JP3392966B2 - Optical component characteristic measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring characteristics of optical components connected to an external optical processing system via an optical fiber. 2. Description of the Related Art Various optical components used in optical communication and the like, especially components arranged in optical fibers such as optical isolators and optical circulators, have the characteristics of the components themselves, of course.
It is necessary to inspect how much the forward and reverse insertion loss, polarization dependence, return loss and the like in the fiber are exhibited. That is, whether or not a certain optical characteristic can be maintained even if the polarization state of light propagating in an optical fiber is disordered, and whether or not the amount of light reflected from the interface of the optical component returns. Needs to be identified. Conventionally, individual test circuits have been used to measure the characteristics of the above-described optical components, and at least for each of forward and reverse insertion loss, forward and reverse return loss, and polarization dependence. Inspection is being carried out. In addition, before mounting optical components on the inspection circuit, measure the inspection circuit itself for each inspection item, and then attach the optical components individually to each inspection item by fiber fusion and attach them to the inspection circuit for measurement. Is being done. [0004] Normally, fiber fusion requires about 10 minutes, and a long setup time is required if fiber fusion for each inspection item described above is included. In addition, measurement data becomes uncertain due to the incorporation of uncertainties as the fiber fusion is repeatedly performed. SUMMARY OF THE INVENTION According to the present invention, at least forward insertion loss, backward insertion loss, forward return loss, reverse return loss, and polarization dependence among the inspection items for optical components. It is an object of the present invention to provide a device for measuring the characteristics of an optical component capable of measuring the optical component accurately and extremely efficiently. An optical component characteristic measuring apparatus according to the present invention comprises an inspection circuit for measuring an optical component characteristic by assembling an optical component to be measured by fusion splicing of a fiber. An optical switch for switching the waveguide between the forward direction and the reverse direction is provided at the incident end of the light emitting source.A polarization controller is disposed in the forward waveguide, and the waveguide following the polarization controller is connected to the optical switch. Branched in three directions with couplers, one of which is the fiber end joining one terminal of the optical component under test, and the other two are an optical power meter for measuring the forward return loss and reverse insertion loss. An optical power meter for measuring the light source reference light intensity is connected. A directional optical circulator is disposed in the waveguide in the opposite direction, and a waveguide extending from one terminal of the directional optical circulator is an optical component to be measured. Fiber to splice other terminals The other terminals are equipped with optical power meters for measuring insertion loss, reverse return loss, and polarization dependence. Further, each of the forward and reverse waveguides has a fiber for joining an optical component to be measured. Equipped with a chuck that bends the end, and among the inspection items for optical components, at least forward insertion loss, reverse insertion loss, forward return loss, reverse return loss,
The polarization dependence is measured separately in the forward and reverse directions before and after the assembly of the optical component to be measured, and the measured data before the assembly of the optical component to be measured is used as the reference light intensity, and the two measured data are compared. Then, based on the difference between the two, the optical component to be measured is bonded once by fiber fusion, so that it is configured as an inspection circuit for measuring the characteristics of the optical component itself. The optical component characteristic measuring device according to the present invention has a circuit configuration capable of measuring the characteristics of the optical component by performing only one fiber fusion to the fiber end of the inspection circuit. Can be embodied. This makes it possible to measure at least the forward insertion loss, the backward insertion loss, the forward return loss, the backward return loss, and the polarization dependence among the inspection items of the optical component, so that the characteristics of the optical component can be efficiently performed. The measurement can be performed without introducing uncertain elements, and the measured data of each inspection item can be divided into forward and reverse directions. Can be measured accurately. Referring to the accompanying drawings, FIG. 1 shows an apparatus for measuring characteristics of an optical component according to the present invention. In the figure, a solid line connecting each device indicates an optical circuit system, and a dotted line indicates an electric circuit system. The inspection circuit is a light source 1
And the characteristics of the optical component are measured by conducting light incident from the light emitting source 1 to an optical component to be measured such as an optical isolator or an optical circulator that is fusion-bonded to the fiber ends in the forward and reverse directions. It is configured as an optical inspection circuit. The inspection items include at least forward insertion loss, backward insertion loss, forward return loss, reverse return loss, and polarization dependence among the characteristics of the optical components. The inspection circuit includes an optical switch 2 and a light emitting source 1.
