Showing papers on "Photonic crystal published in 2021"
74 citations
TL;DR: In this article, a topological photonic crystal design was proposed to generate coherent orbital angular momenta beams of high quantum numbers from light travelling in leaky circular orbits at the interface between two topologically dissimilar photonic structures.
Abstract: The quantum Hall effect involves electrons confined to a two-dimensional plane subject to a perpendicular magnetic field, but it also has a photonic analogue1–6. Using heterostructures based on structured semiconductors on a magnetic substrate, we introduce compact and integrated coherent light sources of large orbital angular momenta7 based on the photonic quantum Hall effect1–6. The photonic quantum Hall effect enables the direct and integrated generation of coherent orbital angular momenta beams of large quantum numbers from light travelling in leaky circular orbits at the interface between two topologically dissimilar photonic structures. Our work gives direct access to the infinite number of orbital angular momenta basis elements and will thus enable multiplexed quantum light sources for communication and imaging applications. A topological photonic crystal design directly generates light that carries orbital angular momentum with high quantum numbers. The beam contains several different states at the same time, promising integrated and multiplexed light sources.
67 citations
TL;DR: In this article, the non-close-packed photonic crystal consisting of ZnS nanospheres and polymers, which have similar refractive indices with guanine nanocrystals and cytosols, respectively, are constructed by a two-step filling strategy.
Abstract: Both the nonclose-packed structure and the large refractive index contrast of guanine nanocrystals and cytosols in iridophores play a vital role in the dynamic camouflage of chameleons, including the bright skin color and color tuning sensitivity to external stimulus. Here, the nonclose-packed photonic crystals consisting of ZnS nanospheres and polymers, which have similar refractive indices with guanine nanocrystals and cytosols, respectively, are constructed by a two-step filling strategy. ZnS@SiO2 nanospheres are self-assembled to build intermediate close-packed photonic crystals followed by filling polymers in their interstices. The nonclose-packed photonic crystal is successfully achieved when the silica portion is etched by HF solution and refilled by polymers. Excitingly, the stimulus response of the designed photonic crystal is as sensitive as the skin of chameleons due to the similar contrast of refractive indices and nonclose-packed structure. The reflection peak of the structure can blue-shift more than 200 nm as the temperature increases from 30 to 55 °C or under 20% compressional strain. This work not only builds the nonclose-packed photonic crystals by introducing a two-step filling strategy but also proves that high refractive contrast in photonic crystals is an effective strategy to achieve ultrasensitivity, which is highly desirable for various applications.
64 citations
TL;DR: A broadband omnidirectional OTS in a heterostructure composed of a Cr layer and a 1D PhC containing layered hyperbolic metamaterials with an angle-insensitive photonic band gap is realized and broadband wide-angle absorption can be achieved.
Abstract: Recently, broadband optical Tamm states (OTSs) in heterostructures composed of highly lossy metal layers and all-dielectric one-dimensional (1D) photonic crystals (PhCs) have been utilized to realize broadband absorption. However, as the incident angle increases, the broadband OTSs in such heterostructures shift towards shorter wavelengths along the PBGs in all-dielectric 1D PhCs, which strongly limits the bandwidths of wide-angle absorption. In this paper, we realize a broadband omnidirectional OTS in a heterostructure composed of a Cr layer and a 1D PhC containing layered hyperbolic metamaterials with an angle-insensitive photonic band gap. Assisted by the broadband omnidirectional OTS, broadband wide-angle absorption can be achieved. High absorptance (A > 0.85) can be remained when the wavelength ranges from 1612 nm to 2335 nm and the incident angle ranges from 0° to 70°. The bandwidth of wide-angle absorption (0°-70°) reaches 723 nm. The designed absorber is a lithography-free 1D structure, which can be easily fabricated under the current magnetron sputtering or electron-beam vacuum deposition technique. This broadband, wide-angle, and lithography-free absorber would possess potential applications in the design of photodetectors, solar thermophotovoltaic devices, gas analyzers, and cloaking devices.
63 citations
TL;DR: In this article, the authors examine various types of photonic crystal sensors, such as waveguides, nanoresonators, LX resonators, holes, multi-channel resonators and fibers.
