Crystal Cavity Research Articles

Ultra-compact low loss electro-optical nanobeam cavity modulator embedded photonic crystal

In this paper, a hybrid electro-optical modulator based on a one-dimensional photonic crystal nanobeam cavity is proposed. The main component of the cavity builder is the indium–tin–oxide that is a transparent conductive oxide. The proposed structure is used to minimize optical losses and also to have a high-quality factor with a tunability from the distributed feedback system. The proposed modulator has a wide range of resonant tunable in a footprint of 1.892 μm2. This structure has the ability to shift the wavelength of 1.55 μm using a very small voltage 0.1 V. Simulation results show that the proposed structure has an insertion loss of 0.027 dB, extension ratio 3.484 dB, 119.89 GHz modulation speed, and 0.59 aJ/bit modulation energy. By comparing the proposed method parameters and other modulators based on the one-dimensional photonic crystal nanobeam cavity, a significant improvement in modulation voltage, insertion losses, energy consumption, and footprint have been observed.

Design of freely suspended photonic crystal microfiber cavity sensors array in a general single mode fiber

Abstract We propose a novel design of refractive index (RI) sensor array based on ultrahigh sensitivity one dimensional (1D) photonic crystal microfiber (PCMF) cavities, which is referred as photonic crystal microfiber cavity sensors array (PCMF-CSA). The proposed PCMF-CSA consists of multiple channels connected in parallel. A transmission only containing the fundamental mode (FM) resonance of the PCMF cavity sensor for sensing purpose is created by connecting an additional PCMF bandgap filter to a PCMF cavity sensor in series on each channel. Due to the photonic bandgap (PBG) of the PCMF bandgap filter, the other high-order resonances are filtered out. With proper engineering of the PBG, multiple ultrahigh sensitivity PCMF cavity sensors can be integrated into microarrays without resonance overlap, and be detected simultaneously between a single input optical fiber and a single output optical fiber without the need for complicated coupling systems. The concept was demonstrated with 7-channel PCMF cavity sensor array containing PCMF bandgap filters. By using three-dimensional finite-difference time-domain (3D-FDTD) method, the performance of the device was investigated theoretically. The simulation results showed that the sensors on each channels can be monitored simultaneously from a single output spectrum. The numerical calculated RI sensitivities (S) for each sensing channel of the proposal 7-channel PCMF-CSA as high as 647.33 nm/RIU, 666.67 nm/RIU, 662.00 nm/RIU, 676.00 nm/RIU, 674.67 nm/RIU, 659.33 nm/RIU, 679.99 nm/RIU can be achieved, respectively. The average RI sensitivity as high as 666.57 nm/RIU can be obtained. Moreover, the extinction ratios of all resonant peaks exceed 20.0 dB. The crosstalk of all channels is lower than −24.5 dB. To the best of our knowledge, this is the first silica PCMF sensors array geometry based on conventional single mode fiber (SMF) that features both high Q and S, and thus is potentially a promising platform for ultra-sensitive RI-based gas sensing with high parallel-multiplexing capability.

Ultrasmall in-plane demultiplexer enabled by an arrayed one-dimensional photonic crystal nanobeam cavity

We propose a design for silicon-on-chip integrated eight-channel wavelength division multiplexing (WDM) demultiplexer, which consists of parallel-arrayed one-dimensional (1-D) photonic crystal nanobeam cavities (PCNCs) with high-Q over 105 and large free spectral range of ∼200 nm. To the best of our knowledge, this is for the first time that a 1-D PCNC-based demultiplexer is presented. The performance of the device is investigated theoretically by using three-dimensional finite-difference time-domain method. To enable eight-channel parallel arrayed 1-D PCNCs to be coupled to on-chip optical networks for higher integration and multiplex application, an 1 × 8 taper-type equal optical power splitter is used to connect all channels simultaneously. The total device footprint is as small as 12 μm × 15 μm (width × length), which is decreased by five times compared to that per channel in the recent two-dimensional (2-D) PC-based demultiplexer. Moreover, the average channel spacing smaller than 115 GHz is achieved, which is more than two times smaller than that of 2-D PC nanocavity devices, demonstrating that the arrayed nanocavities have the potential for developing ultracompact 100-GHz spaced filters in a dense WDM system. Thus, we believe that the results demonstrated in this work is promising for the future on-chip photonics integrated circuits and optical communication systems.

