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In this work, we propose artificial neural networks (ANNs) to predict the optical forces on particles with a radius of 50 nm and inverse-design the subwavelength-grating (SWG) waveguides structure for trapping. The SWG waveguides are applied to particle trapping due to their superior bulk sensitivity and surface sensitivity, as well as longer working distance than conventional nanophotonic waveguides. To reduce the time consumption of the design, we train ANNs to predict the trapping forces and to inverse-design the geometric structure of SWG waveguides, and the low mean square errors (MSE) of the networks achieve 2.8 × 10-4. Based on the well-trained forward prediction and inverse-design network, an SWG waveguide with significant trapping performance is designed. The trapping forces in the y-direction achieve-40.39 pN when the center of the particle is placed 100â nm away from the side wall of the silicon segment, and the negative sign of the optical forces indicates the direction of the forces. The maximum trapping potential achieved to 838.16 kBT in the y-direction. The trapping performance in the x and z directions is also quite superior, and the neural network model has been further applied to design SWGs with a high trapping performance. The present work is of significance for further research on the application of artificial neural networks in other optical devices designed for particle trapping.
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We propose a dual-parameter sensor for the simultaneous detection of temperature and pressure based on a single packaged microbubble resonator (PMBR). The ultrahigh-quality (â¼107) PMBR sensor exhibits long-term stability with the maximum wavelength shift about 0.2056 pm. Here, two resonant modes with different sensing performance are selected to implement the parallel detection of temperature and pressure. The temperature and pressure sensitivities of resonant Mode-1 are -10.59 pm/°C and 0.1059 pm/kPa, while the sensitivities of Mode-2 are -7.69 pm/°C and 0.1250 pm/kPa, respectively. By adopting a sensing matrix, the two parameters are precisely decoupled and the root mean square error of measurement are â¼ 0.12 °C and â¼ 6.48 kPa, respectively. This work promises the potential for the multi-parameters sensing in a single optical device.
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In this work, we propose a slotted photonic crystal nanobeam cavity (PCNC) to trap and sort the 120 nm and 30 nm nanoparticles. The simulation shows that the maximum optical trapping force of the 120 nm particle is 38.7 pN/mW, and that of the 30 nm particle is 10.8 pN/mW. It is calculated that the trapping threshold power of the 120 nm particle is 35.3 µW, and that of the 30 nm particle is 41.6 µW. Because the width of the slot is 100 nm, when the input power is between 35.3 µW and 41.6 µW, only the 120 nm particle can be trapped in the upper cladding of the slotted-PCNC. When the input power is greater than 41.6 µW, the 120 nm particle is still trapped in the upper cladding of the slotted-PCNC, while the 30 nm particle is trapped inside the slot of the slotted-PCNC. By properly controlling the input power and the direction of flow in the microfluidic channel, the sorting of particles can be achieved. In addition, trapping of the particles causes different redshifts of peak wavelengths. Thus, the proposed slotted-PCNC can detect particle trapping and sorting by monitoring the resonant wavelength shifts. What is the most important, compared with previous reported single particle trapping work, is that the proposed work can realize both trapping and sorting. Therefore, provided with the ultra-compact footprint and excellent performance, the proposed slotted-PCNC shows great potential for a multifunctional lab-on-a-chip system.
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We numerically and experimentally present the characteristics of disturbed spatial modes (air mode and dielectric mode) in multi-mode photonic crystal nanobeam cavity (PCNC) in the mid-infrared wavelength range. The results show that the resonance wavelength of the spatial modes can be controlled by modifying the size, period and position of the central periodical mirrors in PCNC, achieving better utilization of the spectrum resource. Additionally, side coupling characteristics of PCNC supporting both air and dielectric modes are investigated for the first time. This work serves as a proof of design method that the spatial modes can be controlled flexibly in PCNC, paving the way to achieve integrated multi-function devices in a limited spectrum range.
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We put forward a dual-mode photonic crystal nanobeam cavity for simultaneous sensing of the refractive index (RI) and temperature (T) designed with the assistance of artificial neural networks (ANNs). We choose the structure of quadratically tapered elliptical holes with a slot to improve the sensitivities of the two modes. To reduce the time consumption of the design, the ANNs are trained to predict the band structure and to inverse design the geometric structure. For the forward prediction and the inverse design neural networks, low mean square errors of 5.1×10-4 and 1.4×10-2 are achieved, respectively. Through a specific design of band properties by the well-trained neural networks, a dual-mode nanobeam sensor with high quality factors of 9.34×104 and 1.55×105 and a small footprint of 23.8×0.7µm2 are designed. The RI and T sensitivities of the air mode are 405 nm/RIU and 40 pm/K, respectively, whereas those of the dielectric mode are 531 nm/RIU and 27 pm/K, respectively. The present work shows significance in further research on the design and applications for dual-mode cavities.
