Photonic Crystal Research Articles

Inverse opal optical Tamm state for sensing applications

We report the excitation of optical Tamm states (OTS) in inverse opal (IO) - based three-dimensional photonic crystal on a flat metal substrate, validated through both numerical simulations and experimental observations. Large area, uniform Tamm inverse opal (Tamm-IO) structures were fabricated without the use of any corrosive chemicals. Upon infiltration of non-reactive solvents such as methanol and ethanol into the IO, a noticeable shift of the OTS, consistent with our simulations is observed, and the temporal dynamics of the same have been investigated. The experimentally obtained sensitivity is ∼ 110 nm/RIU which is of the same order as the computed value, making the IO OTS to be an attractive sensing tool.

Tunable topological edge state in plasma photonic crystals

In this study, we found a kind of edge state located at the interface between plasma photonic crystals (PPCs) and traditional photonic crystals, which depends on the property of the photonic band gap rather than the surface defect. Simulation and theoretical analysis show that by adjusting the plasma density, we can change the topological characteristics of the photonic band gap of PPCs. This makes it different from the photonic band gap of traditional PCs, and thus excites or closes the topological edge states. We further discussed the influence of plasma parameters on edge state characteristics, and the results showed that as the plasma density increased, the first photonic band gap (PBG) of the PPCs closed and then reopened, resulting in band inversion and a change in the PBG properties of the PPCs. We can control the generation of edge states through plasma and adjust the frequency and strength of the edge states. After the appearance of edge states, as the plasma density further increases, the first PBG of the PPCs will shift towards high frequencies and deepen. The frequency of edge states will shift towards higher frequencies, and their strength will also increase. We increased the first PBG depth of the PPCs by increasing the number of arrays and found that when the number of the PPCs arrays increased, only the intensity of the edge states would increase while the frequency remained unchanged. Therefore, flexible adjustment of edge state frequency and intensity can be achieved through plasma density and array quantity parameters. Our study demonstrates the properties of topological edge states in plasma photonic crystals, which we believe can provide some guidance for applications based on edge states.

Enhanced biosensing with rhombic ring resonator in 2D photonic crystals for proteinuria detection

A two-dimensional (2D) photonic crystal (PC) based biosensor was developed and studied to detect albumin and urea levels in patients with proteinuria. Rhombic ring resonator structures are built with the help of FDTD (Finite Difference Time Domain). After the fields are computed using the 2D-FDTD approach, the normalized transmission spectra are produced by applying the Fast Fourier Transform (FFT) to them. The full width at half maximum (FWHM), Quality factor (Q-factor), Sensitivity, Figure of Merit (FOM), and Limit of Detection (LOD) are 15,466.5, 110 nm/RIU, 0.12 nm, 1100 RIU−1 and 54.34X10−6 RIU respectively, when the resonant wavelength is 1546 nm. The novelty of this the project lies in combining 2D photonic crystal, innovative rhombic ring resonator design and high-performance parameters. The achieved values are notably high, which is a novel achievement in the field of biosensing. The project aims to contribute to the field of biosensors and provide a potential tool for healthcare professionals to monitor diabetes, proteinuria, kidney function and overall health.

Angular excitation of exceptional points and pseudospetra of photonic lattices

Abstract Optical parity-time ( PT ) symmetry has triggered a plethora of theoretical and experimental studies, and as a result non-Hermitian photonics is one of the frontiers of optics today. From unidirectional invisibility and coherent perfect absorbers to wireless power transfer and ultrasensitive sensors, non-hermiticity led to numerous important applications that rely on gain-loss synthetic structures. In particular, one such structure is that of complex photonic lattices that may exhibit exceptional points (EPs) around which the corresponding sensitivity is increased by orders of magnitude. Here, we investigate a new multiparametric family of non-Hermitian lattices that respects PT -symmetry, and examine their spectral sensitivity in terms of pseudospectra, as well, the angular excitation of the underlying EPs.

