SKLTOP published key papers(2004-2006)

1. Phys. Rev. Lett. 96, 165003 (2006)

Observation of a Fast Electron Beam Emitted along the Surface of a Target Irradiated by Intense Femtosecond Laser Pulses

Y. T. Li, X. H. Yuan, M. H. Xu, Z. Y. Zheng, Z. M. Sheng, M. Chen, Y. Y. Ma, W. X. Liang, Q. Z. Yu, Y. Zhang,1 F. Liu, Z. H. Wang, Z. Y. Wei, W. Zhao, Z. Jin, and J. Zhang

(Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China

State Key Laboratory of Transient Optics Technology, Chinese Academy of Sciences, Xi'an 710068, China)

Abstract. A novel fast electron beam emitting along the surface of a target irradiated by intense laser pulses is observed. The beam is found to appear only when the plasma density scale length is small. Numerical simulations reveal that the electron beam is formed due to the confinement of the surface quasistatic electromagnetic fields. The results are of interest for potential applications of fast electron beams and deep understanding of the cone-target physics in the fast ignition related experiments.

2 Phys. Rev. B 73, 245337 (2006)

Franz-Keldysh effect and dynamical Franz-Keldysh effect of cylindrical quantum wires

T. Y. Zhang and W. Zhao

State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, 322 West Youyi Road, Xi’an 710068, People’s Republic of China

Abstract. We investigate the interband optical absorption spectra near the band edge of a cylindrical semiconductor quantum wire in the presence of a static electric field and a terahertz electric field polarized along the axis. Optical absorption spectra are nonperturbatively calculated by solving the low-density semiconductor Bloch equations in real space and real time. The influence of the Franz-Keldysh _FK_ effect and dynamical FK effect on the absorption spectrum is investigated. To highlight the physics behind the FK effect and dynamical FK effect, the spatiotemporal dynamics of the polarization wave packet are also presented. Under a reasonable static electric field, substantial and tunable absorption oscillations appear above the band gap. A terahertz field, however, will cause the Autler-Townes splitting of the main exciton peak and the emergence of multiphoton replicas. The presented results suggest that semiconductor quantum wires have potential applications in electro-optical devices.

3. Applied physics B 73.245337(2006)

Matching of both group-velocity and pulse-front for ultrabroadband three-wave-mixing with noncollinear angularly dispersed geometry

Liu Hongjun，ZhaoWei，YangYanlong，WangHongying，WangYishan and ChenGuofu

State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068

Abstract. Ultrabroadband three-wave-mixing is analyzed using the concept of pulse-front-tilt, which is achieved by means of angular dispersion. The results show exactly matching of both group-velocity and pulse-front is the important criterion for constructing an ultrabroadband TWM. A theoretical model is developed, in which the group velocities, noncollinear angles, spatial walk-off angles, linear angular spectral dispersion coefficients and pulse-front tilted angles are suitably linked to each other. Expressions for finding ideal phase matching angle, noncollinear angle and linear angular spectral dispersion coefficient are obtained. Specific numerical results are presented for crystals BBO and LBO with type-I noncollinear angularly dispersed geometry. The numerical simulations verify that our model is valid for designing a practicable ultrabroadband parametric process.

4. Optics Communications 2006.Vol.14，No.12，P163-168

Ultra-broadband optical parametric chirped-pulse amplification by matching of both group-velocity and pulse-front

LiuHongjun，ZhaoWei， Wang Hongying，LiXiaoli，Wang Yishan

State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068

Abstract. Ultra-broadband optical parametric chirped-pulse amplification is analyzed based the compensation of phase-mismatch, which is achieved by matching of both group-velocity and pulse-front between signal and idler by the combination of the noncollinear-phase match and pulse-front-tilt. The results show exactly matching of both group-velocity and pulse-front is the important criterion for constructing an UBOPCPA. Its general model is developed, in which the group velocities, noncollinear angles, spatial walk-off angles, linear angular spectral dispersion coefficients and pulse-front tilted angles are suitably linked to each other. Finally, specific numerical calculations and simulations are presented for -barium borate OPCPA with type-I noncollinear angularly dispersed geometry.

