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Modelling and Device Simulation of Photonic Crystal Surface Emitting Lasers Based on Modal Index Analysis
摘要： We present a novel semi-analytical method utilising modal index analysis, for modelling the field resonances of photonic crystal surface emitting lasers (PCSELs). This method shows very good agreement with other modelling techniques in terms of mode calculations, with the added advantages of computational simplicity, the calculation of threshold gain, and rapid analysis of finite structures. We are able to model the effect of external lateral feedback and simulations indicate that the near-field peak can be electronically displaced and the threshold as well as the frequency can be controlled through external in-plane feedback, paving the way to dynamic control of PCSELs.
关键词： Surface emitting lasers,Photonic crystals,Computational modelling
更新于2025-09-11 14:15:04
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Study on Modulation Bandwidth and Light Extraction Efficiency of Flip-Chip Light-Emitting Diode with Photonic Crystals
摘要： In this study, the photonic crystal structure is employed to increase both the light extraction e?ciency and the modulation bandwidth of ?ip-chip GaN-based light-emitting diodes (LEDs). The ?nite di?erence time domain method is utilized to investigate the in?uence of structure of photonic crystals on the Purcell factor and light extraction e?ciency of ?ip-chip GaN-based LEDs. Simulation results show that the modulation bandwidth is estimated to be 202 MHz at current densities of 1000 A/cm2. The experimental result of modulation bandwidth is in accord with the simulation. The optical f-3dB of the device achieves 212 MHz at current densities of 1000 A/cm2 and up to 285 MHz at current densities of 2000 A/cm2. This design of photonic crystal ?ip-chip LED has the potential for applications in high-frequency visible light communication.
关键词： Purcell e?ect,photonic crystals,light extraction e?ciency,?ip-chip LED,visible light communication
更新于2025-09-11 14:15:04
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Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
摘要： Photonic crystals are periodic nanostructures that can support a variety of confined electromagnetic modes. Such confined modes are usually accompanied by local enhancement of electric field intensity that strengthens light-matter interactions, enabling applications such as surface-enhanced Raman scattering (SERS) and surface plasmon enhanced sensing. In the presence of magneto-optically active materials, the local field enhancement gives rise to anomalous magneto-optical activity. Typically, the confined modes of a given photonic crystal depend strongly on the wavelength and incidence angle of the incident electromagnetic radiation. Thus, spectral and angular-resolved measurements are needed to fully identify them as well as to establish their relationship with the magneto-optical activity of the crystal. In this article, we describe how to use a Fourier-plane (back focal plane) microscope to characterize magneto-optically active samples. As a model system, here we use a plasmonic grating built out of magneto-optically active Au/Co/Au multilayer. In the experiments, we apply a magnetic field on the grating in situ and measure its reciprocal space response, obtaining the magneto-optical response of the grating over a range of wavelengths and incident angles. This information enables us to build a complete map of the plasmonic band structure of the grating and the angle and wavelength dependent magneto-optical activity. These two images allow us to pinpoint the effect that the plasmon resonances have on the magneto-optical response of the grating. The relatively small magnitude of magneto-optical effects requires a careful treatment of the acquired optical signals. To this end, an image processing protocol for obtaining magneto-optical response from the acquired raw data is laid out.
关键词： plasmonics,magneto-optics,magnetoplasmonics,photonic crystals,Issue 153,Engineering,spectroscopy,back focal plane measurement
更新于2025-09-11 14:15:04
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Transmission Enhanced Wavelength Demultiplexer Design Based on Photonic Crystal Waveguide with Gradually Varied Width
摘要： In this study, we propose the design of photonic crystals with linearly tapered waveguide such that waveguide width is gradually varied. Four drop-channels are included to implement wavelength demultiplexing applications. Here, a tapering of the waveguide has been chosen to localize propagating light within the desired positions. Afterwards, the corresponding drop-channels have been opened to confine the light with the targeted wavelengths. The designed structure consists of cylindrical alumina (Al2O3) dielectric rods and operates at microwave frequencies between 13.2 GHz and 15.3 GHz. An optimization algorithm is applied to enhance transmission efficiencies of the drop-channels and to minimize possible cross-talks between the channels by optimally modulating the position of the dielectric rods inside the channels which form cavity-coupling regions. The optimization algorithm is incorporated with the finite-difference time-domain method to evaluate the transmission efficiencies of the drop-channels for the instant designed structure. The physical mechanism of wavelength demultiplexing is related to slowing down and trapping of light in the tapered waveguide and its coupling to drop-channels for selected microwave wavelengths at different positions. Moreover, an experimental verification of the numerical analyses is demonstrated in the microwave regime and corresponding results will be shared in the conference.
关键词： drop-channels,slow light,microwaves,photonic crystals,optimization,wavelength selective devices
更新于2025-09-11 14:15:04
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Self-assembly of colloidal Poly(St-MMA-AA) core/shell photonic crystals with tunable structural colors of the full visible spectrum
摘要： This study used the copolymer emulsion method to synthesize colloidal monodisperse core/shell microspheres composed of the poly(styrene-co-methyl methacrylate-co-acrylic acid) [Poly(St-MMA-AA)]. Colloidal photonic crystal (CPhC) films have prepared by using polymer composite microspheres and successfully fabricated via natural sedimentation. The synthesized results of polymer composite microsphere exhibited uniform and good morphology. The resultant of CPhC color films demonstrated vividly structural colors due to 3D CPhC nanostructures. The structural colors over full visible spectra could be tuned by controlling the filling factor of crystals and diameter of microspheres according to the Bragg law. Additionally, the structural color of Poly(St-MMA-AA) CPhC films has measured under the standard colorimetric system. This study demonstrated a approach to fabricate tunable structural color for numerous applications.
