| 摘要 |
PURPOSE:To prevent the diffraction effect of light due to a shield electrode at patterning by selecting an interval between the shield electrode and the innermost part of an interdigital electrode so as to be parted from the wavelength of a surface acoustic wave by at least (1+1/4) wavelength. CONSTITUTION:The shield electrode 6 is arranged between two opposed submicron interdigital electrodes 4, 5, and a distance H2 between the innermost parts 4a, 5a of the electrodes 4, 5 opposed to the electrode 6 is selected to be (1+1/4) wavelength of that of the surface acoustic wave. That is, the distance H2 between the innermost parts 4a, 5a of the electrodes 4, 5 and the electrode 6 is selected as (1+1/4)lambda=2mum in case of the pattern where the electrode period is a wavelength lambda=1.6mum and the width of the electrode fingers 4c, 5c and the gaps 4b, 5b of the input/output interdigital electrode 4, 5 are nearly 0.4mum. Through the selection as above, the diffraction effect of light by the electrode 6 at patterning is avoided.
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