JPS61219021A - Driving method for optical gate device - Google Patents

Abstract

PURPOSE:To obtain an attenuation ratio m/N based upon the fully open state of N gates of an optical gate array with high-accuracy by obtaining measured values of the quantity of transmitted light corresponding to plural combinations in which (m) out of the N gates are opened, and calculating the means value of plural measured values of the quantity of transmitted light. CONSTITUTION:The quantity of transmitted light when 100 gates are all opened is measured accurately by using a high-accuracy detector 10 and three gates, e.g. the 16th, the 50th, and 83th gates are opened for (t) seconds. Then the 17th, the 51th, and the 84th gates are opened for (t) seconds and thus gates which are opened are shifted in position to right so that the 1st gate is opened cyclically after the 100th gate. After the shift is made up to the 15th, the 49th, and the 82th gates, the gates are closed, the power of light transmitted through the optical gate array 3 within each period is detected by a photosensor 6 for light to be measured, and the mean value is calculated by a signal processing circuit 8. The mean value of the light power is accurately 3/100 as large as the light power when all the gates are opened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for driving an optical gate device that blocks light stepwise and is effective for use in optical power meters, optical power calibrators, etc. .

(Prior Art) Conventionally, in order to calibrate an optical sensor, a standard lamp is used as a light source, the amount of attenuation is varied by changing the distance between the light source and the optical sensor, and the amount of attenuation is determined from that distance. There is also a method of attenuating the amount of light using an aperture or a filter with a known amount of attenuation.

That is, a stable light source and a precise attenuator are required.

A method of directly measuring the power of light is to shine the light on an absorber, measure the temperature rise at that time, and then heat the absorber with a heater to measure the heater consumption required to cause the same temperature rise. There is a calorimetry method that calculates the power of light from electric power.

(Problems to be Solved by the Invention) However, the method using a standard lamp, diaphragm, and filter has a problem in that the operating speed is slow.

The calorimetry method has good accuracy, but the measurement range is 0.5m.
W or more, it is not possible to measure in the nW or μW range used in optical communications. Also, the sensitivity is insufficient and the response is slow.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method for driving an optical gate device that operates at high speed and achieves highly accurate attenuation.

(Means for Solving the Problems) The first invention of the method for driving an optical gate device according to the present invention is as follows:
In a method for driving an optical gate device that attenuates light from a light source at a predetermined attenuation ratio, measured values of the amount of transmitted light are obtained corresponding to a plurality of combinations of opening m gates of Ng gates in an optical gate array, and a plurality of transmitted light amount measurements are obtained. By calculating the average value of the transmitted light amount measurement values and using this as the transmitted light amount output of the optical gate device, an attenuation ratio m/N based on the case where N gates are fully opened is realized with high accuracy. It is characterized by

The second invention of the method for driving an optical gate device according to the present invention is as follows:
In a method of driving an optical gate device that attenuates light from a light source at a predetermined attenuation ratio, after determining the transmitted light amount measurement value when each of the N gates of the optical gate array is opened, a plurality of the transmitted light amount measurements are performed. By calculating the average value of the values and opening the gates in a combination such that the sum of the measured values of the amount of transmitted light is closest to m times the average value, the attenuation ratio is determined based on when N gates are fully opened. It is characterized by realizing m/N with high accuracy.

(Function) According to the configuration according to the first aspect of the present invention, by calculating the average value of a plurality of transmitted light amount measurements, unevenness in the intensity distribution of the light source and variations in the attenuation ratio between gates are averaged out. ,
The adverse effects these have on the accuracy of the attenuation ratio of the optical gate device can be reduced or eliminated.

Further, according to the configuration according to the second aspect of the present invention, by opening a plurality of gates in a specific combination, unevenness in the intensity distribution of the light source and variation in attenuation ratio between the gates are offset, and these are The negative effect on the accuracy of the damping ratio of the device can be reduced or eliminated.

(Example) The present invention will be explained in detail below using the drawings.

FIG. 1 is a configuration explanatory diagram showing an example of an optical gate device for realizing the method according to the present invention.

1 is a stabilized light source, 2 is a polarizer, 3 is a light gate array, 4
5 is an analyzer, 5 is a lens, 6 is an optical sensor to be calibrated, 7 is a measurement circuit, 8 is a signal processing circuit such as a CPU, 9 is a control device that controls the optical gate array 3, and 10 uses a calorimetry method, etc. A high-precision detector, 11 is a high-precision attenuator,
This is for measuring (calibrating) an optical power lower than that obtained by the attenuation ratio of the optical gate array 3.

FIG. 2 is a configuration explanatory diagram showing in detail an example of the configuration of the optical gate array 3, where 31 is a substrate made of an electro-optical element such as PLZT, and 32 is a flat or groove-shaped electrode provided on this substrate 31. , constitutes N gates.

