JPH1062308A - Method for measuring optical circuit part, and measuring device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the insertion loss of a part to be measured with high precision by branching the output of a non-polarization light source, measuring one after passed to the part to be measured, and the other directly by non- polarization sensitive light detecting means, respectively. SOLUTION: A non-polarization light source 11 is formed by combining a high luminance LED with an optical fiber type depolarizer, and non- polarization sensitive optical power meters 13, 14 are formed by arranging optical fiber depolarizers just before the light detecting parts of general power meters. The output of the light source 11 is branched into two by an optical coupler 12, the respective outputs are measured directly by the two meters 13, 14 to determine the branching ratio of the coupler 12. An optical circuit part 18 to be measured is arranged in one circuit, and the outputs of both the circuits are measured by the meters 13, 14, respectively. The insertion loss of the part 18 is determined from the result. Thus, it is not necessary to perform the reference measurement many times, a constant branching ratio can be regularly kept, and the insertion loss can be measured with high precision even when a degree of polarization is generated in the output light of the part 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring an insertion loss, which is one of the optical characteristics of optical circuit components such as an optical coupler and an optical star coupler used in an optical communication system.

[0002]

2. Description of the Related Art An optical subscriber system in which not only a trunk line but also each subscriber line is constructed by an optical fiber and all information communication is performed by light is being put to practical use. In this optical subscriber system, optical circuit components such as an optical coupler and an optical star coupler for splitting and combining optical information are used. These optical circuit components are required to have excellent optical characteristics such as insertion loss, polarization characteristics, wavelength characteristics, and reflection characteristics. Therefore, inspection of its optical properties,
For example, the establishment of inspection technology to measure the insertion loss of optical circuit components with high accuracy and at high speed to satisfy specified conditions has been increasing.
It is strongly desired not only in the development department but also in the production line.

Conventionally, a cutback method has been used as a method for measuring the insertion loss of an optical circuit component. In this method, the input optical fiber of the optical circuit component and the output optical fiber are connected in advance to monitor the power of the light source, and then the light is input to the optical circuit component and the output thereof is measured to thereby reduce the insertion loss of the optical circuit component. Ask for. FIG. 11 shows a configuration of an apparatus for implementing the above-described conventional technology. Before measuring the insertion loss of the optical circuit component, first, a reference measurement as shown in FIG. 11A is performed.

In reference measurement, output light from a light source 1 is sent to an optical power meter 3 via an optical fiber 2. The optical power Pa measured by the optical power meter 3 at this time is stored as a reference value in the insertion loss measurement. Subsequent to the reference measurement, the optical circuit component 18 is disposed between the optical fibers 2 as shown in FIG. Light source 1
Is output to the optical circuit component 18, and the output power Pb is received by the optical power meter 3. At this time, the optical power Pb is stored as a measured value of the optical circuit component 18.

After measuring the reference value Pa and the measured value Pb of the optical circuit component 18 from the above two steps, the insertion loss of the optical circuit component 18 is obtained based on the ratio Pb / Pa of the two measured values. Specifically, the insertion loss of the optical circuit component 18 is changed to Loss.
Then, Loss = −10 × log (Pb / Pa) is calculated. By the way, high measurement accuracy is required for the insertion loss measurement of the optical circuit component 18. Specifically, ±
A technology that guarantees a value of about 0.05 dB is required. This means that it is necessary to realize a measurement having a measurement error of about ± 1.0% or less.

However, it is very difficult to realize an insertion loss measurement system having a measurement error of ± 1.0% in the above conventional measurement technique. First, it is necessary to constantly grasp the temporal output power fluctuation of the light source 1 to be used, and it is necessary to frequently update the reference value. This is because the output power of the light source 1 is constantly changing, and the change directly leads to a measurement error as it is. In order to prevent the output power of the optical circuit component 18, which is the sample to be measured, from fluctuating in the polarization state of the light propagating in the optical fiber 2, care must be taken when handling the optical fiber 2 such as fixing the optical fiber 2. I had to pay. This is because, since the insertion loss of the optical circuit component 18 has a considerable polarization dependence, the output power of the optical circuit component 18 varies depending on the polarization state of the light input to the optical circuit component 18. Furthermore, since the optical power meter 3 as the light detecting means also has a considerable polarization dependency, the measured value varies depending on the polarization state of the light input to the optical power meter 3.

