Abstract: A spatial light modulator having a layer of thermo-optical medium, where the thermo-optical medium is at least partially transparent for at least one spectral component of visible or near infrared light and having the thermal conductivity between 0.01 and 30 W K?1 m?1 at the temperature of 20° C. and the layer having a thickness up to 100 ?m is disclosed. At least one heating microsource in thermal contact with the layer of the thermo-optical medium, where each heating microsource has at least one dimension smaller than 10 ?m, and at least one substrate in thermal contact with the thermo-optical medium, the substrate having a thermo-optic coefficient at least 10 times smaller than a thermo-optic coefficient of the thermo-optical medium and a thermal conductivity of at least 1 W K?1 m?1 while the thermal conductivity of the substrate is higher than the thermal conductivity of the thermo-optical medium.