One-dimensional Photonic Crystal Nanobeam Cavity Research Articles

Assisted Microring Resonator Based on One-Dimensional Photonic Crystal Nanobeam Cavity

Assisted Microring Resonator Based on One-Dimensional Photonic Crystal Nanobeam Cavity

Integrated device for electro-optic modulation and wavelength-mode division hybrid multiplexing based on graphene and photonic crystal

An integrated device for graphene electro-optic (EO) modulation and wavelength-mode division hybrid multiplexing (WMDM) is proposed. The device is composed of three parts: EO modulator, wavelength division multiplexer (WDM), and mode division multiplexer (MDM). The EO modulator and WDM consist of a one-dimensional photonic crystal nanobeam cavity coupled with a nanowire waveguide. The modulation of a certain wavelength can be achieved by utilizing the characteristic that the chemical potential of graphene can be adjusted with voltage. The MDM adopts nanowire waveguides to realize mode conversion. The performance parameters of the integrated device are analyzed using the three-dimensional finite-difference time-domain method of numerical analysis. The results show that the integrated device can simultaneously complete the modulation and WMDM of the fundamental transverse electric (TE0) modes and first-order TE (TE1) modes at 1570.0 and 1573.2 nm, respectively. The extinction ratio is greater than 23.2 dB, the insertion loss is <0.36 dB, and the channel crosstalk is < − 22.7 dB. In addition, the modulation speed reaches 18 GHz.

Integrated device for graphene electro-optic modulation and one-dimensional photonic crystal nanobeam cavity wavelength division multiplexing

Integrated device for graphene electro-optic modulation and one-dimensional photonic crystal nanobeam cavity wavelength division multiplexing

Photonic crystal nanobeam cavities based on 4H-silicon carbide on insulator

The 4H-silicon carbide on insulator (4H-SiCOI) has recently emerged as an attractive material platform for integrated photonics due to its excellent quantum and nonlinear optical properties. Here, we experimentally realize one-dimensional photonic crystal nanobeam cavities on the ion-cutting 4H-SiCOI platform. The cavities exhibit quality factors up to 6.1×103 and mode volumes down to 0.63 × (λ/n)3 in the visible and near-infrared wavelength range. Moreover, by changing the excitation laser power, the fundamental transverse-electric mode can be dynamically tuned by 0.6 nm with a tuning rate of 33.5 pm/mW. The demonstrated devices offer the promise of an appealing microcavity system for interfacing the optically addressable spin defects in 4H-SiC.

Large-dynamic-range athermal lithium niobite on insulator/ TiO2 nanobeam electric field sensor

An integrated optical electric field (E-field) sensor based on a one-dimensional photonic crystal nanobeam cavity on a lithium niobite on insulator (LNOI) platform is reported here. It has a large dynamic range and extreme sensitivity. The dielectric resonant mode has a quality factor Q ≳ 105. The waveguide-coupled structure, only 25 μm long, is beneficial for future on-chip integration. The use of TiO2 compensates for the thermo-optical effect of lithium niobite (LN), while the high dielectric constant of TiO2 influences the E-field distribution. A tri-layer TiO2/LNOI/TiO2 nanobeam structure is proposed to improve electro-optical modulation efficiency in LN. Detailed analysis of noise sources shows the theoretical minimum detectable E-field to be 0.15 V m−1 with a dynamic range of 83 dB. The temperature-induced resonant wavelength variation is within 3 pm °C−1 in the range of −40 °C to 40 °C.

Simulation study on active control of electromagnetically induced transparency analogue in coupled photonic crystal nanobeam cavity-waveguide systems integrated with graphene.

