| 教育和工作经历 |
Education Background
1999.9-2004.7： Xiamen University, China
Ph. D., Condensed Matter Physics
Dissertation Title: Study on WDM Optical Communications Devices Based on Holographic Fresnel lenses
Ph.D. Supervisor: Prof. Liu Shou
1995.9-1999.7： Xiamen University, China
Bachelor degree, Radio Physics
Professional Experience
2004.08–Present: Department of Physics, Xiamen University, China
Associate Professor
2013.07–2014.07: College of Optics and Photonics, University of Central Florida, USA
Visiting Scholar |
代表性文章或专著 |
Sensen Li, Lujian Chen, Xiaopeng Dong, Xuechang Ren, Xiangsu Zhang, and Shou Liu, Spatial frequency doubling with two-step technique, Optics Letters, Vol. 39, Issue 7, pp. 2024-2027 (2014)
ABSTRACT: The phenomenon of spatial frequency doubling generated by a two-step technique with the collimated beam at normal incidence in the second exposure is presented. Theoretical analysis demonstrates that the phenomenon is induced by the Talbot effect in photoresist and the superposition of two exposures, and the minimum achievable period of the grating with double spatial frequency can be close to one half of the exposure wavelength in vacuum, divided by the refractive index of photoresist λ∕2n. The two-step technique has the potential to be a simpler and more practical resolution-improving technique for the Talbot-effect-based approach of spatial frequency doubling.
Zhang Yuanying; Ren Xuechang, Lu Qinghong, Liu Jiazhou, Liu Shou, Optical system design of shelter holographic sight, Chinese Journal of Lasers, Vol. 41, No. 6, 0609005 (2014)
ABSTRACT: Based on the optical system of compact matching holographic sight, a novel shelter holographic sight is proposed. The core of this equipment includes two parts. One part is the diffraction matching holographic optical elements, the other is the corner-turning optical auxiliary system. The holographic sight theory, the designing plan and the manufacturing method are introduced. Meanwhile, experiments and analysis on this system show that this optical system satisfies the corner shooting function without exposure.
Shen Shaoxin; Ren Xuechang; Liu Shou; Yang Zhilin; Zhang Yuanying, Fabrication of large-scale photonic phased array using a holographic lithography system, Opt. Eng., 52 (9), 095103 (2013)
ABSTRACT: A holographic lithography method for fabricating large-scale photonic phased array is presented. The large-scale array could be generated using a specially designed holographic optical element and the period could be decreased by half with the help of a half-wave plate. This method provides a convenient way to obtain the photonic array with a smaller period without shortening the recording wavelength. MATLAB simulations and primary experimental results have demonstrated that the phase modulation and nonlinear photoresist response played collectively significant roles in tuning the distribution of the array. The large-scale photonic phased array with a smaller period is an ideal candidate as a Raman substrate.
Yanshuang Li, Xuechang Ren, Shou Liu, Design and fabrication of high efficiency diffuser film based on laser speckle, Proc. of SPIE, Vol. 8416, 841611, (2012).
ABSTRACT: Diffuser film is one of the main components in liquid crystal display backlight unit. It can cause strong scattering for the light out from the light guide plate, and it have the ability to make diffuse reflection and uniform diffusion of the out light occur. How to improve the brightness, the uniformity of backlight unit, and make it more and more slimmer are not only what manufacturers pursuit to, but also an hotspot recently. In this paper, we make use of the statistical analysis law of laser speckle to achieve the fabrication of diffuser film. According to the requirements for the technical parameters of diffuser film, the structure characteristics of laser speckle and manufacturing methods are analyzed and discussed in detail. They consist of producing the original edition of the laser speckle figure (Photoresist board was used as recording medium to produce embossment laser speckle images, and this is one of the most important process in moulding technology ), using electricity molding system to manufacture metal formwork (It is also called as electrotyping, which is transfer the embossment speckle image from the photoresist board to a metal plate), and moulding replication (In a certain temperature and pressure, template stripes were transferred to the film). The diffusion light uniformity and brightness can be controlled via adjusting intensity distribution and average diameter of the speckles. Then the preliminary experiment results are given under laboratory conditions (argon ion laser, λ =457.9nm), and meanwhile the effects of several common diffuser films are compared in this paper.
Shou Liu, Xiangsu Zhang and Xuechang Ren, Optical matching system for eliminating lateral position displacement of holographic images under varying laser wavelength, 9th International Symposium on Display Holography (2012).
ABSTRACT: The diffraction angle of a hologram is proportional to the wavelength so that a lateral displacement of the holographic image will occur when there is a change in wavelength. Such displacement is more serious when the image is generated at far distance. A matching system including an HOE and a hologram is proposed to eliminate the image lateral displacement under varying wavelength. Theoretical analysis demonstrates that the two elements must have the conditions: (a) They must have the same fringe periods; (b) They must be placed in parallel; (c) The diffracted beam from HOE must be collimated. The two elements were fabricated in the experiment and applied into a holographic sight. A test was carried out on the sight through watching the image lateral movement at 50-meter distance. The experimental result shows that under varying wavelength there is no image lateral displacement observed, verifying the effectiveness of the matching system.