Assuntos
Fótons , Refratometria , Temperatura , Óptica e Fotônica , Redes Neurais de ComputaçãoRESUMO
This publisher's note serves to correct Appl. Opt.61, 1552 (2022)APOPAI0003-693510.1364/AO.452140.
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We propose a sensor with high anti-interference ability using a photonic crystal cavity coupled system for simultaneous sensing of the refractive index (RI) and temperature (T) based on an electromagnetically induced transparency-like effect. A transparent window is achieved in the transmission spectrum through destructive interference between the air mode resonance and dielectric mode resonance in two one-dimensional photonic crystal structures. The T-sensitive material (SU-8) is used in the coupled system, promoting sensitivity and anti-interference ability. The capability of the system to simultaneously detect a small range of RI and T is demonstrated using three-dimensional finite-difference time-domain simulations and the fitting process. The RI sensitivities for the air and dielectric modes were 215 nm/refractive index unit (RIU) and 0 nm/RIU, respectively. The T sensitivities for the air and dielectric modes were 19 pm/K and -83pm/K, respectively. The sensor resists external interference, enabling it to resist the error caused by readings. The footprint of the sensor is 29×1.8µm2 (length×width), contributing to future optical on-chip integration sensor design.
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The optical phase shifter that constantly rotates the local oscillator phase is a necessity in continuous-variable quantum key distribution systems with heterodyne detection. In previous experimental implementations, the optical phase shifter is generally regarded as an ideal passive optical device that perfectly rotates the phase of the electromagnetic wave of 90∘. However, the optical phase shifter in practice introduces imperfections, mainly the measurement angular error, which inevitably deteriorates the security of the practical systems. Here, we will give a concrete interpretation of measurement angular error in practical systems and the corresponding entanglement-based description. Subsequently, from the parameter estimation, we deduce the overestimated excess noise and the underestimated transmittance, which lead to a reduction in the final secret key rate. Simultaneously, we propose an estimation method of the measurement angular error. Next, the practical security analysis is provided in detail, and the effect of the measurement angular error and its corresponding compensation scheme are demonstrated. We conclude that measurement angular error severely degrades the security, but the proposed calibration and compensation method can significantly help improve the performance of the practical CV-QKD systems.
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Artificial neural networks are employed to predict the band structure of the one-dimensional photonic crystal nanobeam, and to inverse-design the geometry structure with on-demand band edges. The data sets generated by 3D finite-difference time-domain based on elliptical-shaped hole nanobeams are used to train the networks and evaluate the networks' accuracy. Based on the well-trained forward prediction and inverse-design network, an ultrabroad bandgap elliptical hole dielectric mode nanobeam cavity is designed. The bandgap achieves 77.7 THz for the center segment of the structure, and the whole designing process takes only 0.73 s. The approach can also be expanded to fast-design elliptical hole air mode nanobeam cavities. The present work is of significance for further research on the application of artificial neural networks in photonic crystal cavities and other optical devices design.
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Integrated mid-infrared sensing offers opportunities for the compact, selective, label-free and non-invasive detection of the absorption fingerprints of many chemical compounds, which is of great scientific and technological importance. To achieve high sensitivity, the key is to boost the interaction between light and analytes. So far, approaches like leveraging the slow light effect, increasing optical path length and enhancing the electric field confinement (f) in the analyte are envisaged. Here, we experimentally investigate a slow light one-dimensional photonic crystal ring resonator operating at high-order photonic bandgap (PBG) in mid-infrared range, which features both strong field confinement in analyte and slow light effect. And the optical path length can also be improved by the resoantor compared with waveguide structure. The characteristics of the first- and second-order bandgap edges are studied by changing the number of patterned periodical holes while keeping other parameters unchanged to confine the bands in the measurement range of our setup between 3.64 and 4.0 µm. Temperature sensitivity of different modes is also experimentally studied, which helps to understand the field confinement. Compared to the fundamental PBG edge modes, the second PBG edge modes show a higher field confinement in the analyte and a comparable group index, leading to larger light-matter interaction. Our work could be used for the design of ultra-sensitive integrated mid-infrared sensors, which have widespread applications including environment monitoring, biosensing and chemical analysis.
