Photonic Crystal Matrix Research Articles

Firefly-inspired bipolar information indication system actuated by white light

The indication of information in materials is widely used in our daily life, and optical encoding materials are ideal for information loading due to their easily readable nature and adjustable optical properties. However, most of them could only indicate one type of information, either changing or unchanging due to the mutual interference. Inspired by firefly, we present a non-interfering bipolar information indication system capable of indicating both changing and unchanging information. A photochemical afterglow material is incorporated into the photonic crystal matrix through a high-throughput technique called shear-induced ordering technique, which can efficiently produce large-area photonic crystal films. The indication of changing and unchanging information is enabled by two different utilizations of white light by the afterglow material and photonic crystals, respectively, which overcome the limitations of mutual interference. As a proof of concept, this system is used to indicate the changing photodegradation level of mecobalamin (a photosensitive medicine) and unchanging intrinsic drug information with anti-counterfeiting functionality, which is a promising alternative to instantly ascertain the efficacy of medicine at home where conventional assays are impractical.

Cactus-Inspired Photonic Crystal Chip for Attomolar Fluorescence Multi-analysis.

Automation and efficiency requirements of environmental monitoring are the pursuit of spontaneous sampling and ultrasensitivity for current sensory systems or detection apparatuses. In this work, inspired by cactus hierarchical structures, we develop a cactus-inspired photonic crystal chip to integrate spontaneous droplet sampling and fluorescence enhancement for sensitive multi-analyte detection. A conical hydrophilic pattern on hydrophobic surfaces can give rise to unidirectional Laplace pressure, which drives droplet transport to the assigned photonic crystal site. The nanostructure of photonic crystals has bigger capillarity to drive the droplet wetting uniformly into the photonic crystal matrix while performing prominent fluorescence enhancement by their photonic bandgap. A low to attomolar (2.24 × 10-19 M) fluorescence limit of detection (LOD) sensitivity can be achieved by the synergy of spontaneous droplet sampling and fluorescence enhancement. Focused on eutrophic water problems and algae pollution monitoring, a femtomolar (1.83 × 10-15 M) LOD and identification of various microcystins in urban environmental water can be achieved. The suitable integration of the unidirectional droplet transport by Laplace pressure and fluorescence enhancement by photonic crystals can achieve the spontaneous sampling and signal enhancement for ultratrace detections and sample survey of environmental monitoring and disease diagnosis.

The technology of manufacturing metal-dielectric photonic crystals for THz and millimeter ranges by 3D printing

The article considers the possibility of using 3D printing technologies to manufacture the photonic crystal structures of THz and millimeter ranges. This approach consists of the manufacturing of a polymer photonic crystal matrix by 3D printing based on photopolymerization, followed by filling the voids of the matrix with fusible material that reflects well in the terahertz range (the Wood alloy was used).

Iodine Plasmonic Crystal as the Visible-Range Spectral Filter

We analyse the optical properties of the new hyperbolic metamaterial based on the one-dimensional mesoporous aluminum oxide (Al2O3) photonic crystal film doped by metallic iodine (I2) nanoparticles. The nanocomposite is a metal-dielectric hybrid and combines the classical photonic crystal features (such as photonic bandgaps, light deceleration, negative refraction etc.) with the metallic ones (low-frequency mirroring, plasmons etc.). To get this, we propose to saturate the pores (microcavities) of the periodic aluminum oxide photonic crystal matrix synthesized by the controlled acid etching at its anonization, by the iodine vapor. This way, in the photonic crystal pores, we form the cold plasma of the iodine free electrons, and make the nanocomposite the plasmonic photonic one. Note, that the iodine saturation level defines the plasma frequency which is directly affects the crystal characteristics, so we get them easy-tunable. For example, we offer the two iodine-saturated photonic crystals with various doping level in the pass-and-reflect scheme to spectral filter the optical radiation. At last, we also wish to note that simplicity of the saturation technology makes the iodine plasmonic crystals attractive for the wide commercial usage in the large-scale optic and photonic applications and devices (such as spectral filters, optical amplifiers, high-performance selective mirrors, photonic sensors etc.).

Luminescence relaxation dynamics for planar and rolled-up CdSe nanocrystals in a photonic-crystal matrix

Samples of inverted photonic-crystal films, containing planar and rolled-up (in the form of scrolls) CdSe nanocrystals, are studied. The transmission spectra of these structures are recorded. These spectra (along with the change in colour) confirm the incorporation of nanocrystals into the films. The photoluminescence decay dynamics is investigated. It is shown that the photonic-crystal matrix affects significantly the luminescence kinetics of nanostructures. The differences in the decay curves measured for nanocrystals in a photonic-crystal matrix and for their ensemble on a glass substrate are explained by the influence of the photonic-crystal stop band and the orientational effect of crystalline matrix, which orients anisotropic nanocrystals and prevents them from aggregation. The results obtained may be important for potential applications in optoelectronic devices.

