Optical filter and imaging device

A near-infrared absorbing dye, comprising a squarylium-based dye of the following formula (AI):

• wherein
• each X is independently a bivalent organic group of the following formula (1) or (2),
• wherein at least one hydrogen atom is optionally substituted with a C1-12 alkyl or alkoxy group;
• —(CH)n1— (1),
• wherein n1 is 2 or 3;
• —(CH2)n2—O—(CH2)n3— (2),
• wherein each of n2 and n3 is independently an integer of 0 to 2, and n2+n3 is 1 or 2;
• each R1 independently represents a saturated or unsaturated C1-12 hydrocarbon group which optionally comprises a saturated ring structure or is optionally branched, a saturated C3-12 cyclic hydrocarbon group, a C6-12 aryl group, or a C7-13 alaryl group;
• each R2 is independently a C1-25 hydrocarbon group in which at least one hydrogen atom is optionally substituted with a halogen atom, a hydroxyl group, a carboxy group, a sulfo group, or a cyano group and that optionally comprises an unsaturated bond, an oxygen atom, or a saturated or unsaturated ring structure between carbon atoms;
• and
• R3 and R4 each independently represent a hydrogen atom, a halogen atom, or a C1-10 alkyl or alkoxy group.