Abstract: Photonic crystals are nanoscale structures that affect the motion of photons. The strong light limitation in photonic crystals and the adjustment of its structural parameters have led to the emergence of photonic crystal biosensors. Moreover, the use of holes as a feature of photonic crystals has resulted in sensors that are very sensitive to low refractive index changes with a small sensing area, which offers flexibility and integration on single-chip systems. Using emerging optofluidic technology, label-free biosensors are on the rise. In this review, we examine various types of photonic crystal sensors, such as waveguides, nanoresonators, LX resonators, holes, multi-channel resonators, nano RINGS resonators, and fibers. These sensors are based on the measurement of biomolecules and the refractive index properties that have been identified. Finally, a variety of challenges and guidelines for the construction of label-free diagnostic biosensors are examined.
61 citations
TL;DR: In this article, the authors reviewed the most common and vital optical elements based on photonic crystals (PhC) such as logic gates, power splitter and polarization splitter, sensors, absorbers for solar thermophotovoltaic applications and electrically pumped lasers.
Abstract: In 1987, Yablonovitch and John proposed an artificial dielectric structure known as Photonic crystals (PhCs) consisting of periodic and random variation of the refractive index to manipulate the flow of light. The photonic devices realized on PhCs can take advantage of the ability to tailor the propagation of the electromagnetic field in these structures on a microscopic scale. Besides, the devices with small footprints can be realized. In recent years, several interesting devices based on PhCs are proposed which comprises small radius bent waveguides (hereafter represented as WGs), miniaturized resonator cavities, and Y-branches, among others. These extraordinary features can lead to the development of a dense integrated circuit. However, the PhC technology is still new and there is a need to investigate this topic more extensively. In this paper, we have reviewed the most common and vital optical elements based on PhCs such as logic gates, power splitter, polarization splitter, sensors, absorbers for solar thermophotovoltaic applications and electrically pumped lasers to sum up the recent developments in this hot topic. These devices show better performance and a small footprint in comparison with conventional photonic devices.
58 citations
TL;DR: In this paper, a structure based on one-dimensional photonic crystals that can be used for both angle sensing and refractive index sensing is proposed, which is achieved by optical Tamm state.
Abstract: In this article, a structure based on one-dimensional photonic crystals that can be used for both angle sensing and refractive index sensing is proposed, which is achieved by optical Tamm state. Under Bragg scattering, its features are investigated by the transfer matrix method. This sensing structure is based on a multi-frequency absorption structure, which can achieve an absorption rate higher than 0.9 for three to four frequency points at the same time. The studied results demonstrate that the absorption peaks of such an absorption structure can be changed from three to four by adjusting the number of periods and silver layer thickness. Absorption peaks can occur red and blue shifts employing tailoring the thickness of defect and the angle of the incident light. By altering the thickness of the defect and the number of periods, the interval between the absorption peaks can be dominated. They are all with high-quality factors and can be used to bring about a high absorption sensor for the refractive index or angle. When it acts as a refractive index sensor, the operating range can cover from 2 to 2.7, whose sensitivity and average figure of merit are 32.3 THz/RIU and 100. If the presented device is used as an angle sensor, those values will become 0.5 THz/degree and 1.2, and its measuring range is from 25° to 70°. It can be said that the emergence of this special sensing structure will be possible to have a broad application prospect in the field of measurement.
58 citations
TL;DR: In this paper, a method to realize a rainbow concentrator of topological photonic states based on the synthetic dimension concept is proposed, where the translational degree of freedom of the nanostructures inside the unit cell of a two-dimensional photonic crystal is constructed using a translational deformation, which gives rise to robust interface states at different frequencies.
Abstract: Synthetic dimension provides a new platform for realizing topological photonic devices. Here, we propose a method to realize a rainbow concentrator of topological photonic states based on the synthetic dimension concept. The synthetic dimension is constructed using a translational degree of freedom of the nanostructures inside the unit cell of a two-dimensional photonic crystal. The translational deformation induces a nontrivial topology in the synthetic dimension, which gives rise to robust interface states at different frequencies. The topological rainbow can trap states with different frequencies, controlled by tuning the spatial modulation of interface state group velocities. The operation frequency as well as the bandwidth of the topological rainbow can be easily tuned by controlling the band gap of the photonic crystal. The topological principle can be applied to photonic crystals of any symmetry and arbitrary material composition, as long as a complete band gap exists. This Letter provides a new and general scheme for the realization of a topological rainbow concentrator and will be useful for the development of topological photonic devices.