We proposed and numerically investigated a coupled photonic crystal nanobeam (PCN) cavity-waveguide system which is composed of a bus waveguide and two one-dimensional PCN cavities, acting as bright and dark mode cavities, to achieve a distinct electromagnetically induced transparency analogue (EIT-like) effect by changing the near-field coupling strength between two cavities. By further integrating with graphene on top of the dark mode cavity, the three-dimensional finite-difference time-domain simulation results show that the generated EIT-like transparency window can be actively tuned and a complete on-to-off modulation of the EIT-like effect is realized by electrically tuning the graphene's Fermi level without reoptimizing or refabricating the structure. Theoretical analysis based on the coupled mode theory is then conducted and the results are highly consistent with the numerical results. In addition, we demonstrated that the group delay of the system can also be actively modulated by changing the Fermi level of graphene, achieving a well-controlled slow light effect. Our proposed coupled PCN cavity-waveguide system, combining the merits of PCN cavity and graphene in a single device, may provide a new platform for applications in chip-integrated slow light devices, tunable switches, optical modulators and high-sensitive sensors.

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.

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.

Low-loss tunable 1D ITO-slot photonic crystal nanobeam cavity

Tunable optical material properties enable novel applications in both versatile metamaterials and photonic components including optical sources and modulators. Transparent conductive oxides (TCOs) are able to highly tune their optical properties with applied bias via altering their free carrier concentration and hence plasma dispersion. The TCO material indium tin oxide (ITO) exhibits unity-strong index change and epsilon-near-zero behavior. However, with such tuning the corresponding high optical losses, originating from the fundamental Kramers–Kronig relations, result in low cavity finesse. However, achieving efficient tuning in ITO-cavities without using light–matter interaction enhancement techniques such as polaritonic modes, which are inherently lossy, is a challenge. Here we discuss a novel one-dimensional photonic crystal nanobeam cavity to deliver a cavity system offering a wide range of resonance tuning range, while preserving physical compact footprints. We show that a vertical silicon-slot waveguide incorporating an actively gated-ITO layer delivers ∼3.4 nm of tuning. By deploying distributed feedback, we are able to keep the Q-factor moderately high with tuning. Combining this with the sub-diffraction limited mode volume (0.1 (λ/2n)3) from the photonic (non-plasmonic) slot waveguide, facilitates a high Purcell factor exceeding 1000. This strong light–matter-interaction shows that reducing the mode volume of a cavity outweighs reducing the losses in diffraction limited modal cavities such as those from bulk Si3N4. These tunable cavities enable future modulators and optical sources such as tunable lasers.

Single nanoparticle trapping based on on-chip nanoslotted nanobeam cavities

Optical trapping techniques are of great interest since they have the advantage of enabling the direct handling of nanoparticles. Among various optical trapping systems, photonic crystal nanobeam cavities have attracted great attention for integrated on-chip trapping and manipulation. However, optical trapping with high efficiency and low input power is still a big challenge in nanobeam cavities because most of the light energy is confined within the solid dielectric region. To this end, by incorporating a nanoslotted structure into an ultracompact one-dimensional photonic crystal nanobeam cavity structure, we design a promising on-chip device with ultralarge trapping potential depth to enhance the optical trapping characteristic of the cavity. In this work, we first provide a systematic analysis of the optical trapping force for an airborne polystyrene (PS) nanoparticle trapped in a cavity model. Then, to validate the theoretical analysis, the numerical simulation proof is demonstrated in detail by using the three-dimensional finite element method. For trapping a PS nanoparticle of 10 nm radius within the air-slot, a maximum trapping force as high as 8.28 nN/mW and a depth of trapping potential as large as 1.15×105 kBT mW−1 are obtained, where kB is the Boltzmann constant and T is the system temperature. We estimate a lateral trapping stiffness of 167.17 pN·nm−1· mW−1 for a 10 nm radius PS nanoparticle along the cavity x-axis, more than two orders of magnitude higher than previously demonstrated on-chip, near field traps. Moreover, the threshold power for stable trapping as low as 0.087 μW is achieved. In addition, trapping of a single 25 nm radius PS nanoparticle causes a 0.6 nm redshift in peak wavelength. Thus, the proposed cavity device can be used to detect single nanoparticle trapping by monitoring the resonant peak wavelength shift. We believe that the architecture with features of an ultracompact footprint, high integrability with optical waveguides/circuits, and efficient trapping demonstrated here will provide a promising candidate for developing a lab-on-a-chip device with versatile functionalities.

