## 留言板

Owing to the strong penetrating ability in the atmosphere, 532 nm-wavelength green laser has wide applications including free-space optical communications and laser three-dimensional mapping. A spectral filter, with a half-power bandwidth of less than 100 pm, is an important optical element to suppress the interference of background light. Therefore, an ultra-narrow band-pass filter based on optical interference film is designed and fabricated in this paper. The high and low refractive index film materials are Tantalum pentoxide (Ta2O5) and Silicon dioxide (SiO2), respectively. The designed optical thin films are deposited on a fused quartz substrate by double-ion-beam sputtering deposition method. The transmission spectrums of the filters are measured by a tunable laser and a power meter. The half-power bandwidths of the filters are 60±2 pm, and the transmittance reaches 62.6%.

Averaged intensity and spectral shift of partially coherent chirped optical coherence vortex lattices (PCCOCVLs) in biological tissue turbulence are investigated, where optical lattice structures in monochromatic optical field and spectral rapid transitions in polychromatic optical field are stressed. It is found that the beam profile evolves from annular structure with vortex core into a periodic array of lobes with dark zone, and it finally present a Gaussian-like pattern in biological tissue. Although lattice parameter modulates beam profile, it cannot affect spectral behavior in biological tissue turbulence. The analysis of spectral shift also shows that a smaller distance is beneficial to spectral rapid transition, where the transverse coordinate decreases with an increase of chirp parameter and a decrease of pulse duration. The accumulated turbulences in a longer distance can suppress not only spectral transition, but spectral shift. The reduction of spectral shift is accompanied by a stronger biological tissue turbulence. The results have the application possibility in image recognition, medical device and noninvasive optical diagnose in biological tissue.

The technology of enhancing fluorescence emission can increase the sensitivity of fluorescence detection and the brightness of LEDs, and is of great significance in improving the performance of light-emitting devices. Since the metal structure has a good effect in enhancing the local field and enhancing the fluorescence emission, and the flexible dielectric material has flexible bendability characteristics, for the enhancement of the fluorescence emission, this paper proposes a flexible structure composed of metal-dielectric-metal (MDM). The influence of the structure on the directional emission enhancement of quantum dots is systematically studied by using the finite difference time domain method. Theoretical calculations show that the local undulations and arcs of the flexible MDM structure promote fluorescence enhancement, and can increase the quantum efficiency of the quantum dots located at the center of the structure by about 7 times. And the refractive index and thickness of the dielectric can be changed to achieve the tunability of the target wavelength. At the same time, the experimental verification shows that the flexible MDM structure does have a positive effect on the fluorescence enhancement. This discovery is useful for future display technologies and flexible light-emitting devices. It is of great value and has certain guiding significance for the development and application of high-efficiency flexible devices.

With the advantages such as simple structure, simple process and easy interface control, the photoelectric devices based on carbon nanomaterial/bulk semiconductor van der Waals (vdW) heterojunctions can fully utilize the ultrahigh carrier mobility of carbon nanomaterials and the excellent photoelectric properties of bulk semiconductors. Especially, the novel mixed-dimensional vdW heterojunctions with atomic-level interfaces, whose bandgaps are matched with those of bulk semiconductors, can be formed by controlling the diameter/chirality and Fermi level of single-walled carbon nanotubes (SWCNTs). Here, we reported a self-powered broadband photodetector based on the p/n vdW heterojunctions by combining (6, 5)-enriched semiconducting SWCNT film with n-type GaAs, and used graphene to reduce the probability of carrier recombination in SWCNT film and to promote the carrier transport. The experimental results suggest that the self-powered device exhibits high-sensitivity photoelectric response toward the incident photons in the 405−1064 nm range, and that the max photoelectric responsivity of 1.214 A/W and the specific detectivity of 2 × 1012 Jones could be achieved at zero bias.

Helmholtz-Kohlrausch effect (H-K effect) described the influence of color purity on the perceived brightness of a color object. Quantum dots (QD) based backlights can enhance the color quality of liquid crystal display (LCD) display with improved perceived brightness due to the well-known H-K effect. However, the H-K effect of QD embedded TV (also known as QLED TV) has not been fully demonstrated. In this paper, we investigated the H-K effect of QLED TV through a comparative study between QLED backlights and YAG-LED backlights. By comparing the viewers’ experimental results with the Kaiser and Nayatani model, we demonstrate that QLED TV shows significant H-K effect. To achieve the same perceived brightness with YAG-LED TV, the physical brightness of QLED TV was greatly decreased to 75% for pure red color, 86% for pure green color, and 74-88% for bright colorful images. Moreover, QLED TV is much preferred than the YAG-LED TV even when both QLED TV and YAG-LED TV show the same perceived brightness. The results imply the bright future of QLED TV toward health display.