53 citations
TL;DR: In this article, nanoscale pores in silicon layers are exploited to model and optimize a one-dimensional hybrid graphene-porous silicon photonic crystal biosensor, and the physical nature of the proposed sensor is based on Tamm resonance.
Abstract: In this paper, nanoscale pores in silicon layers are exploited to model and optimize a one-dimensional hybrid graphene-porous silicon photonic crystal biosensor. The physical nature of the proposed sensor is based on Tamm resonance. The transfer matrix method is applied to detect the change of the index of refraction in an aqueous solution. The proposed model is (PSi1/PSi2)N/G/Substrate, in which PSi1 and PSi2 are porous silicon layers with different porosities, N is the number of periods, and G is the number of graphene layers. The numerical simulations show that the proposed sensor has good performance. The variation of the number of periods, number of graphene layers, porosities, thicknesses of silicon layers, incident angles, and the sample layer thickness affect the performance of the sensor. By varying these parameters, the sensitivity and figure of merit of the sensor can be controlled. The study shows that the sensitivity and figure of merit of the proposed sensor reach 4.75 THz/RIU and 475RIU−1, respectively. The proposed sensor has a good capability in biological detection within terahertz. It is the first time, to our knowledge, that graphene has been used to excite the Tamm resonance using the photonic crystal of porous silicon and using it in biosensing applications.
53 citations
TL;DR: In this paper, the second-harmonic generation (SHG) via nonlinear interaction of double topological valley-Hall kink modes in all-dielectric photonic crystals (PhCs) is demonstrated.
Abstract: Nonlinear topological photonics, which explores topics common to the fields of topological phases and nonlinear optics, is expected to open up a new paradigm in topological photonics. Here, we demonstrate second-harmonic generation (SHG) via nonlinear interaction of double topological valley-Hall kink modes in all-dielectric photonic crystals (PhCs). We first show that two topological frequency band gaps can be created around a pair of frequencies, ${\ensuremath{\omega}}_{0}$ and $2{\ensuremath{\omega}}_{0}$, by gapping out the corresponding Dirac points in two-dimensional honeycomb PhCs. Valley-Hall kink modes along a kink-type domain wall interface between two PhCs placed together in a mirror-symmetric manner are generated within the two frequency band gaps. Importantly, through full-wave simulations and mode dispersion analysis, we demonstrate that tunable, bidirectional phase-matched SHG via nonlinear interaction of the valley-Hall kink modes inside the two band gaps can be achieved. In particular, by using Stokes parameters associated with the magnetic part of the valley-Hall kink modes, we introduce the concept of SHG directional dichroism, which is employed to characterize optical probes for sensing chiral molecules. Our work opens up avenues toward topologically protected nonlinear frequency mixing and active photonic devices implemented in all-dielectric material platforms.
51 citations
TL;DR: The design of proposed logic gates works on beam interference principle and operates efficiently by changing phase of light beams at 1550 nm wavelength and is implemented with only one structure with variations in the phase of applied input signals.
Abstract: We propose a photonic crystal-based all-optical AND, OR, and XOR logic gates using square lattice silicon rods with air background. The design of proposed logic gates works on beam interference principle and operates efficiently by changing phase of light beams at 1550 nm wavelength. The proposed AOX logic gates are implemented with only one structure with variations in the phase of applied input signals. Simulation and verification of design are done by using finite-difference time-domain method. The design offers a contrast ratio of 33.05 dB, 10.50 dB, and 8.29 dB of proposed AND, OR, and XOR logic gates correspondingly with optimized refractive index and silicon rod radius values.
TL;DR: In this paper, the authors proposed an angle-insensitive photonic band gap (PBG) in one-dimensional binary photonic crystal (PC) composed of alternating dielectric and hyperbolic metamaterial (HMM) layers.
TL;DR: In this paper, the authors analyzed the scattering properties of twisted bilayer photonic crystal slabs through a high-dimensional plane wave expansion method, which is applicable for arbitrary twist angles and does not suffer from the limitations of the commonly used supercell approximation.