The waveguide is configured to be switchable between a forward direction and a reverse direction by arranging the waveguide at the incident end. In the forward direction of the waveguide, a polarization controller 3 for controlling the polarization of light by winding the fiber in a coil shape and rotating the fiber by predetermined steps is provided. The waveguide following the polarization controller 3 is branched and connected in three directions by an optical coupler 4. One of the three directions is led out as a fiber end f ₁ for connecting one terminal of the optical component to be measured. The other two are provided with an optical power meter 5 for measuring forward return loss and reverse insertion loss, and an optical power meter 6 for measuring light source reference light intensity. In addition,
Isolators 7 and 8 for preventing return reflection of light are provided between the light emitting source 1 and the optical switch 2, between the polarization controller 3 and the optical coupler 4, and between the optical coupler 4 and each of the optical power meters 5 and 6. , 9,1
0 is assembled. A directional light circulator 11, such as a three-terminal circulator, is disposed in the waveguide in the opposite direction. From this direction optical circulator 11, the fiber end f ₂ for bonding the other terminal of the measured optical component is derived as a subsequent waveguide than 1 terminal. Other terminals include an optical power meter 1 for measuring insertion loss, reverse return loss, and polarization dependence.
2 are provided. In addition to the above-described devices, chucks 13 and 14 for bending the fiber ends f ₁ and f ₂ for joining optical components to be measured are provided in each of the forward and backward waveguides. A jig 15 for inserting and supporting the optical component to be measured is provided between each of the fiber ends f ₁ and f ₂ .
Also, the jig 15 is provided with a semiconductor heating element 16 such as a Peltier or the like that can change the temperature conditions of the optical component to be measured and the waveguide. In the apparatus for measuring the characteristics of optical components having such a circuit configuration, the characteristics of the optical components can be measured by menu operation by the computer 17 or continuously and fully automatically. The measurement data can be in a readable format and recorded on a floppy disk. In addition, wavelengths 1470 to 15
The characteristics of the optical component to be measured may be measured under a variable temperature condition of about −20 ° C. to 80 ° C. by using a variable laser of about 90 mm. By measuring each inspection item in accordance with the variable conditions, a large number of measurement data can be obtained on the characteristics of the optical component in a wide range of wavelengths generally used and in different use environments. In this optical component characteristic measuring apparatus, before assembling the optical component to be measured, each inspection item is individually measured in the forward and reverse directions for the inspection circuit itself, and then the optical component to be measured is assembled in the inspection circuit. Measurement of each test item separately in the forward and reverse directions. The measured data obtained from the test circuit itself is used as the reference light intensity, and the measured data is compared. If the difference between the two is determined, the optical component to be measured is assembled into the circuit by a single fiber fusion. It can measure its own characteristics. First, each test item is measured for the test circuit itself without assembling the optical component to be measured. The entire system is started up, and the optical switch 2 is set to the forward direction as shown in FIG. In the forward direction, light of the designated wavelength is incident from the light emitting source 1, the reference power for return loss in the forward direction is measured by the optical power meter 5, and RLI1w is performed. Next, as shown in FIG. 3, the fiber end f ₁ in the forward direction is bent by the chuck 13, the amount of reflected return light from the end face of the fiber end f ₁ is reduced to zero, and input to the optical power meter 5. Is measured as RLI2w. Thereafter, as shown in FIG. 4, the optical switch 2 is switched in the reverse direction, light of the designated wavelength is incident from the light emitting source 1, the return power reference power in the reverse direction is measured by the optical power meter 12, and the