[0007]

As described above,
With the conventional measurement technique, it is very difficult to measure the insertion loss of the optical circuit component 18 to be measured with a measurement accuracy of ± 1.0% or less. As described further, the conventional measuring method has the following problems.

(1) It is very difficult to control the fluctuation of the output power of the light source 1 used to ± 1.0% or less. In the conventional measurement technique, the output power fluctuation of the light source 1 is directly reflected on the measurement value observed by the optical power meter. Therefore, conventionally, in order to control the measurement error caused by the output power fluctuation of the light source 1 to ± 1.0% or less, the measurement accuracy is maintained by performing the reference measurement frequently. However, this means of repeatedly performing the reference measurement not only greatly limits the processing capability but also has a problem that it is impossible to confirm whether or not the measurement accuracy ± 1.0% can be maintained.

(2) The output light of the light source 1 used has a certain degree of polarization component. The ratio of this polarized light power to the total output power is commonly called the degree of polarization. The output light of a high-brightness LED (i.e., SLD; hereinafter simply referred to as SLD), which is the light source 1 commonly used for measuring the insertion loss of the optical circuit component 18, is usually 20% to 40%.
% Of the polarization component is present. When this polarized light component propagates through the optical fiber 2, its polarization state changes easily under various environmental conditions such as temperature and optical fiber shape, so that the input to the optical circuit component 18 to be measured is input. It is impossible to control the polarization state of light. Regardless of the magnitude, the insertion loss of the optical circuit component 18 to be measured always has polarization dependence. The polarization dependence of the insertion loss is called polarization dependent loss (PDL). Therefore, when the insertion loss of an optical circuit component is measured using an SLD light source having a degree of polarization of several tens of percent, the measured value fluctuates due to the degree of polarization of the light source 1.

FIG. 12 shows an optical circuit component 1 having a different polarization dependent loss (PDL) when an SLD light source having a polarization degree of 30% is used as the light source 1 in the measuring apparatus shown in FIG.
8 is a result obtained by measuring the insertion loss twice each time, and summarizing the relationship between the measured value fluctuation and the polarization dependent loss (PDL) of the optical circuit component 18. The solid line in FIG. 12 indicates that the degree of polarization of the light source 1 is 3
It is the theoretical straight line of the maximum measured value variation that can occur at 0%. It can be seen from FIG. 12 that as the polarization-dependent loss (PDL) of the optical circuit component 18 increases, the measured value variation (vertical axis) of the insertion loss also increases. Thus, when the light source 1 has a degree of polarization of several tens% or more, it is very difficult to achieve a measurement accuracy of ± 0.05 dB or less in measurement value variation of about ± 1.0%. You can see that there is.

(3) Normally, the optical power meter 3 used for the light detecting means also has some polarization dependence. In the standard, there is a polarization dependence of about several percent. Although the development of the optical power meter 3 having low polarization sensitivity by various means has been advanced, the current situation is that the polarization sensitivity has not been completely reduced to 0 dB. Since the polarization-dependent loss exists in the optical circuit component 18 to be measured, the polarization state of the light input to the optical power meter 3 cannot be predicted. Therefore, it is indispensable to use the optical power meter 3 that can accurately measure the optical power regardless of the polarization state of the light in order to improve the measurement accuracy of the insertion loss measurement.

The present invention solves the above-mentioned problems of the conventional measuring technique, and presents a time-varying light source, a degree of polarization of the light source, a polarization-dependent loss of an optical circuit component to be measured, and an optical power meter. It is an object of the present invention to provide a method and an apparatus capable of measuring an insertion loss of an optical circuit component with high accuracy without being affected by polarization sensitivity or the like.

[0013]

The present invention has the following means to solve the above problems.

According to a first aspect of the present invention, in the optical circuit component measuring method, the output of the non-polarized light source is branched into two by an optical branching unit, and one of the branched lights is passed through the optical circuit component to be measured. The optical output intensity is measured by the non-polarization sensitivity light detecting means, the other branched light is directly measured by the non-polarization sensitivity light detecting means, and the insertion loss of the optical circuit component is obtained from the measurement results of both. It is characterized by the following.