Abstract: We analyze scattering properties of twisted bilayer photonic crystal slabs through a high-dimensional plane wave expansion method. The method is applicable for arbitrary twist angles and does not suffer from the limitations of the commonly used supercell approximation. We show strongly tunable resonance properties of this system which can be accounted for semianalytically from a correspondence relation to a simpler structure. We also observe strongly tunable resonant chiral behavior in this system. Our work provides the theoretical foundation for predicting and understanding the rich optical physics of twisted multilayer photonic crystal systems.
TL;DR: In this article, the authors review the recent realizations of semiconductor topological photonic crystals and discuss topological waveguides in valley photonic crystal, which have received increasing attention because of their simple realization.
Abstract: Topological photonics provides a novel route for designing and realizing optical devices with unprecedented functionalities. Topological edge states, which are supported at the boundary of two photonic systems with different band topologies, enable robust light transport immune to structural imperfections and/or sharp bends in waveguides. Furthermore, the topological edge states are expected to revolutionize cavity-based optical devices such as lasers. Optical devices with built-in topological protection with a small footprint are fascinating as on-chip optical devices for low-loss and functional photonic integrated circuits. Semiconductor photonic crystals are promising platforms enabling the miniaturization of topological optical devices. Herein, we review the recent realizations of semiconductor topological photonic crystals. In particular, we discuss topological waveguides in valley photonic crystals, which have received increasing attention because of their simple realization. In addition, we provide recent demonstrations of topological nanocavities, which are another key component of topological nanophotonics. Progress in semiconductor topological photonic crystals will propel the use of topological photonic devices in various applications as well as deepen the understanding of topological photonic phenomena at the wavelength scale.
TL;DR: In this paper, a coupled-mode theory for low-angle twisted bilayer honeycomb photonic crystals was proposed, and a phase diagram was constructed to correlate the twist angle and separation dependencies to the photonic magic angles.
Abstract: The new physics of magic-angle twisted bilayer graphene (TBG) motivated extensive studies of flat bands hosted by moire superlattices in van der Waals structures, inspiring the investigations into their photonic counterparts with potential applications including Bose-Einstein condensation. However, correlation between photonic flat bands and bilayer photonic moire systems remains unexplored, impeding further development of moire photonics. In this work, we formulate a coupled-mode theory for low-angle twisted bilayer honeycomb photonic crystals as a close analogy of TBG, discovering magic-angle photonic flat bands with a non-Anderson-type localization. Moreover, the interlayer separation constitutes a convenient degree of freedom in tuning photonic moire bands without high pressure. A phase diagram is constructed to correlate the twist angle and separation dependencies to the photonic magic angles. Our findings reveal a salient correspondence between fermionic and bosonic moire systems and pave the avenue toward novel applications through advanced photonic band or state engineering.
TL;DR: In this article, a new class of optical parametric oscillators based on a 20-μm-long semiconductor photonic crystal cavity and operating at telecom wavelengths is reported.
Abstract: We report a new class of optical parametric oscillators, based on a 20-μm-long semiconductor photonic crystal cavity and operating at telecom wavelengths. Because the confinement results from Bragg scattering, the optical cavity contains a few modes, approximately equispaced in frequency. Parametric oscillation is reached when these high-quality-factor modes are thermally tuned into a triply resonant configuration, whereas any other parametric interaction is strongly suppressed. The lowest pump power threshold is estimated to be 50–70 μW. This source behaves as an ideal degenerate optical parametric oscillator, addressing the needs in the field of quantum optical circuits and paving the way towards the dense integration of highly efficient nonlinear sources of squeezed light or entangled photons pairs. Photonic crystal-based optical parametric oscillators have remained elusive but have finally been demonstrated. Operating at telecom wavelengths, the source may prove particularly useful in quantum optics applications.
TL;DR: In this article, the authors present a direct quantitative evaluation of topological photonic edge eigenstates and their transport properties in the telecom wavelength range using phase-resolved near-field optical microscopy.