High-power semiconductor laser with a narrow linewidth based on transverse photonic crystal

Broad-area lasers (BA) are practical for producing high output power. However, under a high current operation, high-order modes are easily excited, resulting in the broadened linewidth. Here, based on mode engineering of double-side transverse photonic crystals (TPCs) combined with a longitudinal high-order surface grating, a narrow-linewidth electrically-pumped broad-area laser with high power emission only using I-line lithography is demonstrated. By matching the high-order modes of the wide main waveguide with TPC bands, the effective volume of the high-order modes is expanded, while the fundamental mode remains unchanged. Then, single-lateral mode operation is achieved by selective pumping only for the main waveguide due to the significant distinction in modal gain between the fundamental mode and the high-order modes. In addition, a 27-order grating is constructed above the main waveguide to keep the laser operating in single-longitudinal mode. In the experiment, the device shows an output power of 115 mW, a lasing wavelength of 1552.94 nm with a side-mode suppression ratio (SMSR) of 59.26 dB, a narrow linewidth of 443 kHz, and a relative intensity noise (RIN) < -135 dB/Hz at 600 mA, thus has the potential to meet the needs in fields such as coherent optical communication and LiDAR.

Photonic crystal topological interface state modulation for nonvolatile optical switching

Phase change materials (PCMs), characterized by high optical contrast (Δn>1), nonvolatility (zero static power consumption), and quick phase change speed (∼ns), provide new opportunities for building low-power and highly integrated photonic tunable devices. Optical integrated devices based on PCMs, such as optical switches and optical routers, have demonstrated significant advantages in terms of modulation energy consumption and integration. In this paper, we theoretically verify the solution for a highly integrated nonvolatile optical switch based on the modulation of the topological interface state (TIS) in the quasi-one-dimensional photonic crystal (quasi-1D PC). The TIS exciting wavelength changes with the crystalline level of the PCM. The extinction ratio (ER) of the topological optical switch is over 18 dB with a modulation length of 9 μm. Meanwhile, the insertion loss (IL) can be controlled within 2 dB. Furthermore, we have analyzed the impact of fabrication errors on the device’s performance. The obtained results show that, the topological optical switch, which changes its “on/off” state by modulating TIS, exhibits enhanced robustness to the fabrication process. We provide an interesting and highly integrated scheme for designing the on-chip nonvolatile optical switch. It offers great potential for designing highly integrated on-chip optical switch arrays and nonvolatile optical neural networks.

3D printed photonic crystals with a complete bandgap in the visible range

3D printed photonic crystals with a complete bandgap in the visible range

Unclonable Encryption-Verification Strategy Based on Bilayer Shape Memory Photonic Crystals.

The ability to reversibly exhibit structural color patterns has positioned photonic crystals (PCs) at the forefront of anti-counterfeiting. However, the security offered by the mere reversible display is susceptible to illicit alteration and disclosure. Herein, inspired by the electronic message captcha, bilayer photonic crystal (BPC) systems with integrated decryption and verification modules, are realized by combining inverse opal (IO) and double inverse opal (DIO) with polyacrylate polymers. When the informationized BPC is immersed in ethanol or water, the DIO layer displayed encrypted information due to the solvent-induced ordered rearrangement of polystyrene (PS) microspheres. The verification step is established based on the different structural colors of the IO layer pattern, which result from the deformation or recovery of the macroporous skeleton induced by solvent evaporation. Moreover, through the evaporation-induced random self-assembly of PS@SiO2 and SiO2 microspheres, unclonable structurally colored identifying codes are created in the IO layer, ensuring the uniqueness upon the verification. The decrypted code in the DIO layer is valid only when the IO layer displays the pattern with the predetermined structural color; otherwise, it is a pseudo-code. This structural color-based "decryption-verification" approach offers innovative anti-counterfeiting applications in nanophotonics.

Preparation of Ag@Au core-shell nanoparticles embedded in TiO2 inverse opal for light harvesting and efficiency enhancement in quantum dot sensitized solar cells

