High Optical Efficiency Research Articles

Paperfluidic Chip Device for Small RNA Extraction, Amplification, and Multiplexed Analysis.

Small RNAs have been considered as potential biomarkers of various human diseases. Sensitive and multiplexed determination of small RNAs with point-of-care (POC) assay would be of great significance. Herein, an integrated paperfluidic chip device for multiplexed small RNA analysis was developed for the first time. In this system, the extraction and purification of small RNA was completed through a poly(ether sulfone) (PES) paper chip without the need for centrifugation. Subsequently, a newly designed hairpin probe-exponential amplification reaction (HP-EXPAR) was directly performed within the extraction paper chip. For the simultaneous realization of multiple detection, a multilayer paper chip was designed in a foldable manner with more portability and usability. Quantum dots (QDs) were employed as signal labels, which endowed this assay with high optical detection efficiency. Moreover, magnetic sheets were introduced as an alternative method for layer stacking, not only guaranteeing adjacent layers are in contact but also facilitating the sample dispersion. With these outstanding characteristics, our platform obtained a satisfactory sensitivity range from 3 × 105 to 3 × 108 copies with a limit of 3 × 106 copies. Additionally, the multiplex small RNA analyses from various cancer cells were in good agreement with the results of the real-time polymerase chain reaction (qRT-PCR). More importantly, simultaneous analysis of two types of miRNAs from clinical tumor samples demonstrated the clinical applicability of the system. Therefore, the proposed paper-based device shows great promise for POC applications in the future.

Fabrication of Hexagonal Microlens Arrays on Single-Crystal Silicon Using the Tool-Servo Driven Segment Turning Method.

Single-crystal silicon microlens arrays are increasingly required in advanced infrared optics. In this study, the authors attempted to fabricate hexagonal microlens arrays, which offer high optical efficiency, on a single-crystal silicon wafer using diamond turning. A tool-servo driven segment turning method was proposed to reduce the dynamic error of the machine tool induced by lenslet edges during lens array cutting. From the results of both cutting experiments and theoretical analysis of the machine tool dynamic error, it was demonstrated that the segment turning method reduced significantly the dynamic errors and led to high form accuracy. As a result, sharp edges among the lenslets were generated precisely and microlens arrays with a form error of ~300 nm peak-to-valley and surface roughness of ~5 nmSa, which meets the requirements of infrared optical systems, were successfully fabricated. The subsurface damage, such as the amorphization of silicon, caused by machining was also reduced.

Optimization design and performance analysis of a novel asymmetric compound parabolic concentrator with rotation angle for building application

A novel asymmetric lens-walled compound parabolic concentrator (ALCPC) for integration with the building south wall was proposed and manufactured. Besides of the asymmetric lens-walled structure, the special rotation angle at the bottom is also introduced to optimize the performance. The electrical and optical performance of the ALCPC-PV was detailed analyzed through the experiment and ray tracing simulation. The indoor experiment was conducted by a solar simulator (Oriel Sol3A Model 90943A) from Newport Corporation at the dark environment with the temperature of 25 °C. Form the experiment results, the ALCPC increases the maximum power by a ratio of 1.74x compared to the bare cell. The decrease of the geometric concentration ratio is mainly due to manufacturing errors, mismatch losses, series resistance losses, etc. The optical performance of the ALCPC was also investigated by the software Lighttools, and the optical efficiency and the distribution percentage of the energy collected through the total internal reflection and the specular reflection at different incidence angles are identified at various incidence angles. A good agreement is observed between the experiment results and the ray tracing results. The optical efficiency at the incidence angles of 0–60° is all within 90% of its peak value which means that the proposed ALCPC can achieve 60° acceptance angle with high optical efficiency that it shows a good potential as a static concentrator for the building south wall integration.

