Three-dimensional Photonic Crystal Structures Research Articles

Fiber optic probe integrated with colloidal nanoparticles with directional diffraction selectivity for magnetic field vector detection

A fiber optic probe integrated with colloidal nanoparticles with directional diffraction selectivity is proposed for wide-bandwidth magnetic field vector detection. The probe is constructed with the multimode fiber in which the end-surface is integrated with the Fe3O4@C colloidal nanoparticles by a silicone tube. The colloidal nanoparticles form a three-dimensional photonic crystal structure by magnetic field for diffraction selectivity. The lattice constant and diffraction angle are adjusted by the intensity and direction of the magnetic field, respectively. Obtaining the directional diffraction light through the magnetic field-induced photonic band gap shift with the wavelength blue shift and reflectivity change is confirmed by theory and experiment. The results show that the maximum sensitivity reaches up to 19.7 nm/mT in response range from 13 mT to 200 mT. For vector detection, the peak wavelength shift from 740 nm to 485 nm and reflectance shift from 71% to 7% covering the 0–45° region is verified. In addition, the proposed method could decouple intensity and direction of the magnetic field completely. The fiber optic probe integrated with colloidal nanoparticles has wide detection range and high sensitivity with rapid response. It will open up new horizons for inspiring design and application of magnetic field vector detection in robot posture control and motion perception.

Morphology dependent excitation of hybrid Tamm-bandedge state in metal coated opal three-dimensional photonic crystal

The optical Tamm state is a type of electromagnetic mode that exists at the interface between a periodic dielectric structure and a metal layer. While optical Tamm states have recently gained attention as a potential replacement for surface plasmon polaritons in various applications, most of these demonstrations have been limited to one-dimensional periodic dielectric structures, such as Bragg mirrors. In this article, we present a detailed study on the existence of optical Tamm states at the interface between a metal layer and opal-like three-dimensional photonic crystal (3D-PhC) structures, with a focus on two types of devices with different cross-sectional morphologies. One device consisted of a corrugated silver layer on self-assembled PS opals, while the second one was realized by self-assembling PS opals on a thin flat gold film. Our experimental and numerical observations revealed a dip in the reflection spectra for both configurations, but a hybrid Tamm-PhC bandedge state was found to exist only between the corrugated metal layer and 3D-PhC. Importantly, the nature of the hybrid Tamm-PhC bandedge states was found to strongly depend on the thickness of the metal layer. In contrast, no mode hybridization was observed at the interface between the flat metal and 3D-PhC, and the reflection dip in this case corresponded to a PhC edge mode. Our demonstration highlights the potential for realizing cost-effective and integrated hybrid plasmonic-photonic crystal structures for sensitive nanophotonic sensors.

Controllable preparation of SiO2-VO2 films with desired structural color and thermochromic properties based on 3DPC templates

In order to achieve compatible stealth via VO2 in visible and near-infrared bands, the SiO2-VO2 films with desired structural colors and thermochromic properties were successfully prepared based on three-dimensional photonic crystal (3DPC) structure of SiO2 templates. It is found that with the varying diameters of SiO2 spheres, the SiO2-VO2 films appear beautiful red, green, and blue color, respectively. The SiO2-VO2 films keep the same structural color with SiO2 3DPC templates and the good thermochromic properties of VO2. In addition, the reflectivity of the SiO2-VO2 films increased obviously and possessed thermochromic properties in near infrared region when the temperature ranged from 30 °C to 80 °C. The calculation and preparation methods used in this work may provide both theoretical and practical supports for the feasible preparation of SiO2-VO2 films with required colors and thermochromic properties.

Combining Interference Lithography and Two-Photon Lithography for Fabricating Large-Area Photonic Crystal Structures with Controlled Defects

Interference lithography is a promising method for fabricating large-area, defect-free three-dimensional photonic crystal structures which can be used for facilitating the realization of photonic devices with a fast processing time. Although they can be used in waveguides, resonators, and detectors, their repeated regular array patterns can only be used for limited applications. In this study, we demonstrate a method for fabricating large-area photonic crystal structures with controlled defects by combining interference lithography and two-photon lithography using a light-curable resin. By combining regular array structures and controlled patterns, monotonous but large-area regular structures can be obtained. Furthermore, the patterned structures have considerable potential for use in various applications, such as solar cells, sensors, photodetectors, micro-/nano-electronics, and cell growth.