Dual-wavelength retinal imaging adaptive optics systems are suitable for high contrast and resolution imaging of retinal capillaries. The compensation of the longitudinal chromatic aberrations (LCAs) is considered. The LCA is measured, the measured wavefronts are analyzed, and the arbitrary wavefront LCA compensation method is given. An adaptive correction experiment is done, and the root mean square error of the wavefront is reduced to 0.16 λ (λ=589 nm) and the retinal capillary resolution is improved to 6 μm. This work may be used for the clinical applications of retinal imaging.

A high-sensitivity surface plasmon resonance (SPR) sensor comprising an eccentric core ten-fold photonic quasi-crystal fiber (PQF) with a D-shaped structure and coated with indium tin oxide (ITO) is designed and analyzed numerically. The eccentric core D-shaped structure makes analysis of liquids more convenient and also strengthens the coupling between the core mode and SPP mode to improve the sensing sensitivity. The characteristics of the sensor are investigated by the finite element method (FEM). The wavelength sensitivity increases with increasing refractive indexes (RIs) and the maximum wavelength sensitivity and resolution are 60000 nm/RIU and 1.67×10−6 RIU, respectively. The sensor delivers excellent performance and has large potential applications in measurement of liquid refractive indexes.

目的  紫外探测技术已广泛应用于人类的生产生活各领域，研究宽谱段紫外成像仪系统具有重要意义。  方法  通过推导色差理论公式，提出了单一材料校正宽谱段紫外成像仪光学系统色差的方案，结合高灵敏度大动态紫外成像探测器的性能指标，设计了仅一种透镜材料且所有透镜全部为球面的210−400 nm宽谱段紫外成像仪光学系统，并运用光学设计软件CODE V对系统优化及像质评价。  结果  结果表明：在奈奎斯特频率40 lp/mm下，全视场全波段系统的调制传递函数优于0.6，系统点列图RMS<7.8 μm，具有良好的成像质量。  结论  该系统不含非球面等光学元件，不仅加工装调易于实现，而且降低研制成本，将为宽谱段紫外成像光谱仪的设计奠定技术基础。

目的  夜间有雾图像通常具有低对比度，光照不均匀，颜色偏移以及噪声较多等现象，这些退化现象使得夜间图像去雾问题成为病态问题，具有极大的挑战性。针对夜间图像存在的退化问题，本文提出了一种能够在夜间图像中有效去雾并提高图像质量的方法。  方法  首先，将图像分解成光晕层和有雾层，并对有雾层进行颜色校正。其次，通过一种新提出的带有伽马变换的图像光源分割方法来分割光源,并设置分割阈值作为像素点属于光源区域的概率值。然后，将得到概率值与最大反射先验相结合来估计光源和非光源区域的大气光值。最后，根据图像深度与亮度、饱和度以及梯度三者之间的关系建立线性模型，进一步估计透射率的值。  结果  实验得到的分割阈值为0.07，线性深度估计参数分别为1.0267，−0.5966，0.6735，0.004135。  结论  实验结果表明本文的方法在夜间图像去雾，消除光晕，减少噪声，以及提高可视度方面取得良好的效果。

目的  针对640×512长波红外制冷型探测器，设计了一种制冷型长波红外光学系统，用于对目标的红外跟踪探测。  方法  该光学系统采用二次成像结构型式以满足100%冷光阑效率，采用锗和硫化锌玻璃材料组合，实现了像差校正和消色差设计，通过引入高次非球面很好地校正了系统的高级像差，简化系统结构。光学系统由6个镜片构成，焦距为400 mm，工作波段为7.7 μm~9.3 μm，视场角为1.37°×1.10°，F数为2。系统采用二次成像型式将系统出瞳后置于冷屏处，满足100%冷光阑效率，并引入高次非球面优化平衡系统像差。  结果  设计结果表明：在空间频率33 lp/mm处，轴外视场MTF>0.24，接近衍射极限，具有高的成像品质。  结论  在−35 ℃~+55 ℃工作温度范围内，通过内置调焦镜调焦来保证高温、低温环境下的成像质量，可用于宽温度范围内的红外跟踪探测。

With the development of underwater optical communication, it is very important to study the propagation characteristics of light beams in ocean turbulence. In order to get closer to the actual situation, we build a device which can control both the salinity and the intensity of underwater turbulence to study the propagation characteristics of vortex beams and a Gaussian beam in underwater turbulence. The results show that compared with the underwater turbulence without sea salt, the light spot will be more diffuse and the light intensity will be weaker in the underwater turbulence with sea salt. The scintillation index of the vortex beam with topological charge m=2 in the underwater turbulence with salinity of 4.35‰ is larger than that in the underwater turbulence with salinity of 2.42‰, no matter it is strong turbulence or weak turbulence. When the vortex beam with m=2 propagates to the same distance, the scintillation index increases with the increment of the salinity and the intensity of underwater turbulence. Under different salinity conditions, the radial scintillation index of the vortex beam with m=2 decreases firstly and then increases with the increase of the radial distance. In addition, we set up another experimental device which can transmit a longer distance. The scintillation index of the vortex beam with m=2 is much higher than that of the Gaussian beam in the underwater turbulence within 20 meters, and the scintillation indices of both the vortex beam with m=2 and the Gaussian beam increase with the increase of the propagation distance.

