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981.
魏衍福;李国辉;潘登;温荣;冀婷;冯琳;崔艳霞 《发光学报》2022,43(10):1478-1494
可溶液法制备的钙钛矿拥有优异的光学、电学性能,是一类极具潜力的电泵浦激光增益介质。近年来,基于钙钛矿材料的室温连续光泵浦激光以及大电流电致发光器件陆续被报道,在通向钙钛矿电泵浦激光的研究上取得了可喜进展,本文以此为主题展开综述。首先,介绍了钙钛矿材料实现电泵浦激光的优势。接着,梳理了现阶段通向钙钛矿电泵浦激光的两大问题,即非辐射复合损耗高和热效应严重,同时给出了改善这两大问题可采取的一些有效策略。然后,给出了电荷注入平衡化、降低光学损耗、促进粒子数反转等补充手段,它们有力推动了通向钙钛矿电泵浦激光研究向前发展。此外,还介绍了钙钛矿表面等离激元激光、钙钛矿激子极化激元激光等有望实现低阈值钙钛矿电泵浦激光的新机制。最后,总结全文,并对电泵浦钙钛矿激光未来研究做出了展望。 相似文献
982.
尹朋伟;李彦潮;赵文凯;赵国营;张龙;姜益光 《发光学报》2022,43(11):1705-1720
中红外稀土掺杂连续光纤激光在光声技术、红外制导、医疗手术、塑料加工以及5G通信等领域有着十分广阔的应用前景。然而,制备中红外稀土掺杂连续光纤激光器的光纤基质材料单一,再加上高增益光纤和器件的缺乏,大大限制了大功率单频连续光纤激光器的发展。本文对比了传统的石英光纤、氟化物光纤、硫系光纤和重金属氧化物光纤,最终将碲酸盐光纤作为阐述对象。重点阐述了国内外中红外稀土掺杂碲酸盐连续光纤激光的研究进展,目前2.0μm波段的最高输出功率为8.08W、最高斜率效率为77%;3.0μm波段的理论模拟结果显示最高输出功率高达5.219W、最高斜率效率可达40%。 相似文献
983.
984.
985.
化妆品中的添加剂种类繁多,这些物质的加入可提升化妆品的使用效果和保质期限,但过量使用则可能对人体健康造成不良影响。该研究利用吸光材料－激光解吸附离子化质谱（AR－LDIMS）建立了化妆品中添加剂的快速分析方法。利用该法对化妆品中的3-亚苄基樟脑、4-甲基苄亚基樟脑、对羟基苯乙酮和环吡酮进行检测,检出限分别为4、6、40、10mg/kg。通过加入内标物,可实现化妆品中樟脑衍生物（3-亚苄基樟脑、4-甲基苄亚基樟脑）的定量分析,其线性范围为60～140mg/kg。该方法前处理过程简便,总分析时间不超过5min,分析结果灵敏、准确,在化妆品原位快检中有着较为广阔的应用前景。 相似文献
986.
YU Haihu;WU Jianwen;MA Yue;YANG Xiaotao;ZHENG Yu 《光子学报》2022,51(9):147-155
Supercontinuum refers to the phenomenon that the spectrum of a high power pulse transmitted in a nonlinear medium is broadened by a variety of nonlinear effects. The generation of supercontinuum can greatly broaden the spectrum of optical signals, usually to the range of tens to hundreds of nanometers. In addition, supercontinuum light has the advantages of super brightness, wide band, high stability and high spatial coherence. Therefore, it has great application value in many fields, such as optical frequency calculation, optical communication, optical coherence tomography and biomedical science. In 1976, the supercontinuum in fiber was observed for the first time in nanosecond pulses generated by dye lasers, but the band coverage of the supercontinuum is narrow and the pump power required is high. The photonic crystal fiber made up for these deficiencies. Photonic crystal fiber, also known as microstructured fiber, is a special fiber whose cross section has two-dimensional periodic refractive index variation and extends indefinitely along the fiber axis. Photonic crystal fibers exhibit many special optical properties due to the variation of refractive index contrast between core and cladding. Photonic crystal fiber plays an important role in optical fiber communication, optical fiber sensing, meteorology, medical imaging and supercontinuum generation due to its flexible structure and special optical properties. Photonic crystal fiber can obtain the position of zero dispersion point at the desired wavelength by adjusting the structure, thus generating supercontinuum spectrum based on various nonlinear effects. For the generation of supercontinuum in photonic crystal fibers, the excitation conditions and the optimization and adjustment of its flatness and spectrum width have always been the focus of research. Especially in engineering applications, supercontinuum has many specific requirements. Although some progress has been made in the study of visible to near-infrared supercontinuum in photonic crystal fibers, the reported spectrum broadening is still limited and the required fiber length is relatively long. In order to improve the spectral width and make it have higher application value, in this work, based on the simulation calculation to explore the influence of optical fiber air hole structure size on dispersion, the optimized optical fiber structure geometric parameters are obtained. After independently designing the optical fiber, a kind of solid-core photonic crystal fiber with high nonlinearity is obtained by using the stack method. The full vector finite element method was used to simulate the photonic crystal fiber, and the zero dispersion point of the photonic crystal fiber was obtained at 880 nm. At the pump wavelength, the photonic crystal fiber has a nonlinear coefficient of 33.67 km-1∙W-1 and an effective mode field area of 4.72 µm2. Through the establishment of a supercontinuum experimental device, a 1 030 nm, 150 fs linear polarization ultrafast fiber source is coupled into the photonic crystal fiber, and the coupling efficiency is 52.7% at low power. The generation process of supercontinuum from visible to near infrared region is studied under different pump power and different optical fiber length. It can be seen from the analysis that when the average pumping power increases in 0.5 m long photonic crystal fiber, the output spectrum broadening increases accordingly. At the maximum average pump power of 1 320 mW, a supercontinuum spectrum with a broadening range from 475 nm to 1 870 nm is obtained, and the flatness of the spectrum is improved compared with that at low pump power. By studying the effect of fiber length on the supercontinuum spectrum, it can be found that the supercontinuum is further broadened and flatness is improved with the increase of fiber length under the condition of constant average pumping power. Finally, the broadband supercontinuum output from 450 nm to 1 900 nm was achieved in the 1.5 m long photonic crystal fiber, and the spectrum has good flatness and coherence. Such broadband light sources have potential applications in optical coherence tomography, spectroscopy, communications, early cancer detection and food quality control. 相似文献