Cost-Effective Light-Mixing Module for Solar-Lighting System Appended With Auxiliary RGBW Light-Emitting Diodes

A light-mixing module consisting of a compound parabolic concentrator (CPC) and a light-mixing tube is proposed herein to realize a uniform and efficient solar-lighting system. In this lighting system, the sunlight collected into a fiber and then guided to an indoor destination is the principal light source, while an auxiliary light source including multiple red, green, blue, and white (RGBW) light-emitting diodes (LEDs) is controlled by an auto-compensating module. To mix the principal and the auxiliary sources and to realize the uniform illumination, the light-mixing tube was coated with BaSO4 and optimized as a cylindrical tube. The design of the light-mixing tube is described and discussed in this article. According to the simulated results, the uniformity and the optical efficiency of the designed light-mixing tube are 82.9% and 85.7%, respectively, while from the experimental results, the uniformity of 85.9% and the optical efficiency of 83.3% have been obtained. In terms of the common indoor-lighting standards and the specifications of commercial components used in lighting systems, the proposed light-mixing module has demonstrated the high uniformity and acceptable optical efficiency. Additionally, since the main components of the light-mixing module can be designed as plastic optics, a cost-effective light-mixing module and a profitable lighting system can be realized. Thus, the performance and the price of the proposed light-mixing module fit the demands of the illumination market, while the proposed system shows the potential for indoor solar-lighting applications.

Ray-leakage-free discal solar concentrators of a novel design

For high concentration ratio of the planar concentrator which is mainly used for photovoltaic or solar-thermal applications, the ray-leakage must be prevented during rays propagated in the lightguide. In this paper, the design of a ray-leakage-free discal solar concentrator is proposed which provides a high concentration ratio while acquiring a high optical efficiency. The design structure of the coupling structure is a straightforward hemisphere instead of complicated structure in other concentrators because the emergent rays from the hybrid collectors have any tilt angle, which prompts the ray-leakage-free propagating length can be raised greatly. A mathematical model between geometrical concentration ratio, reflection times and the corresponding parameters is established, where the corresponding parameters include the parabola coefficient, outermost collector width, collector height, the expanding angle and the collector quantity. Numerical simulation results show that more than 1200x geometrical concentration ratio of the proposed concentrator is achieved without any leakage from the lightguide.

Mitigation of Dust Impact on Solar Collectors by Water-Free Cleaning With Transparent Electrodynamic Films: Progress and Challenges

Energy-yield loss caused by soiling of photovoltaic modules and concentrated solar power (CSP) mirrors in utility-scale power plants installed in semiarid lands and deserts would result in unsustainable demands for fresh water needed for cleaning. This paper reviews the progress of the electrodynamic screen (EDS) film technology for frequent water-free cleaning with low-energy requirements. Results presented here, based on laboratory-scale EDS-film-laminated solar panel cleaning, show that the output power can be restored higher than 95% of the initial power under clean conditions. For solar mirrors, the specular reflection efficiency can be maintained over 90% ensuring high efficiency of the CSP plants. Operation of the EDS film for maintaining high optical efficiency of solar collectors requires less than 0.2 Wh/m ${}^2$ /cleaning cycle. Principles, optical modeling, construction, lamination of the EDS films on modules and mirrors, and experimental data showing optical efficiency restoration without water consumption are presented. Current challenges in developing electrodes that would meet optical and conduction properties, low-cost production, and meeting long-term outdoor durability of the EDS films are discussed.

A design of high optical efficiency wedge type light guide plate adopting twin inclined cylindrical surface

AbstractWe propose wedge type light guide plate (LGP) adopting twin inclined cylindrical surfaces (TICS) at the incident part of a LGP. It has higher optical efficiency than conventional wedge type LGP. In dimension of LGP which the thickness of incident part is 1.5 mm and that of luminance part is 0.7 mm, the optical efficiency of wedge type LGP adopting TICS is expected to be 96% in comparison with a normal flat LGP. In addition, there is an advantage to reduce the non‐uniformity of vicinity of light emitted diodes (LEDs) by TICS reflecting light laterally. However, it is necessary that the LED centers are aligned with the intersections of TICS. The misalignment of LED causes non‐uniformity of optical profile that is slightly larger than a normal LGP.

