Multi-color fluorescence imaging based on plasmonic wavelength selection and double illumination by white light

Abstract

We demonstrate the proof-of-concept for developing a multi-color fluorescence imaging system based on plasmonic wavelength selection and double illumination by white light source. This technique is associated with fluorescence excitation by transmitted light via a diffraction of propagating surface plasmons. Since double illumination through both sides of isosceles triangle prism in the Kretschmann configuration enables multiple transmission beams of different wavelengths to interact with the specimen, our approach can be an alternative to conventional fluorescence detection owing to alignment stability and functional expandability. After fabricating a plasmonic wavelength splitter and integrating it with microscopic imaging system, we successfully confirm the performance by visualizing in vitro neuron cells labeled with green and red fluorescence dyes. The suggested method has a potential that it could be combined with plasmonic biosensor scheme to realize a multi-functional platform which allows imaging and sensing of biological samples at the same time.

Evanescent-field-coupled guided-mode sensor based on a waveguide grating

“…For SPPs excited by white light, the gratings were implemented for the angular separation of the SPPs at different wavelengths [17]. An enhancement of fluorescence intensity from a liquid solution of dyes floating over a grating was also demonstrated in [18]. Regardless of the improved efficiency, the sensitivities of sensors based on thin dielectric gratings are worse than the resolutions of conventional silver SPR sensors with an average sensitivity by intensity in water of 54 RIU −1 [19].…”

Ultra-small wavelength splitters in a subwavelength plasmonic waveguide

“…The measured structural parameters are about w 1 700 nm, w 2 180 nm, d 4260 nm, and L slit 280 nm. Therefore the SPP plasmonic wavelength splitter has a very small footprint of only about 1.4 μm 2 , which is much smaller than the previous plasmonic wavelength splitters [3,6,7,9,[11][12][13][14][15][16][17][18]27]. The measured generated spectra are depicted in Fig.…”

“…Because of the remarkable capability to overcome the diffraction limit, surface plasmon polaritons (SPPs) [1,2] are regarded as the promising candidate for significantly miniaturizing optical devices. Hence, the SPPs have attracted increasing attention recently, and various metallic structures based on the SPPs were proposed to realize ultra-small optical devices [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Among them, the plasmonic wavelength splitters, which can separate the incident beams of different wavelengths to propagate in different directions, play an important role in optical communication and optical computing networks.…”

“…Among them, the plasmonic wavelength splitters, which can separate the incident beams of different wavelengths to propagate in different directions, play an important role in optical communication and optical computing networks. Most of the plasmonic wavelength splitters were achieved based on the Bragg resonant condition in metallic array structures [3][4][5][6][7][8][9][10][11][12][13]. However, bulky array structures considerably increased their sizes.…”