Svetlana LIPNITSKAYA^1,2, Karim MYNBAEV^1,2,3*, Lidiya NIKULINA², Vladimir KRAMNIK², Vladislav BOUGROV^1,2, Alexey KOVSH^1,2, Maxim ODNOBLYUDOV^1,2, and Alexey ROMANOV^1,2,3

¹ITMO University, Kronverkskiy 49, Saint-Petersburg 197101, Russia
²Optogan Group, Tallinskoe 206, Saint-Petersburg 198205, Russia
³Ioffe Institute, Polytechnicheskaya 26, Saint-Petersburg 194021, Russia

(Received April 1, 2014; Accepted June 17, 2014)

A research has been carried out on the optimization of the shape of encapsulating cover to minimize optical losses in light-emitting modules fabricated with the “chip-on-board” (COB) technology. Optical properties of the components of a typical COB were taken into account including those of the substrate, light-emitting chips, encapsulating material and phosphor particles. Light losses were analyzed for various types of encapsulant surface structuring in an attempt to design an optical element with maximum light extraction efficiency. Calculations were complemented with experimental measurements. The results of the research showed that structuring the surface of the encapsulant can enhance light extraction by 10 to 15% for the material without phosphor particles and by 10 to 14% for the material with phosphor particles.

Key words: light extraction, light-emitting module, optical coating, chip-on-board

^*E-mail address: karim.mynbaev@niuitmo.ru