Abstract: Topological on-chip photonics based on tailored photonic crystals (PhCs) that emulate quantum valley-Hall effects has recently gained widespread interest owing to its promise of robust unidirectional transport of classical and quantum information. We present a direct quantitative evaluation of topological photonic edge eigenstates and their transport properties in the telecom wavelength range using phase-resolved near-field optical microscopy. Experimentally visualizing the detailed sub-wavelength structure of these modes propagating along the interface between two topologically non-trivial mirror-symmetric lattices allows us to map their dispersion relation and differentiate between the contributions of several higher-order Bloch harmonics. Selective probing of forward- and backward-propagating modes as defined by their phase velocities enables direct quantification of topological robustness. Studying near-field propagation in controlled defects allows us to extract upper limits of topological protection in on-chip photonic systems in comparison with conventional PhC waveguides. We find that protected edge states are two orders of magnitude more robust than modes of conventional PhC waveguides. This direct experimental quantification of topological robustness comprises a crucial step toward the application of topologically protected guiding in integrated photonics, allowing for unprecedented error-free photonic quantum networks.
Journal Article•
TL;DR: The authors combine nanostructured back-gate insulators with a continuous layer of graphene to demonstrate an electrically tunable two-dimensional photonic crystal suitable for controlling the propagation of surface plasmon polaritons.
Abstract: Photonic crystals are commonly implemented in media with periodically varying optical properties. Photonic crystals enable exquisite control of light propagation in integrated optical circuits, and also emulate advanced physical concepts. However, common photonic crystals are unfit for in-operando on/off controls. We overcome this limitation and demonstrate a broadly tunable two-dimensional photonic crystal for surface plasmon polaritons. Our platform consists of a continuous graphene monolayer integrated in a back-gated platform with nano-structured gate insulators. Infrared nano-imaging reveals the formation of a photonic bandgap and strong modulation of the local plasmonic density of states that can be turned on/off or gradually tuned by the applied gate voltage. We also implement an artificial domain wall which supports highly confined one-dimensional plasmonic modes. Our electrostatically-tunable photonic crystals are derived from standard metal oxide semiconductor field effect transistor technology and pave a way for practical on-chip light manipulation. Traditional photonic crystals consist of periodic media with a pre-defined optical response. Here, the authors combine nanostructured back-gate insulators with a continuous layer of graphene to demonstrate an electrically tunable two-dimensional photonic crystal suitable for controlling the propagation of surface plasmon polaritons.
TL;DR: In this article, the authors focus on bottom-up assembled photonic crystals and review the significant advances that have been made in their use as label-free sensors, including their structural design, constituent materials, fabrication strategy, and sensing working principles.
Abstract: Photonic crystals (PhCs) display photonic stop bands (PSBs) and at the edges of these PSBs transport light with reduced velocity, enabling the PhCs to confine and manipulate incident light with enhanced light-matter interaction. Intense research has been devoted to leveraging the optical properties of PhCs for the development of optical sensors for bioassays, diagnosis, and environmental monitoring. These applications have furthermore benefited from the inherently large surface area of PhCs, giving rise to high analyte adsorption and the wide range of options for structural variations of the PhCs leading to enhanced light-matter interaction. Here, we focus on bottom-up assembled PhCs and review the significant advances that have been made in their use as label-free sensors. We describe their potential for point-of-care devices and in the review include their structural design, constituent materials, fabrication strategy, and sensing working principles. We thereby classify them according to five sensing principles: sensing of refractive index variations, sensing by lattice spacing variations, enhanced fluorescence spectroscopy, surface-enhanced Raman spectroscopy, and configuration transitions.
TL;DR: In this paper, a three-band narrowband perfect absorber based on bulk Dirac semi-metallic (BDS) metamaterials was designed for optical switching, biochemical imaging, and space detection.
Abstract: In this paper, we designed a three-band narrowband perfect absorber based on bulk Dirac semi-metallic (BDS) metamaterials. The absorber consists of a hollow Dirac semi-metallic layer above, a gold layer below and a photonic crystal slab (PCS) in the middle. The study found that the terahertz wave absorber achieved three perfect absorption rates of more than 95% in the range of 1 to 2.4 THz. The minimum bandwidth (FWHM) is 0.02 THz, and the maximum quality factor (Q) is 106. A reasonable explanation of high absorption can be obtained by impedance matching, electric dipole and other principles. The absorption spectra of the two polarizations show different responses at different incident angles. In addition, we also obtained the influence of the structural parameters of the upper layer of the metamaterial on the absorption performance. We defined the refractive index sensitivity (S) with a maximum sensitivity of 0.1525 THz RIU-1 and a highest quality factor (FOM) of 4.26 in the refractive index range of 1 to 1.8. The maximum adjustable range is 0.06 THz in the Fermi energy range of 60 to 140 meV. Because of its excellent characteristics, our absorber will have good development prospects in the fields of optical switching, biochemical imaging, and space detection.