分子动力学研究高应变率对单晶铜空洞成核和生长过程的影响

分子动力学研究高应变率对单晶铜空洞成核和生长过程的影响

宽范围可调谐内腔液晶垂直腔面发射激光器设计与研究

宽范围可调谐内腔液晶垂直腔面发射激光器设计与研究

一维光子晶体纳米梁腔结构参量对带隙特性的影响

一维光子晶体纳米梁腔结构参量对带隙特性的影响

Curie’s Symmetry Principle for Selection Rule of Photonic Crystal Defect Modes

Symmetry, which defines invariant properties under a group of transformations, provides a frame of generalization uncovering regularities from given quantitative descriptions. Based on the Curie’s symmetry principle, connecting between causality and symmetry, we formulate the intuitive but formal selection rules and apply to determine the excitable resonant modes of a photonic crystal defect cavity, which is an important element for plasmonic applications. Quantitative agreement with the numerical simulations demonstrates the effectiveness of the fundamental principle in finding the critical symmetry conditions for the available localized defect states within photonic crystals. Moreover, the principle facilitates analysis of the higher-order or even forbidden modes in the asymmetric excitation configurations regarding the polarizations or positions of the light source, which typically require heavy computations. Our results may be extended similarly to develop the qualitative selection rules in other physical systems with a geometric symmetry.

Beneath the Surface of the World: High-Quality Quartzes, Crystal Cavities, and Neolithization in Circumpolar Europe

Beneath the Surface of the World: High-Quality Quartzes, Crystal Cavities, and Neolithization in Circumpolar Europe

The Influence of Point Defects in the Crystal Lattice on Fourier Components of Polarizability of Yttrium-Iron Garnet

The paper analyzed the crystal structure of ferrite-garnets and it shows the presence of cavities, volume of which is comparable with the volume of the atoms in the lattice. It is shown that the displacement of some cations can lead to changes in the Fourier components of polarizability values by up to 7%. The calculation of Fourier components of polarizability with the displacement of various cations in the crystal lattice cavities conducted in the paper.

Self-cavity lasing in optically pumped single crystals of p-sexiphenyl

Organic single-crystal self-cavities are prepared by solution growth of p-sexiphenyl (p-6P). Based on Fabry-Pérot feedback inside a quasi-lozenge-shaped platelet crystal, edge-emitting laser is obtained under optical pumping. The multimode lasing band appears at the 0-1 or 0-2 vibronic progressions depending on the excitation conditions which affect the self-absorption effect. Cavity-size dependence of amplified spontaneous emission (ASE) is investigated with laser-etched single crystals of p-6P. As the cavity length of square-shaped crystal is reduced from 100 to 10 μm, ASE threshold fluence is decreased probably due to size-dependent light confinement in the crystal cavity.

Post-trimming of photonic crystal nanobeam cavities by controlled electron beam exposure.

We theoretically and experimentally demonstrated that the resonant wavelength of photonic crystal (PhC) nanobeam cavities can be individually post tuned by selective electron beam exposure and development. By exposing the SU-8 cladding with different doses, the thickness of the SU-8 can be precisely and individually controlled from 150 nm to 650 nm. The phenomenon is employed in the localized control of the cladding layer from above the cavity region, thereby modifying the resonant wavelengths. The transmission spectrums of the PhC nanobeam cavities are measured before exposure, after exposure and after development, respectively. Utilizing the proposed method, the resonant wavelengths of the PhC nanobeam cavities can be post-tuned as large as 30 nm. This method is applicable to the post-trimming adjustment of the frequency response of the silicon-photonic filters.

High-Q side-coupled semi-2D-photonic crystal cavity.

High-Q semi-2D-photonic crystal cavities with a tapered edge and side-coupled bus waveguide are demonstrated. With a quadratic design, the unloaded cavity presents a theoretical ultrahigh quality factor up to 6.7 × 107 for the condition that there are mere 34 holes in the propagated direction, which is pretty close to the 2D and 1D counterpart. Combined with a side-coupled bus waveguide, an all-pass-type cavity with a loaded quality factor (Q) of over 2.4 × 104 and an extinction ratio over 10 dB are experimentally demonstrated. An experimental loaded Q up to 1.1 × 105 are also achieved by tuning the coupling between the cavity and the bus waveguide, which is much larger than any reported surface-mode cavity. This cavity is quite suitable for sensors, filters and especially optomechanical devices thanks to the mechanical stability of the cavity and flexibility of the bus waveguide.

