Miniature Otto Prism Coupler for Integrated Photonics
Kirill R. Safronov, Vladimir O. Bessonov, Daniil V. Akhremenkov, Maxim A. Sirotin, Maria N. Romodina, Evgeny V. Lyubin, И. В. Соболева, Andrey A. Fedyanin
Abstract
Abstract One of the main issues in integrated photonics is the coupling of free‐space or optical fiber radiation to waveguides on the photonic chip surface. The ideal coupler is miniature, highly efficient, and provides a large number of addressable devices. Here, a new concept of 3D out‐of‐plane coupler is introduced, which is a microscale prism exploiting frustrated total internal reflection in the Otto configuration to excite surface electromagnetic waves or near‐surface waveguide modes. A method for designing the couplers operating at normal incidence is proposed and it is applied to excite Bloch surface waves (BSWs) in 1D photonic crystals. Polymer microprisms are printed using two‐photon laser lithography and allow transferring more than 40% of the incident light energy into BSWs. The couplers enable focusing BSWs simultaneously with their excitation. Advanced design prisms can provide nearly 100% efficiency, making the proposed concept an alternative to actual coupling concepts in integrated photonics.