Improved 2 × 2 Mach-Zehnder switching using coupled-resonator photonic-crystal nanobeams.

Design and simulation results are presented for an on-chip 2×2 Mach-Zehnder-based optical switch where each arm of the interferometer is composed of a coupled-resonator optical waveguide. The individual resonators are one-dimensional photonic crystal nanobeam cavities, and switching occurs through thermally induced changes in the refractive index of the silicon structure using integrated heating pads. The performance of the coupled-resonator device is directly compared to its single resonator counterpart, and significant improvement is found in the bar-state CT metric.

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

Single-Mode Emission From Ge Quantum Dots in Photonic Crystal Nanobeam Cavity

A freestanding one-dimensional photonic crystal nanobeam cavity embedded with Ge self-assembled quantum dots is designed and fabricated on a silicon-on-insulator substrate. Only one photoluminescence peak is observed in the wavelength range of 1000 to 1600 nm at room temperature. The emission peak dominates the photoluminescence spectrum over an almost flat and weak background emission, which indicates single-mode emission is realized in the proposed light emitter.

Cavity Quantum Electrodynamics in Semiconductors: Quantum Dot-Photonic Crystal Nanocavity Coupled Systems

Our recent advances in solid-state cavity quantum electrodynamics (CQED) and lasing oscillation in single quantum dot (QD)-photonic crystal (PhC) nanocavity coupled systems are discussed. These include the fabrication of high quality two-dimensional PhC nanocavities, which enable the generation of spontaneous two photon emission from a single QD, and the realization of lasing oscillation with single QD gain in the strong coupling regime. Moreover, CQED in a one-dimensional PhC nanobeam cavity is discussed.

High-Q AlN photonic crystal nanobeam cavities fabricated by layer transfer

High-quality-factor one-dimensional photonic crystal nanobeam cavities embedding GaN/AlN quantum dots are fabricated by an epilayer transfer method. The GaN/AlN quantum dots are first grown on SiC before being transferred to a Si substrate using a hydrogen silsesquioxane bonding layer and highly selective back-etching of the SiC. Nanobeam cavities are then fabricated by electron-beam lithography, dry etching, and HF underetching of the bonding layer. The resulting nanocavity exhibits quality factors larger than 6.3 × 103, the highest quality factor reported to date for an optically active group-III nitride photonic crystal nanocavity.

Analysis of Electrooptic Modulator With 1-D Slotted Photonic Crystal Nanobeam Cavity

A new nanocavity-based electrooptic modulator on silicon-on-insulator is proposed. This nanocavity is formed by a one-dimensional photonic crystal nanobeam cavity with a slot embedded. The slot lies in both the cavity and the distributed Bragg reflectors region. This results in an ultrasmall modal volume of 0.047 (λ/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> ) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and a high <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> -factor of 8.6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> . Another advantage of the structure is that polymers can be infiltrated into the slot. Accordingly, we rely on the fast and strong electrooptic effect of polymers, rather than on the free-carrier plasma dispersion effect of silicon. Analysis shows a modulator with a bandwidth of 86 GHz, a switching voltage of 0.2 V, and a length of only 14 μm can be obtained.

Strong coupling between a photonic crystal nanobeam cavity and a single quantum dot

We demonstrated the strong coupling between a one-dimensional photonic crystal nanobeam cavity and a single quantum dot (QD). Thanks to a high quality factor (∼25 000) with small mode volume [0.38×(n/λ)3] of the nanobeam cavity, an anticrossing behavior with a vacuum Rabi splitting of 226 μeV was observed. The ratio of the QD-cavity coupling strength to the cavity decay rate, which is a figure of merit of quantum optical applications, is estimated to 2.1. This is the highest value among any QD-based cavity quantum electrodynamics systems reported so far.