1.     Polarimetric imaging

A.    Proposed a novel polarimetric dehazing method based on three linear polarization images (0°, 45°, and 90°) by introducing the polarization orientation angle of the light scattered by the haze particles in the algorithm.

B.    Proposed and demonstrated a polarimetric dehazing method for dense haze removal based on distribution analysis of angle of polarization (AoP).

C.    Designed and fabricated a full-Stokes-vector aperture-division polarimetric camera which is capable of substantially enhancing the contrast and the range of visibility of images taken in dense haze, and preserving image colors.

D.    Proposed and established a universal and robust dehazing algorithm for real-time handling all kinds of hazy images without sky region and not involving any human-computer interaction.

E.     Proposed a much more precise and convenient way to estimate the airlight radiance through extracting the sky region automatically by also introducing the dark channel prior technique.

F.     Proposed a fast dehazing method in Hue, Saturation and Intensity (HSI) color space by implementing the polarimetric dehazing in the Intensity channel, while correcting the color distortion in Hue and Saturation channels.

G.    Proposed a polarimetric dehazing method for visibility improvement based on visible and infrared image fusion.

2.     Microfiber and its applications

A.    Theoretically analyzed and proposed optimized profile parameters for fabricating a tapered microfiber with good optical and mechanical properties, and designed and set up an experimental system for tapered fiber fabrication.

B.    Proposed and established a simple, polymer-microfiber-assisted approach to fabricate the microfiber knot resonator with different structures including two-ring parallel, two-ring serial, multi-ring parallel and multi-ring serial structures.

C.    Proposed and established two novel schemes for fabricating micro-tapered long-period fiber gratings (LPFGs) and helical LPFGs, respectively, by periodically tapering and by directly twisting single mode fibers. Superior sensing characteristics of them are obtained.

D.    Proposed a theoretical model to describe the light-propagation property of the microfiber double-knot resonator with a Sagnac loop reflector, and experimentally verified its double enhancement performance of time delay.

3.     Slow light for optical buffer

A.    Theoretically and experimentally demonstrated tunable slow light in optical single mode fibers (SMFs) based on stimulated Brillouin scattering (SBS).

B.    Described a theoretical analysis of SBS slow light using a gain spectrum tailoring technique with a continuous-wave pump beam.

C.    Proposed and constructed a zero-broadening slow pulse by use of two Gaussian-shaped broadband pump beams with different powers and spectral widths.

D.    Proposed and demonstrated a silicon-on-insulator W1-type photonic crystal waveguide slow light with a large group-index, wide band and low dispersion.

4.     Micro-structured polymer optical fiber

A.    Theoretically and experimentally demonstrated micro-structured polymer optical fiber (mPOF) with specific optical characteristics by simply changing hole size, hole spacing or hole shape.

B.    Designed and fabricated photonic band gap mPOF including the polarization maintaining mPOF (PM-mPOF), hollow core mPOF and dye-doped Bragg type mPOF for datacom, high power laser transmission, fiber laser and fiber amplifier, etc.

C.    Designed and fabricated PM-mPOF preform by using the in-situ chemical method. Experimental results indicate the two orthogonal polarized states of the fundamental mode becomes non-degenerate in the elliptical core and appears obvious an ellipse and strongly linear polarization.

D.    Designed a new kind of polymer porous fiber with elliptical air-holes for obtaining high birefringence up to 0.0445 in the terahertz (THz) frequency range.

5.     Fiber sensing technology

A.    Proposed a novel wavelength interrogation technique and finally developed a fast and high-precision interrogator used for distributed temperature and strain sensing based on fiber Bragg grating (FBG).

B.    Designed and demonstrated a low-cost and simple multipoint liquid level measurement system by use of a group of plastic optical fiber segments and theoretically investigated its working properties.

C.    Established a theoretical model to study the static pressure distribution of the fiber cable spool and experimentally demonstrated the verifications.

D.    Proposed a 3D theoretical model to describe and analyze light propagation characteristics in polymer optical fibers (POF) and obtained the steady state distribution of optical filed in POF, finally established a nondestructive method to measure attenuation coefficient of POF for production line.

Dr. Liyong Ren was born in Dec. 1971 in Shaanxi province, China. He got his S.B. degree in Optoelectronics from the Department of Physics in Northwest University in 1995. Since then he was selected as a college teacher by that university and became a lecturer in 2000. At that university he obtained his S.M. degree in Optics in 2000. From March 2001 to February 2004, he began to pursue his doctorate degree in Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (CAS), and earned Ph. D degree in Optical Engineering in March 2004. After that, as an associate professor, he joined the State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics (XIOPM) of CAS. He was awarded a JSPS (Japan Society for the Promotion of Science) Postdoctoral Fellowship for Foreign Researchers to conduct a collaborating research in the University of Electro-Communications (UEC) from May 2007 to April 2009. He became a professor of XIOPM in January 2009. From Nov. 2013 to March 2019, he was the director of the Research Department of Information Photonics (RDIP) of XIOPM of CAS. Since April 2019, he joined the School of Physics and Information Technology, ShaanXi Normal University, where he is now a professor in Optics and Photonics. His research interests include polarimetric imaging, micro/nano-optics, nonlinear optics, fiber optics, etc. He has published more than 110 peer-reviewed journal papers and obtained more than 10 Chinese patents. He has attended more than 60 international or domestic conferences (including 23 invited talks) and published more than 80 conference papers. There are 16 Ph. D and 15 Master graduates under his supervision, among them 7 Ph. D students and 10 Master students have graduated. He is a Senior member of SPIE, OSA and COS (Chinese Optical Society).

