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10 pages, 2752 KiB

Open AccessCommunication

Dual Coupled Long-Range Hybrid Surface Plasmon Polariton Waveguide for Sub-Wavelength Confinement

by Yindi Wang, Shulong Wang, Juanning Zhao and Mingyuan Xue

Micromachines 2023, 14(12), 2167; https://doi.org/10.3390/mi14122167 - 29 Nov 2023

Viewed by 915

Abstract

In this paper, a long-range hybrid waveguide for subwavelength confinement based on double SPP coupling is proposed. The hybrid waveguide consists of a metal-based cylindrical hybrid waveguide and a silver nanowire. There are two coupling regions in the waveguide structure that enhance mode [...] Read more.

In this paper, a long-range hybrid waveguide for subwavelength confinement based on double SPP coupling is proposed. The hybrid waveguide consists of a metal-based cylindrical hybrid waveguide and a silver nanowire. There are two coupling regions in the waveguide structure that enhance mode coupling. Strong mode coupling enables the waveguide to exhibit both a small effective mode area (0.01) and an extremely long transmission length (700 μm). The figure of merit (FOM) of the waveguide can be as high as 4000. In addition, the cross-sectional area of the waveguide is only 500 nm × 500 nm, allowing optical operation in the subwavelength range, which helps enhance the miniaturization of optoelectronic devices. The excellent characteristics of the hybrid waveguide make it have potential applications in photoelectric integrated systems. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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12 pages, 10484 KiB

Open AccessArticle

X-Intersected Silicon Modulator of Well-Rounded Performance

by Zijian Zhu, Yingxuan Zhao, Zhen Sheng and Fuwan Gan

Micromachines 2023, 14(7), 1435; https://doi.org/10.3390/mi14071435 - 17 Jul 2023

Cited by 1 | Viewed by 975

Abstract

In silicon modulator design, implantation is always a key factor, significantly influencing the doping profile and carrier distribution. As waveguide doping is limited by the compact footprint of the modulator rib, three-dimensional complex optimization is a viable option to improve performance. This work [...] Read more.

In silicon modulator design, implantation is always a key factor, significantly influencing the doping profile and carrier distribution. As waveguide doping is limited by the compact footprint of the modulator rib, three-dimensional complex optimization is a viable option to improve performance. This work proposes an X-intersected modulator based on two inversely slanted junctions using the effective 3D Monte Carlo method for junction generation. The optimized results show that the modulation efficiency of the design is 1.09 V·cm, while the loss is 18 dB/cm, and the 3 dB bandwidth reaches over 35 GHz owing to the decreased resistance and capacitance of the 3D junction. This work demonstrates the benefits of 3D doping design in silicon modulators, contributing to higher efficiency and avoiding additional PN overlap to introduce lower capacitance. The design of 3D doping profiles well balances the DC and AC performance, and provides novel modulator solutions for high-speed datacom. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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15 pages, 3684 KiB

Open AccessArticle

Optimization of Coupling Efficiency in Butterfly Optical Communication Laser Based on Chaotic Adaptive Seeker Optimization Algorithm

by Shunshun Zhong, Cong Xu, Dongmei Sun, Lian Duan and Ji-an Duan

Micromachines 2023, 14(7), 1417; https://doi.org/10.3390/mi14071417 - 14 Jul 2023

Cited by 1 | Viewed by 906

Abstract

A chaotic adaptive seeker optimization algorithm (CASOA) is proposed in this study to improve the coupling efficiency and accuracy of a butterfly optical communication laser. It primarily relies on chaotic disturbance to improve seeker search performance. The chaotic disturbance enables the algorithm to [...] Read more.

A chaotic adaptive seeker optimization algorithm (CASOA) is proposed in this study to improve the coupling efficiency and accuracy of a butterfly optical communication laser. It primarily relies on chaotic disturbance to improve seeker search performance. The chaotic disturbance enables the algorithm to jump out from local extremes. Furthermore, chaos is associated with a novel strategy for optimizing search paths with a small population. A simulation and experiment are conducted to demonstrate that the CASOA with a few seekers has an excellent search success rate with few iterations in the coupling alignment. These results indicate that the proposed CASOA can reliably improve the coupling accuracy and efficiency of laser diodes and single-mode fibers. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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14 pages, 14674 KiB

Open AccessCommunication

Fabrication of Silver Nanobowl Arrays on Patterned Sapphire Substrate for Surface-Enhanced Raman Scattering

by Yanzhao Pang and Mingliang Jin

Micromachines 2023, 14(6), 1197; https://doi.org/10.3390/mi14061197 - 5 Jun 2023

Viewed by 1474

Abstract

The current article discusses surface-enhanced Raman spectroscopy (SERS) as a powerful technique for detecting molecules or ions by analyzing their molecular vibration signals for fingerprint peak recognition. We utilized a patterned sapphire substrate (PSS) featuring periodic micron cone arrays. Subsequently, we prepared a [...] Read more.

