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Dive into the research topics where Enshi Qu is active.

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Featured researches published by Enshi Qu.


Photonics Research | 2014

Method for enhancing visibility of hazy images based on polarimetric imaging

Jian Liang; Liyong Ren; Enshi Qu; Bingliang Hu; Yingli Wang

A novel polarimetric dehazing method is proposed based on three linear polarization images (0°, 45°, and 90°). The polarization orientation angle of the light scattered by the haze particles is introduced in the algorithm. No additional image-processing algorithm is needed in the postprocessing. It is found that the dehazed image suffers from little noise and the details of the objects close to the observer can be preserved well. In addition, this algorithm is also proved to be useful for preserving image colors. Experimental results demonstrate that such an algorithm has some universality in handling all kinds of haze. We think that this robust algorithm might be very suitable for real-time dehazing.


IEEE Photonics Technology Letters | 2014

Low-Cost Multipoint Liquid-Level Sensor With Plastic Optical Fiber

Xiao Lin; Liyong Ren; Yiping Xu; Nana Chen; Haijuan Ju; Jian Liang; Zhengquan He; Enshi Qu; Baowen Hu; Yulin Li

A simple and low-cost discrete liquid-level measurement system is present in this letter. It consists of a group of plastic optical fiber segments, which are aligned coaxially and spaced equally. When the spacing between every two adjacent fiber segments is filled with liquid, the light power will be easier to couple from one segment to the next as compared with the situation that the fibers are exposed in air. Based on this point, we design this intensity-based sensor and investigate its working properties theoretically by using the ray-tracing method. The performance of this sensor is demonstrated in detail where different liquids are utilized as specimens.


Journal of Modern Optics | 2014

Design and fabrication of tapered microfiber waveguide with good optical and mechanical performance

Chengju Ma; Liyong Ren; Yiping Xu; Yingli Wang; Jian Liang; Enshi Qu

In this paper, the inherent dependence of optical and mechanical characteristics of tapered microfiber waveguide on its contour profile is studied. Both theoretical analysis and experimental investigation are given. In theory, the optimal profile parameters of the tapered microfiber are proposed to improve the microfiber performance, where it is better to make the tapered microfiber keep two longer than 5-mm-long transition regions which have a decaying exponential profile. And the uniform waist diameter of the tapered microfiber should be more than 600 nm and less than 1 μm. In this case, the microfiber indicates several favorable advantages, such as low loss, strong evanescent field and relatively shorter transition region. In experiment, according to the profile parameters we proposed, we successfully fabricated a tapered microfiber with a low loss of 0.05 dB in air and 0.8 dB on a MgF2 substrate at the wavelength of 1550 nm, and it has low surface roughness.


Optics Express | 2015

Polarimetric dehazing method for dense haze removal based on distribution analysis of angle of polarization.

Jian Liang; Liyong Ren; Haijuan Ju; Wenfei Zhang; Enshi Qu

Many dehazing methods have proven to be effective in removing haze out of the hazy image, but few of them are adaptive in handling the dense haze. In this paper, based on the angle of polarization (AOP) distribution analysis we propose a kind of polarimetric dehazing method, which is verified to be capable of enhancing the contrast and the range of visibility of images taken in dense haze substantially. It is found that the estimating precision of the intensity of airlight is a key factor which determines the dehazing quality, and fortunately our method involves a high precision estimation inherently. In the experiments a good dehazing performance is demonstrated, especially for dense haze removal. We find that the visibility can be enhanced at least 74%. Besides, the method can be used not only in dense haze but also in severe sea fog.


Journal of Applied Physics | 2014

Visibility enhancement of hazy images based on a universal polarimetric imaging method

Jian Liang; Liyong Ren; Haijuan Ju; Enshi Qu; Yingli Wang

Enhancing the visibility of images taken in the hazy weather is important in many applications. Among many dehazing methods, those based on polarimetric imaging techniques have several advantages, such as ease of keeping detailed information, low cost, and high efficiency. In this paper, we propose a novel and robust dehazing algorithm based on polarimetric imaging. By introducing the orientation-angle information from the Stokes matrix, all the parameters used in dehazing performance can be effectively, precisely and automatically estimated, and no additional human-computer interaction is needed. Besides, this method can also be used in handling hazy images without sky region. Experimental results show that such a method can greatly enhance the visibility of hazy images.