关键词： Photonic crystals,Polymer microspheres,Structural colors,Colloidal crystals,Self-assembly
更新于2025-09-10 09:29:36
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Gas Sensing Mechanism of Silica with Photonic Bandgap Shift
摘要： Two physical models, Replacing model and Filling model, have been proposed to explain the mechanism of effective refractive index change of photonic crystals (PCs). Theoretically, photonic bandgap (PBG) would shift when PCs are exposed to different environment, which leads to change of effective refractive index of PCs. However, the mechanism of effective refractive index change is distinct when PCs are placed in different gases or vapors. Here, silica PCs were successfully fabricated by self-assembled method. The PGB of silica PCs exhibit similar redshift in volatile organic compounds (VOCs) or small-molecule gases. We propose Replacing model to elaborate silica PCs exposed to VOCs, while Filling model to explain silica PCs exposed to small-molecule gases. Additionally, the redshift of PBG was transformed into volume fraction of adsorbed gas in order to achieve selective sensing of silica PCs. The approach could be exploited for application in sensing.
关键词： refractive index,photonic crystals,photonic bandgap,silica,gas sensing
更新于2025-09-10 09:29:36
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Efficient and quantitative analysis of photon density of states for two-dimensional photonic crystals with omnidirectional light propagation
摘要： Omnidirectional light propagation in two-dimensional (2D) photonic crystals (PCs) has been investigated by extending the formerly developed 2D finite element analysis (FEA) of in-plane light propagation in which the corresponding band structure (BS) and photon density of states (PDOS) of 2D PCs with complex geometry configurations had been calculated more accurately by using an adaptive FEA in real space for both the transverse electric (TE) and transverse magnetic (TM) modes. In this work, by adopting a wave-guiding theory under the consideration of translational symmetry, the omnidirectional PDOS corresponding to both the radiative and evanescent waves can be calculated efficiently based on the in-plane dispersion relations of both TE and TM modes within the irreducible Brillouin zone. We demonstrate that the complete band gaps shown by previous work considering only the radiative modes will be closed by including the contributions of the evanescent modes. These results are of general importance and relevance to the spontaneous emission by an atom or to dipole radiation in 2D periodic structures. In addition, it may serve as an efficient approach to identifying the existence of a complete photonic band gap in a 2D PC instead of using time-consuming three-dimensional BS calculations.
关键词： two-dimensional photonic crystals,radiative and evanescent waves,finite element analysis,photon density of states,omnidirectional light propagation
更新于2025-09-10 09:29:36
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Optimization of Epsilon-and-mu-near-zero Refractive Index Photonic Structure to Design Unidirectional Transmission Device
摘要： In this study, we introduce a novel approach for designing an unidirectional transmission device by using a photonic crystal (PC) structure that exhibits the properties of epsilon-mu-near-zero media. The selected PC structure consists of dielectric rods and positions of certain preselected rods in y-direction are optimized via an evolutionary algorithm to obtain the unidirectional transmission of light. Finite-difference time-domain (FDTD) method is used to perform numerical analyses for the proposed device. In addition, experiments are carried out at microwave frequencies to demonstrate the unidirectional light transmission. It is shown that a good agreement between numerical calculations and experimental measurements is achieved.
关键词： phase shift,mode order converter,photonic crystals,differential evolution algorithm,integrated optics
更新于2025-09-10 09:29:36
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Visualized Detection of Polyelectrolytes via 1D Photonic Crystals
摘要： The organic/inorganic hybrid 1D photonic crystal is applied for visible and label-free detection of charged substances. Exposure to aqueous solutions of various polyelectrolytes alters the swelling ratios of quaternized polymer layers due to the ionic interaction. Visible detection is thus attained along with a shift of the photonic stop band. Especially, by virtue of the diverse degrees and speeds of the shift, polyanions with different concentrations and molecular weights can be differentiated. Likewise, natural polyelectrolytes, such as proteins, have different solution pH values and isoelectric points. Thus, different charged properties yield three kinds of proteins that can be distinguished by the device via reflectance spectra. It is worth noting that biomarkers of illness with different concentrations can also be detected via the naked eye, without any labels. Fortunately, the detection sensitivity basically satisfies the usage requirement. Due to the convenience, flexibility, low power consumption and visibility, the label-free sensor is suitable for daily life.
关键词： one-dimensional photonic crystals,polyelectrolyte,isoelectric point,visualized detection,cancer marker
更新于2025-09-10 09:29:36
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Large Area Three-Dimensional Photonic Crystal Membranes: Single-Run Fabrication and Applications with Embedded Planar Defects
摘要： Three-dimensional photonic crystals (3D PhCs) enable light manipulations in all three spatial dimensions, however, real world applications are still faced with challenges in fabrication. Here, a facile fabrication strategy for 3D silicon PhCs with a simple cubic (SC) lattice structure is presented, which exhibits a complete photonic bandgap at near-infrared wavelengths of around 1100 nm. The fabrication process is composed of standard deep ultra-violet stepper lithography, followed by a single-run modified plasma etch process. By applying a direct dry etch release step at the end of the 3D structural etch process, the fabricated 3D PhCs can be released and transferred in the form of a membrane onto other substrates such as glass, polymers, or even substrates with engineered surface. The thickness of the demonstrated membranes is around 2 μm and the size can be up to a few millimeters. A high reflectivity is observed at the stop band frequency, and a planar defect is introduced during the etching process resulting in an optical resonance mode with a small linewidth of around 30 nm. The structure constitutes an optical bandpass filter and can be used as a sensor for organic solvents.
关键词： silicon,3D photonic crystals,planar cavities,plasma etching,DREM process
更新于2025-09-10 09:29:36