Direct Writing of Microfluidic Three-Dimensional Photonic Crystal Structures for Terahertz Technology Applications.

The direct writing technology was used to create microfluidic three-dimensional terahertz photonic crystal structures (3D-TPCSs) with a glass cement ink, which demonstrated potentials for various terahertz technology applications. By a simple injection of liquid alloy into them, metallic 3D-TPCSs could be created easily at a low cost to solve the challenges of their creation by current approaches. These microfluidic 3D-TPCSs also possessed a specific capability of changing their terahertz properties in real time without structural changes by injecting fluidic media with different dielectric properties into their microfluidic channels, which endowed them the easy integration into various terahertz devices that require terahertz modulation for a wide range of applications. Due to their microsized channel structure and subsequent reduction of terahertz irradiation absorption by water in them, they demonstrated the potential as real time, nondestructive biological and chemical sensors to detect changes occurring in them in the fluidic media with the terahertz time-domain spectroscopy (THz-TDS).

Diffraction Properties and Application of 3D Polymer Woodpile Photonic Crystal Structure

We present a new technique for modification of diffraction and optical properties of photonic devices by surface application of polymer Three-Dimensional (3D) woodpile Photonic Crystal (PhC) structure. Woodpile structure based on IP-Dip polymer was designed and fabricated by Direct Laser Writing (DLW) lithography method based on nonlinear Two-Photon Absorption (TPA). At first, we investigated diffraction properties of woodpile structure with a period of 2 μm. The structure was placed on a glass substrate, and diffraction patterns were measured using laser sources with different wavelengths. After diffraction properties investigation, the fabricated structures were used in optoelectronic devices by their surface application. Our polymer 3D PhC woodpile structures were used for radiation properties modification of light emitting devices - optical fiber and Light Emitting Diode (LED) and for angular photoresponse modification of InGaAsN-based photodiode. The modification of the far-field radiation patterns of optical fiber and LED and spatial modulation of light coupling into photodiode chip with applied structures were measured by goniophotometer. Quality of fabricated structures was analyzed by a Scanning Electron Microscope (SEM).

Highly efficient GPU eigensolver for three-dimensional photonic crystal band structures with any Bravais lattice

A null-space free method with the FFT-based matrix–vector multiplications was proposed to solve the Maxwell equations that model the three-dimensional photonic crystals. The most time-consuming parts of this method were the FFT-based matrix–vector multiplications. In this article, we propose new mathematical formulas to compute the FFT-based matrix–vector multiplications and derive highly efficient algorithms on top of the NVIDIA GPU architecture. The resulting algorithms are approximately two- to threefold faster than the previous algorithms. We have successfully used a single NVIDIA Tesla P100 GPU to solve a set of generalized eigenvalue problems of 5,184,000 dimensions in 17 to 22 seconds for each problem. Furthermore, we ported the codes to a GPU cluster and achieved near linear scalability. To our knowledge, these GPU implementations of the proposed algorithms are the fastest implementations. The schemes can be applied to simulate a three-dimensional photonic crystal with all 14 Bravais lattices. These highly efficient schemes and codes raise possibilities for large-scale and near real-time numerical simulations for novel physical discoveries and engineering applications of photonic crystals.

Gel-Based Artificial Photonic Skin to Sense a Gentle Touch by Reflection.

This work demonstrates that engineering a three-dimensional photonic crystal (3DPC) structure in a highly flexible gel is a potential method to achieve flexible tactile artificial photonic skin (p-skin) for future visible-light communication (VLC). We investigated the photonic output modes of 3DPC-coated gel-based pressure sensors and explored their ability to sense low pressures (<10 kPa) through reflection. Such sensors with high sensitivity, fast response, and adjustable detection range can be fabricated in arrays of dots covering large, complex/uneven surfaces and are promising in the development of stimuli-responsive soft materials for future artificial intelligence, health monitoring, and photonic communication systems.