Low-Coherence light source design for ESPI in-plane displacement measurements

The ESPI method for surface deformation measurements requires the use of a light source with high coherence length to accommodate the optical path length differences present in the apparatus. Such high-coherence lasers, however, are typically large, delicate and costly. Laser diodes, on the other hand, are compact, mechanically robust and inexpensive, but unfortunately they have short coherence length. The present work aims to enable the use of a laser diode as an illumination source by equalizing the path lengths within an ESPI interferometer. This is done by using a reflection type diffraction grating to compensate for the path length differences. The high optical power efficiency of such diffraction gratings allows the use of much lower optical power than in previous interferometer designs using transmission gratings. The proposed concept was experimentally investigated by doing in-plane ESPI measurements using a high-coherence single longitudinal mode (SLM) laser, a laser diode and then a laser diode with path length optimization. The results demonstrated the limitations of using an uncompensated laser diode. They then showed the effectiveness of adding a reflection type diffraction grating to equalize the interferometer path lengths. This addition enabled the laser diode to produce high measurement quality across the entire field of view, rivaling although not quite equaling the performance of a high-coherence SLM laser source.

Ray-leakage-free planar solar concentrator featuring achromatic hybrid collectors and innovative secondary optical elements

For high concentration ratio of the planar concentrator which is mainly used for photovoltaic or solar-thermal applications, the ray-leakage must be prevented during rays propagated in the lightguide. In this paper, the design of a ray-leakage-free planar solar concentrator is introduced with achromatic hybrid collectors and innovative secondary optical elements. The distance between two columns of dimple structures is larger because the collector width is irrelevant to the collector length, which prompts the ray-leakage-free propagating length can be raised greatly. Put differently, the proposed concentrator can obtain a high geometrical concentration ratio while achieving a high optical efficiency. To increase the ray-leakage-free propagating distance, a mathematical model between ray-leakage-free propagating length and the corresponding parameters is established, where the corresponding parameters include the parabola coefficient, the width of collector, the concentrator height and the small expanding angle of the dimple structure. Numerical results display that more than 5000x geometrical concentration ratio of the proposed concentrator is achieved without any leakage from the lightguide.

Linearly polarized narrow linewidth ytterbium-doped fiber laser at 1120 nm

Based on a spectrally symmetric cavity with respect to fiber Bragg grating bandwidth, using cladding pump technology, a 1120 nm continuous-wave narrow linewidth ytterbium-doped fiber laser is demonstrated. A maximum output power of 14.67 W is obtained corresponding to an optical efficiency of 63.5% to launched pump power. The measured center wavelength of the output laser is 1118.7 nm with a linewidth as narrow as 0.08 nm. The gain of the laser is more than 60 dB above the amplified spontaneous emission, and the polarization extinction ratio is 19.8 dB. As far as we are aware, this is the highest optical efficiency, largest amplified spontaneous emission suppression, and narrowest linewedth reported from cladding pumped linearly polarized 1120 nm fiber lasers.

Low voltage and high transmittance transflective blue-phase liquid crystal display with opposite polar electrodes

ABSTRACTA single-cell-gap transflective polymer-stabilised blue-phase liquid crystal display with opposite polar pixel electrodes on an etched substrate is proposed. In the proposed structure, the space between common electrodes is adopted as transmissive region, and the space above the common electrode is adopted as reflective region. By optimising the electrode parameters of the transmissive and reflective regions, well-matched voltage-dependent transmittance and reflectance curves can be obtained. In addition, the device has good performances of low operating voltage (~3.2 V), high optical efficiency and a wide viewing angle.

Continuous cubic phase microplates for generating high-quality Airy beams with strong deflection.

