Strategies for Dielectric Contrast Enhancement in 1D Planar Polymeric Photonic Crystals

Abstract

Historically, photonic crystals have been made of inorganic high refractive index materials coupled to air voids to maximize the dielectric contrast and in turn the light confinement. However, these systems are complex, costly, and time-demanding, and the fabrication processes are difficult to scale. Polymer structures promise to tackle this issue thanks to their easy solution and melt processing. Unfortunately, their low dielectric contrast limits their performance. In this work, we propose a concise but exhaustive review of the common polymers employed in the fabrication of planar 1D photonic crystals and new approaches to the enhancement of their dielectric contrast. Transfer matrix method modeling will be employed to quantify the effect of this parameter in standardized structures and to propose a new polymer structure for applications dealing with light management.

Aquivion–Poly(N‐vinylcarbazole) Holistic Flory–Huggins Photonic Vapor Sensors

“…[ 33 ] As mentioned in the introduction, such high dielectric contrast favors the formation of spectrally broad stopbands, that could decrease the FHPS sensitivity. To overcome this limit, we exploited the second‐order stopband of the FHPSs, which is commonly spectrally sharper than the first stopband [ 21,28 ] and was opportunely tuned in the visible spectral range for sensing. As previously reported, this is possible, because the normalized optical responses of the different diffraction orders to the analyte exposure are superimposable.…”

“…As previously reported, this is possible, because the normalized optical responses of the different diffraction orders to the analyte exposure are superimposable. [ 23a,34 ] Notice that, to be able to detect even diffraction orders, the structure needs to be far from the λ/4 condition [ 21 ] that emerges in DBRs having low and high refractive index media with identical optical thickness (4 n 1 d 1 = 4 n 2 d 2 ). In this condition the even diffraction orders of the lattice do not exist and the reflectance values of the odd‐order stopbands is maximized.…”

“…[ 20 ] Moreover, their relatively low dielectric contrast allows spectrally narrow stopbands that are deleterious in light management applications, but allow the detection of very small analyte concentration variations in sensing. [ 21 ] Moreover, sensitivity is enhanced by the large analyte uptake typical of polymer media, [ 22 ] which can swell greatly favoring a much larger periodicity variation with respect to refractive index changes. [ 23 ] The intercalation of an analyte into these polymer DBRs results in an easily detectable spectral (color) change even upon exposure to small environmental concentrations of analytes, which is often visible by the naked eye (see Movies, Supporting Information).…”

All-Polymer Microcavities for the Fluorescence Radiative Rate Modification of a Diketopyrrolopyrrole Derivative

“… 3 , 24 The couple provides the highest dielectric contrast demonstrated for polymer planar microcavities (Δ n = 0.34 in the UV-NIR range) so far. 25 The dye embedded in the cavity is a diketopyrrolopyrrole (DPP) derivative. Diketopyrrolopyrroles are some of the most studied organic dyes for electronics and photonics, 26 including in organic light-emitting diodes and solar cells, 27 due to their tailorable synthesis and high thermal- and photostabilities.…”

Effect of Geometry on the Electromagnetic Wave Transport Properties of Photonic Crystals: Comparison of Top-Flat and Top-Curved Refractive Index Profiles

“…are investigated. In addition, to have a more profound physical insight, many material types are used in photonic crystals, including plasma [32], magnetized plasma [33], porous silicon [34], metamaterials [35], superconductor-Dielectric [36], Dirac semimetals [37], graphene [38], containing semiconductors [39], Anti-Parity-Time-Symmetric [40], Polymeric [41], mu-negative materials [42], etc.…”