Xuechang Ren, Canhui Wang, Yanshuang Li, Shaoxin Shen, Shou Liu, “Optical tweezers array system based on 2D photonic crystals”, Physics Procedia, v 22, p 493-497, (2011).
ABSTRACT: A simple optical interference method for creating multiple optical tweezers from a single laser beam, using two dimentional photonic crystals (PhCs) as a diffractive beam splitter, was described. To obtained clear periodic traps, all diffracted beams sould be used and the intensity of each splitted beam should be same. So the period and the surface features of PhCs was adjusted in the present study As a demonstration of this technique, using 2D PhCs with 700 nanometer period, hexagonal lattice patterns with one micrometer period have been implemented. The image of periodic intensity gradient of light fabricated by this method is presented.
Sensen Li, Shou Liu, Xiangsu Zhang, and Xuechang Ren, “Demultiplexer based on an off-axis holographic lens with low monochromatic aberrations”, Chinese Optics Letters 9(2011).
ABSTRACT: A novel scheme is proposed, in which the aberrations in the off-axis holographic lenses used as demultiplexers are reduced to a low enough level for relatively small channel spacing. The scheme includes optimizing the recording and reconstruction geometries and collimating the reconstruction wave with a gradient-index lens. A demultiplexer operated in the 1 550-nm band with 5-nm channel spacing and −∞-dB crosstalk is obtained using the scheme. The channel spacing can be decreased to 2 nm by etching the cladding of the output fibers to a smaller size.
Guohua Liu, Xuechang Ren, Canhui Wang et al., “A New Solar Concentrator Based on One-Dimensional Grating”, Symposium on Photonics and Optoelectronic (2010).
ABSTRACT: A new way of concentrating sunlight, which is based on one-dimensional grating, and could be used for concentrator photovoltaic, is described. The light changes its direction in the plane perpendicular to the grating direction, the diffracted lights translates through the glass and radiates on the solar cell which is on the edge of the glass. The diffraction efficiency is calculated in theory, and the concentration ratio is estimated.
Xuechang Ren, Xiangsu Zhang, Canhui Wang et al., “1×2 demultiplexer for a light waveguide communications system based on a holographic grating”, Proc. SPIE Vol. 73580L (2009).
ABSTRACT: 2-channel multiplexer/demultiplexer (Muxer/Demuxer) is a key component for bidirectional data traffics applied for optical communication. Up to date various types of Muxer/Demuxer have been proposed and demonstrated. A grating coupler diffracts light into substrates or waveguides, along which light beam propagates by total internal reflection. In addition, one can exploit the dispersive and filtering characteristics of gratings, for dropping or separating one or several wavelengths from one another. When a laser beam containing two wavelengths is striking the surface of the grating with an incident angle within certain range, four diffracted beams will be generated. If two diffracted beams, corresponding to different wavelengths, meet the condition of total internal reflection, they will propagate inside the glass substrate (performs as a waveguide). While the third one cannot meet total reflection condition, and the last one should become the evanescent wave. Therefore it can separate two signals and couple signals to different waveguides. These functions are suited for WDM application and directional couplers. For convenience sake, the visible lights at 458nm and 633nm were used as the incident laser beams. To give a simple sample for 1°¡2 demultiplexing system, a holographic grating was recorded, with the period around 441nm which was chose discretionally within the certain range. The primary experimental results indicate that the two-wavelength signal can be separated and coupled into the respective waveguide as long as the grating is recorded and operated complying with the certain condition. The average insertion loss and crosstalk of the device were presented in this paper.
Canhui Wang, Xuechang Ren, Xiangsu Zhang et al., “Small-angle beam deviation with high resolution using gratings”, Proc. SPIE Vol. 7358, 73580M (2009).
ABSTRACT: Small-angle beam deviation has many applications and is conventionally performed by wedge prisms. The usual method suffers from a disadvantage that the manufacturing tolerances limit the resolution to about an arc second. The paper presents a new technique of using low frequency gratings to realize small-angle beam deviation with higher resolution. By rotating a grating placed in the laser beam path, the deviation of the diffracted light beams can be controlled. Using the proposed method, very small beam deviation angle can be achieved under large grating rotation angle, resulting in high reduction ratio. Theoretical analysis shows that as long as the grating period is large enough, the reduction ratio can be much higher than that given by a wedge prism. The theoretical result has been verified experimentally using a holographic grating with 7.25 μm period placed in a Mach-Zehnder interferometer.
Jianzhong Li, Xiangsu Zhang, Shou Liu, and Xuechang Ren, “Adaptive watermarking scheme using a gray-level computer generated hologram”, Applied Optics, Vol. 48, Issue 26, 4858-4865, (2009).