Owing to the distinguishing properties of nondiffraction, self-healing, and transverse acceleration, Airy beams have attracted much attention in the past decade. To date, a simple approach for exquisitely fabricating cubic phase plates with both continuous variation of phase and micro size still remains challenging, which limits the generation of high-quality Airy beams for integrated micro-optics. Here, we report the elaborate design and fabrication of a continuous cubic phase microplate (CCPP) for generating high-quality Airy beams in micrometer scale. A CCPP with a precise size (60 μm×60 μm×1.1 μm) is fabricated by femtosecond laser direct writing, exhibiting a high optical efficiency (∼79%). The high-quality Airy beam generated via the CCPP demonstrates an unprecedentedly strong deflection (∼4.2 μm within a 90μm propagation distance) as well as being diffraction-free. Our research on the design and fabrication of miniature Airy phase plates paves the way toward high-performance integrated optics, optical micromanipulation, and optical imaging.

All‐Dielectric Heterogeneous Metasurface as an Efficient Ultra‐Broadband Reflector

Conventional all‐dielectric metasurfaces made from high‐index and low‐loss materials (such as Si or GaAs) can achieve high optical efficiencies as well as broadband characteristics, mostly for the infrared (IR) light. However, maintaining the bandwidth and efficiency for conventional all‐dielectric metasurfaces for visible or near‐IR light becomes challenging, due to the limitations from material selection as well as fabrication techniques. In this paper, the idea of heterogeneous all‐dielectric metasurfaces is proposed for a better metasurface design in shorter‐wavelength ranges. An ultra‐broadband reflector, as a proof‐of‐principle demonstration, is presented in this paper, both numerically and experimentally. The broadband reflector demonstrates a good optical efficiency, a broadband reflectance, as well as a great manufacturability. Nanoimprint lithography patterning process and advanced etching recipes are developed for the large‐area and low‐cost heterogeneous metasurface fabrication.

Compact integrated optical system for a tip-enhanced Raman spectrometer.

A compact integrated optical system is presented to overcome the low optical efficiency, poor coordination, bulk size, and high cost of a traditional tip-enhanced Raman spectroscopy (TERS) instrument. In this optical system, the excitation and collection optics are integrated with white light illumination and micro-imaging optics and Raman spectrometer optics. The optics are simplified, the optical path is decreased, and the Raman spectrometer structure is improved. The integrated optical system has high optical efficiency, high resolving power, and compact size; it is designed to couple with a specific homemade STM head and cooperative control circuit to develop a small integrated TERS instrument.

Optimization of solar linear Fresnel reflector system with secondary concentrator for uniform flux distribution over absorber tube

Solar linear Fresnel reflectors (LFR) are attractive because of low cost and optimal utilization of land area. They provide high concentration ratio when used in conjunction with secondary concentrators. A pilot plant of LFR system with 154m2 of primary mirror field installed at Vallipuram, India has been considered for the present analysis. This type of collectors give rise to high variation of solar radiation flux in the circumferential direction of absorber for the cases with fixed aim line of primary mirrors. In the present work, the concept of variable aim lines for primary mirrors is introduced to defocus and spread the radiation flux in a more uniform manner over the absorber. In particular, both the tilt angles and the radii of curvature of the individual Fresnel mirrors are modified to obtain a better flux uniformity. In addition, a novel segmented parabolic secondary concentrator profile has also been developed, which in conjunction with the variable aim line concept leads to a high optical efficiency of 76.4% and a coefficient of flux variation value of 0.13. On the other hand, 74.9% and 70.9% of optical efficiencies along with 0.17 and 0.33 values of coefficient of variation are obtained with more commonly employed compound parabolic concentrator and trapezoidal concentrator profiles respectively.