5. OpticsExpress 2006.Vol.14，No.12，P5803

Structuring by multi-beam interference using symmetric pyramids

Ming Lei, Baoli Yao*

State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068 yaobl@opt.ac.cn

Romano A. Rupp

Institute for Experimental Physics, University of Vienna, Boltzmanngasse 5, A-1090 Wien, Austria

Abstract: A method for producing optical structures using rotationally symmetric pyramids is proposed. Two-dimensional structures can be achieved using acute prisms. They form by multi-beam interference of plane waves that impinge from directions distributed symmetrically around the axis of rotational symmetry. Flat-topped pyramids provide an additional beam along the axis thus generating three-dimensional structures. Experimental results are consistent with the results of numerical simulations. The advantages of the method are simplicity of operation, low cost, ease of integration, good stability, and high transmittance. Possible applications are the fabrication of photonic micro-structures such as photonic crystals or array waveguides as well as multi-beam optical tweezers.

6. Journal of Materials 2006.Vol.53,No.15,P2137-2151

Soliton-induced waveguides in photorefractive photovoltaic materials

KEQING LU, WEI ZHAO, YANLONG YANG, YANG YANG, XUEMING LIU, YANPENG ZHANG and JINGJUN XU

State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academic of Sciences, Xi’an 710068, China

Department of Electronic Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China

Department of Physics, Nankai University, Tianjin 300071, China

(Received 6 August 2005)

Abstract: Waveguides induced by one-dimensional spatial photovoltaic solitons are investigated in both self-defocusing-type and self-focusing-type photorefractive photovoltaic materials. The number of possible guided modes in a waveguide induced by a bright photovoltaic soliton is obtained using numerical techniques. This number of guided modes increases monotonically with increasing intensity ratio, which is the ratio between the peak intensity of the soliton and the sum of the background illumination and the dark irradiance. On the other hand, waveguides induced by dark photovoltaic solitons are always single mode for all intensity ratios, and the higher the intensity ratio, the more confined is the optical energy near the centre of the dark photovoltaic soliton. Relevant examples are provided where photorefractive photovoltaic materials are of self-defocusing and self-focusing types. The properties of soliton-induced waveguides in both self-defocusing-type and self-focusing-type materials are also discussed.

7. Optics Express 2006.Vol.114,No.7,P2589-2595

An automatic step adjustment method for average power analysis technique used in fiber amplifiers

Liu Xueming

State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068

Abstract: An automatic step adjustment (ASA) method for average power analysis (APA) technique used in fiber amplifiers is proposed in this paper for the first time. In comparison with the traditional APA technique, the proposed method has suggested two unique merits such as a higher order accuracy and an ASA mechanism, so that it can significantly shorten the computing time and improve the solution accuracy. A test example demonstrates that, by comparing to the APA technique, the proposed method increases the computing speed by more than a hundredfold under the same errors. By computing the model equations of erbium-doped fiber amplifiers, the numerical results show that our method can improve the solution accuracy by over two orders of magnitude at the same amplifying section number. The proposed method has the capacity to rapidly and effectively compute the model equations of fiber Raman amplifiers and semiconductor lasers.

8. Optics Communications 2006.Vol.259,P158-163

Resonance-enhanced group delay times in an asymmetric single quantum barrier

Chun-Fang Li a,b, Spieker Harald c

a.Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444, People’s Republic of China

b.State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068

c.Institute for Electromagnetic Compatibility, Technical University Braunschweig, Schleinitzstrasse 23, 38106 Braunschweig, Germany

Abstract: It is shown that transmission and reflection group delay times in an asymmetric single quantum barrier are greatly enhanced by the transmission resonance when the energy of incident particles is larger than the height of the barrier. The resonant transmission group delay is of the order of the quasibound state lifetime in the barrier region. The reflection group delay can be either positive or negative, depending on the relative height of the potential energies on the two sides of the barrier. Its magnitude is much larger than the quasibound state lifetime. These predictions have been observed in microwave experiments.

