Photonic Crystal Waveguide Research Articles

High coupling efficiency photonic crystal waveguide for compact channel drop filter design on silicon-on-insulator platform

High coupling efficiency photonic crystal waveguide for compact channel drop filter design on silicon-on-insulator platform

Independent Electrical Control of Two Quantum Dots Coupled through a Photonic-Crystal Waveguide.

Efficient light-matter interaction at the single-photon level is of fundamental importance in emerging photonic quantum technology. A fundamental challenge is addressing multiple quantum emitters at once, as intrinsic inhomogeneities of solid-state platforms require individual tuning of each emitter. We present the realization of two semiconductor quantum dot emitters that are efficiently coupled to a photonic-crystal waveguide and individually controllable by applying a local electric Stark field. We present resonant transmission and fluorescence spectra in order to probe the coupling of the two emitters to the waveguide. We exploit the single-photon stream from one quantum dot to perform spectroscopy on the second quantum dot positioned 16 μm away in the waveguide. Furthermore, power-dependent resonant transmission measurements reveal signatures of coherent coupling between the emitters. Our work provides a scalable route to realizing multiemitter collective coupling, which has inherently been missing for solid-state deterministic photon emitters.

88×nm High-Efficiency Narrow Divergence Angle Laser Diodes With Coupled Waveguide Photonic Crystal

88x nm laser diodes with coupled waveguide photonic band crystal (CPBC) are designed and fabricated. By optimizing the optical confinement factor in the lightly doped coupled waveguide, the internal loss reduces to 0.52 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The CPBC lasers achieve maximum power conversion efficiency of 65.57% under a continuous wave (CW) mode condition at room temperature, which is the highest reported value to our knowledge at 88x nm. The corresponding vertical divergence angel is 19.8°.

Analysing group indices and dispersion characteristics of engineered photonic crystal waveguides using artificial neural network

Analysing group indices and dispersion characteristics of engineered photonic crystal waveguides using artificial neural network

Optimizing slow light parameters in 2D-heterostructure photonic crystals with circular and square rods and holes

Theoretically, we aim to optimize the parameters related to slow light in a 2D heterostructure photonic crystal. Two types of heterostructures were investigated by joining two photonic crystals: one composed of square holes and the other with circular rods or vice versa. The plane wave expansion and supercell method are used to analyze the waveguide mode. Germanium is assumed to be the material for the rods and background. The group index and bandwidth for the waveguide appearing at the interface were optimized. A comprehensive survey of rod and hole size values reveals that the achieved group index bandwidth product of 0.72 is primarily due to the high bandwidth achieved within the optimized structure. Furthermore, our results confirm that rotating the square rods can further enhance slow light parameters, leading to a significantly higher group-index-bandwidth product than traditional semiconductor photonic crystal waveguides.

X-shaped Photonic Crystal Waveguide with Phase-Change Materials for Non-blocking Wavelength-Selective Routing

X-shaped Photonic Crystal Waveguide with Phase-Change Materials for Non-blocking Wavelength-Selective Routing

Pure quartic wave modulation in optical fiber with the presence of self-steepening and intrapulse Raman scattering response

Modulational instability (MI) is addressed in an optical fiber under competing effects between pure-quartic dispersion (PQD), self-steepening, and intrapulse Raman response. The self-steepening parameter reduces the maximum MI gain and the frequency bandwidth. Under the combined effects of the self-steepening and intrapulse Raman scattering, more spectral windows appear in the gain spectrum, induced by the increasing Raman effect. Numerical results fully concur with the theoretical predictions. The MI is manifested by the emergence of ultrashort pulses trains and rogue wave breathing trains. Under increasing self-steepening effect, asymmetric sidebands, reversible via the Raman scattering effect, appear in the spectral and temporal evolution of the pulse trains, which probes the tunability of energy transfer between the mode during signal propagation. Our results open up further perspectives for exploring mechanisms to generate ultrashort pulses in PQD optical media under higher-order nonlinearities, with applications to silicon photonic crystal waveguides and silica photonic crystal fibers.

