Integrated fluorescence excitation, collection, and filtering on a GaN waveguide chip

Fluorescence detection is widely used in biology and medicine, while the realization of on-chip fluorescence detection is vital for the portable and point-of-care test (POCT) application. In this Letter, we propose an efficient fluorescence excitation and collection system using an integrated GaN chip consisting of a slot waveguide and a one-dimensional photonic crystal (1D PC) waveguide. The slot waveguide is used to confine the excitation light for intense light-sample interaction, and the one-trip collection efficiency at the end of slot waveguide is up to 14.65%. More interestingly, due to the introduction of the 1D PC waveguide, the fluorescence signal is directly filtered out, and the excitation light is reflected to the slot waveguide for multiple excitations. Its transmittances for the designed exciting wavelength of 520 nm and the fluorescent wavelength of 612 nm are 0.2% and 85.4%, respectively. Finally, based on numerical analysis, the total fluorescence collection efficiency in our system amounts to 15.93%. It is the first time, to our knowledge, that the concept of an all-in-one-chip fluorescence detection system has been proposed, which paves the way for on-chip fluorescence excitation and collection, and may find potential applications of miniaturized and portable devices for biomedical fluorescence detection.

Automated summary

The study proposes an efficient fluorescence excitation and collection system using an integrated GaN chip. The system utilizes a slot waveguide to confine excitation light and introduces a one-dimensional photonic crystal waveguide to filter out fluorescence signals and enable multiple excitations. Through numerical analysis, the total fluorescence collection efficiency is determined to be 15.93%. This study introduces the concept of an integrated chip fluorescence detection system, paving the way for miniaturized and portable devices in biomedical fluorescence detection.