JPS6016604B2 - acousto-optic element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an acousto-optic device, particularly a sonic steering type acousto-optic light polarization device, and more particularly to a method for electrically connecting piezoelectric vibrators provided on a plane and divided into segments. be.

One of the important characteristics desired in an acousto-optic optical deflection element is a wide band of deflection efficiency.

One of the means for widening the band is a sound wave steering method in which the frequency is changed to change the traveling direction of the sound wave so as to always satisfy the diffraction conditions between the laser light that undergoes optical deflection and the sound wave. Regarding this sound wave steering method, the connection method of the piezoelectric vibrator is alternately changed between the element with the adhesive surface of the piezoelectric vibrator of the acousto-optic medium made into a stepped shape as shown in Figure 1, and the element with the adhesive surface of the piezoelectric vibrator left flat as shown in Figure 2. There are possibly two types of elements.
In FIG. 1, reference numeral 1 indicates the entire steering type light polarizing element.

Reference numeral 2 denotes an acousto-optic medium, on one surface of which a step-like step whose height is equal to 1/2 skin length of the sound wave is formed.

A piezoelectric vibrator 3, which is sandwiched between a base electrode 4 and an upper electrode 5 on both sides, is formed in each stepped portion of the acousto-optic medium 2, and operates as a transducer that converts an electric signal into a sound wave. Reference numeral 6 denotes a lead wire that electrically connects the base electrode 4 and the upper electrode 6 of the adjacent piezoelectric vibrator 3.

In such a stepped steering element 1, the height of the step becomes very small in the high frequency range, making it extremely difficult to manufacture, and therefore it is not suitable for high frequency applications.

For this reason, a planar steering element as shown in FIG. 2 has been considered.

Components in the figure that are the same as those in FIG. 7 is a conductive paste.

In this planar element, a single pressure force oscillator is glued together, and then divided into multiple pieces according to the driving frequency, and the phase of the excitation state is changed by half a wavelength to produce a steering effect using a relatively high-frequency wave. However, it is easy to manufacture. For example, in tellurium dioxide single crystals and lead molybdate crystals that are often used in the acousto-optic light deflection element 2, the division width of the piezoelectric vibrator 3 is wide at a center frequency of up to about 200 MHz, which is more than a few sides. For connection, use lead wire 6 such as silver wire.
It is also possible to carry out the process using conductive paste 7 as shown in FIG. However, in the case of an optical deflection element operated in a higher frequency region of 200 MHz or higher, the width of the piezoelectric vibrators to be divided becomes even narrower, and the method of electrically connecting each piezoelectric vibrator 3 becomes a problem.

For example, if an optical deflection bandwidth of 240 MHz is required, the center frequency will be 360 MHz, and the division width of the piezoelectric vibrator 3 with a planar steering element amount using tellurium dioxide crystal will be approximately 0.55. The thickness of the piezoelectric vibrator 3 is approximately 10 mm in the commonly used lithium niobate crystal.
Becomes a department. In this case, each piezoelectric vibrator 3 is generally bonded with a vapor-deposited film of indium, tin metal, or the like, and this vapor-deposited layer is used as the base electrode 4. A vapor deposited layer of gold, aluminum, or the like is used for the upper electrode 5 of the piezoelectric vibrator. The conventional method of bonding lead wires 6 with conductive paste 7 cannot be used as a method for connecting piezoelectric vibrators 3 that are narrowly divided to perform a steering action because the piezoelectric vibrators 3 are narrow. Further, wire bonding is difficult because the piezoelectric vibrator 3 is thin and the upper electrode 5 is not firmly deposited. The present invention provides a structure that facilitates the above-mentioned difficult electrical connection of piezoelectric vibrators.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 3 about an optical deflection element using tellurium dioxide single crystal as an acoustic medium and having a center frequency of 360 MHz. In the optical deflection element according to the present invention, a piezoelectric vibrator 3 having a thickness of approximately 10 cm is crimped with indium or tin metal as a base electrode 4 on a tellurium dioxide single crystal 2, and a Ni plate C is placed on the top thereof. An upper electrode 6 made of gold is vapor deposited, and then the upper electrode 5 is cut at 0.55 inch intervals using a wire saw.

In this case, as shown in Fig. 3, the piezoelectric vibrator 3 and the adhesive layer 4 of the base are
Cut up to. Cutting is stopped until the middle kerf blade slightly digs into the piezoelectric vibrator 3, and the underlying adhesive layer 4 is not cut, but is used to connect the underlying electrode 4.In order to provide a steering effect. To connect the upper electrode 5, an organic adhesive or a synthetic resin, such as silicone, is applied to the groove 8 cut to the base electrode 4 in order to insulate the upper and lower electrodes 4, 5 and the cut base electrode 4 from each other. A zoacrylate adhesive 9 is filled and applied.Next, a conductive paste is applied to cover the insulating layer 9 and connect the adjacent upper electrodes.Finally, the piezoelectric vibrator at both ends is A lead wire 6 is attached to a wide electrode portion unrelated to excitation.In the acousto-optic device according to the present invention having such a configuration, it is easy to manufacture a high frequency, broadband steering type optical deflection device.

Also, since there is no lead wire connecting the electrodes, no stray capacitance or line inductance occurs.

Furthermore, mechanical strength becomes stronger. It exhibits excellent effects such as, and is particularly useful as an acousto-optic element for high frequency and broadband applications.

[Brief explanation of the drawing]

Figure 2 is a cross-sectional view of a step-type steering optical deflection element. Figure 3 is a cross-sectional view of a conventional planar steering optical deflection element. It is a cross-sectional view.Government... Steering type optical deflection element 2... Acousto-optic medium, 8... Piezoelectric vibrator, 4... Base electrode, Humidity...
Upper electrode 6...'Lead wire, conductive paste also box...cutting groove 9...Organic adhesive, dragon sardine...
W intermediate kerf. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. an acousto-optic medium, a plurality of piezoelectric vibrators having first and second planar electrodes on both surfaces and arranged such that the first planar electrode is in close contact with one plane of the acousto-optic medium, the plurality of piezoelectric vibrators; an insulating layer that separates the vibrators from each other; a conductive paste that is formed on the insulating layer and electrically connects second planar electrodes of mutually adjacent piezoelectric vibrators; an acousto-optic element having a kerf that separates into two.