RLO 1w is measured. And Also, as shown in FIG. 5, the fiber end f ₂ is bent by the chuck 14, and the amount of reflected return light from the end face of the fiber end f ₂ is set to zero, so that the amount of parasitic return light in the reverse direction is measured by the optical power meter 12. , RLO2w. Until now, the respective fiber ends f ₁ and f ₂ were kept in a disconnected state. Next, the respective fiber ends f ₁ and f ₂ are connected to measure the parasitic loss and the polarization dependence of the inspection circuit itself. I do. In this measurement, the optical switch 2 is switched in the forward direction as shown in FIG. 6, or the optical switch 2 is maintained in the reverse direction following the previous process as shown in FIG. The measurement may be performed first. In the forward direction, the polarization controller 3 and the semiconductor heating element 16 are operated as shown in FIG. The upper and lower limits of the dependence amount are measured by the optical power meter 12, and the parasitic loss is also measured. Further, as shown in FIG. 7, the parasitic loss in the reverse direction was measured by the optical power meter 5, and
Rwt. The polarization dependence of the inspection circuit itself (PDLR)
(wt) can be obtained from the light source reference light intensity (OPM2wti) obtained by the optical power meter 6 and the measurement value (OPM3wti) obtained by the optical power meter 12 using the following equation (1). Here, i indicates a position number in the Poincare sphere, and specifically, the λ / 2 phase difference element in the polarization controller 3 and the λ / 2
The numbers corresponding to the respective rotation angles of the / 4 phase difference element are shown. MAX and MIN indicate the maximum power value and the minimum power value of the OPM3wti, respectively. [Formula 1] PDLRwt = −10 * log (OPM3wt
MAX / (OPM2wti + OPM3wti))-(-
10 * log (OPM3wtMIN / (OPM2wti
+ OPM3wti))) Also, the forward parasitic loss (ILRwt (d
B)) is a value measured by the optical power meter 12 (OPM3).
wti) is obtained by the following equation (2). ## EQU2 ## ILRwt = −10 * log (OPM3wtM
AX / (OPM2wti + OPM3wti)) Until now, each test item was measured for the test circuit itself. From now on, as shown in FIGS. 8 and 9, the optical component D to be measured is connected to each fiber end f ₁ , f Each of the inspection items is measured by bonding to the fiber ₂ by fiber fusion. At this time, light of the designated wavelength is incident from the light emitting source 1 and the semiconductor heating element 16 is operated to perform measurement in the forward direction and the reverse direction under variable temperature conditions. First, as shown in FIG. 8, the optical switch 2 is set in the forward direction, and the polarization dependency (PDLwt) in the forward direction is measured. Since the polarization dependence is compared with the above-described polarization dependence (PDLRwt) of the inspection circuit itself, the polarization dependence is obtained as that of the optical component itself by the following Expression 3. Formula 3 PDLwt (dB) = − 10 * log (OPM
3wtMAX / (OPM2wti + OPM3wti))
− (− 10 * log (OPM3wtMIN / (OPM2
wti + OPM3wti)))-PDLRwt Also, the forward polarization dependence (PDLwt)
The loss in the forward direction (ILwt) is compared with the parasitic loss (ILRwt) of the detection circuit itself based on the above measurement data, and can be obtained from the following Expression 4. [Formula 4] ILwt (dB) = − 10 * log (OPM3
wtMAX / (OPM2wti + OPM3wti))-
ILRwt Next, the forward return loss (RLIw
(DB)) is the reference power for return loss in the forward direction (RLI1w) by the optical power meter 5, and the forward parasitic return light amount (RLI2) by the optical power meter 5 of the detection circuit itself.
w) and is calculated by the following equation 5. [Formula 5] RLIw (dB) = − 10 * log (KR (O
PM1w-RLI2w) / (RLI1w-RLI2
w)) where KR is the reflection coefficient of light from the interface between the core (quartz) and the air medium at the cut portion of the optical fiber, and is assumed to be 0.03336. This reflection coefficient (KR) is
Refractive index of quartz 1.4469 (n1), refractive index of air 1
It is obtained by the following Expression 6 based on (n2). Note that OP
M1w is a value measured by the optical power meter 5. KR = ((n ₁ −n ₂ ) / (n ₁ + n ₂ )) ² This time, the optical switch 2 is switched in the reverse direction.
The reverse loss (ISwt) is determined by the reverse parasitic loss (ISRwt) of the detection circuit itself and the above-described forward loss (ILw).
