Liquid crystal medium, optical device and liquid crystal compound

A liquid crystal composition that contains an achiral component T containing at least one compound (1) represented by formula (1) as a first component and a chiral agent containing at least one compound represented by formulas (K6) to (K7) to develop an optically isotropic liquid crystal phase:

• wherein, in formula (1), R1 is hydrogen, alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkynyl having 2 to 12 carbons or alkoxy having 1 to 11 carbons;
• L1 is fluorine, L2 is hydrogen and L3 is fluorine;
• and Y1 is fluorine, CF3 or —OCF3;
• wherein, in the formulas, RK is each independently hydrogen, halogen, —C≡N, —N═C═O, —N═C═S or alkyl having 1 to 12 carbons, at least one piece of —CH2— in RK may be replaced by —O—, —S—, —COO— or —OCO—, at least one piece of —CH2—CH2— in RK may be replaced by —CH═CH—, —CF═CF— or and at least one piece of hydrogen in RK may be replaced by fluorine or chlorine;
• AK is each independently an aromatic 6-membered to 8-membered ring, a non-aromatic 3-membered to 8-membered ring or a condensed ring having 9 or more carbons, and at least one piece of hydrogen of the rings may be replaced by halogen, alkyl or haloalkyl having 1 to 3 carbons, —CH2— of the rings may be replaced by —O—, —S— or —NH—, and —CH═ may be replaced by —N═;
• ZK is each independently a single bond or alkylene having 1 to 8 carbons, at least one piece of —CH2— in ZK may be replaced by —O—, —S—, —COO—, —OCO—, —CSO—, —OCS—, —CH═N— or —N═CH—, at least one piece of —CH2—CH2— in ZK may be replaced by —CH═CH—, —CF═CF— or and at least one piece of hydrogen of ZK may be replaced by halogen;
• XK is each independently a single bond, —COO—, —OCO—, —CH2O—, —OCH2—, —OCF2— or —CH2CH2—;
• and
• mK is each independently an integer from 1 to 3.