Journal of Modern Optics | 2014

Wide-bandwidth zero-dispersion slow light in MKRs with a two-ring parallel connection structure based on an analogue of electromagnetically induced transparency

Yiping Xu; Liyong Ren; Chengju Ma; Yingli Wang; Jian Liang; Enshi Qu

Based on an analog of electromagnetically induced transparency (EIT) in microfiber knot resonators with a two-ring parallel connection structure, a wide bandwidth and zero-dispersion slow-light waveguide is proposed. The EIT-like transmission spectrum with the variation of wavelengths for different coupling coefficients is numerical simulated. By appropriately adjusting the coupling coefficients of the two knot rings, a group time delay of about 72.4 ps with a flat wavelength bandwidth of about 82.7 pm and a full width at half-maximum of about 228 pm at one of the induced transparency windows is achieved theoretically. And the group time delay dispersion at the same induced transparency window nearly reaches to zero with a wavelength bandwidth of about 82.7 pm.


Applied Optics | 2016

Polarimetric dehazing method for visibility improvement based on visible and infrared image fusion

Jian Liang; Wenfei Zhang; Liyong Ren; Haijuan Ju; Enshi Qu

Polarimetric dehazing methods have proven effective in enhancing the quality of chromatic hazy images. Considering that the infrared radiance has a better capacity for traveling through the haze, in this paper we propose a polarimetric dehazing method based on visible and infrared image fusion to improve the visibility of hazy images, especially for dense haze conditions. Experimental results demonstrate that the visibility of hazy images can be effectively enhanced, and the color information can be finely maintained. The visibility of dehazed images can be promoted at least 100%. This kind of dehazing method can be used widely in many dehazing applications.


Journal of Modern Optics | 2014

Design of vibration-insensitive Sagnac fiber-optic current sensors using spun high-birefringence fibers

Menghua Kang; Yingli Wang; Liyong Ren; Jintao Xu; Jian Liang; Enshi Qu

A novel fiber-optic current sensing element is proposed to enhance sensor performance using spun high-birefringence fibers. Such element includes three fiber sections. Two terminal sections with a varying spin rate along the fiber are utilized to replace the fiber quarter-wave plates, each converting the light polarization state from linear to circular and vice versa. The middle section with a uniform spin rate is utilized as the current sensing fiber that maintains the circular polarization state during the light propagation. The fiber is also wound into a special geometric structure so that the Sagnac phase shift can be inherently eliminated, and the sensing result does not depend on the position of the current conductor. The evolution of the light polarization state was analyzed using coupled-mode theory with different polarization state incidents in the sensing fiber. A sensor scheme based on this type of spun fiber is also proposed.


Journal of Lightwave Technology | 2013

Theoretical and Experimental Study on Nonintrusive Light Injection Via Cladding in Plastic Optical Fibers

Xiao Lin; Liyong Ren; Enshi Qu; Jian Liang; Haijuan Ju

Based on the fiber macrobending and the refractive index matching technologies, a novel scheme of nonintrusive light injection, namely, the light signal is injected into the fiber core from the fiber cladding without any destruction, is proposed in plastic optical fibers (POFs). Using the ray-tracing method, a 3-D theoretical model is established to characterize the performance of the light injection. The influences of the fiber bending radius, the light source placement, and the surrounding medium refractive index on the light injection efficiency are investigated and assessed. Meanwhile, correlative experiments have also been conducted to contrast theoretical simulations. The experiment results fit theoretical ones well. This nonintrusive light injection technology in POFs might have many potential applications such as the optical signal uploading and downloading, the optical coupling, and the local area networks.


Applied Optics | 2017

Real-time image haze removal using an aperture-division polarimetric camera

Wenfei Zhang; Jian Liang; Liyong Ren; Haijuan Ju; Enshi Qu; Zhaofeng Bai; Yao Tang; Zhaoxin Wu

Polarimetric dehazing methods have been proven to be effective in enhancing the quality of images acquired in turbid media. We report a new full-Stokes polarimetric camera, which is based on the division of aperture structure. We design a kind of automatic polarimetric dehazing algorithm and load it into the field programmable gate array (FPGA) modules of our designed polarimetric camera, achieving a real-time image haze removal with an output rate of 25 fps. We demonstrate that the image quality can be significantly improved together with a good color restoration. This technique might be attractive in a range of real-time outdoor imaging applications, such as navigation, monitoring, and remote sensing.

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Dive into the Enshi Qu's collaboration.

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Liyong Ren

Chinese Academy of Sciences

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Jian Liang

Chinese Academy of Sciences

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Haijuan Ju

Chinese Academy of Sciences

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Wenfei Zhang

Chinese Academy of Sciences

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Yingli Wang

Chinese Academy of Sciences

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Chengju Ma

Xi'an Shiyou University

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Yiping Xu

Chinese Academy of Sciences

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Jing Wang

Chinese Academy of Sciences

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Qingkun Xie

Chinese Academy of Sciences

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Yanru Jiang

Chinese Academy of Sciences

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