Elastic wave resonator, elastic wave filter, and duplexer

An elastic wave resonator comprising:

• a piezoelectric substrate;
• and
• an IDT electrode provided on the piezoelectric substrate, wherein
• the IDT electrode includes a first electrode finger and a second electrode finger, the second electrode finger being adjacent to the first electrode finger in an elastic wave propagation direction;
• a metallization ratio (W1/L) of the first electrode finger is smaller than a metallization ratio (W2/L) of the second electrode finger;
• and
• a sum (W1/L+W2/L) of the metallization ratio of the first electrode finger and the metallization ratio of the second electrode finger is between about 0.65 and about 1.00 inclusive, and a ratio (W2/W1) between a width of the first electrode finger and a width of the second electrode finger is between about 1.12 and about 2.33 inclusive;
• or
• the sum (W1/L+W2/L) of the metallization ratio of the first electrode finger and the metallization ratio of the second electrode finger is larger than about 1.00, and the ratio (W2/W1) between the width of the first electrode finger and the width of the second electrode finger is between about 1.40 and about 2.34 inclusive;
• where W1 is the width of the first electrode finger along the elastic wave propagation direction, W2 is the width of the second electrode finger along the elastic wave propagation direction, and L is a pitch or an electrode finger center distance between the first electrode finger and the second electrode finger.