9. Optics Communications 2006.Vol.259,P470-473

Experimental observation of negative lateral displacements of microwave beams transmitting through dielectric slabs

Li Chunfanga,b, Q.B.Zhua, G.Nimtea,c, X.Chena, Y.Zhanga

a.Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444, PR China

b.State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068

c.Physikalisches Institut, Universita¨t zu Ko¨ ln, Zu¨ lpicher Strasse 77, D-50937 Ko¨ ln, Germany

Abstract: It was theoretically predicted that when a beam of light travels through a thin slab of optically denser medium in the air, the emerging beam from the slab will suffer a lateral displacement that is different from the prediction of geometrical optics, that is, the Snell_s law of refraction and can be zero and negative as well as positive. These phenomena have been directly observed in microwave experiments in which large angles of incidence are chosen for the purpose of obtaining negative lateral displacements.

10. Optics Communications 247 (2005) 437–445

One-dimensional modulation instability of broad optical beams in biased photorefractive-photovoltaic crystals under steady-state conditions

Keqing Lu, Wei Zhao, Yanlong Yang, and Jinping Li

State Key Laboratory of Transient Optics Technology, Xi’an Institute of Optics and Precision Mechanics, Chinese Academic of Sciences, Xi’an 710068, China

Yanpeng Zhang

Department of Electronic Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China

Jingjun Xu

Department of Physics, Nankai University, Tianjin 300071, China.

Abstract. We present a comprehensive study of the one-dimensional modulation instability of broad optical beams in biased photorefractive-photovoltaic crystals under steady-state conditions. We obtain the one-dimensional modulation instability growth rate by globally treating the space-charge field and by considering distinction between values of in nonlocal effects and local effects in the space-charge field, where is the field constant correlated with terms in the space-charge field, which depends on the external bias field, the bulk photovoltaic effect, and the ratio of the optical beam’s intensity to that of the dark irradiance. The one-dimensional modulation instability growth rate in local effects can be determined from that in nonlocal effects. When the bulk photovoltaic effect is neglectable, irrespective of distinction between values of in nonlocal effects and local effects in the space-charge field, the one-dimensional modulation instability growth rates in nonlocal effects and local effects arethose of broad optical beams studied previously in biased photorefractive-nonphotovoltaic crystals. When the external bias field is absent, the one-dimensional modulation instability growth rates in nonlocal effects and local effects predict those of broad optical beams in open- and closed-circuit photorefractive-photovoltaic crystals.

PACS: 42.65.Hw; 42.65.Jx; 42.65.Tg; 72.40.+w

Keywords: Spatial soliton; Photovoltaic effect; LiNbO3

11. Eur. Phys. J. B 46, 433–440 (2005)/ THE EUROPEAN PHYSICAL JOURNAL B

The reflection and transmission group delay times in an asymmetric single quantum barrier

Xi Chen1,aand Chun-Fang Li1,2,b

1 Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444, P.R. China

2 State Key Laboratory of Transient Optics Technology, Xi'an Institute of Optics and Precision Mechanics, Academia Sinica, 322 West Youyi Road, Xi’an 710068, P.R. China

Received 18 January 2005 / Received in final form 12 May 2005

Published online 18 August 2005 _ @EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2005

Abstract. The reflection and transmission group delay times are systematically investigated in an asymmetric single quantum barrier. It is reported that the reflection times in both evanescent and propagating cases can be either negative or positive, depending on the relative height of the potential energies on the two sides of the barrier. In the evanescent case where the energy of incident particles is less than the height of the barrier, the reflection and transmission times in the opaque limit are both independent of the barrier’s thickness, showing superluminality. On the other hand, in the propagating case where the energy of incident particles is larger than the height of the barrier, the reflection and transmission times as the periodical function of the barrier’s thickness can be greatly enhanced by the transmission resonance. It is also shown that the transmission time and the reflection times for the two propagation directions in the same asymmetric configuration satisfy the reciprocal relation, as consequence of time reversal invariance in quantum mechanics. These phenomena may lead to novel applications in electronic devices.