987.
988.
Wenhui FAN;Hui YAN;Xiaoqiang JIANG;Longchao CHEN;Zhuanping ZHENG;Jia LIU;Hui LI;Ling DING;Chao SONG 《光子学报》2022,51(7):51-89
Terahertz （THz） waves （0.1 THz ~ 10 THz, 1 THz = 1012 Hz） locate in the transitional region of the electromagnetic spectrum, between the classical electronics （radio, microwave and millimeter wave） and the photonics （infrared, visible, ultraviolet and x-ray）. As a kind of coherent measurement technology in THz frequency range, THz characteristic spectroscopy, with high sensitivity, rapidness and nondestructive testing as well as other unique advantages, has shown an attractive promising application prospect in detection, analysis and identification of biochemical molecules and materials. As the widely used broadband THz wave source, THz Photoconductive Antenna （THz-PCA） can emit broadband THz radiation. Therefore, as one of the promising THz emitters and detectors, THz-PCA has the advantages to overcome the defects confronted by other devices （e.g., low operation frequency, strict working condition and bulk size） and these unique advantages have made THz-PCA become the most commonly utilized THz sources in THz Time-Domain Spectroscopy （THz-TDS）. Although a variety of THz-PCAs are commercially available and become indispensable in many practical applications currently, the insufficient radiation THz power still hinder the further development of THz technologies based on THz-PCA. In order to further promote the research interests of THz-PCA, the working mechanism and some new research progress, technical challenges in the process of practical application and strategies of THz-PCA have to be discussed and analyzed. The underlying physical mechanism of the transient response in THz-PCA emitter and detector are investigated, as well as the influence of several parameters including the power intensity of femtosecond pump laser, the laser pulse duration and the carrier lifetime of the substrate material, are also analyzed based on theoretical models, which provide the technical foundation for designing the efficient THz-PCA. Moreover, a plenty of valuable research schemes have been proposed to develop the THz technologies based on THz-PCA in the past decades, including photoconductive materials and structure design of THz-PCA. To be specific, the sub-picosecond carrier life time of photoconductor can be realized by creating a massive density of defects, dislocations and scattering centers in the substrate material. As for structure design of THz-PCA, the previous researches on THz-PCA was mainly focused on the saturation effect at high pump power and the large aperture dipoles, dipole arrays and interdigitated electrodes structures have been investigated during the early stage. In the recent years, as the quick development of micro-nano fabrication technologies, the THz-PCA incorporated with plasmonic nanostructures and all-dielectric nanostructures have also been widely investigated for improving its performances.In this paper, the working principle and development status of THz-PCAs based on ultrashort pulsed laser are introduced, including theoretical models, substrate materials and different structures of photoconductive antennas. Furthermore, with the dramatic development of source and detector components, THz spectroscopy technology has been utilized in various fields such as chemical detection and substance identification, biomedical application and pharmaceutical industry. THz-TDS is the most commonly used technique in current commercial THz spectroscopy, which has attracted wide attention for its spectral fingerprint, high temporal-spatial resolution, noninvasive and nonionizing properties. Various important biomolecules, such as amino acids, nucleobases and saccharides reveal rich absorption features in THz range. It is verified that THz spectral features originate from the collective molecules of low frequency vibration, rotation and weak interaction with the surrounding molecules （hydrogen bonding, van der Waals force, etc.）, so they are very sensitive to the molecular structure and surrounding environment. It is a powerful tool to investigate molecular conformation, positional isomerism of functional groups, intermolecular interactions of organic acids and their salts, optical isomerism, etc. However, it is worth noting that the investigated targets are usually in the form of multi-component mixtures in actual scenario. When the spectral features became more complicated, the much broader