Crystalline silicon photovoltaic cells used for power transmission from solar-pumped lasers: I. Light trapping concepts

We have proposed a light trapping concept for crystalline silicon photovoltaic (PV) cells used for power transmission from solar-pumped lasers (SPLs) emitting at 1064 nm. The underlying mechanism is multiple reflection between a multilayered angle-selective filter on the front surface and a diffuse reflector on the rear surface of the cell. For the stationary use and optical fiber connection of the SPL-PV combination in which the incident angles of the laser light to the PV cells (ϕ) change within 5–10°, double-cavity bandpass filters realize the required angle selection function. When the SPLs illuminate moving electric vehicles equipped with the PV cells at larger ϕ values, shortpass filters are appropriate. These specially designed angle-selective filters provide significant light trapping performance and consequently absorbances higher than the Yablonovitch limit up to ϕ = 45°. The fact that the present light trapping configuration requires no microfabrication processes is also a great advantage over two- and three-dimensional photonic crystal structures.

Evidence of near-infrared partial photonic bandgap in polymeric rod-connected diamond structures.

We present the simulation, fabrication, and optical characterization of low-index polymeric rod-connected diamond (RCD) structures. Such complex three-dimensional photonic crystal structures are created via direct laser writing by two-photon polymerization. To our knowledge, this is the first measurement at near-infrared wavelengths, showing partial photonic bandgaps for this structure. We characterize structures in transmission and reflection using angular resolved Fourier image spectroscopy to visualize the band structure. Comparison of the numerical simulations of such structures with the experimentally measured data show good agreement for both P- and S-polarizations.

Optical transfer function of three-dimensional photonic crystals by volume holographic recording

We investigate optical transformations by three-dimensional photonic crystals fabricated via holographic lithography. Large-area three-dimensional photonic crystal structures are created by multiple-beam interference in photosensitive materials. We perform calculations of the optical transfer function for monochromatic incident light. Our approach is based on three-dimensional vector rigorous coupled-wave approach, which allows modeling the dynamic interaction of light waves generated by diffraction inside a crystal grating. We analyze the Bragg-conditioned energy transfer for different crystal structures and address the influence of the refractive index contrast. Diffractive-optical properties of the fabricated crystals are investigated by laser scanning and monitoring the transmitted light in three-dimensional angular space. The scan results agree well with the modeling predictions for different crystals and recording photopolymers.

Study of natural photonic crystals in beetle scales and their conversion into inorganic structures via a sol–gel bio-templating route

The origin of the structural colors from several different examples of the weevil and longhorn families (Curculionidae and Cerambycidae, respectively) was investigated by structural and optical characterization techniques. A range of interesting three-dimensional photonic crystal structures operating at visible wavelengths was discovered, including both disordered and ordered non-close-packed lattices of cuticular spheres and bicontinuous diamond-based architectures. The discovered photonic structures display a large variation in lattice constants and dielectric filling fractions and thereby create optical reflectance colors spanning the entire visible range. To transform these bio-polymeric photonic crystals into heat and photo-stable inorganic structures, a low-temperature bio-templating method was developed. Using organic–inorganic hybrid silica sol–gel infiltration–templation chemistry combined with acid-etching template removal, stable inverse photonic structures were fabricated. The inverse structures display good structural quality and vivid reflection properties.

Three-dimensional direct writing of novel sol-gel composites for photonics applications

Two-photon polymerisation of photosensitive materials has emerged as a very promising technique for the fabrication of photonic crystals and devices. In this paper we present our investigations into the structuring by two-photon polymerisation of a new class of photosensitive sol-gel composites exhibiting ultra-low shrinkage. We particularly focus on two composites, the first containing a zirconium alkoxide and the second a nonlinear optical molecule. The three-dimensional photonic crystal structures fabricated using these materials demonstrate high resolution and clear band- stops in the near IR region.

Tunable photonic crystals on a freestanding polymer membrane

Two- and three-dimensional polymer photonic crystal structures are fabricated by multi-beam interference lithography. The cross-linked photonic crystal structures are obtained on a freestanding P(MMA-5% MaBP) membrane by combining with the standard silicon process. The resulting photonic crystal structures swell in response to the sorption of acetone solvent in the surrounding atmosphere. The optical effect of the swelling process is characterized by dynamic diffraction experiments. The results indicate that controlled polymer swelling may be used to tune the period (as well as the thickness, and thus efficiency) of the polymer-based photonic crystal structures on freestanding membranes.