In the fabrication of Quantum dot sensitized solar cells (QDSSCs), it is important to fabricate a photoanode with a high ability to trap photons as well as transfer photogenerated electrons. TiO2 inverse opal (TIO) photonic crystals with their organized porous structures, besides their chemical nature, have unique optical features such as the slow-photon effect, photon localization, and photonic bandgap (PBG). Herein, to improve the efficiency of QDSSCs, gold, silver, and silver/gold core-shell (Ag@Au) plasmonic nanoparticles (nps) are loaded on TIO. The plasmonic nanoparticle-decorated inverse opal improves the light scattering process and provides direct charge transfer tunnels, which can effectively prevent the recombination of electron-hole pairs. In this work, fabricated QDSSCs with TIO (double-layer)/ZnS/CdS/CdSe/ZnSe/ZnS photoanode, and a 6 μm total thickness of the TIO multilayer, has an open circuit voltage (Voc) of 0.745 V and short-circuit current density (JSC) of 16.22 mA/cm2. The obtained results are higher than the common anatase TiO2 (TiO2-A)/ rutile TiO2 (TiO2-R)/QD photoanode. Also, the TIO (double-layer)/Ag@Au/QDs photoanode exhibits JSC=20.3283 mA/cm2, Voc= 0.75 V, and a power conversion efficiency (PCE) of ƞ=10.79 %.

Bio-inspired colloidal photonic crystal pattern with multiple optical variable images

Colloidal photonic crystals (CPCs) are highly significant for display and anti-counterfeiting applications due to their vibrant structural colors and light-manipulating properties. Efficient and extensive CPC patterns is required for practical applications. Additionally, it is essential to incorporate complex optical elements or responsive qualities to the CPC patterns in order to enhance their performances for security applications. Herein, we proposed CPC patterns with alterable images revealed by changes in viewing angle or exposure to certain vapors. The CPC patterns were prepared by inkjet printing method. Through substrate modification to achieve varying wettability, angle-dependent optical adaptable images could potentially be shown by the patterns. The mesoporous silica nanoparticles (MSNs) were employed as building blocks to impart vapor-chromic characteristics to the CPC patterns. The CPC complex patterns responsive optical characteristics rendered them suitable for use in public authentication and anti-counterfeiting applications.

Фотонные кристаллы: оптимизация характеристик и перспективы оптических приложений

Background: Photonic crystals (PCs) have emerged as a new material for light manipulation, providing unprecedented control over light-matter interaction. This unique capacity is due to their periodic dielectric structure, which may produce photonic band gaps that impact photon transmission. Objective: The article summarizes current advances in photonic crystal design and use, focusing on their significance in creating next-generation optical systems. Methods: The article performed a complete literature analysis, concentrating on the most recent PC production and characterization approaches. Innovative techniques like 3D printing, nanoimprint lithography, self-assembly, and advanced computational modelling were studied in depth to optimize their optical characteristics. Results: Recent studies show that PC manufacturing accuracy has increased significantly, allowing for more effective light manipulation and enhanced optical device functioning. Applications such as ultrasensitive sensors, improved optical fibers, and innovative laser designs demonstrate PCs' rising value. Conclusion: The ongoing advancement of photonic crystal technology is laying a solid basis for the next generation of optical devices. These developments improve existing applications and provide opportunities to investigate new functionality in optical and other electromagnetic systems. Incorporating PCs into numerous technical sectors holds the prospect of significant advances in both commercial and scientific fields.

Stretchable Distributed Bragg Reflectors as Strain-Responsive Mechanochromic Sensors.

Mechanochromic materials exhibit color changes upon external mechanical stimuli, finding wide-ranging applications in colorimetric sensing, display technology, and anticounterfeiting measures. Many of these materials rely on fluorescence properties and therefore necessitate external optical or electrical excitation. However, for broader applicability, the detection of color changes by the naked eye only or without complicated detection instrumentation is highly desirable. Photonic crystals offer a promising avenue for attaining such performances. In this work, we present elastomeric distributed Bragg reflectors (DBRs) characterized by a series of photonic bandgaps exhibiting mechanochromic response from the near-infrared to the visible wavelengths. To achieve this, we engineered alternating thin films of a thermoplastic fluoropolymer and a styrene-butadiene copolymer using different elastomeric substrates to attain different behaviors. The reported system demonstrates a reversible and instantaneous shift of the photonic bandgaps in response to 100% strain in multiple deformation cycles. Comparing the DBR stress-strain response with the optical strain response confirms a mechanochromic sensitivity of ∼1.7-6.9 nm/% and ∼80 nm/MPa, with an optical Poisson's ratio in the range 0.3-0.7. All these properties are spectrally dependent, as demonstrated by exploiting the properties of different diffraction order photonic band gaps.