Accurate and efficient prediction of photonic crystal waveguide bandstructures using neural networks

We demonstrate the use of neural networks to predict the optical properties of photonic crystal waveguides (PhCWs) with high accuracy and significantly faster computation times compared to traditional simulation methods. Using 100,000 PhCW designs and their simulated bandstructures, we trained a neural network to achieve a test set relative error of 0.103% in predicting gap guided bands. We use pre-training to improve neural network performance, and numerical differentiation to accurately predict group index curves. Our approach allows for rapid, application-specific tailoring of PhCWs with a runtime of sub-milliseconds per design, a significant improvement over conventional simulation techniques.

Frequency comb generation in rod type 2D photonic crystal coupled cavity waveguide

Frequency comb generation in rod type 2D photonic crystal coupled cavity waveguide

Topological rainbow based on coupling of topological waveguide and cavity.

Topological photonics and topological photonic states have opened up a new frontier for optical manipulation and robust light trapping. The topological rainbow can separate different frequencies of topological states into different positions. This work combines a topological photonic crystal waveguide (topological PCW) with the optical cavity. The dipole and quadrupole topological rainbows are realized through increasing cavity size along the coupling interface. The flatted band can be obtained by increasing cavity length due to interaction strength between the optical field and defected region material which is extensively promoted. The light propagation through the coupling interface is built on the evanescent overlapping mode tails of the localized fields between bordering cavities. Thus, the ultra-low group velocity is realized at a cavity length more than the lattice constant, which is appropriate for realizing an accurate and precise topological rainbow. Hence, this is a novel release for strong localization with robust transmission and owns the possibility to realize high-performance optical storage devices.

Transport of a topologically protected photonic waveguide on-chip

We propose a design on integrated optical devices on-chip with an extra width degree of freedom by using a photonic crystal waveguide with Dirac points between two photonic crystals with opposite valley Chern numbers. With such an extra waveguide, we demonstrate numerically that the topologically protected photonic waveguide retains properties of valley-locking and immunity to defects. Due to the design flexibility of the width-tunable topologically protected photonic waveguide, many unique on-chip integrated devices have been proposed, such as energy concentrators with a concentration efficiency improvement of more than one order of magnitude, and a topological photonic power splitter with an arbitrary power splitting ratio. The topologically protected photonic waveguide with the width degree of freedom could be beneficial for scaling up photonic devices, and provides a flexible platform to implement integrated photonic networks on-chip.

A Topological Multichannel Add-Drop Filter Based on Gyromagnetic Photonic Crystals.

We theoretically proposed a topological multichannel add-drop filter (ADF) and studied its unique transmission properties. The multichannel ADF was composed of two one-way gyromagnetic photonic crystal (GPC) waveguides, a middle ordinary waveguide, and two square resonators sandwiched between them, which can be regarded as two paralleling four-port nonreciprocal filters. The two square resonators were applied with opposite external magnetic fields (EMFs) to support one-way states propagating clockwise and counterclockwise, respectively. On the basis of the fact that the resonant frequencies can be tuned by the EMFs applied to the square resonators, when the intensities of EMFs were the same, the multichannel ADF behaved as a power splitter with a 50/50 division ratio and high transmittance; otherwise, it functioned as a demultiplexer to separate two different frequencies efficiently. Such a multichannel ADF not only possesses excellent filtering performance but also has strong robustness against various defects due to its topological protection property. Moreover, each output port can be switched dynamically, and each transmission channel can operate independently with little crosstalk. Our results have the potential for developing topological photonic devices in wavelength division multiplexing systems.