DOI: 10.1140/epjb/e2005-00264-6

PACS. 03.65.Xp Tunneling, traversal time, quantum Zeno dynamics _73.23.-b Electronic transport in mesoscopic systems _03.65.-w Quantum mechanics

12. OPTICS LETTERS / Vol. 30, No. 22 / November 15, 2005/ pp.3060-3062

Polarization multiplexed write-once–read-many optical data storage in bacteriorhodopsin films

Baoli Yao, Ming Lei, Liyong Ren, Neimule Menke, and Yingli Wang

(State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068, China)

Thorsten Fischer and Norbert Hampp

(Department of Chemistry, University of Marburg, D-35032 Marburg, Germany, and Material Science Center, D-35032 Marburg, Germany)

Abstract. In polymeric films of bacteriorhodopsin (BR) a photoconversion product, which was named the F620 state, was observed on excitation of the film with 532 nm nanosecond laser pulses. This photoproduct shows a strong nonlinear absorption. Such BR films can be used for write-once–read-many (WORM) optical data storage. We demonstrate that a photoproduct similar or even identical to that obtained with nanosecond pulses is generated on excitation with 532 nm femtosecond pulses. This photoproduct also shows strong anisotropic absorption, which facilitates polarization storage of data. The product is thermally stable and is irretrievable to the initial B state either by photochemical reaction or through a thermal pathway. The experimental results indicate that the product is formed by a two-photon absorption process. Optical WORM storage is demonstrated by use of two polarization states, but more polarization states may be used. The combination of polarization data multiplexing and extremely short recording time in the femtosecond range enables very high data volumes to be stored within a very short time.

13. OPTICS EXPRESS/ Vol. 13, No. 1 / 10 January 2005 / pp.20-25

Polarization patterns hide and display using photoinduced anisotropy of photochromic fulgide

Baoli Yao, Yingli Wang, Ming Lei, Neimule Menke, and Guofu Chen

(State Key Laboratory of Transient Optics Technology, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710068, China)

Yi Chen, Tiankai Li, and Meigong Fan

(Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100101, China)

Abstract. Photoinduced anisotropy of a photochromic pyrrylfulgide/PMMA film was investigated by using two linearly polarized beams. Excitation by linearly polarized light induces into the film an optical axis that has the same polarization as the excitation beam. This causes a change of the transmittance and of the polarization state of the detection beam. With a microscope a matrix of 4x4 light spots with different polarizations were recorded in the pyrrylfulgide/PMMA film. If readout with non-polarized light, the matrix of light spots show no information pattern. However, when readout with differently polarized lights, different patterns can be displayed. The experiment demonstrates that pyrrylfulgide/PMMA films can be used to hide two differently polarized patterns, which may be applied in camouflage technology.

14. PHYSICAL REVIEW B 72, 165310 (2005)

Optical response in a quantum dot superlattice nanoring under a lateral electric field

T. Y. Zhang,1,2W. Zhao,1and J. C. Cao2

1State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, 322 West Youyi Road, Xi’an, 710068, People’s Republic of China

2State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, People’s Republic of China

（Received 17 April 2005; revised manuscript received 27 June 2005; published 6 October 2005）