3/2001-2/2004 Shanghai Institute of Optics and Fine Mechanics of CAS, Ph.D. in Optical Engineering
9/1997-6/2000 Northwest University, M.S. in Optics
9/1991-6/1995 Northwest University, B.S. in Optoelectronics

4/2019-present ShaanXi Normal University, Professor, and Leader of Advanced Optical Imaging (AOI) Research Group.
5/2009-3/2019 Xi’an Institute of Optics and Precision Mechanics (XIOPM) of Chinese Academy of Sciences (CAS), Professor, and Director of Research Department of Information Photonics (RDIP) since 2013 Nov.
5/2007-4/2009 The University of Electro-Communications (UEC), JSPS Postdoctoral Fellow
3/2004-4/2007 State Key Laboratory of Transient Optics and Photonics, XIOPM of CAS, Associate Professor
7/1995-2/2001 Northwest University, Lecturer

1.     Chinese Academy of Sciences (CAS) Outstanding Supervisor Award (2018).
2.     2017 Acta Optica Sinica Editor-in-Chief Choice Award (2018).
3.     Special Award for Key Scientific and Technological Innovation Team in Shaanxi Province, “Super-resolution optical imaging” (2013).
4.     The K. C. Wong Education Foundation (2012).
5.     First Class Award for Science and Technology of Shaanxi Province, “Study on organic photochromic optical information storage, processing mechanics and applications” (2010).
6.     Second Class Award for Excellence Research Paper of Natural Science of Shaanxi Province, “Casting preform fabrication technology for microstructured polymer optical fibre” (2008).
7.     The K. C. Wong Education Foundation (2006).
8.     The Excellent Graduate Ph. D Student of Shanghai Institute of Optics and Fine Mechanics of Chinese Academy of Sciences (2004).
9.     The Excellent Graduate Master Student of Northwest  University (2001).