TL;DR: In this article, a novel design of an optical biosensor will be used as a tuberculosis detector based on a resonance cavity with high sensitivity in one-dimensional photonic crystals demonstrated theoretically.
Abstract: Tuberculosis is one of the most widespread infectious and deadliest diseases in the world. The death percentage is larger than that in the case of the current Coronavirus. Bio-photonic sensors represent a promising option for developing reliable, simple, and affordable tools for the effective detection of tuberculosis. In this paper, a novel design of an optical biosensor will be used as a tuberculosis detector based on a resonance cavity with high sensitivity in one-dimensional photonic crystals demonstrated theoretically. The results show that the increase of the defect layer thickness shifts the defect mode to a longer wavelength region. Besides, it is shifted to a shorter wavelength region via the increase of the incidence angle. The change in thickness of the defect layer and incident angle of light cause an optimization for our suggested structure and the sensitivity reaches 1390 nm/RIU. Our structure is very simple for industrial design.
TL;DR: In this article, an all-optical half-subtractor is designed and simulated using two-dimensional photonic crystals and the FDTD method is used in the simulation of light propagation in the structure.
Abstract: In this research, an all-optical half-subtractor is designed and simulated using two-dimensional photonic crystals. First, a photonic crystal structure is created using Si rods in the air context to obtain the optical half-subtractor. Afterward, using point and line defects, two waveguides are created for the input and two waveguides are created for the outputs. A high logical value and a low logical value are defined based on the optical power in each port. The FDTD method is used in the simulation of light propagation in the structure. The simulation results show that the designed half-subtractor has high optical power values for logic “1” and low values for logic “0”. The small size of the designed structure is among the advantages of this structure. Moreover, given that this half-subtractor is devoid of ring resonators, it can be used in high-speed integrated optical circuits. Another advantage of the proposed half-subtractor is that the optical powers in the outputs are similar in the high and low optical states.
TL;DR: This work theoretically and experimentally achieves large-area one-way transport by using heterostructures consisting of a domain of an ordinary photonic crystal sandwiched between two domains of magnetic photonic crystals.
Abstract: We have theoretically and experimentally achieved large-area one-way transport by using heterostructures consisting of a domain of an ordinary photonic crystal sandwiched between two domains of magnetic photonic crystals. The nonmagnetized domain carries two orthogonal one-way waveguide states which have amplitude uniformly distributed over a large area. We show that such one-way waveguide states can be used to abruptly narrow the beam width of an extended state to concentrate energy, and the transport is robust against different kinds of defects and imperfections. They are also immune to the Anderson-type localization when large randomness is introduced.
25 Apr 2021
TL;DR: Topological photonics is an emerging field that attracts enormous interest for its novel ways to engineer the flow of light as mentioned in this paper, and with the help of topological protection, the surface modes of topologica...
Abstract: Topological photonics is an emerging field that attracts enormous interest for its novel ways to engineer the flow of light. With the help of topological protection, the surface modes of topologica...
TL;DR: In this article, the characteristics and development of femtosecond laser direct writing, spatial light modulator-based fabrication and interference-based approaches are reviewed and typical applications and approaches related to the manufacturing of cutting-edge optical devices including microlens arrays, micro/nano gratings, photonic crystals, and optical fibers are summarized.
Abstract: The unique advantages of surface and volume processing enabled by femtosecond laser fabrication makes it one of the most powerful tools for manufacturing optical and photonic devices based on complex three-dimensional structures with diverse functions. In this review, we focus on the recent advancements of femtosecond laser fabrication technologies and their versatile applications in different fields (e.g., nanotechnology, soft robotics, optics, and optoelectronics). Herein, the characteristics and development of laser direct writing, spatial light modulator-based fabrication and interference-based approaches are reviewed. Furthermore, typical applications and approaches related to the manufacturing of cutting-edge optical devices including microlens arrays, micro/nano gratings, photonic crystals, and optical fibers are summarized. Finally, the current challenges and emerging trends of this technology are discussed.