Design of a Narrow Band Filter Based on a Photonic Crystal Cavity for CO2 Sensing Application

This paper investigates the use of a miniaturized filter based on a triangular lattice of holes in a photonic crystal (PhC) slab. The plane wave expansion method (PWE) and finite-difference time-domain (FDTD) techniques were utilized to analyze the dispersion and transmission spectrum, as well as the quality factor and free spectral range (FSR) of the filter. A 3D simulation has demonstrated that for the designed filter, an FSR of more than 550 nm and a quality factor of 873 can be attained by adiabatically coupling light from a slab waveguide into a PhC waveguide. This work designs a filter structure that is implemented into the waveguide and is suitable for a fully integrated sensor. The small size of the device provides a strong potential for the realization of large arrays of independent filters on a single chip. The fully integrated character of this filter has further advantages such as reducing power loss in coupling light from sources to filters and also from filters to waveguides. The ease of fabrication is another benefit of completely integrating the filter.

Higher order dispersions effect on high-order soliton interactions

The object of the research is deleting the interaction of the higher order soliton interaction by introducing the third and fourth order dispersions inside an optical fiber. The results are obtained by the simulation of the nonlinear Schrödinger equation, which models the propagation of solitons in the optical fiber using the method of Fast Fourier Transform. The interaction of two higher order solitons due to the attraction of their electric field can lead to losing the solitons' properties. Hence, this can prevent the use of solitons in high-bit-rate optical fiber communication systems because it increases the bit error rate, significantly limiting the potential of the communication system. To resolve this problem, we should diminish the bit rate error by avoiding the interaction of the co-propagative solitons when they are too close. It is well known that, during higher order soliton propagation in the presence of the third order dispersion, the irregular shape of the higher order soliton disappears, and a splitting towards its fundamental constituents occurs after a considerable propagation. As for the fourth order, dispersion gives rise to two dispersive wave sidebands on the red or blue side. Our results reveal that bringing two higher order solitons together in the presence of the fourth order dispersion, a series of interactions between the components generated after their fission is obtained. In the third-order distribution, besides the fourth-order diffusion, the rare form and the supercontinuum generated by the fission of the higher-order solitons disappear, and we get two fundamental solitons propagating in parallel with a temporal shift and some inconsiderable dispersive waves. The most important aspect is that both higher-order dispersions are able to suppress the interactions of higher-order solitons thanks to the time shift induced by the third-order distribution and the intermittent compression caused by the fourth-order scattering. These results can be obtained in practice inside the dispersion-engineered photonic crystal waveguide (PhC-wg), which allows for manipulating the high order dispersion.

Hybrid Integration of GaP Photonic Crystal Cavities with Silicon-Vacancy Centers in Diamond by Stamp-Transfer

Optically addressable solid-state defects are emerging as some of the most promising qubit platforms for quantum networks. Maximizing photon-defect interaction by nanophotonic cavity coupling is key to network efficiency. We demonstrate fabrication of gallium phosphide 1-D photonic crystal waveguide cavities on a silicon oxide carrier and subsequent integration with implanted silicon-vacancy (SiV) centers in diamond using a stamp-transfer technique. The stamping process avoids diamond etching and allows fine-tuning of the cavities prior to integration. After transfer to diamond, we measure cavity quality factors (Q) of up to 8900 and perform resonant excitation of single SiV centers coupled to these cavities. For a cavity with a Q of 4100, we observe a 3-fold lifetime reduction on-resonance, corresponding to a maximum potential cooperativity of C = 2. These results indicate promise for high photon-defect interaction in a platform which avoids fabrication of the quantum defect host crystal.

2-Photon Polymerized IP-Dip 3D Photonic Crystals for Mid IR Spectroscopic Applications

Photonic Crystals (PhC) are periodically structured dielectric materials that have been subject to extensive research efforts over the last two decades. PhC are known for the slow-light phenomenon, which increases the interaction time between light and the target gas, thereby enhancing sensitivity when applied to sensors. Slow light is best realized using three-dimensional (3D) PhC with a complete photonic band-gap (PBG). However, they are inherently difficult to fabricate with planar microfabrication techniques. In this work, we present two-photon polymerized (2PP) stereolithographically fabricated 3D PhC targeting mid-infrared (MIR) spectroscopic range. Finite Element Analysis (FEA) was performed on a two-dimensional (2D) PhC waveguide (PhCW) to analyze the significance of PBG and slow light properties. Additional FEA was conducted and validated experimentally using fabricated 3D PhC. The ability to tune PhC to a desired wavelength along with their repeatability and feasibility is experimentally demonstrated. This letter presents the first, to our knowledge, 3D PhC fabricated using 2PP stereolithography operating at this wavelength.