According to a second aspect of the present invention, there is provided an optical circuit component measuring apparatus, comprising: a non-polarized light source; and an output from the non-polarized light source.
A light branching means for branching, and one light output intensity which is branched by the light branching means and transmitted through the optical circuit component to be measured and the other light which is branched by the light branching means and does not transmit through the optical circuit component It is characterized by having non-polarization sensitivity light detecting means for measuring the output intensity.

According to a third aspect of the present invention, in the optical circuit component measuring apparatus, a combination of a high-intensity LED and an optical fiber type depolarizer is used as the non-polarized light source.

According to the method and apparatus for measuring an optical circuit component of the present invention, since a non-polarized light source that outputs unpolarized light having a very small degree of polarization and having all polarization components uniformly is used, It has become possible to always maintain the polarization state of light propagating in the fiber in a non-polarization state. As a result, stable measurement can be realized even under severe conditions where the external environment of the optical fiber is severe. Further, since the output light of the non-polarized light source is split into two by the light splitting means and one of the split lights is directly input to the light detection means without being input to the optical circuit component, the output power of the light source is provided. Can be constantly monitored.
As a result, even in an environment where the output power of the light source varies greatly, stable measurement can be realized by correcting the variation. Furthermore, since the non-polarization sensitivity light detection means that can always measure the optical power regardless of the polarization state of the input light is used as the light detection means, it can be measured even when measuring an optical circuit component having a large polarization dependent loss. Stable measurement with few errors can be realized.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in FIGS. FIG.
1 is a schematic configuration diagram of an apparatus for performing an insertion loss measuring method of the present invention. The output light from the non-polarized light source 11 is split into two by an optical coupler 12 as an optical splitter, and one of the split lights passes through an optical circuit component 18 to be measured, and the other splits the optical circuit component 18. Without passing through, each output light
An optical power meter 13, which is a non-polarization sensitivity light detecting means,
By measuring at 14, the insertion loss of the optical circuit component 18 is obtained. FIG. 1A is a schematic configuration diagram of an apparatus for explaining reference measurement performed before insertion loss measurement. First, the output from the non-polarized light source 11 is
, And the respective optical outputs are directly measured by two optical power meters 13 and 14 having no polarization sensitivity to obtain a branching ratio r = P1a / P2a of the optical coupler 12.

Since the branching ratio r of the optical coupler 12 has wavelength dependence, when using light sources having different wavelengths, it is necessary to determine the branching ratio of the plurality of light sources in advance. At this time, even if the output power of the non-polarized light source 11 varies with time, the branching ratio of the optical coupler 12 is constant, so that highly accurate reference measurement can be performed. Also,
The branching ratio of the optical coupler 12 also has polarization dependence.
The branching ratio varies in the polarization state of the light input to the optical coupler 12. Therefore, when only a specific polarization component is present in the light input to the optical coupler 12, the measured value becomes unstable unless the polarization state is stably maintained, and stable reference measurement cannot be realized. However, in the present invention, since the non-polarized light source 11 is used as the light source, the polarization state of the input light to the optical coupler 12 is non-polarized.
Is always kept constant, and a very stable reference measurement becomes possible.

FIG. 1B shows an arrangement in which an optical circuit component 18 to be measured is disposed in only one of two circuits connecting the optical coupler 12 and the optical power meters 13 and 14. FIG. 2 is a schematic configuration diagram of an apparatus for measuring insertion loss. The output light intensity P1b from the optical circuit component 18 and the light intensity P2b not passing through the optical circuit component 18 are measured by two non-polarization sensitivity optical power meters 13 and 14, respectively. From this result, the insertion loss L of the optical circuit component 18 to be measured is
oss can be obtained from Loss = −10 × log (P1b / (r × P2b)).

In the measuring method of the present invention, the output power fluctuation of the light source is constantly monitored using the optical coupler 12, so that
Even when an unstable light source is used, it is not necessary to perform reference measurement many times, and it is possible to measure insertion loss with high accuracy. Further, in the present invention, since the non-polarized light source 11 which outputs unpolarized light having a very low degree of polarization including all polarization states uniformly is used as the light source, the optical coupler
Even if the branching ratio has polarization dependence, a constant branching ratio can be always maintained, and highly accurate measurement can be realized.