THz features would be severely overlapped and accompanied by baseline drift in THz spectra. Identification and quantitative analysis of complex multi-component mixtures will become a great challenge for THz spectral analysis. To overcome such problem, a practical strategy has been proposed by combining machine learning methods with THz-TDS for implementation of practical applications. Moreover, another issue worth noting is conventional free-standing spectroscopy measurement devices are hardly adequate for the detection of microgram level or trace substance. Combination of metamaterials and conventional free-standing THz spectroscopy to enhance the sensing signal is a feasible and effective method, which is crucial for the practicability of clinical adoption. Furthermore, some recent progress we have achieved in THz characteristic spectral technology and its applications are also summarized and discussed. 相似文献
989.
Yuqiang GUO;Qionghua WANG 《光子学报》2022,51(7):271-288
At present, Liquid Crystal Display （LCD） has become an important display technology, especially in the large-size display field. Since the liquid crystal is optically anisotropic materials, LCD has inherent viewing angle-related problems, which is increasingly becoming a bottleneck restricting its further development. In this case, LCD needs to constantly innovate to cope with the fierce competition with other display technologies and the increasing performance demands from consumers. In recent years, some technologies that can improve the LCD’s viewing angle problem have been proposed. In order to make the researchers quickly find out the relevant technical progress, we summarize some research on improving the viewing angle-related performance in recent years. This overview can be divided into the following three parts： LCD structure and display mode, the research progress of viewing angle-related performance, and special viewing angle control technology. 1） LCD structure and display mode. The basic structure and display principle of LCD are first introduced, and four common display modes, including twisted nematic, vertical alignment, in-plane switching, and fringe-field switching, are described in the order in which they were proposed. We then describe the spatial positions of the electrode structures and the initial liquid crystal orientation in the four display modes. Besides, the specific display principles of the different display modes are explained in detail. Then, the advantages and disadvantages of the different display modes and their suitable applicable fields are briefly introduced. As we know, the viewing angle problems of different display modes are different, and thus the corresponding improvement measures are also different. 2） Research progress of viewing angle-related performance. Among the many display performances, some performances have the dependence on viewing angle. Here, we introduce the properties related to viewing angle, such as brightness, contrast, grayscale, color, and color gamut. Representative improvement methods are pointed out at these performances, and the advantages and disadvantages of different methods are analyzed. In terms of brightness, several methods that can improve the brightness at the full viewing angle are introduced, such as high brightness backlight, narrow electrode technology, and field sequential color technology. We introduce the wide viewing angle compensation film, regional dimming technology, dual-cell display technology, and surface anti-reflection structure to improve the contrast. In terms of the grayscale and color performance, we introduce the use of light scattering films, single-domain and multi-domain electrode structures, and optimized driving methods to reduce the gamma shift and color difference. In addition, the methods to improve the color gamut of LCD are pointed out, such as high color gamut backlights and broadband optical filters. Each of the above methods has an important reference value for improving the viewing angle-related performance of LCD, but each approach focuses on a different viewing angle problem, and each method has its advantages and disadvantages. Therefore, researchers need to choose the appropriate methods to solve their specific problems. 