A case in which the method for driving the device configured as described above is applied to an optical power calibrator will be described below.

Here, as an example, a case will be described in which the number N of gates is 100, and by opening (m-)3 of them, an optical output with an attenuation ratio of 3/100 is obtained.

(a) First, the amount of transmitted light when 100 gates are fully opened is measured with high accuracy using the high-precision detector 10. (One-point calibration) (b) Three gates, for example 16th + 50th.

Open the 83rd gate for t seconds. Next is number 17.

Open the 51st and 84M gates for t seconds, and then open the 18th gate for t seconds.
The positions of the gates to be opened are shifted to the right by opening the th, 52nd, and 85th gates for t seconds. After the 100th gate, shift in a ring shape to return to the 1st gate. After shifting to the 15th, 49th, and 82nd gates, close the gates. The power of the light transmitted through the array 3 is detected by the optical sensor 6 to be measured.

(c) The average power of the light transmitted through the optical gate array per second for each of the above is determined in the signal processing circuit 8, and this is used as the transmitted light amount output of the optical gate device.

In the above method, each of the three gates is shifted to all the gates, so the average value of the optical power is exactly 3/100 of the optical power when all the gates are open. In other words, the light intensity I when using a laser light source
Errors due to non-uniformity of t (Gaussian distribution) and gate processing accuracy limits are eliminated by the above averaging operation, and 1
Highly accurate optical power can be obtained with a resolution of /N.

Note that in the above embodiment, the number of times each open gate is shifted may be smaller than the total number of gates N, although the accuracy is somewhat degraded.

Another embodiment of the method according to the present invention will now be described with reference to FIG. 1 as in the previous embodiment.

(b) Power aI of light passing through each of the N gates
+ a2 + . . . aN are each measured and stored in the memory within the signal processing circuit 8.

(b) The average value S of the above measurement data aI + a2 + .

S=Instrument a,/N No. 1 (C) Among the measurement data stored in (B), select n pieces (n) whose sum is closest to m times the reference value, as shown in the following formula =m or a combination of 0 to m) is selected, the corresponding gate is opened, and the measured value of the transmitted light amount at this time is set as the transmitted light amount output of the optical gate device.

ms:aj+ak+al+am+... If CPLI is used in the signal processing circuit 8, the above operation can be easily realized.

According to this method, most of the errors caused by non-uniformity of the light intensity of the light source, limits of gate processing accuracy, etc. are canceled out and reduced by the above addition operation, and highly accurate optical power can be obtained at high speed. I can do it.

In the above embodiment, a single optical gate array having N gates is used to achieve a resolution of 1/N, but the invention is not limited to this. 2) 1 in series with respect to the optical path
/N2 high resolution can also be obtained.

Furthermore, by arranging the high-precision attenuator 11 and the optical gate array 3 in series with respect to the optical path, it is also possible to measure even lower optical power.

Furthermore, in each of the above embodiments, P as an optical gate array is used.
When LZT is used, since it is sequentially switched and used, there is also the effect that the drift of PLZT is reduced.

(Effects of the Invention) As described above, according to the present invention, a method for driving an optical gate device that operates at high speed and produces a highly accurate attenuation layer with small errors due to variations in the light intensity distribution of the light source and gate characteristics. can be provided. Therefore, accuracy, linearity, etc. can be improved in an optical power calibrator using this.

[Brief explanation of drawings]

FIG. 1 is a structural explanatory diagram showing an example of an optical gate device for realizing the method according to the present invention, and FIG. 2 is a detailed diagram showing a structural example of the optical gate array 3 of FIG. 1 (this is a diagram for explaining growth). 1...Light source, 3...Light gate array.

Claims (4)

[Claims] (1) In a method for driving an optical gate device that attenuates light from a light source at a predetermined attenuation ratio, a measured value of transmitted light amount is calculated for each of multiple combinations of opening m gates out of N gates of an optical gate array. By calculating the average value of the plurality of transmitted light quantity measurements and using this as the transmitted light quantity output of the optical gate device, the attenuation ratio m/N based on when the N gates are fully open can be determined with high precision. A method for driving an optical gate device characterized by realizing the following. (2) In a method of driving an optical gate device that attenuates light from a light source at a predetermined attenuation ratio, after determining the amount of transmitted light when each of the N gates of the optical gate array is opened, Calculate the average value of the transmitted light amount measurement values, and open the gates in a combination such that the sum of the transmitted light amount measurement values is closest to m times the average value, using the time when N gates are fully opened as a reference. A method for driving an optical gate device, characterized in that it achieves an attenuation ratio m/N with high precision. (3) A method for driving an optical gate device according to claim 1, using PLZT as an electro-optical element of an optical gate array. (4) A method for driving an optical gate device according to claim 2, using PLZT as an electro-optical element of an optical gate array.