Nanomechanical Crystalline AlN Resonators with High Quality Factors for Quantum Optoelectromechanics.

High-quality factor (Qm) mechanical resonators are crucial for applications where low noise and long coherence time are required, as mirror suspensions, quantum cavity optomechanical devices, or nanomechanical sensors. Tensile strain in the material enables the use of dissipation dilution and strain engineering techniques, which increase the mechanical quality factor. These techniques have been employed for high-Qm mechanical resonators made from amorphous materials and, recently, from crystalline materials such as InGaP, SiC, and Si. A strained crystalline film exhibiting substantial piezoelectricity expands the capability of high-Qm nanomechanical resonators to directly utilize electronic degrees of freedom. In this work, nanomechanical resonators with Qm up to 2.9 × 107 made from tensile-strained 290 nm-thick AlN are realized. AlN is an epitaxially-grown crystalline material offering strong piezoelectricity. Nanomechanical resonators that exploit dissipation dilution and strain engineering to reach a Qm × fm-product approaching 1013 Hz at room temperature are demonstrated. A novel resonator geometry is realized, triangline, whose shape follows the Al-N bonds and offers a central pad patterned with a photonic crystal. This allows to reach an optical reflectivity above 80% for efficient coupling to out-of-plane light. The presented results pave the way for quantum optoelectromechanical devices at room temperature based on tensile-strainedAlN.

Topological photonic quasicrystal alloy

Recently, a concept of topological photonic alloy was proposed by mixing magnetized and non-magnetized gyromagnetic rods in a two-dimensional square photonic crystal that supports tunable Chern bandgaps and robust chiral edge states even at a low concentration of magnetized rods. However, whether such a notion can be extended to non-crystalline systems is still an open question. Here, we theoretically demonstrate that topological photonic quasicrystal alloys can also sustain nontrivial Chern bandgaps and nonreciprocal chiral edge states. More interestingly, compared with the conventional topological photonic alloy with a crystalline lattice, we find that the topological photonic quasicrystal alloy with a non-crystalline lattice needs a higher threshold concentration of magnetized rods to open the Chern bandgap. These results not only broaden our understanding of topological photonic alloy but also offer a platform for exploring the unique properties of topological photonic quasicrystals.

Block Copolymer-Directed Single-Diamond Hybrid Structures Derived from X-ray Nanotomography.

Block copolymers are recognized as a valuable platform for creating nanostructured materials. Morphologies formed by block copolymer self-assembly can be transferred into a wide range of inorganic materials, enabling applications including energy storage and metamaterials. However, imaging of the underlying, often complex, nanostructures in large volumes has remained a challenge, limiting progress in materials development. Taking advantage of recent advances in X-ray nanotomography, we noninvasively imaged exceptionally large volumes of nanostructured hybrid materials at high resolution, revealing a single-diamond morphology in a triblock terpolymer-gold composite network. This morphology, which is ubiquitous in nature, has so far remained elusive in block copolymer-derived materials, despite its potential to create materials with large photonic bandgaps. The discovery was made possible by the precise analysis of distortions in a large volume of the self-assembled diamond network, which are difficult to unambiguously assess using traditional characterization tools. We anticipate that high-resolution X-ray nanotomography, which allows imaging of much larger sample volumes than electron-based tomography, will become a powerful tool for the quantitative analysis of complex nanostructures and that structures such as the triblock terpolymer-directed single diamond will enable the generation of advanced multicomponent composites with hitherto unknown property profiles.

Hollow cylindrical three-dimensional nonlinear photonic crystal for annular beam generation

We present a hollow cylindrical three-dimensional nonlinear photonic crystal for annular beam shaping. By inducing a modification with the near-infrared femtosecond laser inside lithium niobate, we experimentally achieve second-order nonlinear optical coefficient modulation in three dimensions. The center dark spot ratio of the generated annular beam can be adjusted by varying the hollow ratio of the cylindrical structure. To demonstrate the controlled linear variation of the annular distribution, we generate annular beams with center dark spot ratios ranging from 0 to 0.7. Furthermore, we illustrate the feasibility of the generated annular beam in optical trapping by manipulating glass powder particles with diameters of 4–10 μm in water. Our hollow cylindrical structure owns effective control of beam dark spot ratio, while providing a tool for generating annular beam.