Furthermore, since the optical power meters 13 and 14 having no polarization sensitivity whose measured value does not depend at all on the polarization state of the input light are used as the light detecting means, the optical circuit component 18 to be measured is used. Even when a large polarization dependence (polarization-dependent loss) exists in the insertion loss and a degree of polarization occurs in the output light of the optical circuit component 18, the insertion loss can be measured with high accuracy.

(Embodiment 1) A first embodiment of a method and apparatus for measuring an optical circuit component according to the present invention will be described more specifically with reference to FIG. As shown in FIG. 1, a non-polarized light source 11, an optical coupler 12, and two optical power meters 1
3, 14 and the optical circuit component 18 are all optical fibers 15
Connected by As shown in FIG. 2, the non-polarized light source 11 is a high-brightness LED 1 having a polarization degree of 30% and a wavelength of 1.31 μm.
1A and an optical fiber type depolarizer 11B. Generally, light output from an SLD has a degree of polarization of 20% to 40%. This polarization component easily changes into various polarization states depending on the environment and conditions of the measurement system when propagating through the optical fiber, and thus has become one of the factors that deteriorate the measurement accuracy in the insertion loss measurement.

The depolarizer is a polarization conversion element for equally dividing a polarization component of a light wave into an S-polarization component and a P-polarization component that do not interfere with each other, and turning the light wave into a non-polarization state. In other words, the depolarizer can reduce the degree of polarization of the incoming light wave. The optical fiber type depolarizer 11B has a length ratio L1: L2 = 1: 1, as shown in FIG.
The two polarization maintaining fibers 11B1 and 11B2 are connected such that their main axes are inclined at 45 ° to each other. The minimum length L1 of the polarization maintaining fiber required to completely eliminate the polarization component of the output light of the light source from the light source is determined by the coherence length Lc of the output light of the light source and the birefringence B of the polarization maintaining fiber. It is limited by the relational expression of L1> Lc / B.

Generally, the birefringence B of the polarization maintaining fiber is about 0.0004. Therefore, if the coherence length Lc of the SLD light source 11A having a wavelength of 1.31 μm used in the present embodiment is assumed to be 100 μm, for example, the fiber length L necessary to constitute the optical fiber type depolarizer 11B is set.
1 means about 250 mm. Actually, an optical fiber type depolarizer with L1 = 1 m and L2 = 2 m was used with a margin for the optical fiber length. This depolarizer 11B can handle light sources with a coherence length Lc of about 400 μm. When the depolarizer 11B is used, the 1.31 μm SLD light source 11A can make the output light completely non-polarized, so that the non-polarized light is input to the optical circuit component 18 to be measured. be able to.

The output light from the non-polarized light source 11 is divided by a branching ratio r =
The output light power of the light source 11 can be constantly monitored by directly measuring the output light power of the light source 11 without passing through the optical circuit component 18 on one side by splitting into two at the 50:50 optical coupler 12. Since the measured value can be corrected by the power fluctuation, even when an unstable light source is used in which the temporal power fluctuation of the light source 11 exceeds the measurement accuracy ± 0.05 dB to be achieved, the power fluctuation can be ignored. High insertion loss measurement can be realized. Further, the optical power meters 13 and 14 having no polarization sensitivity can be obtained by disposing an optical fiber type depolarizer 13B (14B) immediately before the light detection portion of the normal optical power meter 13A (14A) as shown in FIG. Make up.

Even if non-polarized light is used as the input light of the optical circuit component 18 to be measured, if the insertion loss itself of the optical circuit component 18 has polarization dependence, the output light of the optical circuit component 18 Then, a degree of polarization corresponding to the polarization dependent loss (PDL) of the optical circuit component 18 is generated. Since this corresponds to the polarization of the input light to the optical power meter, the measurement accuracy is deteriorated unless the polarization sensitivity of the optical power meter is zero. Therefore, in order to improve the accuracy of the insertion loss measurement of the optical circuit component, the polarization state of the light input to the optical power meter is set to non-polarization, or the polarization sensitivity of the light receiving unit of the optical power meter is set to 0. It is necessary to devise.