From t), it is obtained by the following equation 7. In addition, OPM1wt
Is a measured value of the optical power meter 5. ## EQU7 ## ISwt (dB) = − 10 * log (OPM1
wt / ISRwt) -ILwt Also, the return loss in the reverse direction (RLOw)
(DB)) is measured. This return loss is compared with the amount of parasitic return light (RLO2w) in the reverse direction of the detection circuit itself,
It is obtained by the following equation (8). However, KR is set to 0.03336. The OPM 3w is a value measured by the optical power meter 12. [Formula 8] RLow (dB) = − 10 * log (KR (O
PM3w-RLO2w) / (RLO1w-RLO2
w)) By measuring the characteristics of the optical component in this way, it is only necessary to bond the optical component once to the inspection circuit by fiber fusion, so that uncertain elements can be prevented from being mixed. In addition, by simply switching the optical switch, the insertion loss in the forward direction, the insertion loss in the reverse direction,
Efficient measurement of forward return loss, reverse return loss, and polarization dependence. As described above, according to the optical component characteristic measuring apparatus according to the present invention, the measurement of each inspection item can be performed only by bonding the optical component once in the inspection circuit by fiber fusion. Since the operation can be performed, work efficiency can be improved, and uncertain elements can be prevented from being mixed in the measurement data, so that the characteristics of the optical component itself can be accurately measured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an apparatus for measuring characteristics of an optical component according to the present invention. FIG. 2 is an operation circuit diagram for measuring the forward return loss reference power of the inspection circuit itself in the same device. FIG. 3 is an operation circuit diagram for measuring the amount of forward parasitic return light of the inspection circuit itself in the same device. FIG. 4 is an operation circuit diagram for measuring the return power reference power in the reverse direction of the test circuit in the device. FIG. 5 is an operation circuit diagram for measuring the amount of parasitic return light of the inspection circuit itself in the reverse direction in the same device. FIG. 6 is an operation circuit diagram for measuring the forward polarization dependence of the inspection circuit itself and the parasitic loss in the same device. FIG. 7 is an operation circuit diagram for measuring a reverse parasitic loss of the inspection circuit itself in the same device. FIG. 8 is an operation circuit diagram for measuring the polarization dependence and the return loss in the forward direction when the optical components are assembled in the same device. FIG. 9 is an explanatory diagram of the operation of measuring the parasitic loss in the reverse direction in the state where the optical components are assembled in the same device. [EXPLANATION OF SYMBOLS] 1 light source 2 optical switch 3 polarization controller 4 the optical coupler 5 and 6 an optical power meter 11 directional optical circulator 12 optical power meter 13 chuck _f 1, _{f 2} fiber ends D optics

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01M 11/00-11/08

Claims (1)

(57) [Claims 1] An inspection circuit for measuring characteristics of an optical component by assembling an optical component to be measured by fusion splicing of a fiber,
An optical switch for switching the waveguide between the forward direction and the reverse direction is provided at the incident end of the light emitting source, and a polarization controller is disposed in the forward waveguide, and the waveguide following the polarization controller is optically controlled. Branched in three directions with couplers, one of which is the fiber end joining one terminal of the optical component under test, and the other two are an optical power meter for measuring the forward return loss and reverse insertion loss. An optical power meter for measuring the light source reference light intensity is connected. A directional optical circulator is disposed in the waveguide in the opposite direction, and a waveguide extending from one terminal of the directional optical circulator is an optical component to be measured. The other end is a fiber end to be spliced. The other terminal is equipped with an optical power meter that measures insertion loss, reverse return loss, and polarization dependence. Further, each forward and reverse waveguide has Bend the fiber end for joining the optical component to be measured Comprising a chuck for at least a forward insertion loss of the test item of the optical component,
The reverse insertion loss, forward return loss, reverse return loss, and polarization dependence are measured separately in the forward and reverse directions before and after the optical component under test is assembled, and the optical component under test is measured. Inspection that measures the characteristics of the optical component itself by comparing the measured data before and after assembling with the measured data as the reference light intensity and joining the optical component to be measured once by fiber fusion based on the difference between the two. A device for measuring characteristics of an optical component, comprising a circuit.