Abstract. The optical absorption of a GaAs/AlGaAs quantum dot superlattice nanoring (QDSLNR) under a lateral dc electric field and with magnetic flux threading the ring is investigated. This structure and configuration provides a unique opportunity to study the optical response of a superlattice under an inhomogeneous electric field, which is not easily realized for general quantum well superlattices (QWSLs) but naturally realized for QDSLNRs under a homogeneous lateral electric field. It has been shown that a lateral dc electric field gives rise to a substantial change of the optical absorption spectra. Under a low field, the excitonic optical absorption is dominated by a 1s exciton. And with the electric field increasing, the optical absorption undergoes a transition from 1s excitonic absorption to 0 excitronic WSL absorption. (The number of 0, and −1 and +1 below are WSLs index.) The −1 and the +1 WSLs corresponding to the maximum effective field can also be identified. Due to the inhomogeneity of the electric field, the peaks of the −1 and the +1 WSLs are diminished and between them there exist rich and complicated structures. This is in contrast to the general QWSLs under a homogenous electric field. The complicated structures can be understood by considering the inhomogeneity of the electric field along the ring, which results in the nearest-neighbor transition, the next-nearest-neighbor transition, etc., have a different value repectively, at different sites along the ring. This may give rise to multiple WSLs. We have also shown that the line shape of the optical absorption is not sensitive to the threading magnetic flux. The threading magnetic flux only gives rise to a slight diamagnetic shift. Thus the enhancement of the sensitivity to the flux allowing for observation of the excitonic Aharanov-Bohm effect in the plain nanoring is not expected in QDSLNRs.

DOI: 10.1103/PhysRevB.72.165310 PACS number_s_: 78.67.Lt, 78.67.Pt, 71.35.Cc, 78.20.Bh

PHYSICAL REVIEW B 72, 165310 (2005)

15. JOURNAL OF APPLIED PHYSICS 98, 094311 (2005)

Interband optical-absorption spectra of a finite quantum dot superlattice in a cylindrical nanowire

T. Y. Zhangand W. Zhao

State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, 322 West Youyi Road, Xi’an 710068, People’s Republic of China

J. C. Cao and G. Qasim

State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People’s Republic of China

(Received 1 November 2004; accepted 5 October 2005; published online 14 November 2005)

Abstract.Theoretical calculations of the interband optical-absorption spectra of a finite quantum dot superlattice in a wire (QDSLW) in the presence of a homogeneous dc or terahertz field are presented. The QDSLW has miniband structures of the electron states as general quantum well superlattices do and shows the two features common to one-dimensional structures, viz., strong excitonic absorption below and weak absorption above the band edge. The applied dc field causes a redshift of the location and a decrease in height of the main excitonic peak and leads to an increase in height of the minor peak next to the main peak. In the presence of a terahertz field, the Autler-Townes splitting of the main excitonic peak and the emergence of one-photon and two-photon gain peaks on the spectra are demonstrated. © 2005 American Institute of Physics.

[DOI: 10.1063/1.2131190]

JOURNAL OF APPLIED PHYSICS 98, 094311 (2005)

16. August 10, 2005/ Vol. 3, No.8/ CHINESE OPTICS LETTERS

High-power double-clad large-mode-area photonic crystal fibre laser

Kang Li (李康)1,3** , Yishan Wang(王屹山)1 , Wei Zhao (赵卫)1, Guofu Chen (陈国夫)1, Qinjun Peng (彭钦军)2,3, Dafu Cui (崔大复)2, and Zuyan Xu (许祖彦)2

1State Key Laboratory of Transient Optics Technology, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an, 710068

2Key Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080

3Graduate School, Chinese Academy of Sciences, Beijing 100039

** likang@opt.ac.cn TEL 029-88472107-8628 FAX 029-88498711

Abstract. A high power double-clad ytterbium-doped large-mode-area photonic crystal fibre (LMA PCF) laser was demonstrated using a unique Fabry-Perot (F-P) configuration. The pump power source is a fibre coupled diode array at 976 nm. A Continuous-wave output power of 50 W at ~1.04m with a slope efficiency of 76.3% was obtained. Single transverse mode operation is achieved without any thermal problems. This laser has the potential for scaling to much higher output power.