 (*corresponding author, †first author under his supervision):
1. Jian Liang†, Xiaobo Tian, Haijuan Ju, Daodang Wang, Heng Wu, Liyong Ren*, Rongguang Liang, “Reconfigurable snapshot polarimetric imaging technique through distributed spectral-polarization filtering,” Optics Letters, 44(18), (2019) (in press).
2. Liming Yang†, Jian Liang, Wenfei Zhang, Haijuan Ju, Liyong Ren*, and Xiaopeng Shao, “Underwater polarimetric imaging for visibility enhancement utilizing active unpolarized illumination,” Optics Communications, 438, 96-101 (2019).
3. Qingkun Xie†, Yanru Jiang, Jian Liang, Enshi Qu, and Liyong Ren*, “Hybrid phase-amplitude super-oscillation element for non-scanning optical super-resolution imaging,” J. Opt. Soc. Am. A, 36(2), 196-201 (2019).
4. Haijuan Ju†, Liyong Ren*, Jian Liang, Enshi Qu, and Zhaofeng Bai, “Method for Mueller matrix acquisition based on a division-of-aperture simultaneous polarimetric imaging technique,” Journal of Quantitative Spectroscopy & Radiative Transfer, 225, 39-44 (2019).
5. Chengfang Xu†, Bin Zhuang, Yi Geng, Hui Chen, Liyong Ren*, and Zhaoxin Wu, “A scanning-free wide-field single-fiber endoscopic image retrieval method based on optical transmission matrix,” Laser Physics, 29, 046202 (2019).
6. Wenfei Zhang†, Jian Liang, and Liyong Ren*, “Haze-removal polarimetric imaging schemes with the consideration of airlight's circular polarization effect,” Optik, 182, 1099-1105 (2019).
7. Xudong Kong†, Liyong Ren*, Jian Liang, Kaili Ren, Haijuan Ju, Yiping Xu, and Chengfang Xu，“A chiral long-period grating fabrication method based on axis-offset rotating optical fiber，” Optical and Quantum Electronics, 51, 124 (2019).
8. Yi Geng†, Guangzhi Zhao, Hui Chen, Chengfang Xu, Bin Zhuang, and Liyong Ren*, “High-speed focusing and scanning light through a multimode fiber based on binary amplitude-only modulation parallel coordinate algorithm,” Applied Physics B, 125, 83 (2019).
9. Jian Liang†, Haijuan Ju, Liyong Ren*, Wenfei Zhang, Liming Yang, Zhaofeng Bai, and Rongguang Liang, “High resolution reconstruction of short-wave infrared polarimetric images using intensity information of visible images,” Applied Optics, 58(18), 4866-4870 (2019).
10. Hui Chen†, Yi Geng, Chengfang Xu, Bin Zhuang, Haijuan Ju, and Liyong Ren*, “Efficient light focusing through an MMF based on two-step phase shifting and parallel phase compensating,” Applied Optics, 44(26), (2019) (in press).
11. Yanru Jiang†, Qingkun Xie, Enshi Qu, Liyong Ren*, Jian Liang, and Jing Wang, “A multi-wavelength multi-focus Fresnel solar concentrator with square uniform irradiance: design and analysis,” Applied Optics, 58(19), 5206-5212 (2019).
12. Qingkun Xie†, Jing Wang, Yanru Jiang, Jian Liang, Enshi Qu, and Liyong Ren*, “Far-field super-oscillation imaging based on the super-oscillation elements and PSF feature extraction algorithm,” J. Opt. Soc. Am. A, 35(3), 491-495 (2018).
13. Bin Zhuang†, Chengfang Xu, Yi Geng, Guangzhi Zhao, Hui Chen, Zhengquan He, Zhaoxin Wu, and Liyong Ren*,“Round-trip imaging through scattering media based on optical transmission matrix,”Chinese Optics Letters, 16(4), 041102 (2018).
14. Xudong Kong†, Kaili Ren, Liyong Ren*, Jian Liang, Haijuan Ju, and Yiping Xu，“Tunable wavelength-selective coupler based on microtapered long period fiber gratings,” IEEE Photonics Technology Letters, 30(9), 821-824 (2018).
15. Liming Yang†, Jian Liang, Wenfei Zhan, Haijuan Ju, Liyong Ren*, Jun Han, Enshi Qu, “Clear underwater imaging based on polarimetric descattering by use of unpolarized illumination,” ACTA Photonica Sinica，38(6),0611003(2018).
16. Bin Zhuang†, Chengfang Xu, Yi Geng, Guangzhi Zhao, Hui Chen, Zhengquan He, Liyong Ren*, “An early study on imaging 3D objects hidden behind highly scattering media: round-trip optical transmission matrix method, Journal of Applied Sciences, 8, 1036 (2018).（Special Issue Holography, 3D Imaging and 3D Display）
17. Guangzhi Zhao†, Yi Geng, Hui Chen, Chengfang Xu, Bin Zhuang, Zhengquan He, Baowen Hu, Liyong Ren*, “A method for focusing and scanning light through a multimode fiber based on binary amplitude modulation DMD technique,” ACTA Phtonica Sinica，38(9), 0911004  (2018).
18. Kaili Ren†, Liyong Ren*, Jian Liang, Xudong Kong, Haijuan Ju, and Zhaoxin Wu, “Highly strain and bending sensitive microtapered long-period fiber gratings,” IEEE Photonics Technology Letters, 29(13), 1085-1088 (2017).
19. Wenfei Zhang†, Jian Liang, Liyong Ren*, Haijuan Ju, Zhaofeng Bai and Zhaoxin Wu, “Fast polarimetric dehazing method for visibility enhancement in HSI colour space,” Journal of Optics, 19, 095606, (2017).
20. Wenfei Zhang†, Jian Liang, Haijuan Ju, Liyong Ren*, Enshi Qu, Zhaoxin Wu, “Study of visibility enhancement of hazy images based on dark channel prior in polarimetric imaging,” Optik,130, 123-130, (2017).
