JPS61151515A - Optical gate device - Google Patents

Abstract

PURPOSE:To reduce the output drift generated in an optical gate array element by dividing an input light to plural optical paths and providing plural optical gate arrays which intercept lights of individual optical paths in stages and switching these optical gate arrays in time division. CONSTITUTION:The light emitted from a light source 32 is separated to a p- polarized wave and an s-polarized wave by a polarizing beam splitter 61, and the p-polarized wave is inputted to an optical gate array 68, and the s-polarized wave is inputted to an optical gate array 67. When the optical gate array 67 is turned on, the electrooptic effect is generated, and the s-polarized wave which passes it has the plane of polarization rotated at 90 deg. and becomes a p-polarized wave and is outputted in the direction of an arrow A, and the p-polarized wave which passes the optical gate array 68 is outputted in the direction of an arrow B. When the optical gate array 68 is turned on, the electrooptic effect is generated, and the p-polarized wave which passes it has the plane of polarization rotated at 90 deg. and becomes an s-polarized wave and is outputted in the direction of the arrow, and the s-polarized wave which passes the optical gate array 67 is outputted in the direction of the arrow B. Thus, optical gate arrays are switched by a cycle T0 to reduce the bad influence due to drift of PLZT.

Description

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

(Prior Art) As a technology related to an optical gate device, an example of an optical power calibrator shown in FIG. 6 will be described. 1 is a dark room, 2 is a reference light source, 3 is a slit having a certain hole, and 4 is a photodetector. 5 is a first lens for parallelizing the light from the reference light source 2 from the slit 3; 6 is a light shielding means for limiting the amount of light transmitted from the first lens; 7 is a light shielding means 6; This is a second lens for converging the transmitted light. 8 is a shielding control means for increasing the shielding amount of the light shielding means 6 by i+11111; 9 is a CR
This is a display means for displaying on a T or plotter.

FIG. 7 is a diagram illustrating details of the light shielding means 6.
A plurality of electrodes 2 are mounted on a substrate 20 made of an electro-optic material such as
1a, 21b, . A predetermined electric field is applied to the electrodes 21a, 21b, . A transmission window is configured to pass through the second polarizing plate 23, and the application of the electric field is controlled by the shielding amount control means 8.

In the power calibrator configured as above, when an arbitrary number of transmission windows is opened (or closed), the photodetector 4 is irradiated with an amount of light proportional to the number of transmission windows, and the amount of shielding at that time is controlled. The photodetector 4 can be calibrated by inputting the output signal of the means 8 and the electric signal of the photodetector 4 to the display means 9, performing calculations and comparisons, and displaying the results on a CRT or plotter.

(Problem to be solved by the invention) However, the PLZT used in the light shielding means 6
Since the electro-optic effect of PLZT changes over time, the gate array element has the disadvantage that when used as a switch, it induces output drift and deteriorates accuracy and linearity.

This is especially a problem when the light energy is high.

The present invention has been made to solve the above problems, and an object of the present invention is to realize an optical gate device in which output drift occurring in an optical gate array element is reduced.

(Means for Solving the Problems) A first aspect of the optical gate device of the present invention is an optical gate device that blocks input light in stages, and includes means for dividing the input light into a plurality of optical paths, and a method for dividing the input light into a plurality of optical paths. It is characterized by having a plurality of optical gate arrays that block light in an optical path in stages, and a control circuit that switches the plurality of optical gate arrays in a time-division manner, thereby reducing drift occurring in output light.

The second aspect of the optical gate device of the present invention is a control circuit that switches the input light and the plurality of optical gate arrays in a time division manner, and applies a drive signal whose average value in one cycle is 0 to each optical gate array. It is characterized by reducing drift occurring in output light.

(Function) According to the configuration according to the first aspect of the present invention, since the time for applying a drive signal to each optical gate array is shortened, the amount of drift occurring in each optical gate array can be reduced.

Further, according to the configuration according to the second aspect of the present invention, drifts can be canceled out by applying drive signals having mutually opposite polarities.

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

FIG. 1 is an explanatory diagram of a configuration in which an optical gate device according to the present invention is applied to an optical power calibrator, and shows an example in which two gate arrays are used alternately. 32 is a reference light source, 35 is a lens for condensing the light emitted from this reference light source 32, 36 is a ψ light shielding means for limiting the amount of light transmitted from this lens 35, and 61 and 64 are polarizing beam filters. , 62 and 63 are total reflection prisms, 6
1 and 66 are collimators with the same characteristics that limit the width of the light beam; 67 and 68 are PLZT optical gate arrays with the same characteristics installed so that the two polarized waves emitted from the polarizing beam splitter 61 are irradiated; 37 is a condensing lens for condensing light onto the photodetector 34. 67.6
The 8 PLZT optical gate array has electrodes 21a shown in FIG.
Electrodes similar to those 21b, . . . 21n are provided.