OSCI code: 140.3480, 140.3510, 060-2430

17. Physical Review E 69,055601(R) 2004

Prediction of simultaneously large and opposite generalized Goos-Hänchen shifts for TE and TM light beams in an asymmetric double-prism configuration

Chun-Fang Li1,2 and Qi Wang1

1 Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200436, People's Republic of China

2 State Key Laboratory of Transient Optics Technology, Xi'an Institute of Optics and Precision Mechanics, Academia Sinica, 322 West Youyi Road, Xi'an 710068, People's Republic of China

Abstract: It is predicted that large and opposite generalized Goos-Hänchen (GGH) shifts may occur simultaneously for TE and TM light beams upon reflection from an asymmetric double-prism configuration when the angle of incidence is below but near the critical angle for total reflection, which may lead to interesting applications in optical devices and integrated optics. Numerical simulations show that the magnitude of the GGH shift can be of the order of beam's width. ©2004 The American Physical Society

18. J.Opt.A:Pure Appl.Opt.6(2004) 658-665

Steady-state vector spatial solitons in biased photorefractive–photovoltaic crystals

Lu Keqing1,Zhao Wei1,Yang Yanlong1,Sun Chuandong1,Xiang Libin1,Zhang Yanpeng2and Xu Jingjun3

1 State Key laboratory of Transient Optics Technology,Xi’an Institute of Optics and Precision Mechanics, The Chinese Academic of Sciences,Xi’an 710068,People’s Republic

2 Department of Electronic Science and Technology,Xi’an Jiaotong University,Xi’an 710049,people’s Republic of China

3 Department of physics,Nankai University,Tianjin 300071,People’s Republic of China

Abstract: We show that self-coupled and cross-coupled vector beam evolution equations in properly oriented biased photorefractive–photovoltaic crystals can exhibit bright–bright and dark–dark soliton pair solutions under steady-state conditions. When the bulk photovoltaic effect is neglectable under short-circuit conditions, these vector solitons are self-coupled and cross-coupled vector solitons for screening solitons. When the external field is absent, these vector solitons predict self-coupled and cross-coupled vector solitons for photovoltaic solitons in open- and closed-circuit photorefractive–photovoltaic crystals. The stability properties of thesevector pairs are also discussed in detail.

19. Appl.Phys.B 79,569-576(2004)

Investigation of spectral bandwidth of optical parametric amplification

Liu Hongjun,Zhao Wei,Chen Guofu,Wang Yishan,Chen Zhao,Ruan Chi

1State Key lab.of Transient Optics and Technology,Xi’an Institute of Optics and Precision Mechanics, Chinese Academic of Sciences,Xi’an China

Abstract: The spectral bandwidth of three-wave mixing optical parametric amplifications has been investigated. A general mathematical model for evaluating spectral bandwidth of optical parametric amplifications is developed with parametric bandwidth and gain bandwidth via three-wave noncollinear interactions. The spectral bandwidth is determined by expanding the wave vector mismatch in a Taylor series and retaining terms through second order. The model takes into account the effects of crystal-length, noncollinear-angle, group-velocity, group-velocity- dispersion, and gain-coefficient. The relation between parametric bandwidth and gain bandwidth is clearly defined. The model is applied to a BBO OPA, a LBO OPA and a CLBO OPA, respectively.

20. Optics Communications 239 (2004) 367–372

Characteristics of beam profile of Gaussian beam passing through an axicon

Ming Lei, Baoli Yao*

State Key Laboratory of Transient Optics Technology, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068, China

Abstract: Bessel beam can overcome the limitation of the Rayleigh range of Gaussian beam with the same spot size propagation without any spreading due to diffraction, which is considered as an useful function in guiding particles in the next generation of optical tweezers. The mathematical description of the Bessel beam generated by an axicon is usually based on the Fresnel diffraction integral theory. In this paper we deduce another type of analytic expression suitable for describing the beam profile generated from the axicon illuminated by the Gaussian beam based on the interferential theory. Compared with the Fresnel diffraction integral theory, this theory does not use much approximation in the process of mathematical analysis. According to the derived expression, the beam intensity profiles at any positions behind the axicon can be calculated not just restricted inside the cross region as the Fresnel diffraction integral theory gives. The experiments prove that the theoretical results fit the experimental results very well.