21. Chengju Ma†, Liyong Ren, Wenge Guo, Haiwei Fu, Yiping Xu, Yinggang Liu, and Jin Wen, “Numerical investigation of a microfiber-plane-grating composite optical waveguide for gas refractive index sensing,” Applied Optics, 56(14), 3984-3988, (2017).
22. Wenfei Zhang†, Jian Liang, Liyong Ren*, Haijuan Ju, Enshi Qu, Zhaofeng Bai, Yao Tang and Zhaoxin Wu, “Real-time image haze removal using an aperture-division polarimetric camera,” Applied Optics, 56(4), 942-947 (2017).
23. Yiping Xu†, Liyong Ren, Chengju Ma, Xudong Kong, and Kaili Ren, “Demonstration of a stable and uniform single-wavelength erbium-doped fiber laser based on microfiber knot resonator,” Optical Engineering, 55(12), 126111 (2017).
24. Kaili Ren†, Liyong Ren*, Yingli Wang, Xiao Lin, Jian Liang, Yiping Xu and Haijuan Ju, “Theoretical study on core-mode to radiation-mode coupling in chiral fiber long-period gratings,” Optics & Laser Technology, 92, 150-155 (2017).
25. Xudong Kong†, Kaili Ren, Liyong Ren*, Jian Liang, and Haijuan Ju, “Chiral long-period gratings: fabrication, high-sensitive torsion sensing and tunable single-band filtering,” Applied Optics, 56(16), 4702-4707 (2017).
26. Yiping Xu†, Liyong Ren, Chengju Ma, Xudong Kong, Kaili Ren, Feng Song, “Stable and uniform multiwavelength erbium-doped fiber laser based on a microfiber knot resonator with a Sagnac loop reflector,”J Opt, 1, 1-5 (2017).
27. Kaili Ren†, Liyong Ren*, Jian Liang, Xudong Kong, Haijuan Ju, and Zhaoxin Wu，“Online and efficient fabrication of helical long-period fiber gratings,” IEEE Photonics Technology Letters, 29(14), 1175-1178  (2017).
28. Chengju Ma†, Liyong Ren*, Wenge Guo, Haiwei Fu, Yiping Xu, Ying-Gang Liu, and Xiaozhen Zhang, “Wideband slow-light propagation with no-distortion in a nanofiber-plane grating composite waveguide,” Optical Engineering, 55(6), 066120 (2016).
29. Jian Liang†, Wenfei Zhang, Liyong Ren*, Haijuan Ju, and Enshi Qu，“A polarimetric dehazing method for visibility improvement based on visible and infrared image fusion，”Applied Optics, 55(29), 8221-8226 (2016).
30. Kaili Ren†, Liyong Ren*, Jian Liang, Xudong Kong, Haijuan Ju, Yiping Xu, and Zhaoxin Wu, “Online fabrication scheme of helical long-period fiber grating for liquid-level sensing, “ Applied Optics，55(34), 9675-9679 (2016).
31. Yadong Wang, Xuetao Gan, Chenyang Zhao, Liang Fang, Dong Mao, Yiping Xu, Fanlu Zhang, Teli Xi, Liyong Ren, Jianlin Zhao, “All-optical control of microfiber resonator by graphene’s photothermal effect,” Applied Physics Letters, 108, 171905 (2016).
32. Yiping Xu†, Liyong Ren, Chengju Ma, Xudong Kong, and Kaili Ren, “Slow light and fast light in microfiber double-knot resonator with a parallel structure,” Applied Optics, 55(30), 8612-8617 (2016).
33. Wenfei Zhang†, Jian Liang, Haijuan Ju, Liyong Ren*, Enshi Qu and Zhaoxin Wu, “A robust haze-removal scheme in polarimetric dehazing imaging based on automatic identification of sky region,” Optics & Laser Technology, 86, 145-151 (2016).
34. Jian Liang†, Liyong Ren*, Haijuan Ju, Wenfei Zhang, Enshi Qu, “A polarimetric dehazing method for dense haze removal based on distribution analysis of angle of polarization,” Opt. Express, 23(20), 26146-26157 (2015).
35. Yiping Xu†, Liyong Ren*, Jian Liang, Chengju Ma, Yingli Wang, Xudong Kong, and Xiao Lin, “Wideband slow light in microfiber double-knot resonator with a parallel structure,” J. Applied Physics, 118, 073105 (2015).
36. Chengju Ma†, Liyong Ren*, Yiping Xu, Yingli Wang, Hong Zhou, Fu Wei, Jin Wen, “Theoretical and experimental study of structural slow light in a microfiber coil resonator,” Applied Optics, 54(18), 5619-5623 (2015).
37. Yiping Xu†, Liyong Ren*, Yingli Wang, Xudong Kong, Jian Liang, Kaili Ren, Xiao Lin, “Enhanced slow light in microfiber double-knot resonator with a Sagnac loop reflector,” Optics Communications, 350, 148-153 (2015).
38. Yiping Xu†, Liyong Ren*, Yingli Wang, Xudong Kong, Jian Liang, Haijuan Ju, Dun Qiao, “Slow-light effect in Microfiber Double-knot Resonator with a Parallel Structure,” Acta Photonica Sinica, 44(5), 0506002-1-0506002-6 (2015).
39. Yiping Xu†, Liyong Ren*, Chengju Ma, Yingli Wang, Xudong Kong, Jian Liang, Haijuan Ju, “Theoretical and Experimental Study on Spectral Characteristics of Microfiber Double-knot Resonator with Different Structures,” Acta Photonica Sinica, 44(4), 0406001-1-0406001-7 (2015).
40. Xinchao Du, Zhengquan He, Xiao Lin, Libin Zhou, Baowen Hu, Baoke Luo, Xiaoyi Guo, Depeng Kong, Liyong Ren, Yulin Li, “Low-cost robust polymer optical fiber temperature sensor based on FIR method for in situ measurement”, Acta Photonica Sinica, 44(4), 0406003-1-0406003-7 (2015).
