There are provided a wavelength selective absorption filter including a resin, and four types of dyes A to D each having a main absorption wavelength range in different specific wavelength regions, in which an absorbance Ab () of the wavelength selective absorption filter at a wavelength nm satisfies specific Relational Expressions (I) to (VI), and an organic electroluminescent display device.

An optical filter, including a first absorption layer containing a near-infrared absorbing dye and a transparent resin. The optical filter also includes a reflection layer. The first absorption layer has a thickness of 0.3 m to 10 m. The optical filter satisfies conditions described in the disclosure. An imaging apparatus including the optical filter.

The invention provides a novel class of cyanine dyes that are functionalized with sulfonic acid groups and a linker moiety that facilitates their conjugation to other species and substituent groups which increase the water-solubility, and optimize the optical properties of the dyes. Also provided are conjugates of the dyes, methods of using the dyes and their conjugates and kits including the dyes and their conjugates.