21. Optics Communications 2004

One-dimensional modulation instability of broad optical beams in biased photorefractive–photovoltaic crystals under steady-state conditions

Keqing Lu1, Wei Zhao1, Yanlong Yang1, Jinping Li1, Yanpeng Zhang2, and Jingjun Xu3

1 State Key laboratory of Transient Optics Technology,Xi’an Institute of Optics and Precision Mechanics, The Chinese Academic of Sciences,Xi’an 710068,People’s Republic

2 Department of Electronic Science and Technology,Xi’an Jiaotong University,Xi’an 710049,people’s Republic of China

3 Department of physics,Nankai University,Tianjin 300071,People’s Republic of China

Abstract: We present a comprehensive study of the one-dimensional modulation instability of broad optical beams in biased photorefractive–photovoltaic crystals under steady-state conditions. We obtain the one-dimensional modulation instability growth rate by globally treating the space-charge field and by considering distinction between values of E0 in nonlocal effects and local effects in the space-charge field, where E0 is the field constant correlated with terms in the space-charge field, which depends on the external bias field, the bulk photovoltaic effect, and the ratio of the optical beam_s intensity to that of the dark irradiance. The one-dimensional modulation instability growth rate in local effects can be determined from that in nonlocal effects. When the bulk photovoltaic effect is neglectable, irrespective of distinction between values of E0 in nonlocal effects and local effects in the space-charge field, the one-dimensional modulation instability growth rates in nonlocal effects and local effects are those of broad optical beams studied previously in biased photorefractive–nonphotovoltaic crystals. When the external bias field is absent, the one-dimensional modulation instability growth rates in nonlocal effects and local effects predict those of broad optical beams in open- and closed-circuit photorefractive–photovoltaic crystals.

22. Optics Communications 238 (2004) 363–369

Dynamic characteristics of holographic recording and ﬁxing in LiNbO3:Ce:Cu crystal

Liyong Rena , Liren Liub, De’an Liub, Baoli Yaoa

a State Key Laboratory of Transient Optics and Technology, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, 322 West Youyi Road, Xi’an 710068, PR China

b Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800, PR China

Abstract: Some dynamic diffraction characteristics of photorefractive holograms are observed in the experiment of holographic recording and ﬁxing in LiNbO3:Ce:Cu crystal. The self-enhancement and self-depletion phenomena as well as the oscillatory characteristic of diffraction during the recording step are reported. By use of our recently presented time–space dynamic theory of two-center holographic recording, the experimental results are theoretically analyzed and numerically simulated. We found that: (1) The self-enhancement in both steps of recording and ﬁxing can obviously enhance the recorded and ﬁxed hologram and thus the nonvolatile diffraction effciency. (2) There exists an optimal switching time from the recording step to the ﬁxing step for a high diffraction of ﬁxed hologram. (3) During holographic recording there is a spatially changed direction of energy transferring between the two writing beams, and the energy transferring direction will be reversed as the relative phase difference between the induced space-charge ﬁeld (SCF) and the exciting interference pattern becomes opposite in the sign.

23. Optics & Laser Technology 36 (2004) 309-314

Noncollinear optical parametric amplification in lithium triborate seeded by a cww Ti:sapphire laser

Hong-jun liu, Wei Zhao, Guo-fu Chen, Yi-shan Wang, Lian-jun Yu, Chi Ruan

1State Key lab.of Transient Optics and Technology,Xi’an Institute of Optics and Precision Mechanics, Chinese Academic of Sciences,Xi’an China

Abstract: Experimental investigations of a type-I noncollinear phase-matched optical parametric amplification based on lithium triborate, which was pumped by a 5-ns second-harmonic pulses from a Q-switched Nd:YAG, seeded by a cw Ti:sapphire laser at 800 nm, was presented. The experiments generated 2-ns signal output pulses at 800 nm, the maximum signal output pulse energy reached 19μJ, the corresponding parametric gain was 44 dB. Furthermore, the experiments demonstrate that the 65 nm-FWHM parametric fluorescence gain spectrum could also be observed. A quantitative account of the ultrabroadband parametric fluorescence gain spectrum was given with our theory. The experimental measurements are in agreement with theoretical calculations.

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