UiO-67 metal-organic gel material deposited on photonic crystal matrix for photoelectrocatalytic hydrogen production.

Robust UiO-67 metal–organic framework nanoparticles have been precisely and uniformly anchored on the surface of a photonic crystal via metal–organic gelation, resulting in a nanoscale UiO-67 composite. Mott–Schottky measurements indicate that UiO-67/B is an n-type semiconductor with electron conduction, and the band gap significantly decreases with the assistance of the photonic crystal matrix with a band gap of 0.75 eV. Benefiting from the abundant photoelectrons trapped from the photonic crystal, good hydrogen evolution reaction performance is achieved under light irradiation. The current density increases from 3.2 to 7.0 mA cm−2 at −0.6 V (vs. RHE) for UiO-67/B. The optimized carrier density obtained from UiO-67/B is apparently increased 2.15 times under light irradiation for 30 min. This work provides a rational strategy to address the photo-capture and energy transfer issues of metal–organic frameworks under visible light irradiation for H2 production in artificial photosynthesis.

Gold nanostructure formation in the photonic crystal matrix by means of MOCVD technique

The matrix of a photonic crystal was deposited with gold nanoparticles and thin films using MOCVD technique. Nanoparticles were obtained in a pulse pressure MOCVD reactor; Me2Au(thd) (thd=2,2,6,6-tetramethyl-3,5-heptanedionato) was used as a precursor. The deposition of thin gold coating was carried out in a stagnant-flow MOCVD reactor, Me2Au(OAc) (OAc=acetate) was used as a precursor. It was demonstrated that deposition conditions affect the morphology of nanoparticles deposited from Me2Au(thd). An increase in the evaporator temperature was found to cause an increase in the concentration of gold nanoparticles on the surface of SiO2 microspheres, whereas their size is almost unchanged. Increasing the deposition temperature results in an increase in the size of the nanoparticles. Using the system of gold nanoparticles – fluorescein, we demonstrated that luminescence is enhanced by a factor of 2 as compared to the pure dye. We performed the deposition of thin gold films onto SiO2 microspheres and demonstrated that the thickness of gold coating is affected by the deposition temperature. Optical characteristics inherent in photonic crystals formed from gold microspheres were studied. The amount of impurities in the films is less than 3%.

Spectral properties of self-assembled polystyrene nanospheres photonic crystals doped with luminescent dyes

Three-dimensional ordered photonic crystals have been fabricated on solid substrates with a self-assembling method starting from a suspension of dye-doped polymeric nanospheres in water. These photonic crystals showed angle-dependent stop band for light transmission and, correspondingly, Bragg reflection peak due to the photonic crystal lattice. Polystyrene nanoparticles of 306nm and 288nm diameter, respectively in the case of the Rhodamine B and Fluored dye, were used to obtain self-assembled photonic crystals. They show 40% reflectance at 610nm for Rhodamine B and 35% reflectance at 574nm for Fluored doped materials. The size of the spheres calculated by Bragg’s law are in good agreement with those evaluated by scanning electron microscopy (SEM). The appropriate choice of sphere diameters results in an overlap between the photonic stop-band and the dye emission spectrum. The photonic crystals showed angle-dependent suppression of spontaneous emission of the dye in the wavelength range of the photonic stop band and enhancement near the band edge. In reflection geometries, spectral narrowing and directional emission, all indicative of stimulated emission, were observed from the active photonic crystal matrix. The results of laser induced emission studies on the dye doped photonic crystals are presented.

Laser emission from self-assembled active photonic crystal matrix

Three-dimensionally ordered photonic crystals were grown using self-assembly technique from Rhodamine-B dye doped polystyrene micro-spheres resulting in a stop band at 611 nm overlapping the emission spectrum of the dye. When excited at a wavelength away from the stop band, using a frequency-doubled Nd:YAG laser, the crystal showed angle- dependent suppression of spontaneous emission of the dye in the wavelength range of the photonic stop band and enhancement at the band edge, in reflection and transmission geometries. Spectral narrowing, a sharp threshold and a highly directional emission, all indicative of stimulated emission, were observed from the active photonic crystal matrix.