In this embodiment, the optical fiber type depolarizers 13B and 14B (L1 = 1m, L2 = 2m) having the same structure as the optical fiber type depolarizer 11B composed of the two polarization maintaining fibers 11B1 and 11B2 shown in FIG. ) Is arranged in front of each of the optical power meters 13A and 14A to make the polarization state of the input light of the optical power meters 13A and 14A non-polarized. The degree of polarization of the output light of the optical circuit component 18 depends on the polarization-dependent loss of the optical circuit component 18. For example,
When non-polarized light is input to the optical circuit component 18 where the polarization dependent loss is 1 dB, the degree of polarization of the output light from the optical circuit component 18 is about 15%. If the polarization dependent loss is large, the degree of polarization of the output light tends to be large. However, in the measuring method according to the present embodiment, since light having a coherence length of 0 μm is used as input light to the optical circuit component 18, the coherence length of the output light of the optical circuit component 18 is naturally zero.
μm.

Therefore, the length L1 of the polarization maintaining fiber required to bring the output light from the optical circuit component 18 into the non-polarization state is as follows.
0 m. That is, in order to make the degree of polarization of the output light from the optical circuit component 18 zero, a depolarizer in which two polarization maintaining fibers of an arbitrary length are simply connected by being inclined at 45 ° may be used. According to this embodiment,
Optical circuit components 18 having different polarization dependent losses (sample number N
= 36) was measured. In this measurement, the insertion loss of the optical circuit component 18 is measured twice each, and the fluctuation of the measured value is used as the polarization-dependent loss (PD) of the optical circuit component 18.
FIG. 5 shows the results summarized on the basis of L).

The solid line is the theoretical straight line of the maximum variation that the 30% effect of the light source can have on the measurement variation. From FIG.
Irrespective of the magnitude of the polarization-dependent loss of the optical circuit component 18 to be measured and the degree of polarization existing in the output light of the light source, the measurement reproducibility of ± 0.05 dB to be achieved is obtained. I understand. Comparing the same measurement with the result obtained by the conventional cutback method (FIG. 12), it can be seen that the measurement accuracy is dramatically improved by using the measurement method of the present invention.

(Embodiment 2) In Embodiment 1 described above, an example is described in which one SLD light source is used as a non-polarization light source. However, in the present invention, the number of light sources is one and the type is SLD light source. However, the number and type of light sources can be appropriately adopted. FIG. 6 is a diagram for explaining another embodiment of the present invention. The feature of the present embodiment is that four types of light sources 21A, 21B, 21C, and 21D are used for the insertion loss of the optical circuit component 18 to be measured. The light source 21A is an SLD having a wavelength of 1.31 μm,
B is an SLD having a wavelength of 1.55 μm, and the light source 21C is a SLD having a wavelength of 1.5 μm.
31 μm LD, light source 21D is 1.55 μm wavelength LD
It is.

Each of the light sources 21A, 21B, 21C,
In order to make the output light from 21D non-polarized, the same depolarizer 11B as in Embodiment 1 corresponding to the coherence length of the output light is used in Embodiment 1.
Is the same as Each light source 21A, 21B, 21
All the output lights from C and 21D are input to the optical switch 22 having a 4 × 1 structure. Output light from the optical switch 22 is input to the optical coupler 12. Switching of the light source is performed by an optical switch 22 which is a core line switching unit.

According to the present embodiment, four types of light sources 21
The insertion loss of the optical circuit component 18 with respect to A, 21B, 21C, and 21D can be obtained. In the reference measurement performed before the measurement, four types of light sources 21A and 21A are used.
The measurement of the reference values for B, 21C and 21D is the same as in the first embodiment. In the present embodiment, the same components as those in the first embodiment are described in the first embodiment.
The same reference numerals are given and detailed description is omitted.

(Embodiment 3) In Embodiment 2 described above, a plurality of light sources are switched by using the optical switch 22, but as shown in FIG. Thus, multiple light sources can be used. In FIG. 7, the light source 31A has a wavelength of 1.31 μm S
The LD and the light source 31B are SLDs having a wavelength of 1.55 μm.
In order to make the output light from each of the light sources 31A and 31B into a non-polarized state, the same depolarizer 11B as in the first embodiment corresponding to the coherence length of the output light is used as in the first embodiment. is there.

