Photonic crystal resonances for sensing and imaging

Abstract

This review provides an insight into the recent developments of photonic crystal (PhC)-based devices for sensing and imaging, with a particular emphasis on biosensors. We focus on two main classes of devices, namely sensors based on PhC cavities and those on guided mode resonances (GMRs). This distinction is able to capture the richness of possibilities that PhCs are able to offer in this space. We present recent examples highlighting applications where PhCs can offer new capabilities, open up new applications or enable improved performance, with a clear emphasis on the different types of structures and photonic functions. We provide a critical comparison between cavity-based devices and GMR devices by highlighting strengths and weaknesses. We also compare PhC technologies and their sensing mechanism to surface plasmon resonance, microring resonators and integrated interferometric sensors.

Dielectric Nanohole Array Metasurface For High-Resolution Near-Field Sensing and Imaging

“…The sensitivity is expressed as a wavelength change vs refractive index change Δλ/Δn in nm/RIU. So the gure of merit is SQ [25]. The sensitivity is commonly understood with respect to the bulk refractive index change, i.e.…”

“…Two-dimensional plasmonic nanohole arrays, for example, can achieve bulk sensitivities above 700 nm/RIU [23,26] and dielectric nanohole arrays operating at 1550 nm can be even better with a demonstrated sensitivity of S ~ 800 nm/RIU [27] and theoretically up to 4000 nm/RIU in the visible range [19], while 1-D arrays typically achieve between 100-300 nm/RIU [28]. While the bulk sensitivity is easy to measure, it is not the most relevant parameter for a surface-a nity sensor; instead, the surface sensitivity should be used, which describes the response of the sensor to refractive index changes at the very surface of the sensor [25,29] which is much more representative of surface-bound proteins or DNA. Since there is no agreed thickness for the surface sensitivity, we here chose a thickness of 10 nm and a layer of SiO2 (n = 1.45) to represent the thickness of a typical protein bound to a surface via an antibody [30].…”

Photonic crystal slab between orthogonal polarizers: details on the guided mode resonance wavelength

“…Because a resonance wavelength's position can be tuned by and is sensitive to changing the structure's period and the materials' refractive indices, photonic crystal slabs are used, e.g., as optical filters and sensors (Pitruzzello and Krauss 2018;Kilic et al 2008). For compact optical systems and also for characterization measurements in the lab it can be advantageous to place a one-dimensional photonic crystal slab between two orthogonal polarizers (OP), aligned at 45 • and −45 • to the grating lines, respectively (Nazirizadeh et al 2008).…”

An energy window study of light transmission-disorder relationship in 1D photonic structures

“…Altering the periodicity of the high and low refractive index materials we made photonic materials with a disorder level. The optical behaviour of a photonic crystal is characterized by an energy region in which light is not transmitted, the photonic band gap [1][2][3][4][5][6], and the energy regions that are transparent. In disordered photonic materials transmission valleys occur all over the studied energy range [7][8][9][10][11][12].…”