The single wedge compensation test method, as a testing method for large convex aspheric surface, has good applicability, robustness, and flexibility. However, various errors are coupled with one another during the test process and these errors are difficult to decouple; this affects the accuracy and reliability of the test process. To address this, a method is developed to calibrate the system error of single optical wedge test path using computer generation hologram (CGH). This study first analysed the source of the system error in the optical path of single optical wedge compensation test as well as the feasibility of using CGH for the calibration of an optical wedge compensation test system. In combination with engineering examples, a CGH is designed for optical wedge compensators with a diameter of 150 mm. Based on the analysis results, the calibration accuracy of the CGH is 1.98 nm RMS, and after calibration the test accuracy of single wedge compensation is 3.43 nmRMS, thereby meeting the high-precision test requirements of large convex aspheric mirrors. This shows that CGH can accurately calibrate the pose of single optical wedge compensators and test system errors of optical paths, address the problem of error decoupling in test optical paths, and improve the accuracy and reliability of the single optical wedge compensation method. Meanwhile, using CGH calibration, the system errors of the test optical paths, Tap#2 and Tap#3, are 0.023 and 0.011 λ RMS, respectively.

2021, 14(6): 1305-1316.   doi: 10.37188/CO.2021-0135
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2021, 14(6): 1317-1326.   doi: 10.37188/CO.2021-0067
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2021, 14(6): 1327-1340.   doi: 10.37188/CO.2021-0075
[摘要](148) [HTML全文](69) [PDF 4896KB](15)

In order to reduce the manufacturing cost of the narrow-bandwidth Metamaterial Absorber (MA) and broaden its application field, a dual-wavelength dielectric narrow-bandwidth MA, composed of Au substrate, SiO2 dielectric layer and Si dielectric asymmetric grating, is designed based on the finite-difference time-domain method using dielectric materials. It is found by simulation that the proposed narrow-bandwidth MA has ultra-high absorption efficiency at λ1 = 1.20852 μm and λ2 = 1.23821 μm, and the FWHM is only 0.735 nm and 0.077 nm, respectively. The main principle that MA achieves the narrow-bandwidth absorption at λ1 is mainly due to the formation of Fabry-Pérot (FP) cavity resonance in the SiO2 layer, while the narrow-bandwidth absorption of MA at λ2 is mainly due to the guided mode resonance effect of the incident light in the asymmetric grating. The theoretical calculations show that the absorption characteristics can be affected more significantly by changing the structural parameters of the MA.

2021, 14(6): 1341-1347.   doi: 10.37188/CO.2021-0013
[摘要](154) [HTML全文](66) [PDF 3406KB](11)

2021, 14(6): 1348-1354.   doi: 10.37188/CO.2021-0107
[摘要](195) [HTML全文](91) [PDF 3550KB](11)

2021, 14(6): 1355-1361.   doi: 10.37188/CO.2021-0054
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2021, 14(6): 1362-1367.   doi: 10.37188/CO.2021-0103
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2021, 14(6): 1368-1377.   doi: 10.37188/CO.2021-0051
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2021, 14(6): 1378-1386.   doi: 10.37188/CO.2021-0064
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2021, 14(6): 1387-1394.   doi: 10.37188/CO.2021-0128
[摘要](125) [HTML全文](59) [PDF 7236KB](16)

2021, 14(6): 1395-1399.   doi: 10.37188/CO.2021-0077
[摘要](202) [HTML全文](169) [PDF 3504KB](17)

2021, 14(6): 1400-1409.   doi: 10.37188/CO.2021-0105
[摘要](188) [HTML全文](82) [PDF 5215KB](15)