High efficiency optical coupling in long wavelength quantum cascade infrared detector via quasi-one-dimensional grating plasmonic micro-cavity

A combination of quasi-one-dimensional grating and plasmonic micro-cavity is proposed as a normal-illuminated optical coupler for a long wavelength quantum cascade infrared detector. A finite difference time-domain method is used to numerically simulate the reflection spectra and the field distributions of the optical coupler. The average |Ez|2 in the active layer reaches 4.1 (V/m)2 under the 13.5 μm infrared normal illumination with a strength of 1 (V/m)2. A mixed state of localized surface plasmon and surface plasmonic polariton is observed. The results confirm that the quasi-one-dimensional grating plasmonic micro-cavity structure could generate more plasma excitation source, and as a consequence, a high optical coupling efficiency of 410% in the active region is obtained. Moreover, an excellent polarization-discriminating performance is observed.

Effect of oil on an electrowetting lenticular lens and related optical characteristics.

While there are many ways to realize autostereoscopic 2D/3D switchable displays, the electrowetting lenticular lens is superior due to the high optical efficiency and short response time. In this paper, we propose a more stable electrowetting lenticular lens by controlling the quantity of oil. With a large amount of oil, the oil layer was broken and the lenticular lens was damaged at relatively low voltage. Therefore, controlling the amount of oil is crucial to obtain the required dioptric power with stability. We proposed a new structure to evenly adjust the volume of oil and the dioptric power was measured by varying the volume of oil. Furthermore, the optical characteristics were finally analyzed in the electrowetting lenticular lens array with a proper amount of oil.

High efficiency quasi-three level thin film laser enabled on a sinusoidal grating substrate.

The excitation and emission properties of optical materials can be adjusted by nanostructures and to achieve high optical efficiency in the optically pump laser, especially for lasers with short absorption length and high pump threshold. We present and theoretically investigate a Yb-doped thin film on a 1D grating structure in this paper. High reflectivity at the pump and emission wavelength are realized simultaneously and in terms of the guided-mode resonance theory, the local field of high reflected light is enhanced which will increase the absorption of associated laser wavelength. We analyze parameters of the nanostructure in detail based on rigorous coupled-wave theory and an appropriate structure is decided. Finally, we demonstrate that this designed structure can effectively improve the optical efficiency of optically pump solid state laser.

Improvement of the blue-color quenching and optical efficiency of laser for the head-up display

ABSTRACTThis paper presents an examination of the control of optical quenching according to the junction temperature of a high-brightness laser. A high-brightness blue laser source is being reviewed for head-up display). The laser is problematic, however, because its luminous efficiency, and hence its lifetime, is reduced due to its low laser junction temperature, and particularly due to its blue optical quenching, which is a disadvantageous characteristic. This problem was addressed by applying a current supply method with a high-frequency pulse width modulation (PWM) scheme and a digital micro-mirror device panel based on a method using a color wheel that uses yellow phosphor material. PWM of the frequency and analysis and optimization of the duty ratio enabled the prevention of the optical quenching of the blue laser to obtain high optical efficiency.

Micro-pulse upconversion Doppler lidar for wind and visibility detection in the atmospheric boundary layer.

For the first time, to the best of our knowledge, a compact, eye-safe, and versatile direct detection Doppler lidar is developed using an upconversion single-photon detection method at 1.5 μm. An all-fiber and polarization maintaining architecture is realized to guarantee the high optical coupling efficiency and the robust stability. Using integrated-optic components, the conservation of etendue of the optical receiver is achieved by manufacturing a fiber-coupled periodically poled lithium niobate waveguide and an all-fiber Fabry-Perot interferometer (FPI). The double-edge technique is implemented by using a convert single-channel FPI and a single upconversion detector, incorporating a time-division multiplexing method. The backscatter photons at 1548.1 nm are converted into 863 nm via mixing with a pump laser at 1950 nm. The relative error of the system is less than 0.1% over nine weeks. In experiments, atmospheric wind and visibility over 48 h are detected in the boundary layer. The lidar shows good agreement with the ultrasonic wind sensor, with a standard deviation of 1.04 m/s in speed and 12.3° in direction.