38 is a control signal Q1.38 that drives the gates of the optical gate arrays 67 and 68. This is a control circuit that generates Q2. (l;i
Optical beam splitter 61, 64 and total reflection prism 6
2.63 constitutes means for dividing input light into a plurality of optical paths.

The operation of the apparatus having such a configuration will be described next. Now, a case will be explained in which the two optical gate arrays 67 and 68 alternately switch the amount of light of one unit. The light emitted from the light source 32 is separated into P waves and S waves by a polarizing beam splitter 61, and the P waves are sent to the optical gate array 68 and the S waves are sent to the optical gate array 6.
7 each.

When the optical gate array 67 is turned on, an electro-optic effect occurs, and the polarization plane of the S wave passing through it is rotated by 90' to become a P wave, and the total reflection prism 63. Polarized light/bell splitter 6
4 and is output in the direction of the claw.

Since the front gate array 68 is turned off, no electro-optic gate effect occurs, and the P wave passing through it is output in the B direction via the polarizing beam splitter 64.

Conversely, when the optical gate array 68 is turned on, an electro-optic effect occurs, and the polarization plane of the P wave passing through it is rotated by 90'' to become an S wave, which is outputted in the direction of the nail via the polarizing beam splitter 64. - Power tip gear 17 - Since the array 67 is off, no electro-optic effect occurs, and the S wave passing through it is output in the B direction via a total reflection prism 63 and a polarizing beam splitter 64.

When this is repeated at the To period, one unit of light that has passed through different optical gate arrays is output alternately, and as a result, the output light in the B direction becomes as shown in the time chart of FIG. 2. Even when multiple units of light intensity are set for the optical gate array, multiple units of light are output alternately in the same way, so the B for the number of optical gates is
The output light m in the direction changes as shown in the characteristic curve diagram in FIG.

By switching the optical gate array at the To period in this manner, the adverse effects of PLZT drift can be reduced.

In the above embodiment, control signals Q+ and Q2 of the same polarity were used, but as shown in the time chart of FIG. If added to each rabbit gate array from the control circuit,
By applying voltages with different polarities, the tri-tets occurring in the PLZT in opposite directions are canceled out, and drift can be further reduced.

Furthermore, in each of the above embodiments, if the optical output in the claw direction is also used, it becomes possible to calibrate two photodetectors at the same time.

In each of the above embodiments, as shown in FIG.
It is possible to obtain twice the amount of output light.

Furthermore, in each of the above embodiments, a plurality of PLZTs and collimators are provided between the polarizer and the analyzer, for example, as shown in the paper of FIG.
If you place it in the straight direction) and use it by switching sequentially,
The usage time per PLZT can be shortened and drift can be roughly reduced.

(Effects of the Invention) As described above, according to the present invention, it is possible to realize an optical gate device that reduces the output drift that occurs in an optical gate array element, and to improve accuracy and Linearity can be improved.

[Brief explanation of the drawing]

#I! ! Fig. 1 is a diagram showing the construction of an optical power calibrator to show one embodiment 11 of the optical gate device according to the present invention, and Fig. 2 is a diagram showing the construction of an optical power calibrator to show an embodiment 11 of the optical gate device according to the present invention. 3 is a characteristic curve diagram for explaining the operation of the device shown in FIG. 1, and FIG. 4 is a time chart for explaining the operation of a modified example of the device shown in FIG. 1. , Figure 5 is the first
FIG. 6 is an explanatory diagram of the main part configuration for explaining another modification of the apparatus, FIG. 6 is an example of a related optical power calibrator, and FIG. 7 is a light shielding means used therein. 38... Control circuit, 61.62, 63.64... Means for dividing input light into a plurality of optical paths, 67.68... Optical gate array, Ql, Q2... Drive signal.

Claims (4)

[Claims] (1) An optical gate device that blocks input light in stages, including means for dividing input light into a plurality of optical paths, a plurality of optical gate arrays that block light in each optical path in stages, and An optical gate device comprising a control circuit that switches a gate array in a time-division manner and reduces drift occurring in output light. (2) An optical gate device that blocks input light in stages, comprising: means for dividing input light into a plurality of optical paths; a plurality of optical gate arrays that block light in the plurality of optical paths in stages; Switching the optical gate array in time division and 1
1. An optical gate device comprising: a control circuit that applies a drive signal whose period has an average value of 0 to each optical gate array, thereby reducing drift occurring in output light. (3) The optical gate device according to claim 1, which uses PLZT as the electro-optical element of the optical gate array. (4) The optical gate device according to claim 2, which uses PLZT as the electro-optical element of the optical gate array.