2021, 14(6): 1410-1416.   doi: 10.37188/CO.2021-0065
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2021, 14(6): 1417-1425.   doi: 10.37188/CO.2021-0078
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2021, 14(6): 1426-1434.   doi: 10.37188/CO.2021-0045
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2021, 14(6): 1435-1450.   doi: 10.37188/CO.2021-0087
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An initial construction satisfying aberration balance and multi-constraint control is essential for the design of an off-axis multi-reflective optical system with minimal aberration. In this paper, a mathematical model for calculating the initial structure of off-axis multi-reflective is established based on the grouping design method combining spatial ray tracing and aberration correction, and an improved Particle Swarm Optimization (PSO) is proposed to solve the initial structure problem of an off-axis multi-reflective optical system. The PSO of natural selection with shrinkage factor is applied to improve calculation accuracy and design efficiency, so as to obtain the initial structure of the off-axis multi-reflection optical system. In the last part of this paper, taking an Extreme UltraViolet (EUV) lithography projection objective with six-mirror reflective aspheric mirrors as an example, the reliability and effectiveness of this method are verified. A 0.33 numerical aperture EUV lithographic objective with wave-front error better than 1/80λ (λ=13.5 nm) RMS is achieved.

2021, 14(6): 1451-1458.   doi: 10.37188/CO.2020-0190
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2021, 14(6): 1459-1467.   doi: 10.37188/CO.2021-0073
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2021, 14(6): 1468-1475.   doi: 10.37188/CO.2020-0221
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2021, 14(6): 1476-1485.   doi: 10.37188/CO.2021-0052
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2021, 14(6): 1486-1494.   doi: 10.37188/CO.2021-0040
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2021, 14(6): 1495-1503.   doi: 10.37188/CO.2019-0255
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2021, 14(5): 1039-1055.   doi: 10.37188/CO.2021-0003

2021, 14(5): 1056-1068.   doi: 10.37188/CO.2021-0071

2021, 14(5): 1069-1088.   doi: 10.37188/CO.2021-0044

2021, 14(5): 1089-1103.   doi: 10.37188/CO.2021-0022

2021, 14(5): 1104-1119.   doi: 10.37188/CO.2021-0033

2021, 14(5): 1120-1132.   doi: 10.37188/CO.2021-0125

2021, 14(5): 1133-1145.   doi: 10.37188/CO.2020-0216

2021, 14(5): 1146-1161.   doi: 10.37188/CO.2021-0032

2021, 14(3): 447-457.   doi: 10.37188/CO.2020-0199

2021, 14(3): 458-469.   doi: 10.37188/CO.2020-0180

2021, 14(3): 470-486.   doi: 10.37188/CO.2020-0093

2021, 14(3): 487-502.   doi: 10.37188/CO.2020-0134

Acoustic-to-seismic coupling landmine detection technology based on the unique mechanical characteristics of landmines and the acoustic-to-seismic coupling principle has broad application prospects in safe and effective detection of landmines. However, a significant amount of work must be done to study the practical landmine detection system. Among them, the acoustic coupled surface vibration signals are very weak and complicated, which has always been a challenging problem to detect such signals accurately and quickly. In this paper, the non-contact laser measurement techniques of surface vibrations based on the principle of the acoustic-to-seismic coupling landmine detection technology were reviewed, including laser Doppler interferometry, electronic speckle pattern interferometry and laser self-mixing interferometry, etc., and the application feasibility of electronic speckle-shearing pattern interferometry in acoustic-to-seismic coupling landmine detection was analyzed.

2021, 14(3): 503-515.   doi: 10.37188/CO.2020-0039

2021, 14(3): 516-527.   doi: 10.37188/CO.2020-0051

2021, 14(2): 227-244.   doi: 10.37188/CO.2020-0126

2021, 14(2): 245-263.   doi: 10.37188/CO.2020-0121

Quasi-distributed fiber sensing systems play an important role in the fields of civil engineering, energy surveying, aerospace, national defense, chemicals, etc. Interrogation technology for quasi-distributed fiber sensing systems based on microwave photonics is widely used in high-speed and high-precision signal demodulation and sensor positioning in optical fiber multiplexing systems. Compared to conventional optical wavelength interrogation, this technology greatly improves system demodulation rate and compensates for the defects of traditional sensor positioning methods. This paper introduces the recent research progress of quasi-distributed fiber sensing interrogation technology based on microwave photonics; compares and analyzes the advantages and disadvantages of several existing microwave demodulation systems from the perspective of their fiber grating quasi-distributed sensing and fiber Fabry-Perot quasi-distributed sensing systems, respectively; and provides a summary of the prospective direction of future research in quasi-distributed fiber sensing interrogation technology based on microwave photonics.

2021, 14(2): 264-274.   doi: 10.37188/CO.2020-0193

2021, 14(2): 275-288.   doi: 10.37188/CO.2020-0098

2020, 13(6): 1171-1181.   doi: 10.37188/CO.2020-0033

2020, 13(6): 1182-1193.   doi: 10.37188/CO.2020-0049

ISSN 2095-1531

CN 22-1400/O4

CODEN ZGHUC8