The current article discusses surface-enhanced Raman spectroscopy (SERS) as a powerful technique for detecting molecules or ions by analyzing their molecular vibration signals for fingerprint peak recognition. We utilized a patterned sapphire substrate (PSS) featuring periodic micron cone arrays. Subsequently, we prepared a three-dimensional (3D) PSS-loaded regular Ag nanobowls (AgNBs) array using self-assembly and surface galvanic displacement reactions based on polystyrene (PS) nanospheres. The SERS performance and structure of the nanobowl arrays were optimized by manipulating the reaction time. We discovered that the PSS substrates featuring periodic patterns exhibited superior light-trapping effects compared to the planar substrates. The SERS performance of the prepared AgNBs-PSS substrates was tested under the optimized experimental parameters with 4-mercaptobenzoic acid (4-MBA) as the probe molecule, and the enhancement factor (EF) was calculated to be 8.96 × 10⁴. Finite-difference time-domain (FDTD) simulations were conducted to explain that the AgNBs arrays’ hot spots were distributed at the bowl wall locations. Overall, the current research offers a potential route for developing high-performance, low-cost 3D SERS substrates. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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14 pages, 5162 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Stability Study of Multi-Level Grayscales Based on Driving Waveforms for Electrowetting Displays

by Wanzhen Xu, Zichuan Yi, Zhengxing Long, Hu Zhang, Jiaquan Jiang, Liming Liu, Feng Chi, Ding Tan and Huan Wang

Micromachines 2023, 14(6), 1123; https://doi.org/10.3390/mi14061123 - 26 May 2023

Cited by 1 | Viewed by 1088

Abstract

Electrowetting Display (EWD) is a new reflective display with an outstanding performance of color video playback. However, some problems still exist and affect its performance. For instance, oil backflow, oil splitting, and charge trapping phenomena may occur during the driving process of EWDs, [...] Read more.

Electrowetting Display (EWD) is a new reflective display with an outstanding performance of color video playback. However, some problems still exist and affect its performance. For instance, oil backflow, oil splitting, and charge trapping phenomena may occur during the driving process of EWDs, which would decrease its stability of multi-level grayscales. Therefore, an efficient driving waveform was proposed to solve these disadvantages. It consisted of a driving stage and a stabilizing stage. First, an exponential function waveform was used in the driving stage for driving the EWDs quickly. Then, an alternating current (AC) pulse signal waveform was used in the stabilizing stage to release the trapped positive charges of the insulating layer to improve display stability. A set of four level grayscale driving waveforms were designed by using the proposed method, and it was used in comparative experiments. The experiments showed that the proposed driving waveform could mitigate oil backflow and splitting effects. Compared to a traditional driving waveform, the luminance stability was increased by 8.9%, 5.9%, 10.9%, and 11.6% for the four level grayscales after 12 s, respectively. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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11 pages, 3361 KiB

Open AccessArticle

A Novel Surface Modification on Core–Shell Yellow Particles for Electrophoretic Display

by Zhi Zhang, Qun Chen, Yao Wang, Guanchen Li, Qingguo Gao, Liming Liu, Jianjun Yang, Xinjian Pan, Feng Chi and Lingling Shui

Micromachines 2023, 14(5), 1063; https://doi.org/10.3390/mi14051063 - 17 May 2023

Viewed by 1223

Abstract

This paper reports the synthesis of yellow-charged particles with a core–shell structure by modifying yellow pigment 181 particles using an ionic liquid under the sol–gel and grafting methods. The core–shell particles were characterized using various methods, including energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, [...] Read more.

This paper reports the synthesis of yellow-charged particles with a core–shell structure by modifying yellow pigment 181 particles using an ionic liquid under the sol–gel and grafting methods. The core–shell particles were characterized using various methods, including energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, colorimetry, thermogravimetric analysis, and others. The changes in zeta potential and particle size before and after modification were also measured. The results demonstrate that the surface of the PY181 particles was successfully coated with SiO₂ microspheres, resulting in weak color change but increased brightness. The shell layer also caused an increase in the particle size. Moreover, the modified yellow particles exhibited apparent electrophoretic response, indicating improved electrophoretic properties. The core–shell structure significantly enhanced the performance of organic yellow pigment PY181, making this method a practical modification approach. This method provides a novel way of improving the electrophoretic performance of color pigment particles that are challenging to directly connect with an ionic liquid, leading to the improved electrophoretic mobility of pigment particles. It is suitable for the surface modification of various pigment particles. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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0 pages, 5069 KiB

Open AccessArticle

A Novel Method to Detect Partial Shadow Effects in Perovskite-Based Simulated Solar Cell System Faults

by Amir Sharifi Miavaghi and Asghar Esmaeili

Micromachines 2023, 14(4), 832; https://doi.org/10.3390/mi14040832 - 11 Apr 2023

Cited by 1 | Viewed by 1557

Abstract

When a fault occurs in photovoltaic systems, a human expert should be present at the scene and perform tests to determine the location and type of the fault. In such a situation, in order to maintain the safety of the specialist, protective measures [...] Read more.

