Light outcoupling based on guided-mode resonance

Chiao-Tzu Huang^1*, Chien-Ju Lee¹, Hsiang-Chi Hu¹, Po-Sen Mao¹, Wen-Hsuan Hsieh², Tien-Chang Lu², Wen-Hao Chang^1,3

¹Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
²Department of Photonics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
³Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Chiao-Tzu Huang, email:chiaotzu.sc11@nycu.edu.tw

Guided-mode resonance (GMR) can be used to selectively transmit or reflect light at a certain angle and wavelength through a grating structure, which can be used as an optical filter. Due to the coupling of grating diffractive mode and waveguide mode, GMR occurs and scatters light into specific directions determined by grating diffractions. Here we propose a new photonic structure to scatter light out of the waveguide with zero divergence and wavelength selection based on GMR. The whole photonic structure is composed of three parts: a circular grating, a high-index waveguide and a back mirror. The circular grating is applied to eliminate polarization selection of linear gratings. The back mirror is made by a distributed Bragg reflector, which increases the total extraction efficiency. In our simulation, we achieve over 70% light extraction of a dipole emitter embedded in the waveguide layer. Mode profile and emission divergency is analyzed by the Finite-Difference Time-Domain method. The proposed photonic structure based on GMR provides a new option to efficiently out-couple dipole emission from a high-index layer without etching the waveguide layer.

Keywords: waveguide, photoluminescence