41. Xinchao Du, Libin Zhou, Zhengquan He, Feng Liu, Xiao Lin, Baowen Hu, Xiaoxi Guo, Baoke Luo, Liyong Ren, Yulin Li, “A fiber-optic temperature sensor based on dual fluorescence by using FIR method”, Chin. J. of Lasers, 42(8), 141-149 (2015).
42. Yidan Dai, Enshi Qu, Liyong Ren, “Rapid modeling method of LED free-form surface lens based on Scheme language,” Infrared and Laser Engineering, 44(9), 2690-2695 (2015).
43. Jian Liang†, Liyong Ren*, Haijuan Ju, Enshi Qu, Yingli Wang, “Visibility enhancement of hazy images based on a universal polarimetric imaging method,” J. Appl. Phys., 116，173107 (2014).
44. Xiao Lin†, Liyong Ren*, Yiping Xu, Nana Chen, Haijuan Ju, Jian Liang, Zhengquan He, Enshi Qu, Baowen Hu, Yulin Li, “Low-cost multipoint liquid-level sensor with plastic optical fiber,” IEEE Photonics Technology Letters, 26(16), 1613-1616 (2014).
45. Yiping Xu†, Liyong Ren*, Chengju Ma, Jian Liang, “Theoretical study on slow light in different structures of optical microfiber knot resonators (OMKRs),” Optik, 125, 2856-2861 (2014).
46. Jian Liang†, Liyong Ren*, Enshi Qu, Bingliang Hu, Yingli Wang, “A new method for enhancing visibility of hazy images based on polarimetric imaging,” Photonics Research, 2(1), 38-44 (2014).
47. Yiping Xu†, Liyong Ren*, Jian Liang, Chengju Ma, Yingli Wang, and Nana Chen, Enshi Qu, “A simple, polymer-microfiber-assisted approach to fabricating the silica microfiber knot resonator,” Optics Communications, 321, 157-161 (2014).
48. Chengju Ma†, Liyong Ren*, Yiping Xu, Yingli Wang, Jian Liang, Enshi Qu, “Design and fabrication of tapered microfiber waveguide with good optical and mechanical performance,” Journal of Modern Optics, 61(8), 683-687 (2014).
49. Yiping Xu†, Liyong Ren*, Chengju Ma, Yingli Wang, Jian Liang, Enshi Qu, “Wide-bandwidth and zero-dispersion slow light in MKRs with two-ring parallel connection structure based on an analogue of electromagnetically induce transparency”, Journal of Modern Optics, 61(13), 1109-1114 (2014).
50. Menghua Kang, Yingli Wang, Liyong Ren, Jintao Xu, Jian Liang, Enshi Qu, “Design of vibration-insensitive Sagnac fiber-optic current sensors using spun high-birefringence fibers”, Journal of Modern Optics, 61(14), 1120-1126 (2014).
51. Haijuan Ju†, Liyong Ren*, Xiao Lin, Jian Liang, Chengju Ma, “Wide-range continuously-tunable slow-light delay line based on stimulated Brillouin scattering,” IEEE Photonics Technology Letters, 25(19), 1920-1923 (2013).
52. Nana Chen†, Jian Liang，Liyong Ren*, “High-birefringence, low-loss porous fiber for single-mode terahertz-wave guidance,” Applied Optics, 52(21), 5297-5302 (2013).
53. Xiao Lin†, Liyong Ren*, Jian Liang, “Nondestructive scheme for measuring the attenuation coefficient of polymer optical fiber,” Optics Letters, 38(4), 528-530 (2013).
54. Xiao Lin†, Liyong Ren*, Enshi Qu, Jian Liang, Haijuan Ju, “Theoretical and experimental study on nonintrusive light injection via cladding in plastic optical fibers,” J. Lightwave Technology, 31(3), 359-365 (2013).
55. Jian Liang†, Liyong Ren*, Nana Chen, Changhe Zhou, “Broadband, low-loss, dispersion flattened porous-core photonic bandgap fiber for terahertz (THz)-wave propagation,” Optics Communications, 295, 257-261 (2013).
56. Haijuan Ju†, Liyong Ren*, Jian Liang, Chengju Ma, “Stability-improved slow light in polarization-maintaining fiber based on polarization-managed stimulated Brillouin scattering,” J. of Optics, 15, 035404, (2013).
57. Chengju Ma†, Liyong Ren*, Enshi Qu, Feng Tang, Quan Liang, “Modeling and testing of static pressure within an optical fiber cable spool using distributed fiber Bragg gratings,” Optics Communications, 285(24), 4949-4953 (2012).
58. Chengju Ma†, Liyong Ren*, Yiping Xu, “Slow-light element for tunable time delay based on optical microcoil resonator,” Applied Optics, 51(26), 6295-6300 (2012).
59. Maojin Yun, Yong Wang, Jian Liang, Feng Xia, Meiling Liu, Liyong Ren, “Multi-channel biosensor based on photonic crystal waveguide and microcavities”, Optik, 123, 1920-1922, (2012).
60. Jian Liang†, Liyong Ren*, Maojin Yun, Xingjun Wang, “Wideband slow light with ultralow dispersion in a W1 photonic crystal waveguide,” Applied Optics, 50(31), G98-G103 (2011).
61. Jian Liang†, Liyong Ren*, Maojin Yun, Xu Han, Xingjun Wang, “Wideband ultraflat slow light with large group index in a W1 photonic crystal waveguide,” J. Applied Physics, 110(6), 063103 (2011).
62. Yani Zhang, Liyong Ren*, Yongkang Gong, Xiaohui Li, Leiran Wang, Chuandong Sun, “Design and optimization of highly nonlinear low-dispersion crystal fiber with high birefringence for four-wave mixing,” Applied Optics, 49(16), 3208-3214(2010).
63. Zuoliang Duan, Liyong Ren*, Yani Zhang, Hanyi Wang, Baoli Yao, Wei Zhao, “Theoretical and experimental study of polarization characteristics of polarization maintaining fiber based on wavelength-sweeping modulation,” Microwave and Optical Technology Letters, 52(7), 1466-1469 (2010).
