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Study on the adaptability of augmented reality smartglasses for astigmatism based on holographic waveguide grating
摘要： Background Augmented reality (AR) smartglasses are considered as the next generation of smart devices to replace mobile phones, and are widely concerned. But at present, AR smartglasses are usually designed according to the human normal eyes. In order to experience AR smartglasses perfectly, abnormal eye users must first wear diopters. Methods For people with astigmatism to use AR smartglasses without wearing a diopter lens, a cylindrical lens waveguide grating is designed in this study based on the principle of holographic waveguide grating. First, a cylindrical lens waveguide substrate is constructed for external light deflection to satisfy the users' normal viewing of the real world. Further, a variable period grating structure is established based on the cylindrical lens waveguide substrate to normally emit the light from the virtual world in the optical machine to the human eyes. Finally, the structural parameters of grating are optimized to improve the diffraction efficiency. Results The results show that the structure of cylindrical lens waveguide grating allows people with astigmatism to wear AR smartglasses directly. The total light utilization rate reaches 90% with excellent imaging uniformity. The brightness difference is less than 0.92% and the vertical field of view is 10°. Conclusions This research serves as a guide for AR product designs for people with long/short sightedness and promotes the development of such products.
关键词： Astigmatism,Augmented reality smartglasses,Holographic waveguide grating,Cylindrical lens
更新于2025-09-23 15:19:57
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Effect of insertion of bathocuproine buffer layer at grating-structured cathodea??organic-layer interface in bulk-heterojunction solar cells
摘要： A grating-structured interface of a poly(3-hexylthiophene) (P3HT) and n-type [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-based bulk-heterojunction (BHJ) photovoltaic (PV) cell was designed and fabricated to obtain a desirable thickness distribution of the deposited bathocuproine (BCP) buffer layer to efficiently utilize its potentials. As a master mold of the grating-structure, a commercially available recordable digital versatile disc (DVD-R) substrate was employed. The grating-structured surface of the P3HT:PCBM layer was successfully produced by duplication from a poly(dimethylsiloxane) secondary mold using the spin cast molding technique. From morphological observations of the grating-structured surface covered with vapor-deposited BCP, we roughly estimated the ratio of the BCP thickness at “walls” to that at “top” and “bottom” regions to be ～0.5. The grating-type BHJ PV cell with a 5-nm-thick BCP layer exhibited the maximum power-conversion efficiency (ηp) of 3.51%. Compared with the conventional flat-type BHJ PV cell with a 20-nm-thick BCP layer, the performance of the grating-type BHJ PV cell with a 20-nm-thick BCP layer was remarkably improved, owing to the contribution of the wall side contact, which provides a lower-barrier path of the electrons toward the cathode through the thinner BCP layer.
关键词： bathocuproine buffer layer,grating-structured interface,bulk-heterojunction solar cells,power-conversion efficiency
更新于2025-09-23 15:19:57
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Electromagnetically induced grating in semiconductor quantum dot and metal nanoparticle hybrid system by considering nonlocality effects
摘要： The optical polarization from a hybrid system including a closely spaced spherical SQD (modeled as a three-level V-type system) and a metal nanoparticle which are considered classically and are connected by the dipole–dipole interaction mechanism is investigated. The interaction between the SQD and the MNP shows an interesting optical response. In the weak probe field regime and MNP nonlocality correction, the absorption spectrum of the hybrid system exhibits an EIT window with two absorption peaks and the plasmon-assisted quantum interference plays an important role in the position and amplitude of these peaks, which are intensely altered by including the nonlocal effects. The probe diffraction grating is created based on the excitons-induced transparency by applying a standing-wave coupling field. The results of this study are useful in numerous areas of all-optical communications.
关键词： Metal nanoparticles (MNP),Hybrid system,Electromagnetically induced grating (EIG),Nonlocality,Semiconductor quantum dot (SQD)
更新于2025-09-23 15:19:57
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[IEEE 2019 4th International Conference on Mechanical, Control and Computer Engineering (ICMCCE) - Hohhot, China (2019.10.24-2019.10.26)] 2019 4th International Conference on Mechanical, Control and Computer Engineering (ICMCCE) - Design of a Stroboscopic Laser Grating Stripe Projection Device
摘要： A three-dimensional measuring system based on a line-structured laser and a high-speed rotating multi-faced prism has been designed and described in detail. The grating fringe can be produced using stroboscopic effect the system. The relationship between grating stripe and modulation signal and prism rotation speed are analyzed from both theoretical and experimental aspects. At the same time, the grating stripe projection device is applied to the three-dimensional measurement of gypsum section.
关键词： grating fringe,stroboscopic effect,laser,three-dimensional reconstruction
更新于2025-09-23 15:19:57
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Evaluation of Chirped Fiber Bragg Grating with APD on Designed Optical Fiber Communication Link
摘要： Application of fiber Bragg grating (FBG) in optical communication is an evolving field. In this research paper, various types of chirped FBG’s (CFBG) have been used with avalanche photodiode (APD) on the designed optical fiber communication (OFC) link. Data rate of 20 Gbps and return-to-zero modulation format has been kept as fixed parameters. The designed link has been evaluated for varying fiber lengths (100, 200, 300, 400 and 500 km), various type of CFBG’s (linear, quadratic, square root and cubic root) with Gaussian apodization function, varying grating lengths (10, 20, 30, 40 and 50 mm) and operating temperatures (5°C, 10°C, 15°C, 20°C, 25°C, 30°C). The designed OFC link has also been evaluated for APD with and without CFBG. The performance evaluation matrix parameters selected are Q-factor, bit error rate and eye diagram. The OFC link employing CFBG with APD has been found to be superior. In compensating chromatic dispersion, optimum results have been observed for linear CFBG with Gaussian apodization function in comparison to other types of CFBG with 50 mm grating length for the maximum transmission distance.
