Influence of depolarized superposition of multi-beams on characteristics of focal spot

Meng Qinglong; Zhong Zheqiang; Li Zelong; Zhang Bin

In inertial confinement fusion (ICF) driver design, by varying the polarization of beamlets, a orthogonal polarization control plate (OPCP) is applied to achieve incoherent superposition of beamlets on target for improving illumination uniformity. The model for the transmittance function of OPCP was built up. The depolarizing characteristics and uniformity of focal spot of single beam and of multi-beam superposition were simulated numerically and analyzed. The effects of the element number of OPCP on the characteristics of focal spot were further discussed. The results show that, the depolarized laser beam could be achieved by using the orthogonal polarization control plate, and the light field exhibits partially polarization in time scale. The complementary combination of orthogonal PCPs is better for the superposition of depolarized multi-beams. Moreover, the depolarizing effect remains almost unchanged with the element number of OPCP. Thus, the number of elements could be fewer to reduce requirements of processing technology.

1. College of Electronics and Information Engineering,Sichuan University,Chengdu 610065,China

Received Date: 2013-11-25

Rev Recd Date: 2014-01-17

Publish Date: 2015-01-25

Key words:

Abstract: In inertial confinement fusion (ICF) driver design, by varying the polarization of beamlets, a orthogonal polarization control plate (OPCP) is applied to achieve incoherent superposition of beamlets on target for improving illumination uniformity. The model for the transmittance function of OPCP was built up. The depolarizing characteristics and uniformity of focal spot of single beam and of multi-beam superposition were simulated numerically and analyzed. The effects of the element number of OPCP on the characteristics of focal spot were further discussed. The results show that, the depolarized laser beam could be achieved by using the orthogonal polarization control plate, and the light field exhibits partially polarization in time scale. The complementary combination of orthogonal PCPs is better for the superposition of depolarized multi-beams. Moreover, the depolarizing effect remains almost unchanged with the element number of OPCP. Thus, the number of elements could be fewer to reduce requirements of processing technology.

HTML

Reference (31)

[1]	Lindl J D, Amendt P, Berger R L, et al. The physics basis for ignition using indirect-drive targets on the national ignition facility[J]. Phys Plasmas, 2004, 11(2): 339-479.
[2]
[3]
[4]	Glenzer S H, MacGowan B J, Michel P, et al. Symmetric inertial confinement fusion implosions at ultra-high laser energies[J]. Science, 2010, 327: 1228-1231.
[5]	Kruer W L, Wilks S C, Afeyan B B, et al. Energy transfer between crossing laser beams[J]. Phys Plasmas, 1996, 3(1): 382-385.
[6]
[7]	Kirkwood R K, Afeyan B B, Kruer W L, et al. Laser plasmas interactions in ignition-scale hohlraum plasmas [J]. Phys Plasmas, 1996, 3(5): 2029-2040.
[8]
[9]
[10]	Kruer W L. The Physics of Laser Plasmas Interactions [M]. US: Addison-Wesley Publishing Company, Inc, 1988.
[11]
[12]	Kruer W L, Wilks S C, Afeyan B B, et al. Energy transfer between crossing laser beams[J]. Phys Plasmas, 1996, 3(1): 382-385.
[13]	Skupsky S, Short R W, Kessler T, et al. Improved laser-beam uniformity using the angular dispersion of frequency-modulated light[J]. J Appl Phys, 1989, 66(8): 3456-3462.
[14]
[15]	Lawrence G N, Lin Y, Kessler T J. Distributed phase plates for supper-Gaussian focal-plane irradiance profiles [J]. Opt Lett, 1995, 20(7): 764-766.
[16]
[17]
[18]	Nauport J, Ribeyre X, Daurios J, et al. Design and optical characteristic of a large continuous phase plate for laser integration line and laser Megajoule facilities [J]. Applied Optics, 2003, 42(13): 2377-2382.
[19]
[20]	Tsubakimoto K, Nakatsuka M, Nakano H, et al. Suppression of interference speckles produced by a random phase plate, using a polarization control plate [J]. Opt Commun, 1992, 91: 9-12.
[21]
[22]	Michel P, Divol L, Williams E A, et al. Energy transfer between laser beams crossing in ignition [J]. Phys Plasmas, 2008, 3(1): 382-386.
[23]
[24]	Xiao Jun, LBaida. Characteristics of polarization control plate smoothing interference speckles [J]. Chinese J Laser, 2000, 27(7): 627-632. (in Chinese) 肖峻, 吕百达. 偏振控制板对干涉斑纹的匀滑特性[J]. 中国激光, 2000, 27(7): 627-632.
[25]
[26]	Zhongyong Liu, Yu Zhao, Dianyuan Fan. Improvement of the illumination uniformity in ICF using a random polarization control plate[J]. Optics Commun, 1998, 152(1): 1-5.
[27]
[28]	Smith D R, Pendry J B, Wiltshire C K. Metamaterials and negative refractive index[J]. Science, 2004, 305: 788-792.
[29]
[30]	廖延彪. 偏振光学[M]. 北京: 科学出版社, 2003: 51-55.
[31]	数学手册编写组. 数学手册[M]. 北京: 高等教育出版社, 1979: 788-789.

Influence of depolarized superposition of multi-beams on characteristics of focal spot

Abstract

References

Proportional views

通讯作者: 陈斌, bchen63@163.com

Article Metrics

Related

Proportional views