64. Liyong Ren* and Yasuo Tomita, “Transient and nonlinear analysis of slow-light pulse propagation in an optical fiber via stimulated Brillouin scattering,” J. Opt. Soc. Am. B,  26(7), 1281-1288 (2009).
65. Liyong Ren* and Yasuo Tomita, “Reducing group-velocity-dispersion-dependent broadening of stimulated Brillouin scattering slow light in an optical fiber by use of a single pump laser,” J. Opt. Soc. Am. B, 25(5), 741-746 (2008).
66. Shihe Wang†, Liyong Ren*, Yu Liu, and Yasuo Tomita, “Zero-broadening SBS slow light propagation in an optical fiber using two broadband pump beams,” Opt. Express, 16(11), 8067-8076 (2008).
67. Liyong Ren*, Hanyi Wang, Yani Zhang, Baoli Yao, Wei Zhao, “Theoretical design of single polarization single mode microstructured polymer optical fibers,” Chin. Phys. Lett., 24(5), 1298-1301 (2007).
68. Yani Zhang, Runcai Miao, Liyong Ren, Hanyi Wang, Lili Wang, Wei Zhao, “Polarization properties of elliptical core non-hexagonal symmetry polymer photonic crystal fiber,” Chinese Physics, 16(6), 1719-1724 (2007).
69. Yani Zhang, Liyong Ren, Kang Li, Hanyi Wang, Wei Zhao, Lili Wang, Runcai Miao, Maryanne C. J. Large, Martijn A. van Eijkelenborg, “Guiding mode in elliptical core microstructured polymer optical fiber,” Chin. Opt. Lett., 5(4), 194-196 (2007).
70. Neimule Menke, Baoli Yao, Yingli Wang, Yuan Zheng, Ming Lei, Liyong Ren, Guofu Chen, Yi Chen, Meigong Fan, and Tiankai Li, “Optical image processing using the photoinduced anisotropy of pyrrylfulgide,” J. Opt. Soc. Am A, 23 (2), 267-271 (2006).
71. Yani Zhang, Kang Li, Lili Wang, Liyong Ren, Wei Zhao, Runcai Miao, Maryanne C. J. Large, and Martijn A. van Eijkelenborg, “Casting preforms for microstructured polymer optical fibre fabrication,” Opt. Express, 14 (12), 5541-5547 (2006).
72. Baoli Yao, Ming Lei, Liyong Ren, Neimule Menke, Yingli Wang, Thorsten Fischer, Norbert Hampp. “Polarization multiplexed write-once-read-many optical data storage in bacteriorhodopsin films,” Optics Letters, 30 (22), 3060-3062, (2005).
73. Qinjun Peng, Guiling Wang, Yong Bo, Xinjun Guo, Aicong Geng, Zuyan Xu, Liyong Ren, Yani Zhang, Yishan Wang, Wei Zhao, Lili Wang “Highly efficient tunable tapered-polymer-fiber lasers, ” Applied Physics Letters, 87, 251101-1-251101-3 (2005).
74. Baoli Yao, Yingli Wang, Neimule Menke, Ming Lei, Yuan Zheng, Liyong Ren, Guofu Chen, Yi Chen and Meigong Fan. “Optical properties and applications of photochromic fulgides,” Molecular Crystals and Liquid Crystals, 430, 211-219 (2005).
75. Lili Wang, Yani Zhang, Liyong Ren, Xuezhong Wang, Wei Zhao, “A new approach to mass fabrication technology of microstructured polymer optical fiber preform,” Chin. Opt. Lett., 3, s94-s97 (2005).
76. Liyong Ren*, Liren Liu, Dean Liu, Jifeng Zu, Zhu Luan, “Optimal switching from recording to fixing for high diffraction from a LiNbO3:Ce:Cu photorefractive nonvolatile hologram,” Opt. Lett., 29(2), 186-188 (2004).
77. Liyong Ren*, Liren Liu, Dean Liu, Baoli Yao, “Dynamic characteristics of holographic recording and fixing in LiNbO3:Ce:Cu crystal,” Optics Commun. 238, 363-369 (2004).
78. Qianmin Dong, Liren Liu, Dean Liu, Cuixia Dai, Liyong Ren, “Effect of dopant composition ratio on nonvolatile holographic recording in LiNbO3:Cu:Ce crystals,” Applied Optics, 43(26), 5016-5022 (2004).
79. Dean Liu, Liren Liu, Liyong Ren, Zhu Luan, Y. Zhou, “Material optimization for low scattering noise during nonvolatile holographic recording in doubly doped LiNbO3 crystals,” Chin. Opt. Lett., 2(11), 630-633 (2004).
80. Liyong Ren*, Liren Liu, Dean Liu, Jifeng Zu, Zhu Luan, “Recording and fixing dynamics of nonvolatile photorefractive holograms in LiNbO3:Fe:Mn crystals,” J. Opt. Soc. Am. B, 20 (10), 2162-2173 (2003).
81. Liyong Ren, Liren Liu, Dean Liu, Changhe Zhou, Guangao Li, “Experimental and theoretical study of non-volatile photorefractive holograms in doubly doped LiNbO3:Fe:Cu,” Optical Materials, Vol 23/1-2, 261-267 (2003).
82. Baoli Yao, Liyong Ren, X. Hou, “Z-scan theory based on a diffraction model,” J. Opt. Soc. Am B 20 (6), 1290-1294 (2003).
83. Liyong Ren*, Baoli Yao, X. Hou, Liren Liu, Changhe Zhou, “Analyses and computations of asymmetric Z-scan for large phase shift from diffraction theory,” Chin. Opt. Lett., 1(2), 111-113 (2003).
84. Dean Liu, Liren Liu, Changhe Zhou, Liyong Ren, Guangao Li, “Nonvolatile holograms in LiNbO3:Fe:Cu by use of the bleaching effect,” Appl. Opt., 41(32), 6809-6814 (2002).
85. Dean Liu, Liren Liu, Changhe Zhou, Liyong Ren, Guangao Li, “Bleaching effect and nonvolatile holographic storage in doubly doped LiNbO3:Fe:Cu crystals,” Chin. Sci. Bull., 47(20), 1704-1707 (2002).