The switching of the measurement wavelength is performed by the light sources 31A and 31A.
This is done directly by turning on / off the output of B. In general, the power fluctuation is extremely unstable immediately after turning on the power of the normal light source.
Since the output power of 1A and 31B is monitored, the light source 3
High-accuracy measurement is possible without being affected by output power fluctuations of 1A and 31B. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the detailed description is omitted.

(Embodiment 4) In Embodiment 1 described above, the splitting ratio of the optical coupler 12 for splitting the output light of the non-polarization light source 11 into two is, for example, 5 when the wavelength is 1.31 μm.
The thing of 0:50 was adopted. However, since the branching ratio of the optical coupler has wavelength dependence, the branching ratio of the optical coupler used in the present invention is not limited to 50:50. According to the insertion loss measurement of the present invention, the branching ratio of the optical coupler with respect to the measurement wavelength is obtained in advance by performing the reference measurement in advance, so that even if the branching ratio of the optical coupler has wavelength dependency, the measurement accuracy is high. There is no need to worry about deteriorating.

(Embodiment 5) In Embodiment 1 described above, in order to reduce the polarization sensitivity of the optical power meter 13A (14A), the optical fiber type depolarizer 13B (14
B) was disposed immediately before the light receiving portion of the optical power meter 13A (14A), and the polarization state of the input light to the optical power meter 13A (14A) was changed to a non-polarization state. However, when the coherence length of the output light of the light source used is 0 μm, the coherence length of the output light of the optical circuit component to be measured is always 0 μm.
m, the above depolarizer 13B (14
The purpose of B) is simply to make the degree of polarization of light 0%. As a method for achieving this object, the method shown in FIG. 8 is also possible.

In the method shown in FIG. 8, the polarized output light from the optical circuit component 18 to be measured is transmitted to the optical power meter 13.
Before the light is received at A, it is forced to be in a non-polarized state by transmitting through a ground glass 51 as a scatterer. In FIG. 8, reference numeral 52 denotes an optical fiber collimator. By transmitting the ground glass 51, the degree of polarization of the light input to the optical power meter 13A is always 0% regardless of the magnitude of the polarization-dependent loss of the optical circuit component. Can be realized. In the present embodiment, the ground glass is used as the light polarization conversion element. However, this is merely an example and the light is scattered, and if the insertion loss of itself is small, it is limited to the ground glass. Others can be used instead.

(Embodiment 6) As a method of relaxing the polarization sensitivity of the optical power meter as the light detecting means, an embodiment as shown in FIG. 9 can be adopted. Means for rotating the polarizer 61 by 360 ° at a constant speed, for example, a motor 62 and its controller 63 are disposed between the optical circuit component 18 and the optical power meter 13A. Polarizer 6 rotating at constant speed
1, the output light from the optical circuit component 18 is transmitted, and the output light power is measured using the optical power meter 13A at an average time lower than the rotation speed.

The feature of this embodiment resides in that the polarization state of the output light from the rotator changes to all linearly polarized lights at a constant speed by the rotating polarizer 61. When measuring the output power changed to linearly polarized light, if the power measurement is performed at an average time that is slower than the speed of the rotating polarizer 61, the power of substantially all linearly polarized states is measured within the average time. Therefore, even when the output light of the optical circuit component 18 is polarized, the power can be stably measured. The rotation of the polarizer 61 can be performed manually, but it is preferable that the rotation be automated in order to set the average time of the optical power meter 13A. The purpose of the polarizer 61 used in the present embodiment is to convert the polarization state of the output light from the optical circuit component 18, that is, to serve as a polarization state conversion element. Paying attention to the fact that the polarization state of the transmitted light of the polarizer 61 changes depending on the rotation angle of the polarizer 61, a λ / 2 wavelength plate, a λ / 4 wavelength plate, or the like may be used instead of the polarizer 61. Can be used.

(Embodiment 7) In Embodiment 1 described above, two optical power meters 13 and 14 having polarization-free sensitivity are used.
Is used to configure the measurement system, but it is also possible to configure the measurement system with one optical power meter 13 by using a core wire switching means such as the optical switch 71 as shown in FIG. The output light of the optical circuit component 18 to be measured and the output light of the optical coupler 12 that does not pass through the optical circuit component 18 are input to an optical switch 71 having a 2 × 1 structure.
Is input to one non-polarization sensitivity optical power meter 13. According to the present embodiment, by appropriately selecting the input port of the optical switch 71, one optical power meter 13
And realizes highly accurate insertion loss measurement.

