JPS60216619A - Surface acoustic wave splitter - Google Patents

Abstract

PURPOSE:To allow an SAW generator to produce plural surface acoustic waves (SAW) by constituting the generator where plural slots are arranged with a prescribed interval and a prescribed angle on an SAW propagating path of a medium through which a surface acoustic wave SAW is propagated. CONSTITUTION:The SAW generator 11 where many parallel electrodes are connected alternately and formed by metallic vapor-deposition is provided on an acoustooptic substrate 10 made of an LiNbO3 crystal. A high frequency signal is impressed to the SAW generator 11 from a high frequency signal generator 13. An SAW splitter 12 made of many slots having an angle satisfying the diffraction condition of the Bragg in the propagating direction of the SAW1 and with a prescribed interval is formed. A part of the SAW1 is subjected to the Bragg diffraction is branched as an SAW2 by the splitter 12 and the other part is transmitted as it is and becomes an SAW3.

Description

BACKGROUND OF THE INVENTION The present invention relates to a surface acoustic wave splitter that branches or splits surface acoustic waves propagating on the surface of a substrate or other medium into at least two directions.

Surface acoustic waves (hereinafter referred to as SAW) are being widely applied to elements of optical, electronic, and communication equipment. However, a SAW splitter that branches one SAW into two or more directions has not yet been realized. When a plurality of SAWs are required in a SAW-using element, a plurality of SAW generating means, such as an interdigital one-transducer (hereinafter referred to as "T"), have been installed. however,
When multiple SAW generation means are installed on one substrate, the space required for the arrangement increases, which increases the size of the element.Due to variations in the shape of the SAW generation means, it is difficult to obtain SA and W with the same characteristics. When an IDT is employed as a SAW generating means, there are various problems such as a decrease in yield in the electrode manufacturing process when attempting to form a plurality of IDTs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a SAW splitter that branches and splits one SAW obtained from one SAW generating means into at least two, and to solve the above-mentioned problems.

The SAW splitter according to the present invention is characterized in that a plurality of grooves are formed at predetermined intervals on a SAW propagation path of a medium through which the SAW propagates, and are arranged at a predetermined angle in the SAW propagation direction.

According to the present invention, since one SAW is branched into a plurality of SAWs propagating in different directions, it is possible to reduce the number of SAW generation means to be formed on one substrate,
The device shape can be made smaller, and even when an IDT is used as a SAW generating means, it is possible to improve the yield in the manufacturing process. Further, +iJ of the branched SAWs can be made equal. It is preferable if the substrate is isotropic because the characteristics of the branched SAWs will be the same.

By changing the length and depth of the grooves, the strength of the branch covering SA and W can be arbitrarily set, and the branching angle can be arbitrarily determined by changing the interval between ports.

Description of Examples In FIG. 1, an acousto-optic substrate (such as a LiNb0a crystal)
10) I D T (11) is formed in a part of the upper part. As I D T (11) is well known,
It is constructed by connecting a large number of mutually parallel electrodes alternately. The jD block (11) is formed by metal vapor deposition using a masking technique. This ID
(A high frequency signal is applied to 111 from the high frequency signal generator (13). As a result, from ID T (11) to S
AW1 is generated and propagates in a direction perpendicular to the electrode of I D T (11).

On the propagation path of 5AWI generated from IDT (11), there is a SAW splitter (12) on the substrate (10).
) is formed. The splitter (12) is formed on the surface of the substrate (10), as shown enlarged in FIG.
4). The direction of the groove (14) is 5AW
It is formed at an angle θ that satisfies the Bragg diffraction condition with respect to the propagation direction of I.

A portion of 5AW1 undergoes Bragg diffraction due to the groove (14) and is branched as 5AW2. The other part of 5AW1 passes through the groove (14) as it is and goes straight as 5AW3.

The widths of 5AW2 and 5AW3 are equal. 5AW2 and 5AW3
The branching ratio to can be arbitrarily set by the depth and length T of the groove (14). Furthermore, the branching angle can be arbitrarily set by changing the interval d between the grooves (14). The groove (14) is formed by, for example, ion beam processing (etching), laser processing, or the like.

FIG. 3 shows an application example of the SAW splitter, in which a Matsuhatsu Enda type SAW propagation path is formed. The substrate (20) is made of an isotropic material such as glass. IDT formed on a part of the substrate (20)
(11) On top is a piezoelectric crystal such as ZnO (21)
is equipped with fJ. A part of the upper surface of this crystal (21) is formed in an inclined shape so that the thickness decreases in the direction of propagation of 5AWI. The presence of the piezoelectric crystal (21) improves the propagation efficiency of the SAW.

5AW1 generated from ID 7 (11) is divided into diffracted wave 5AW2 and straight wave 5A by SAW splitter (12).
It is branched into W3. The directions of these 5AW2 and 5AW3 are changed by reflection grooves (22) and (23) formed on the substrate (20), respectively, and 5AW3. After this reflection, the signal travels straight and is converted into an electrical signal by the SAW detector (25), ie, the IDT.

5AW2 reflected by the reflection groove (22) is further reflected by the reflection groove (22).
4) and is detected by the detector (25). Detector (
The output signal of 25) is sent to a high frequency analyzer (26).

If the propagation path lengths of 5AW2 and 5AW3 are equal, the detector (
25) detects a SAW having the same waveform as 5AW1 excited by I D T (11). One SAW propagation path,
For example, in the propagation path of 5AW3, anti-04 tfli (
A region (R) to which some physical quantity such as heat is applied is set between the position of reflection ff+7 (24) and the density, refractive index, etc. of the substrate (20) in this region (R). change. 5AW3 is modulated by the physical quantity applied to the region (R) when passing through this region (R>. Therefore, 5AW2 and 5AW3 are the reflection grooves (
When multiplexed on the detector (25) side of the detector (24), the signals interfere, and information regarding this interference is analyzed by the analyzer (26). Based on the analysis of SAW coherence by the analyzer (26), it is possible to know the magnitude of the physical quantity added to the region (R).

[Brief explanation of drawings]

Figure 1 is a perspective view showing an embodiment of this invention, Figure 2 is a SA
FIG. 3 is a plan view showing an enlarged W splitter, and FIG. 3 is a perspective view showing an application example of the SAW splitter. (10)...Substrate, (12)...SAW splitter, (14)...Reflection groove. Above is Figure 2＼

Claims (1)

[Claims] A surface acoustic wave splitter in which a plurality of grooves are formed at predetermined intervals on a surface acoustic wave propagation path of a medium through which surface acoustic waves propagate, and are arranged at a predetermined angle in the propagation direction of the surface acoustic waves.