each fiber. 6. The optical switch 8 comprises an optical waveguide terminal 16 branched by the first coupler, an optical waveguide terminal 17 branched by a second coupler, and each waveguide terminal of the fiber group 6. 18 and 18 are arranged and fixed on the circumference 19 at equal intervals, are separated from the terminal arrangement plate 20, are arranged so as to face the terminal arrangement plate 20, and can rotate about the central rotation axis 44. Yes, and the terminal 1
A rotating disk 21 having one opening 22 for transmitting light emitted from one of the optical disks 6, 17, and 18, and facing the opening of the rotating disk, mounted inside thereof, and from the waveguide terminal. The collimator lens 23 that collimates the emitted light and the collimator lens 23, which is arranged between the rotating disk 21 and the photodetector 7, collects the collimated light emitted from the collimator lens 23 and forms the light as a spot. The apparatus according to claim 1, further comprising: a condenser lens 24 that is incident on the detector 7, a rotation driving unit that rotationally drives the rotating disk 21, and a light shielding unit that blocks stray light that enters the photodetector.