1. Liyong Ren, Jian Liang, Wenfei Zhang, Haijuan Ju, Enshi Qu, “A polarimetric dehazing method based on dark channel prior principle,” ZL 2015 1 0405375.0，issued in Oct 2018.
2. Liyong Ren, Enshi Qu, Jian Liang, Haijuan Ju, “A polarimetric imaging system and method based on aperture-division, co-focal plane, full-Stokes vector simultaneous detection,” ZL 201510777564.0, issued in June 2017.
3. Liyong Ren, Enshi Qu, Jian Liang, Haijuan Ju, “A polarimetric imaging system based on aperture-division, full-Stokes vector simultaneous detection,” ZL 201520906066.7, issued in April 2016.
4. Liyong Ren，Xiao Lin，“Nondestructive instrument for measuring the attenuation coefficient of polymer optical fibers, ZL 201220153761.7, issued in March 2013.
5. Liyong Ren, Baoli Yao, Lili Wang, “Measurement and system of diffraction efficiency of real-time dynamic volume grating,” ZL 200510041856.4, issued in December 2008.
6. Liyong Ren, Baoli Yao, Lili Wang, “Measurement equipment of diffraction efficiency of real-time dynamic volume grating,” ZL 200520078510.7, issued in June 2006.
7. Yiping Xu, Liyong Ren，Yingli Wang, Chengju Ma, Jian Liang, “A method for fabricating microfiber knot resonator,” ZL 201310232308.4, issued in March 2015.
8. Jian Liang, Enshi Qu, Haijuan Ju, Liyong Ren, “A haze removal method based on polarimetric imaging,” ZL 201418004203.9, issued in March 2017.
9. Jian Lian, Liyong Ren, Enshi Qu, “A high accurate fiber length measurement system,” Zl 201220086728.7, issued in January 2013.
10. Jintao Xu, Liyong Ren, Wei Zhao, “An earthquake instrument,” ZL 200820029172.1, issued in February 2009.
11. Xu Han, Liyong Ren, “Tunable multi-wavelength fiber laser,” ZL 201120117014.3, issued in November 2011.

