Bloch Surface Waves Mediated Micro‐Spectroscopy

Abstract

implementation of ultra-compact, low-cost and time-saving spectrum retrieval techniques. [4][5][6] Surface plasmon resonance (SPR) has been widely used for the study of affinity interactions between biomolecules and kinetic analysis in research laboratories, [7][8][9] since the excitation of electromagnetic surface waves at a metaldielectric interface provides a resonance that is highly sensitive to the refractive index of surrounding analyte. The field enhancement of SPR has been applied to enhanced fluorescence or Raman spectrum which is a promising method for the development of highly sensitive point-of-care spectroscopy. [10][11][12] However, the solution of inverse problem, which means to obtain the spectrum of incident beam or near-field fluorescence and Raman signal from the response, is difficult due to low wavelength resolution of SPR. [13,14] Recently, an all-dielectric metasurface was proposed to solve this problem in middle infrared range, while complex structure preparation in large area limited its application especially in the visible range. [15] The use of Bloch surface wave (BSW), which is excited at the surfaces of truncated periodic dielectric multilayers, has been proposed to circumvent the intrinsic metallic losses in plasmonic systems. As a prominent counterpart to surface plasmon polaritons (SPPs), BSWs have similar properties, including optical near-field confinement and enhancement, [16] but have lower propagation losses, [17,18] transverse electric (TE) and transverse magnetic (TM) mode compatibility, [19] stronger dispersion relations, and can be fabricated on a CMOS-compatible material platform. Dielectric nano-antennas on the dielectric multilayer substrate including nanowires, [20] gratings, [21,22] and periodic ring structures [23][24][25] have the potential to provide tools for excitation and manipulation of the BSWs. On the one hand, the free top surface of BSW devices and their strong field localization allow their use in sensing applications. [26,27] Compared with the SPPs, the resonance angle of BSW varies more sharply with wavelength but less sensitively with index of dielectric loading, implying a more effective way to obtain the message of spectrum of incident beam or fluorescence and Raman signal by utilizing BSW. [28] The dispersion properties of BSWs may provide more powerful tools for spectrometers development.In this paper, a computational BSW-based micro-spectrometer is proposed, where a single nanoparticle with a diameter of 94 nm sitting on a dielectric multilayer substrate is used to excite BSWs at different incident wavelengths which can also be regarded as a nanoscale source. The angular spectrum Micro-spectroscopy is a critical instrument for spectrum analysis in various applications such as chemical and biological analysis, environment detection, and hyperspectral imaging. However, current micro-spectral technique requires bulky and costly spectrometer. In this report, a new type of Bloch surface wave (BSW) based micro-spectrometer is proposed. A single silicon ...

Planar photonic chips with tailored dispersion relations for high-efficient spectrographic devices

“…However, if the range of coupling angle for each discrete wavelength is large, the reflective dips for each incident wavelength will overlap, then, a certain inversion algorithm is required to solve the inverse problem 26,31 . Fortunately, due to the low-loss of BSWs loaded on the all-dielectric planar chip, the coupling angle range for the BSWs at the visible light band is narrow 58 .…”

“…3 (a). The miniatured prism is used for the excitation of the BSWs, which also can be realized with an oil-immersed objective used in the leakage radiation microscope (LRM) 31,64,65 . The chip 1 was attached to the prism with the refractive index oil.…”

“…For these micro-spectrometers, the unknown spectrum can be reconstructed as long as that the spectral-retrieving matrix composed of the spectral response function of the detector is full rank 25,26 . Diverse matrices can be constructed from a wide range of physical processes, such as reflective resonance arrays 27,28 , absorptive filter arrays 29,30 , mode coupling factors 25,31 , or engineered electrical signal response 32,33,34 . All the above retrieve methods rely on computational techniques and precise reconstruction algorithms are necessary to approximate the inversion results.…”

“…Even a small perturbation in initial conditions will induce a huge impact on the reconstructed results. Thus, much attention is focused on improving the signal-to-noise ratio, while the spectral resolution is always been ignored 31,35,36 . To improve the spectral resolution, many state-of-the-art techniques have employed tunable narrowband filters 37,38,39,40 .…”

“…The localized electromagnetic surface waves known as Bloch surface waves (BSWs), are extremely sensitive to the environmental changes and also the incident wavelengths, which have been widely used in the field of imaging and sensing and integrated photonic elements 41,42,43,44,45,46,47,48,49,50 . Similar structure combining metallic particle or metallic layer have been used to retrieve the optical spectra, unveiling a new type of design for micro spectrometer 25,31 . Nevertheless, the loss caused by the metal structure reduces the spectral resolution, and the reconstruct algorithm is also affected by the detecting noise.…”