Dez River Araphid/Bi-raphid diatoms for nano-optic applications

Micro and nano-silica structure technology is sumptuous and has empirical intricacies, so employing natural nanostructures can be inexpensive and more environmentally friendly. This green capacity can be the starting point of engineering and nanotechnology studies. Diatoms are good candidates for these structures, abundant in water and soil. They are types of algae with silicate frustules that may have periodic structures. Diatoms have a high potential to be used as sensors. They are very similar to photonic crystals.In this article, for the first time, some Araphid and Bi-raphid diatoms of the Dez River have been reported, and some of their optical characteristics have been investigated. The studied Dez-river Bi-raphid diatom shows no photonic band gap. Its periodic structure shows a maximum reflectance at λ=600nm, which seems to be an appropriate wavelength for the effective refractive index guiding mechanism through a siliceous defect. The studied Araphid diatoms show that the PBG waveguiding mechanism is achieved at the wavelength of about λ=690nm, too. This structure can be used as a narrow-band filter with a more than %95 efficiency for the mentioned wavelength. So the extraordinary structure of the Dez River Araphid and Bi-raphid diatoms can overtake the boundaries of the most advanced lithography techniques without spending time and money.

Vortex light bullets in rotating Quasi-Phase-Matched photonic crystals

We present a methodology for the generation of stable vortex light bullets (LBs) in rotating Quasi-Phase-Matched (QPM) photonic crystals with quadratic nonlinearity. The photonic crystal is designed with a checkerboard structure, which is feasible to realize by using contemporary technological advancements. Within this framework, square- and rhombus-shaped LBs are observed, both of which are constructed as four-peak vortex mode. The control parameters include the effective phase mismatch, power, rotating frequency, and the size of checkerboard cells. These parameters play key roles in determining the distribution and stability domains of vortex LBs. In contrast to the stable vortex solitons observed in two-dimensional (2D) quadratic systems, the LBs investigated in the 3D rotating system exhibit narrower stability domains within the system’s parameter space. The rotating frequency results in the transition of LBs from quadrupole to traditional vortex modes. Potential applications of this research lie in the field of optical communications and information processing.

Quantized Dirac cones generated by one-dimensional multi-connected optical waveguide networks

This paper introduces one-dimensional (1D) limited periodic multi-connected vacuum optical waveguide networks (LPMVOWN), a fascinating class of photonic bandgap structures designed to produce Dirac cones. Unlike previously explored materials such as graphene, metamaterials, photonic crystals, and phononic crystals, optical waveguide networks produce a sequence of Dirac cones while also exhibiting quantum properties in the angular frequencies corresponding to these cone points. We used the topological translational periodicity inherent in optical waveguide networks to establish analytical relationships governing the angular frequency, slope, and number of Dirac cones generated by the system. These relationships are used to elucidate how parameters like the waveguide length ratio of the units, the number of waveguide connections, and the waveguide material influence these properties. This analysis improves our understanding of linear, degenerate, and concatenated energy band structures, as well as their potential applications. Furthermore, it offers valuable insights for enhancing the control of electromagnetic wave propagation and provides experimentalists with greater convenience and flexibility in their research endeavours.

Compact Topological Edge States in Flux-Dressed Graphenelike Photonic Lattices.

Flat band lattice systems promote the appearance of perfectly compact bulk states, whereas topology favors edge localization. In this work, we report the existence of compact topological edge states on flux-dressed photonic graphene ribbons. We found that robust localization is achieved through a synergy of Aharonov-Bohm caging and topological protection mechanisms. The topological nontriviality of the compact edge states is characterized through both theoretical derivations and experimental observations of an integer Zak phase obtained from the mean chiral displacement. Experiments are performed using direct laser writing of a graphene ribbon photonic lattice having 0 or π effective magnetic fluxes. Mode stability is demonstrated by the exceptional localization of the edge compact mode and its resilience to fabrication tolerances and input phase deviations. Our findings demonstrate the existence of perfectly compact topological edge states, as a concrete and promising example of synergy in between flat band physics and topology.