Filter, and cyanine compound

Plasma Display Panel unnecessary near-infrared or neon light or the like cut in such, it is possible to prevent such reflection of fluorescent light, well visible light transmittance, heat resistance, moisture resistance is also good optical wave dye contained filter is required. The present invention has been made to solve these problems, a salt of a cation with di (halogenoalkyl) imide anion of the cyanine dye, preferably represented by the following formula ## STR1 ## (The above formula (1) At a Q, Q 'each independently a benzene ring or a naphthalene ring which may have a substituent, R, R' each independently an alkyl group or an alkoxyalkyl group, L is carbocyanine relates an optical filter containing a cyanine compound represented by each represents) a linking group for forming a useful as a near infrared cut for display or image characteristics for improving filter.