[0042]

As described above, according to the optical circuit component measuring method and the measuring apparatus of the present invention, a non-polarized light which outputs non-polarized light having a very small degree of polarization and having all polarized components uniformly is output. Since the light source is used, the polarization state of light propagating in the optical fiber can be always maintained in the non-polarization state. As a result, stable measurement can be realized even under severe conditions where the external environment of the optical fiber is severe.

Further, the output light of the non-polarized light source is split into two by the light splitting means, and the means for directly inputting one of the split lights to the light detecting means without inputting to the optical circuit component is provided. Output power fluctuations can be constantly monitored. As a result, even in an environment where the output power of the light source varies greatly, stable measurement can be realized by correcting the variation.
Furthermore, since the non-polarization sensitivity light detection means that can always measure the optical power regardless of the polarization state of the input light is used as the light detection means, it can be measured even when measuring an optical circuit component having a large polarization dependent loss. Stable measurement with few errors can be realized.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic structural views of an apparatus for explaining an embodiment of a method for measuring an optical circuit component according to the present invention.

FIG. 2 is a schematic configuration diagram of a non-polarized light source used in the optical circuit component measuring method of FIG.

FIG. 3 is an explanatory diagram of a depolarizer used in the method for measuring the optical circuit component of FIG. 1;

FIG. 4 is a schematic configuration diagram of a non-polarization sensitivity optical power meter used in the method for measuring the optical circuit component of FIG. 1;

FIG. 5 shows a measured value variation when the insertion loss of optical circuit components having different polarization-dependent losses is measured twice each using an SLD light source having a polarization degree of 30% in the first embodiment of the present invention.
FIG. 10 is an explanatory diagram of a result obtained based on polarization dependent loss of an optical circuit component.

FIG. 6 is a schematic configuration diagram of an apparatus for explaining another embodiment of the optical circuit component measuring method of the present invention.

FIG. 7 is a schematic configuration diagram of an apparatus for explaining another embodiment of the optical circuit component measuring method of the present invention.

FIG. 8 is a schematic configuration diagram of an apparatus for explaining another embodiment of the optical circuit component measuring method according to the present invention.

FIG. 9 is a schematic configuration diagram of an apparatus for explaining another embodiment of the optical circuit component measuring method of the present invention.

FIG. 10 is a schematic configuration diagram of an apparatus for explaining another embodiment of the optical circuit component measuring method of the present invention.

FIG. 11 is a schematic configuration diagram of an apparatus for explaining an example of a conventional method for measuring an optical circuit component.

FIG. 12 is a graph showing the dependence of the variation in the measured value when the insertion loss of an optical circuit component is measured twice using an SLD light source having a polarization degree of 30% in the cutback method, which is a conventional measurement method, depending on the polarization of the optical circuit component. It is an explanatory view of the result summarized on the basis of sex loss.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Non-polarization light source 11A SLD light source 11B Optical fiber type depolarizer 12 Optical coupler 13, 14 Non-polarization sensitivity optical power meter 13A, 14A Normal optical power meter 13B, 14B Optical fiber type depolarizer 18 Optical circuit parts

Claims (3)

[Claims] An output of a non-polarization light source is split into two by an optical splitter, and one of the split lights is passed through an optical circuit component to be measured, and the light output intensity is measured by a non-polarization sensitivity light detector. And measuring the other split light directly by the non-polarization sensitivity light detecting means, and obtaining the insertion loss of the optical circuit component from the measurement results of both. 2. An unpolarized light source, an optical branching unit for splitting an output from the non-polarized light source into two, and an optical output intensity of one of the two branched by the optical branching unit and transmitted through an optical circuit component to be measured. And a non-polarization sensitivity light detecting means for measuring the other light output intensity which is branched by the light branching means and does not pass through the optical circuit component. 3. The optical circuit component measuring apparatus according to claim 2, wherein a combination of a high-brightness LED and an optical fiber type depolarizer is used as the non-polarized light source.