1. Hui Chen, Yi Geng, Chengfang Xu, Bin Zhuang, Liyong Ren, “High-speed light focusing through multimode fiber for spot-scanning imaging,” CIOP2019，Aug. 7-9, Proc. of SPIE, Xi’an, China. (in press) (2019).
2. Liyong Ren, Bin Zhuang, Guangzhi Zhao, Chengfang Xu, Yi Geng, Hui Chen, Zhengquan He, Baowen Hu, Yulin Li, “Multimode-fiber/scattering-medium computational optical endoscopic imaging based on digital wavefront modulation,” The 10th International Conference of Information Optics and Photonics (CIOP2018), 8-11 July 2018, Proc. of SPIE, Vol. CIOP100, 109640F, Beijing, China. (invited talk).
3. Liyong Ren, Xudong Kong, Kaili Ren, Jian Liang, Haijuan Ju, Zhaofeng Bai, and Enshi Qu, “Superior long-period fiber gratings based on CO2 laser direct writing method: fabrication, properties and applications,” 99-100, The 11th Asia-Pacific Laser Symposium (APLS2018)，28-30 May 2018, Xi’an, China. (invited talk).
4. Liyong Ren, Wenfei Zhang, Jian Liang, Haijuan Ju, Zhaofeng Bai, Enshi Qu, Zhaoxin Wu, “An aperture-division full-stokes vector polarimetric camera and its polarimetric imaging applications,” Optics & photonics International Congress (OPIC2017), 18-21 April 2017, Yokohama, Japan.
5. Liyong Ren, Kaili Ren, Xudong Kong, Jian Liang, Haijuan Ju, Zhaoxin Wu, “Novel long-period fiber gratings：fabrication and sensing applications,” Conference on Lasers and Electro-Optics (CLEO2017), 14-19 May 2017, San Jose, USA.
6. Liyong Ren, Yiping Xu, Yingli Wang, Chengju Ma, Xudong Kong, Jian Liang, Haijuan Ju, Kaili Ren, Xiao Lin, Xuejiao Li, “Optical microfiber knot resonator (MKR) and its slow-light performance,” The 5th Advances in Optoelectronics and Micro/nano-optics (AOM2015), Journal of Physics: Conferences Series, 680, 012032 (2016), 28-31 Oct. 2015, Xi’an, China. (invited talk).
7. Liyong Ren, Yiping Xu, Haijuan Ju, Chengju Ma, Jian Liang, Yingli Wang, “Fiber-based slow light: theory, experiment and application,” The 7th International Photonics and OptoElectronics Meetings (POEM2014), 18-21 June 2014, Wuhan, China. (invited talk).
8. Liyong Ren, Jian Liang, Yu Liu, Haijuan Ju, Maojin Yun, Chengju Ma, Xu Han, Xiao Lin and Yasuo Tomita,“Slow-light in photonic crystal waveguides/fibers: dispersion tailoring schemes for obtaining a high group index with wide band and low GVD”, SPIE Photonics West 2012, Proc. of SPIE, Vol 8273, 82730L, 21-26 Jan. 2012, San Francisco, USA. (invited talk).
9. Liyong Ren, Xiao Lin, Jian Liang, Changhe Zhou, “Online measuring transmission loss of polymer optical fiber based on nonintrusive light injection and extraction via fiber cladding”, 2012 Beijing International Forum on Science and Technology, 13-16 Nov. 2012, Beijing, China. (invited talk).
10. Liyong Ren and Yasuo Tomita, “SBS-based slow light in optical fibers: optimum design considerations for undistorted slow-light signal propagation in steady-state and transient regimes,” SPIE Photonics West 2009, Proc. of SPIE Vol. 7226, 722605, 24-29 Jan. 2009, San Jose, USA. (invited paper)
11. Liyong Ren, Jian Liang, Maojin Yun, “Hollow-core photonic bandgap fiber with microfluid-infiltrated air holes for slow-light propagation,” SPIE Optics and Photonics 2012, Proc. of SPIE, Vol. 8497, 849710，12-16 Aug. 2012, San Diego, USA. (2012).
12. Liyong Ren, Chengju Ma, Enshi Qu, Feng Tang, and Xu Han, “Analysis and study of static pressure distribution in an optical cable spool using distributed fiber Bragg gratings,” The 3rd Asia-Pacific Optical Sensors Conference 2012 (APOS2012), Proc. of SPIE, Vol. 8351, 835119, Jan. 31-Feb 3, 2012, Sydney, Australia.
13. Liyong Ren, Yasuo Tomita, Xu Han, Chengju Ma, Yu Liu, “On the slow-light pulse propagation in optical fibers via stimulated Brillouin scattering,” The 2010 International Symposium on Ultra-fast Phenomena and Terahertz Waves (ISUPTW 2010), P144, 12-16 Sept. 2010, Xi’an, China.
14. Liyong Ren，Yanlong Yang, Wei Zhao and Yasuo Tomita, “Spatial and temporal evolution of transient stimulated-Brillouin-scattering slow-light pulse in an optical fiber,” SPIE Photonics West 2010, Proc. of SPIE Vol. 7612, 761207, 23-28 Jan. 2010, San Francisco, CA, USA.
15. Liyong Ren and Yasuo Tomita, “Brillouin slow light of sub-nanosecond pulse in an optical fiber using double broadband pumps,” Japanese Society of Applied Physics, The 56th Spring Meeting, March 30-April 2, 2009, Tsukuba, Japan.
16. Liyong Ren and Yasuo Tomita, “Distortion management of SBS slow light in a single-mode optical fiber by optimization of broadband SBS gain spectrum,” SPIE Photonics Europe, Photon management III, Proc. of SPIE Vol. 6994, 69940G, 7-11 April 2008, Strasbourg, France.
17. Liyong Ren and Yasuo Tomita, “Distortion management of wide bandwidth SBS slow light in a single-mode optical fiber by using two broadband pump beams,” Optics & Photonics Japan 2007, P.586-587, 26-28 Nov 2007, Osaka, Japan.
18. Liyong Ren and Yasuo Tomita, “Reducing GVD-dependent broadening of SBS slow light in an optical fiber by use of a single cw pump laser,” University of Electro-Communications 21st Century COE Program, International Symposium on Coherent Optical Science, P.26, 15 Dec. 2007, Tokyo, Japan. 
19. Liyong Ren, Hanyi Wang, Yani Zhang, Lili Wang, Wei Zhao, “Theoretical Design and Performance Evaluation of Polarization-Maintaining Microstructured Polymer Optical Fibers,” The 15th International Conference on Polymer Optical Fiber (ICPOF2006), P. 251-255, 11-14 Sep. 2006, Seoul, Korea.
20. Liyong Ren, Hanyi Wang, Yani Zhang, Lili Wang, Xuezhong Wang, Baoli Yao, Wei Zhao, “Study progress of polymer optical fibers in XIOPM,” 2006 China-Italy Bilateral Workshop, 24-26 Oct. 2006, Xi’an, China.
21. Liyong Ren, Baoli Yao, Neimule MenKe, “Dynamic characteristics of holographic recording and fixing in doubly doped LiNbO3 crystal,” Trends in Optics and Photonics (TOPS) Vol 99, 398-404 (2005), The 10th International Conference on Photorefractive Effects, Materials and Devices (PR2005), 19-23 July 2005, Sanya, China.
22. Liyong Ren, Baoli Yao, Lili Wang, Yongfa Kong, Neimule MenKe, Zhiwei Ren, Ming Lei, “Real-time non-destructive testing of dynamic holograms in doubly-doped LiNbO3 crystals using phase-conjugate technique,” The 7th International Symposium on Optical Storage (ISOS’2005), Proc. of SPIE Vol. 5966, 59660V (2005), 2-6 April 2005, Zhanjiang, China.
23. Liyong Ren, Yani Zhang, Xuezhong Wang, Yulin Li, Wei Zhao and Lili Wang, “Fabrication and characteristics of Rhodamine-doped microstructured polymer optical fibers,” The 14th International Conference on Polymer Optical Fiber (ICPOF2005), 143-146, 20-22 Sep. 2005, HongKong, China.
24. Liyong Ren, Liren Liu, Dean Liu, Baoli Yao, Neimule Menkea, Zhiwei Ren, Yongfa Kong, “Self-enhancement effect and optimal switching scheme for high fixed diffraction efficiency in LiNbO3:Ce:Cu crystals,” Photonics Asia 2004, Proc. of SPIE, 5636, 329-333, 7-12 Nov. 2004, Beijing, China.
25. Liyong Ren, Liren Liu, Dean Liu, Zhu Luan, “Time-space dynamics of holographic recording and fixing in LiNbO3 :Fe:Mn crystal,” Proc. SPIE. 5206, 255-263, (2003).
26. Liyong Ren, Dean Liu, Liren Liu, Changhe Zhou, “Nonvolatile photorefractive holograms in doubly doped LiNbO3: uniform theory and verification,” Proc. of SPIE 4803, 53-64, (2002). (invited paper).
27. Liyong Ren, Liren Liu, Dean Liu, Changhe Zhou, “The optimization of dynamic holographic storage in photochromic LiNbO3:Fe:Mn crystals,” Proc. of SPIE. Vol. 4924, 153-161, (2002).

We hold group meeting on every Monday.