Spontaneous emission control of silicon nanocrystals by silicon three-dimensional photonic crystal structure fabricated by self-aligned two-directional electrochemical etching method

A silicon three-dimensional photonic crystal (3DPC) structure has been fabricated using a self-aligned, two-directional electrochemical etching method. The spectral component of the photoluminescence (PL) for silicon nanocrystals deposited on the 3DPC structures increase at 750 nm and slightly decrease at 800 nm. Time-resolved PL measurements reveal that the radiative recombination lifetime of the silicon nanocrystals on 3DPC structures decreases at 750 nm and increases at 800 nm compared to those on a silicon substrate without 3DPC structures. We conclude that the spontaneous emission control of silicon nanocrystals has been observed using the 3DPC structures.

Ultra-Low Shrinkage Hybrid Photosensitive Material for Two-Photon Polymerization Microfabrication

Investigations into the structuring by two-photon polymerization of a nonshrinking, photosensitive, zirconium sol-gel material are presented. This hybrid material can be photostructured even when it contains up to 30 mol % of zirconium propoxide (ZPO); by varying the material's inorganic content, it is possible to modify and tune its refractive index. The introduction of ZPO significantly increases the photosensitivity of the resulting photopolymer. The fabricated three-dimensional photonic crystal structures demonstrate high resolution and a clear band-stop in the near-IR region. In contrast to common practice, no additional effort is required to precompensate for shrinkage or to improve the structural stability of the fabricated photonic crystals; this, combined with the possibility of tuning this material's optical, mechanical, and chemical properties, makes it suitable for a variety of applications by two-photon polymerization manufacturing.

Two-Photon Polymerization of Hybrid Sol-Gel Materials for Photonics Applications

Two-photon polymerization of photosensitive materials has emerged as a very promising technique for the fabrication of photonic crystals and devices. We present our investigations into the structuring by two-photon polymerization of a new class of photosensitive sol-gel composites exhibiting ultra-low shrinkage. We particularly focus on two composites, the first containing a zirconium alkoxide and the second a nonlinear optical chromophore. The three-dimensional photonic crystal structures fabricated using these materials demonstrate high resolution and clear bandstops in the near IR region.

Fabrication of three-dimensional photonic crystal structures by interferometric lithography and nanoparticle self-assembly

We report a simple approach to fabrication of three-dimensional photonic crystal structures. One-dimensional photoresist patterns (lines) are defined as templates using interferometric lithography and silica nanoparticles are self-assembled around the photoresist patterns using spin coating. Multiple-layer structures are formed by repeating these processing steps. The photoresist patterns are removed through high temperature calcination to fabricate three-dimensional photonic crystals with void channels in a woodpile structure. The optical properties of as-prepared photonic crystal structures are in good agreement with simulation results. This approach provides a versatile and facile technology to fabricate photonic bandgap materials and photonic crystals with defects.

Photonic bandgap of gradient quasidiamond lattice photonic crystal

A three-dimensional (3D) photonic crystal (PhC) structure consisting of gradient quasidiamond lattices was fabricated using multiphoton photopolymerization nanofabrication technique. The photonic bandgap (PBG) of this 3D PhC was experimentally confirmed by reflection and transmission measurements and simulated with finite-difference time domain calculations. The results indicate that a 3D PhC with gradient lattices could effectively expand the width of the PBG and may be beneficial for developing complete-bandgap PhCs with low refractive index materials for applications in polymer based optoelectronic devices and integrated systems.

Fabrication of three-dimensional photonic crystal structures containing an active nonlinear optical chromophore

Direct laser writing by two-photon polymerization of photosensitive materials has emerged as a very promising technique for rapid and flexible fabrication of photonic crystals. In this work, a photosensitive silica sol-gel containing the nonlinear optical chromophore Disperse Red 1 is synthesized, and the two-photon polymerization technique is employed to fabricate three-dimensional photonic crystals with stop-gaps in the near-infrared. The composite material exhibits minimal shrinkage during photopolymerization, eliminating the need for shrinkage compensation or the fabrication of support structures.