Abstract: A surface acoustic wave element includes: metal patterns that include interdigital transducers, each of the metal patterns being formed with a first alloy or multi-layer film of metals having different standard electrode potentials; and metal films each formed with a second alloy or multi-layer film containing metals having different standard electrode potentials from the standard electrode potentials of the metals forming the first alloy or multi-layer film, the metal films being formed at least on a part of the regions other than the regions corresponding to the electrode fingers of the interdigital transducers of all the metal patterns that are electrically independent of one another.

Abstract: A duplexer includes a ladder filter and a multimode filter that are formed on the same surface of a predetermined substrate. In this duplexer, a first comb-like electrode of the ladder filter and a second comb-like electrode of the multimode filter have the same layer structure with the same film thickness. The first comb-like electrode and the second comb-like electrode are formed with single-layer films mainly containing aluminum.

Abstract: A wavelength filter includes lattice structures that are arranged at predetermined intervals in the direction of an optical axis. Each of the lattice structures has regions of two different refractive indices that are alternately arranged.

Abstract: A tunable capacitor includes a substrate, a stationary electrode and a movable electrode supported by the substrate, piezoelectric actuators that are supported by the substrate and drive the movable electrode, and a dielectric layer interposed between the stationary electrode and the movable electrode.