TL;DR: In this article, the authors proposed a two-dimensional gain and loss sections to enable high peak power short-pulse operation in the fundamental mode while suppressing lasing in higher-order modes to avoid laser instability.
Abstract: Realizing high-peak-power (tens to hundreds of watts or higher) short-pulse (tens of picoseconds or less) operation in semiconductor lasers is crucial for state-of-the-art applications including eye-safe high-resolution remote sensing and non-thermal ultrafine material processing. However, it has been challenging to introduce mechanisms that enable stable high-peak-power short-pulse operation in conventional semiconductor lasers. Here, we propose photonic crystal lasers that have two-dimensionally arranged gain and loss sections to enable high-peak-power short-pulse operation in the fundamental mode while suppressing lasing in higher-order modes to avoid laser instability. On the basis of this concept, we experimentally realize a high peak power of ~20 W and a short pulse width of ~35 ps with an injection current of only 3-4 A using a 400-μm-diameter device and theoretically predict that even higher peak power (>300 W) can be achieved in a 1-mm-diameter device. Our results will contribute to the realization of next-generation laser sources for the aforementioned applications. By using engineered gain and loss sections in a photonic crystal laser, pulses with a peak power of ~20 W and pulse width of ~35 ps have been experimentally demonstrated and even higher peak power operation (>300 W) has been theoretically predicted.
Rice University1, Florida Polytechnic University2, Purdue University3, Shenzhen University4, Shandong University of Science and Technology5, Bundelkhand Institute of Engineering & Technology6, University of Southern Denmark7, Shandong University of Technology8, Southern University of Science and Technology9, National University of Singapore10
TL;DR: In this paper, the authors describe the fundamentals of self-assembled colloidal plasmonic nanostructures and various applications of such devices and discuss the advancements in the self-assembly based plasmoric PC and their applications.
29 Mar 2021
TL;DR: The temperature response of CLCs, comprising of dynamic reflection color changes upon variation of temperature, can be exploited using material systems consisting of small mesogenic molecules, polymerdispersed liquid crystals (PDLCs), polymer-stabilized liquid crystal (PSLCs) or liquid-crystalline polymers.
Abstract: Cholesteric liquid crystals (CLCs) are a major class of photonic materials that display selective reflection properties arising from their helical ordering The temperature response of CLCs, comprising of dynamic reflection color changes upon variation of temperature, can be exploited using material systems consisting of small mesogenic molecules, polymer‐dispersed liquid crystals (PDLCs), polymer‐stabilized liquid crystals (PSLCs), or liquid‐crystalline polymers Taking advantage of the easy processability and flexibility of the molecular design, these temperature‐responsive CLCs have been fabricated into different forms of photonic devices, including cells, coatings, free‐standing films, and three‐dimensional objects Temperature‐responsive devices developed from CLCs could be integrated for application in temperature sensors, energy‐saving smart windows, smart labels, actuators, and adding aesthetically pleasing features to common objects This review summarizes the device capabilities of the different material systems of temperature‐responsive CLCs: small mesogenic molecules, PDLCs, PSLCs, and CLC polymers For each system, examples of different device forms are presented, with their temperature responsiveness and the underlying mechanisms discussed Additionally, the potential of each material system for future device applications and product developments is envisioned
TL;DR: More than 150,000 photonic band calculations for thousands of natural crystal templates from which they predict 351 photonic crystal templates - including nearly 300 previously-unreported structures - that can potentially be realized for a multitude of applications and length scales, including several in the visible range via colloidal self-assembly as discussed by the authors.
Abstract: Many butterflies, birds, beetles, and chameleons owe their spectacular colors to the microscopic patterns within their wings, feathers, or skin. When these patterns, or photonic crystals, result in the omnidirectional reflection of commensurate wavelengths of light, it is due to a complete photonic band gap (PBG). The number of natural crystal structures known to have a PBG is relatively small, and those within the even smaller subset of notoriety, including diamond and inverse opal, have proven difficult to synthesize. Here, we report more than 150,000 photonic band calculations for thousands of natural crystal templates from which we predict 351 photonic crystal templates - including nearly 300 previously-unreported structures - that can potentially be realized for a multitude of applications and length scales, including several in the visible range via colloidal self-assembly. With this large variety of 3D photonic crystals, we also revisit and discuss oft-used primary design heuristics for PBG materials.