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In this paper, we propose a coupled-double-photonic-crystal-slab (CDPCS) sensor for simultaneously detecting refractive index (RI) and temperature (T) with high accuracy and strong anti-interference ability, using transverse magnetic-like (TM-like) mode and transverse electric-like (TE-like) mode. Based on the temporal coupled-mode theory, the theoretical model of the structure is established and the transmission formula is derived. The agreement between the theoretical and the simulated transmission spectra is proved. In order to achieve both high quality (Q)-factor and high modulation depth, the structure is optimized by adjusting the geometric parameters. The Q-factors of both TM-like mode and TE-like mode reach a magnitude order of 105. For the dual-parameter sensing, high RI sensitivities of 960 nm/RIU and 210 nm/RIU, and T sensitivities of -66.5 pm/K and 50.75 pm/K, are obtained for TM-like mode and TE-like mode, respectively. The relative deviations of RI and T sensing are as low as 0.6% and 1.0%, respectively, indicating high detection accuracy. Even considering the influence of external interference, the sensor can effectively resist external interference. The proposed CDPCS sensor has remarkable performance improvements in sensitivity, Q-factor, detection accuracy, and anti-interference ability. This study shows great potential in on-chip sensing and multi-parameter detection.
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We propose an eight-spatial-mode ring-core few-mode fiber (RC-FMF), utilizing the cross-arranged different-material-filling side holes (CA DMFSH) for effective index difference improvement. Two GeO2-doped-silica side holes and two air-filling side holes are arranged orthogonally around the ring core, which have directionally different effects on the refractive index and the mode field distribution in the RC-FMF. The results indicate that the effective index difference (Δneff) between adjacent spatial modes is larger than 1.96×10-4, and the Δneff between adjacent non-degenerated modes can be above 1.01×10-3 at the same time. Bend-resistant performance and low nonlinearity are achieved in the designed RC-FMF. Broadband performances ranging from 1510 to 1630 nm are also analyzed. The CA-DMFSH-assisted structure shows great potential for enlarging the effective index difference, and the proposed fiber targets applications in the short-reach space-division multiplexing optical networking while eliminating the complex multi-input/multi-output digital signal processing.
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Healthcare and biosensing have attracted wide attention worldwide, with the development of chip integration technology in recent decades. In terms of compact sensor design with high performance and high accuracy, photonic crystal structures based on Fano resonance offer superior solutions. Here, we design a photonic crystal structure for sensing applications by proposing modeling for a three-cavity-coupling system and derive the transmission expression based on temporal coupled-mode theory (TCMT). The correlations between the structural parameters and the transmission are discussed. Ultimately, the geometry, composed of an air mode cavity, a dielectric mode cavity and a cavity of wide linewidth, is proved to be feasible for simultaneous sensing of refractive index (RI) and temperature (T). For the air mode cavity, the RI and T sensitivities are 523 nm/RIU and 2.5 pm/K, respectively. For the dielectric mode cavity, the RI and T sensitivities are 145 nm/RIU and 60.0 pm/K, respectively. The total footprint of the geometry is only 14 × 2.6 (length × width) µm2. Moreover, the deviation ratios of the proposed sensor are approximately 0.6% and 0.4% for RI and T, respectively. Compared with the researches lately published, the sensor exhibits compact footprint and high accuracy. Therefore, we believe the proposed sensor will contribute to the future compact lab-on-chip detection system design.
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A deterministic design method and experimental demonstration of single photonic crystal nanocavity supporting both air and dielectric modes in the mid-infrared wavelength region are reported here. The coexistence of both modes is realized by a proper design of photonic dispersion to confine air and dielectric bands simultaneously. By adding central mirrors to make the resonance modes be confined at the bandgap edges, high experimental Q-factors of 2.32 × 104 and 1.59 × 104 are achieved at the resonance wavelength of about 3.875µm and 3.728µm for fundamental dielectric and air modes, respectively. Moreover, multiple sets of air and dielectric modes can be realized by introducing central aperiodic mirrors with multiple bandgaps. The realization of coexistence of air and dielectric modes in single nanocavity will offer opportunities for multifunctional devices, paving the way to integrated multi-parameter sensors, filters, nonlinear devices, and compact light sources.
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We present a novel high-sensitivity broad free-spectral-range (FSR) two-dimensional three-slot photonic crystal sensor integrated with a 1D photonic crystal tapered nanobeam bandgap filter (1DPC-TNBF) based on thin-film silicon. Designed to lie in the wavelength at around 1550 nm, the resonance of the two-dimensional photonic crystal three-slot cavity (2DPC-TSC) shows strong light-matter interaction in the slot region, which enhances the bulk refractive index sensitivity of the sensor significantly. The simulated sensitivity is over 900 nm/refractive index unit (RIU). By connecting an additional 1DPC-TNBF to a 2DPC-TSC in series, the high-order modes are suppressed, which means only a fundamental mode exists with a broad FSR over 200 nm. Thus, the proposed structure is promising in designing lab-on-a-chip applications, especially in compact parallel-integrated sensor arrays.