When a fault occurs in photovoltaic systems, a human expert should be present at the scene and perform tests to determine the location and type of the fault. In such a situation, in order to maintain the safety of the specialist, protective measures such as shutting down the power plant or isolating the faulty part are usually taken. Given the fact that the equipment and technology of photovoltaic systems are expensive and their efficiency is currently relatively low (about 20%), a complete shutdown of the plant or part of it can be economical, return on investment and achieve profitability. Therefore, as much as possible, efforts should be made to detect and eliminate errors in the shortest possible time without shutting down the power plant. On the other hand, most solar power plants are located in desert areas, which make them difficult to access and visit. In this case, training skilled manpower and the constant presence of an expert on site can be very costly and uneconomical. Also, if these errors are not detected and fixed in time, they can lead to power loss (not using the maximum potential of the panel), device failure and eventually fire. In this research, using fuzzy detection method, a suitable method for detecting the error of partial shadow occurrence in solar cells is presented. Based on the simulation results, the efficiency of the proposed method is confirmed. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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12 pages, 3431 KiB

Open AccessArticle

The Effect of Cooling Layer Thickness and Coolant Velocity on Crystal Thermodynamic Properties in a Laser Amplifier

by Shuzhen Nie, Tianzhuo Zhao, Xiaolong Liu, Pubo Qu, Yuchuan Yang and Yuheng Wang

Micromachines 2023, 14(2), 299; https://doi.org/10.3390/mi14020299 - 23 Jan 2023

Viewed by 1253

Abstract

Laser diode pumped solid-state lasers (DPSSLs) have been widely used in many fields, and their thermal effects have attracted more and more attention. The laser diode (LD) side-pumped amplifier, as a key component of DPSSLs, is necessary for effective heat dissipation. In this [...] Read more.

Laser diode pumped solid-state lasers (DPSSLs) have been widely used in many fields, and their thermal effects have attracted more and more attention. The laser diode (LD) side-pumped amplifier, as a key component of DPSSLs, is necessary for effective heat dissipation. In this paper, instead of the common thermal analysis based only on a crystal rod model, a fluid–structure interaction model including a glass tube, cooling channel, coolant and crystal rod is established in numerical simulation using ANSYS FLUENT for the configuration of an LD array side-pumped laser amplifier. The relationships between cooling layer thickness, coolant velocity and maximum temperature, maximum equivalent stress, inlet pressure and the convective heat transfer coefficient are analyzed. The results show that the maximum temperature (or maximum equivalent stress) decreases with the increase in the coolant velocity; at low velocity, a larger cooling layer thickness with more coolant is not conductive enough for improved heat dissipation of the crystal rod; at high velocity, when the cooling layer thickness is above or below 1.5 mm, the influence of the cooling layer thickness on the maximum temperature can be ignored; and the effect of the cooling layer thickness on the maximum equivalent stress at high velocity is not very significant. The comprehensive influence of various factors should be fully considered in the design process, and this study provides an important reference for the design and optimization of a laser amplifier and DPSSL system. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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Review

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32 pages, 9451 KiB

Open AccessReview

Recent Progress in Semitransparent Organic Solar Cells: Photoabsorbent Materials and Design Strategies

by Shabaz Alam, Suhui Sim, Meng Qiang Li, Bong-Jun Chang and Jaewon Lee

Micromachines 2024, 15(4), 493; https://doi.org/10.3390/mi15040493 - 2 Apr 2024

Viewed by 1189

Abstract

The increasing energy demands of the global community can be met with solar energy. Solution-processed organic solar cells have seen great progress in power conversion efficiencies (PCEs). Semitransparent organic solar cells (ST-OSCs) have made enormous progress in recent years and have been considered [...] Read more.

The increasing energy demands of the global community can be met with solar energy. Solution-processed organic solar cells have seen great progress in power conversion efficiencies (PCEs). Semitransparent organic solar cells (ST-OSCs) have made enormous progress in recent years and have been considered one of the most promising solar cell technologies for applications in building-integrated windows, agricultural greenhouses, and wearable energy resources. Therefore, through the synergistic efforts of transparent electrodes, engineering in near-infrared photoabsorbent materials, and device engineering, high-performance ST-OSCs have developed, and PCE and average visible transmittance reach over 10% and 40%, respectively. In this review, we present the recent progress in photoabsorbent material engineering and strategies for enhancing the performance of ST-OSCs to help researchers gain a better understanding of structure–property–performance relationships. To conclude, new design concepts in material engineering and outlook are proposed to facilitate the further development of high-performance ST-OSCs. Full article

(This article belongs to the Special Issue Advances in Optoelectronic Devices, 2nd Edition)

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