质子注入型光子晶体垂直腔面发射激光器制备

质子注入型光子晶体垂直腔面发射激光器制备

质子注入型光子晶体垂直腔面发射激光器制备

质子注入型光子晶体垂直腔面发射激光器制备

Study of two dimensional photonic crystal nanocavities based on Gallium Nitride (GaN)

Abstract In this work, we shed light on a theoretical study of photonic crystal (PhC) cavities on Gallium Nitride (GaN). Particularly, the photonic band gap (PBG), resonant wavelength and quality factor ( Q ) of designed PhC structures were studied. In fact, the PBG was calculated by the plane wave expansion (PWE) method and the normalized transmission spectra of suspended GaN-based PhC cavities were obtained using finite difference time domain (FDTD) method. Accordingly, the resonant mode of GaN-based PhC cavity was observed at ∼460 nm wavelength. Furthermore, the optical confinement of the hexagonal cavity can be improved by adjusting the diameter and the distances of the adjacent holes along with the change of the cavity's type from the H 0 to the L 3 . Indeed, the transmission spectrum of the cavity was found to be strongly modified by the increase in the size of the structure, in the shifted distance value and the number of the shifted holes as well as the decrease of the holes diameters surrounding the defect in addition with changing the type of the cavity in order to obtain a significantly narrow FWHM of 0.002 pm. To sum up, our simulation results were in accord with those obtained from OptiFDTD software.

Self-compensated microstructure fiber optic sensor to detect high hydrogen concentration.

Dual-cavity microstructure fiber optic hydrogen sensor based on evaporated Pt/WO(3) film was proposed and experimentally explored in this paper, which provides a novel solution to detect high hydrogen concentration (10-30% H(2)). Dual-cavity microstructure fabricated by splicer is composed of an inner air-cavity and a collapsed photonic crystal fiber cavity. The proposed sensor has the advantages of miniature structure, stable configuration, low cost. Based on three-beam interference model and verification experiments, the compensation function to the fluctuation of light source and fiber loss is proved from the theoretical simulation and experimental investigation. The sensor has a short response time (1min), good repeatability and reliability. Besides, the change of temperature affects the response value of the hydrogen sensor, but the impact can be neglected in 10-30% H(2).

Improving cavity lifetime by electromagnetic-induced-transparency-like meta-atoms

In this paper, lifetime enhancement in a microstrip photonic crystal (PC) cavity by embedding electromagnetic-induced-transparency (EIT)-like meta-atoms is reported. Both microwave experiments and numerical simulations confirm that cavity lifetime can be lengthened about four times, with enhanced Q-factor simultaneously. Further study on electromagnetic field distribution reveals that these enhancements are mainly originated from the confinement along the propagating direction provided by PC cavity and the in-unit localization from the EIT-like meta-atoms. Moreover, study on the group delay shows that by introducing multiple EIT-like meta-atoms, these improvements of cavity lifetime and Q-factor can even be superimposed. As these advantages are not at a cost of extra device volume, the design principle of composite PC–EIT structure is promising to be applied in nonlinear optical devices, optical storage, lasing optics, and so on.

Scalable Cavity Quantum Electrodynamics System for Quantum Computing

We introduce a new scalable cavity quantum electrodynamics platform which can be used for quantum computing. This system is composed of coupled photonic crystal (PC) cavities which their modes lie on a Dirac cone in the whole super crystal band structure. Quantum information is stored in quantum dots that are positioned inside the cavities. We show if there is just one quantum dot in the system, energy as photon is exchanged between the quantum dot and the Dirac modes sinusoidally. Meanwhile the quantum dot becomes entangled with Dirac modes. If we insert more quantum dots into the system, they also become entangled with each other.

Two-dimensional hybrid photonic/plasmonic crystal cavities

We present a 2-D plasmonic crystal design with visible band-gap by combining a 2-D photonic crystal with TM band-gap and a silver surface. Simulations show that the presence of the silver surface gives rise to an expanded band-gap. A plasmonic crystal defect cavity with Q ~300 and mode volume ~1.9x10(-2) (λ/n) (3) can be formed using our design. The total Q of such a cavity is determined by both the radiative loss of the dielectric component, as well as absorption loss to the metal. We provide design criteria for the optimization of the total Q to allow high radiative or extraction efficiency.

Optically Pumped Lasing from Single Crystals of a Cyano‐Substituted Thiophene/Phenylene Co‐Oligomer

Room temperature optically pumped lasing is achieved for a new n-type molecular crystal of 2,5-bis(4′-cyanobiphenyl-4-yl)­thiophene (BP1T-CN). Efficient stimulated emission in the Fabry–Pérot crystal cavity is supported with a high group refractive index (4.18–4.98), Q factor (910–1860), material gain coefficient (120 cm-1), and a high stimulated emission rate demonstrated by pump–probe measurements.