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The ink-jet technique was developed to print the wedge polymer microdisk lasers. The characterization of these lasers was implemented using a free-space optics measurement setup. It was found that disks of larger edge inclination angles have a larger free spectral range (FSR) and a lower resonance wavelength difference between the fundamental transverse electric (TE) and transverse magnetic (TM) whispering-gallery modes (WGMs). This behavior was also confirmed with simulations based on the modified Oxborrow's model with perfectly matched layers (PMLs), which was adopted to accurately calculate the eigenfrequencies, electric field distributions, and quality parameters of modes in the axisymmetric microdisk resonators. Combined with the nearly equivalent quality factor (Q-factor) and finesse factor (F-factor) variations, the correlations between the TE and left adjacent TM modes were theoretically demonstrated. When the edge inclination angle is varied, the distinguishable mode distribution facilitates the precise estimation of a resonance wavelength shift. Therefore, the flexible and efficient nature of wedge polymer microdisk lasers extends their potential applications in precision sensing technology.
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We developed chip-scale remote refractive index sensors based on Rhodamine 6G (R6G)-doped polymer micro-ring lasers. The chemical, temperature, and mechanical sturdiness of the fused-silica host guaranteed a flexible deployment of dye-doped polymers for refractive index sensing. The introduction of the dye as gain medium demonstrated the feasibility of remote sensing based on the free-space optics measurement setup. Compared to the R6G-doped TZ-001, the lasing behavior of R6G-doped SU-8 polymer micro-ring laser under an aqueous environment had a narrower spectrum linewidth, producing the minimum detectable refractive index change of 4 × 10-4 RIU. The maximum bulk refractive index sensitivity (BRIS) of 75 nm/RIU was obtained for SU-8 laser-based refractive index sensors. The economical, rapid, and simple realization of polymeric micro-scale whispering-gallery-mode (WGM) laser-based refractive index sensors will further expand pathways of static and dynamic remote environmental, chemical, biological, and bio-chemical sensing.
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We investigate nanocavities in deterministic aperiodic photonic crystal (PhC) nanobeams. We reveal that even a single nanocavity can support multiple mode-matched resonances, which show an almost perfect field overlap in the cavity region. The unique property is enabled by the existence of adjustable multiple bandgaps in deterministic aperiodic PhC nanobeams. Our investigation may inspire related studies on low threshold lasers, integrated nonlinear devices, optical filters, and on-chip sensors.
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Compared to the conventional strip waveguide microring resonators, subwavelength grating (SWG) waveguide microring resonators have better sensitivity and lower detection limit due to the enhanced photon-analyte interaction. As sensors, especially biosensors, are usually used in absorptive ambient environment, it is very challenging to further improve the detection limit of the SWG ring resonator by simply increasing the sensitivity. The high sensitivity resulted from larger mode-analyte overlap also brings significant absorption loss, which deteriorates the quality factor of the resonator. To explore the potential of the SWG ring resonator, we theoretically and experimentally optimize an ultrasensitive transverse magnetic mode SWG racetrack resonator to obtain maximum quality factor and thus lowest detection limit. A quality factor of 9800 around 1550 nm and sensitivity of 429.7 ± 0.4nm/RIU in water environment are achieved. It corresponds to a detection limit (λ/S·Q) of 3.71 × 10-4 RIU, which marks a reduction of 32.5% compared to the best value reported for SWG microring sensors.
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AIMS: New P2Y12 adenosine diphosphate receptor antagonists have been used in the treatment of acute coronary syndrome (ACS) with different results. This systematic review analyzed and compared the evidence from large, clinical trials regarding the efficacy of clopidogrel relative to that of cangrelor, prasugrel, and ticagrelor in reducing the incidence of cardiovascular events in patients with ACS. METHODS AND RESULTS: This analysis compared newer P2Y12 inhibitors with clopidogrel of 13 clinical trials involved a total of 87,985 patients with ACS. The newer P2Y12 inhibitors include cangrelor, prasugrel, and ticagrelor. Newer P2Y12 inhibitors significantly decreased the risk of myocardial infarction and showed a trend toward reduction of cardiovascular death (odds ratio [OR] = 0.86, 95% confidence interval [CI], 0.77-0.96, and I = 54%, P < 0.05); (OR = 0.85, 95% CI, 0.77-0.93, and I = 42%, P < 0.001). The rates of stroke events and the incidence in patients with ACS did not differ statistically between the clopidogrel group and the group with newer P2Y12 inhibitors (OR = 0.95, 95% CI, 0.79-1.14, and I = 0%, P = 0.57). However, newer P2Y12 inhibitors showed a significant increase in thrombosis in MI major or minor bleeding (OR = 1.21, 95% CI, 1.03-1.42, and I = 56%, P = 0.02) compared with clopidogrel. CONCLUSIONS: Based on this meta-analysis, newer P2Y12 inhibitors were significantly more effective than clopidogrel in the events of myocardial infarction and cardiovascular death in patients with ACS, although the incidence of thrombosis in MI-defined bleeding was higher compared with clopidogrel.