ABSTRACT: We present a new adaptive blind watermarking scheme using a gray-level computer generated hologram in the discrete wavelet transform domain. By utilizing an improved fuzzy clustering technique and human visual system , the watermark can be adaptively embedded according to block classification. To keep imperceptibility and robustness, a novel iterative embedding algorithm is adopted to change the to-be-embedded coefficients. Compared with the standard Fuzzy c-means (FCM) clustering, the suggested improved FCM (IFCM) converges more quickly and can avoid local optimum effectively. The experimental results demonstrate that the proposed scheme provides good robustness to withstand different kinds of common attack. Compared with other methods, the proposed method has the distinct advantage of better robustness to a JPEG compression attack.
Han Lin, Shou Liu, Xiangsu Zhang, Baolin Liu and Xuechang Ren, “Enhanced external quantum efficiency of light emitting diodes by fabricating two-dimensional photonic crystal sapphire substrate with holographic technique”, ACTA PHYSICA SINICA, 58 (2), 959-963, (2009).
ABSTRACT: Investigation in fabricating two2dimensional (2D) photonic crystal ( PC) on sapphire substrates for enhancing external efficiency of GaN based light emitting diodes (LEDs) is presented. 2D2PC was fabricated on a sapphire substrate using holographic lithography and inductively coupled plasma ( ICP) dry etching. LEDs with 2μm thick n2GaN layer ,four pairs of InGaNPGaN quantum well structures and 200 nm thick p2GaN layer were grown on the patterned sapphire substrate ( PSS) by metal organic chemical vapor deposition (MOCVD) . The PC fabricated on PSS has 2D hexagonal lattice pattern ,with 318μm lattice constant and 800 nm depth. LEDoutput measurement shows 100 % increase in the average luminous intensity of PSS2LEDs compared with that of conventioanl LEDs. The measured X2ray rocking curves of (0002) diffraction for GaN layers grown on patterned and non2patterned sapphire substrates indicate that the quality of GaN crystal grown on PSS is not improved ,which implies that the large enhancement of external quantum efficiency of PSS2LED is not caused by the increase in internal efficiency but possibly by the increase in extraction efficiency ,which results from the scattering of the PSS.
Zhang XS, Liu S, Liu Y, Chen XY, Han L, Ren XC, “Enhancement of LED light extraction via diffraction of hexagonal lattice fabricated in ITO layer with holographic lithography and wet etching”, PHYSICS LETTERS A, Volume: 372 Issue: 20 Pages: 3738-3740, (2008).
ABSTRACT: A novel method for enhancing light extraction efficiency of LEDs via diffraction of the lattice fabricated in ITO layers of LEDs is proposed. The lattice fabrication process includes holographic lithography and wet etching. 3-beam interference holographic approach was used to fabricate large-area hexagonal lattice mask which can cover 2-inch semiconductor wafer, and acid etching was used to transfer the lattice structure into p-contact ITO layer. 1.4 fold enhancement of light output at 20 mA injection current was obtained from GaN-based LEDs in the primary experiment. The lattice fabrication process is rapid and cost-effective thus enabling industrial mass production of high brightness LEDs.
Xuechang Ren, Shou Liu, Xiangsu Zhang et al.,”Multiplexer/demultiplexer in optical communications based on holographic Fresnel lens”, PHYSICS LETTERS A, 354（3）：243-247 (2006).
ABSTRACT: Multiplexer/demultiplexer for WDM based on off-axis holographic Fresnel lens was fabricated. The principle and fabricating technology of the demultiplexer with the central working wavelength of 1310 nm and the channel spacing of 25 nm were described. The reduction of third-order aberrations was the main consideration. The theoretical analysis indicates that it can be effectively reduced if the condition tanαC/tanαR = -λC/λO is applied in geometry design and long object distance is selected. The experiment method and results were presented in this paper.
Shou Liu, Xiangsu Zhang, Xiaoyun Chen, Ying Liu, Xuechang Ren, “One-to-many laser fanout generated by single large-size 2-dimensional holographic photonic crystal”, Applied Physics Letters87, (24): No. 241111, (2005).
ABSTRACT: The phenomenon of one-to-many laser fanout in large-size two-dimensional (2D) holographic photonic crystals (H-PhCs) is presented. Theoretical analysis demonstrates that the phenomenon is induced by multiple substrate waveguiding effect of 2D H-PhCs, and the orientations of the waveguided beams depend on the lattice structures of 2D H-PhCs. The fanout angle and separations between output spots are determined by _ /d , light incident angle and thickness of glass substrate, therefore can be controlled via fabricating special lattice structures. The phenomenon has the potential to enable the application of 2D PhCs as interconnection devices in optical networks.
Shou Liu, Xiangsu Zhang, Xuechang Ren, “Rainbow holographic camera”, Optics Letters, v 26, n 15, pp: 1146-1148 (2001).
ABSTRACT: A rainbow holographic camera system is presented. The system uses only a sin... |