3） Special viewing angle control technology. In some special application fields, the wide viewing angle technology is no longer applicable, such as business mobile phones, bank automated teller machines, ciphers, and aviation display that require privacy protection. In order to address the needs of the above fields, several special viewing angle control technologies are introduced, including narrow viewing angle, specified viewing angle, and viewing angle controllable technologies. In the aspect of narrow viewing angle technology, two commonly used methods of shading privacy film and viewing angle compensation film are introduced. In terms of the more special non-face-to-view display field, the specified viewing angle display technology based on the viewing angle deflection film is introduced. Besides, several viewing angle controllable technologies are introduced, such as dual-pixel structure, dual-cell device structure, electrode bias method. These methods can make LCD exhibit the viewing angle performance different from the common LCD with wide viewing angle, and they have the application value for some application fields with special viewing angle requirements. In different practical situations, relevant researchers should select out the appropriate technical solutions according to the actual needs, so as to solve the specific viewing angle problems in the design and manufacturing processes.Due to the limited space of this overview, the research on the various viewing angle performances cannot be summed up in all. And thus, only some representative research works are reviewed. It should be noted that, in addition to the viewing angle-related performance introduced in this overview, LCD needs to be continuously optimized in terms of flexible display, reducing the motion picture response time, and reducing the power consumption, etc. Driven by market competition, consumers pay more attention to the comprehensive performances of display technology, thus we should not sacrifice other performances just to improve one performance of LCD. In fact, how to realize the “multi-parameter linkage optimization” has become an important task to improve the comprehensive performance of LCD, which also poses a greater challenge to future research works. At present, LCD is still a relatively important display technology. From the perspective of development trends, the overall display performance of LCD based on the Mini LED backlight and regional dimming is excellent. It has the advantages of a million-level dynamic contrast ratio, more than 2 000 nits peak brightness, and ultra-high color gamut. Therefore, Mini LED LCD is an important display technology in the future, the methods mentioned in the paper are also effective in improving the viewing angle-related performance of LCD. 相似文献
990.
QIAN Xiaotong;TIAN Ailing;LIU Bingcai;WANG Hongjun;NIU Rui;ZHU Xueliang;WEI Xiang 《光子学报》2022,51(4):126-134
The phase shift digital holographic micromeasurement system based on Liquid Crystal Spatial Light Modulator （LCSLM） is simple and easy to operate. However, LCSLM has problems of spatial inhomogeneity and edge field effect, resulting in phase distortion after modulation. To improve the measurement accuracy of phase shift digital holographic microscopy system based on LCSLM, a method of phase shift digital holographic measurement with secondary phase calibration is proposed in this paper. Firstly, based on the Fizeau interferometric system, the relationship between the gray level and the phase shift of the reflection LCSLM was calibrated once, and the phase of the distorted wavefront was measured. Then, two dimensional image interpolation algorithm and grayscale algorithm are used to design distorted phase conjugated grayscale image with the same resolution as LCSLM. Finally, the conjugated grayscale map is loaded on the LCSLM to obtain the ideal modulation phase, and the purpose of the second phase calibration is achieved. The experimental results show that after the second phase calibration, the PV value of LCSLM wavefront difference decreases from 0.182λ to 0.088λ , and the RMS value decreases from 0.039λ to 0.022λ . The overall liquid crystal surface modulation effect is more close to the ideal value, which proves that the proposed method can effectively improve the phase modulation accuracy of LCSLM. The phase shift digital holography micromeasurement system based on LCSLM was constructed, and the measurement experiment of the microlens array was carried out. The results show that under the condition of without using additional noise filtering, calibration before measuring wave of serrated fluctuation, calibration of measuring wave is relatively smooth, the micro lens array longitudinal secondary calibration rise of relative measurement error reduced to 1.15% from 3.08%, which proves that the method can effectively improve the accuracy of measurement of phase shift digital hologram. It can be seen that the precision of phase reconstruction can be controlled by using liquid crystal devices in the interferometry device, and the calibrated LCSLM has strong wave-front control ability, and significantly improved phase images can be obtained. Compared with the traditional mechanical moving phase shift measurement technology, this technology has convenient operation and simple device. Only LCSLM is controlled to change the loading pattern, and data acquisition is faster, reducing the requirements for environmental and other experimental conditions. It can be applied to deformation analysis and 3D measurement of micro-nano devices, so it has good research value and application prospect. 相似文献