Raman based on-chip photonic quantizers for ADCs

In this work, a model for an on-chip all-photonic analog to digital converter is proposed. Here, the underlying quantization technique is based on slicing the supercontinuum generated inside the highly nonlinear nanocrystal embedded slotted photonic crystal waveguide at specifically chosen wavelengths. It is shown that although both the broadening and splitting of the spectrum can be used for four level quantization, only broadening can be used for designing eight (or more) level quantization. The highly nonlinear device system makes the eight level quantization scheme incremental within a footprint of 50×20µm2, which can convert 0–11 mW analog optical power to respective quantization levels. Although both Kerr and stimulated Raman scattering (SRS) contribute to the generation of the supercontinuum, the giant SRS gain of the silicon nanocrystal essentially outweighs that of the Kerr, with, consequently, unprecedented miniaturization in both operating power and footprint.

High stability with low polarization and confinement loss based new structure of photonic crystal fiber waveguide profile

Abstract Nowadays ethanol is broadly used chemical item in various industrial purpose. So, detection of this organic chemical has become very important task in industrial basis. In this paper, a hexagonal core PCF has constructed in which silica is used as base material. A finite element method is applied and mesh analysis has been done for investigating boundary conditions of proposed PCF sensor. After simulation, 59.48 % sensitivity and an ignorable loss of confinement which is 8·956020 × 10−13 cm−1 at 2.5 THz frequency has been gained. Focusing on easy construction of fiber, conventional fabrication procedures are attainable. Having satisfactory waveguiding attributes, the proposed sensor can be applicable effectively for sensing ethanol and also polarization-based applications of terahertz waves.

Photonic spin Hall effect with high coupling efficiency in the combined structure of periodic dielectric waveguides and photonic crystal waveguide

In this paper, we discuss the photonic spin Hall effect (PSHE) in the combined structure of periodic dielectric waveguides (PDWs) and photonic crystal waveguide (PCW). By controlling the polarization of the dipole source, we have successfully achieved the arbitrary manipulation of PSHE for the PDW guided mode in our structure. The advantage of PDW is that it can be designed to different shapes without the geometric constraints, and still maintains a relatively high transmission rate. Therefore, by further changing the structure, including the adjustment of the intersection angle between PDW and PCW, and the alteration of the straight PDW to the bending or bifurcated shapes, we find that the output of highly unidirectional PSHE is mainly determined by the intersection angle between PDW and PCW and almost independent of the detailed shape of PDW.

Stongly Confined Electromagnetic Waves in a Hybrid Photonic–Plasmonic Resonator for Enhancing Light–Matter Interaction

In this paper, a 1D photonic crystal waveguide and a plasmonic compound nano-system are utilized to design a hybrid photonic-plasmonic device for enhancement of light–matter interaction. Strongly localized light waves in a very small volume intensify the optical field, via surface plasmons due to presence of a gold nanoparticle, which interacts with the resonator’s cavity mode while the photonic crystal nanobeam ensures a high temporal confinement. The enhancement factor of light–matter interaction in the hybrid resonator is investigated through the single-atom cooperativity parameters based on numerically obtained results, which is calculated to be 14 as a result of the considerably reduced optical mode volume in the presence of the plasmonic nanoparticle. Additionally, the theoretical models and calculation procedures, presented in this paper, are demonstrated to be pioneering for the fabrication of efficient quantum devices based on hybrid photonic-plasmonic resonators.