关键词： bit error rate (BER),Optical fiber communication (OFC),eye diagram,chirped fiber Bragg grating (CFBG),vertical cavity surface emitting laser (VCSEL),avalanche photodiode (APD),Q-factor
更新于2025-09-23 15:19:57
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Femtosecond-laser direct-writing volume phase gratings inside Gea??Asa??S chalcogenide glass
摘要： In this study, volume-phase gratings (VPGs) were fabricated inside Ge–As–S chalcogenide glasses (ChG) with femtosecond-laser writing technology. VPGs with high thicknesses were obtained through single-step writing by exploiting the self-focusing effect of highly nonlinear ChGs. The clear diffraction patterns and high diffraction efficiency of the prepared gratings indicated their high optical performance. Testing results showed that the diffraction efficiency of VPGs first increased with laser pulse energies and then decreased when the laser damage threshold of the glass reached 9.42 nJ. Grating thickness also exhibited the same trend as laser pulse energies and reached the maximum value of 28 μm at 9.42 nJ. The changes in the refractive indexes of volume gratings fabricated under different laser pulse energies were carefully investigated. The changes in the refractive indexes of the gratings remained at the same level while laser pulse energy was increased. Meanwhile, grating thickness played a key role in diffraction efficiency. The maximum diffraction efficiency of the prepared VPGs reached 50% at 808 nm under optimized laser parameters.
关键词： chalcogenide glass,volume-phase grating,laser direct-writing,nonlinear optics
更新于2025-09-23 15:19:57
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An air-coupled ultrasonic sensor based on cascaded fibre Bragg grating and Fabry-Perot interference cavity
摘要： In this paper, we proposed and demonstrated experimentally an air-coupled fiber-optic ultrasonic sensor, based on cascaded fibre Bragg grating (FBG) and Fabry-Perot interference (FPI) cavity. Because of the modulation effect of FPI cavity, the sensor’s responses to ultrasonic wave (UW) have been improved. With side-band filtering technology-based intensity interrogation, the voltage responses of 1.2 V and 1.34 V to the continuous and pulse UW at 1 MHz respectively are obtained in air, and its SNR is about 37 dB. Further results of the directivity and stability of the sensor indicate that the sensor has the potential of imaging in air.
关键词： Fibre Bragg grating,Air-coupled,Ultrasonic sensor,Fibre-optic sensor
更新于2025-09-23 15:19:57
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Electromagnetically induced grating in double quantum dot system
摘要： Electromagnetically induced grating (EIG) in the ladder-plus-Y double quantum dot system is modeled and the diffraction grating properties are explored in this structure. A high transmission function is obtained under the high pump field. This function is reduced under increasing the probe field due to the Kerr effect. The phase of this function depends on pumping. It is shown that the application of another two fields from the wetting layer (WL)-quantum dot (QD) type is more efficient in obtaining very high diffraction intensity. So, EIG with high diffraction intensity is obtained under a four-field application. Note that, WL-QD field effect is not studied earlier. Neglecting the WL effect reduces the transmission by five times. The diffraction intensity of this system is six times higher than that obtained from a single QD structure.
关键词： Quantum dot,Electromagnetically induced grating,Diffraction intensity
更新于2025-09-23 15:19:57
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Observation of topologically enabled unidirectional guided resonances
摘要： Unidirectional radiation is important for various optoelectronic applications, such as lasers, grating couplers and optical antennas. However, almost all existing unidirectional emitters rely on the use of materials or structures that forbid outgoing waves—that is, mirrors, which are often bulky, lossy and difficult to fabricate. Here we theoretically propose and experimentally demonstrate a class of resonances in photonic crystal slabs that radiate only towards one side of the slab, with no mirror placed on the other side. These resonances, which we name ‘unidirectional guided resonances’, are found to be topological in nature: they emerge when a pair of half-integer topological charges in the polarization field bounce into each other in momentum space. We experimentally demonstrate unidirectional guided resonances in the telecommunication regime by achieving single-side radiative quality factors as high as 1.6 × 105. We further demonstrate their topological nature through far-field polarimetry measurements. Our work represents a characteristic example of applying topological principles to control optical fields and could lead to energy-efficient grating couplers and antennas for light detection and ranging.
关键词： Unidirectional radiation,Light detection and ranging,Photonic crystal slabs,Telecommunication regime,Grating couplers,Topological charges
更新于2025-09-23 15:19:57
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Near-infrared absorption enhancement for perovskite solar cells via the rear grating design
摘要： Optical management and design is one of the most effective methods to unlock the full potential of photocurrent density and power conversion efficiency for perovskite solar cells (PSCs). However, the common-used optical designs are still limited by the near-infrared response. Here, we proposed an effective optical structure in PSCs by texturing the rear-side perovskite layer with a rectangular grating to promote the optical response in the near-infrared region. Through the comprehensive numerical simulations, the new design under the optimized structural configuration shows an improved photocurrent density, i.e., from 22.75 (flat structure) to 23.72? mA/cm2. We confirm that the optical absorption enhancement occurs at the near-infrared region by the wavelength-dependent absorption and reflection spectra. Besides, the light-trapping mechanism was clarified by the comprehensive analysis of the electric field distributions. Moreover, PSCs having the rear-grating design demonstrate the superior optical performance compared to that of flat design in the varied incident angles. Our simulation results displayed in this study provide an easy scheme to promote the optical absorption in near-infrared region.
关键词： Near-infrared light,Rear grating,Perovskite solar cells,Optical absorption
更新于2025-09-23 15:19:57