掺杂碳纳米管的向列相液晶中的空间光孤子的研究
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摘要
对于空间光孤子的研究,向列相液晶是比较理想的材料,但在研究中发现纯液晶在观测空间光孤子时也存在着不足,为了弥补纯液晶的缺点,科研工作者发现在液晶中掺入其他的材料会改善液晶的不足。碳纳米管是由石墨烯片卷成的具有螺旋周期的管状结构,在其管壁周围仍然有大量的未成对电子游动,因而碳纳米管具有光学活性。由于其较好的光学及电学性质,本文将从理论与实验两个方面分析讨论掺入碳纳米管的液晶中空间光孤子。
理论上,分析了掺入碳纳米管的向列相液晶中重新取向角的影响因素,对向列相液晶中的光波演化方程进行了适当的简化和修正,推导出了掺杂碳纳米管的液晶中的空间光孤子的演化方程并给出了亮、暗空间光孤子的解和孤子宽度的表达式;另外,根据上述的方程模拟了不同参数时孤子的横截面光强分布。
实验中,配制了不同浓度碳纳米管掺杂的液晶样品,制备了不同厚度的平行取向的液晶盒,搭建了观测空间光孤子的实验光路,使用532 nm的DPSS激光器作为光源观测了空间光孤子的形成过程以及变化不同因素时对空间光孤子的影响,使用CCD拍摄了全部的实验结果,并将实验中观测的空间光孤子与纯液晶中的空间光孤子进行了对比。
最后,详细地分析了液晶盒的厚度、入射光的功率、碳纳米管的掺杂浓度、外加电压以及入射光的偏振方向对空间光孤子的影响,对掺杂碳纳米管的向列相液晶中空间光孤子的性质进行了分析和总结。
For spatial optical solitons research, nematic liquid crystal is the ideal material. It has been found that pure liquid crystal also exist shortcomings when observe the spatial optical solitons, in order to improve the pure liquid crystal, researchers found that the shortcomings would be eliminated when other materials was incorporated in the pure liquid crystals. The CNT(carbon nanotube)is a tubular structure with spiralization cycle, which is twisted from graphene sheet. There are a large number of unpaired electrons moving about around the tube wall. The carbon nanotube has both the conductivity of metal and the properties of semiconductor. There are helical angles in the CNT, which will be positive or negative, so the CNT has optical activity. In consideration of the good optical and electrical properties of the CNT, this paper will analyze and discuss the spatial optical solitons in the liquid crystal incorporating the CNT in both theory and experiment.
In theory, we analyzed the factors influencing the reorientation angle of the nematic liquid crystals incorporating the CNT, so as to get the concrete expression of the angle since the molecular reorientation. Then according to the proper simplification and correction of the light wave evolution equation in the nematic liquid crystal, the equation of the spatial optical solitons in the liquid crystal incorporating the carbon nanotubes is deduced and the solution of the bright、dark solitons are gave, the width of the spatial optical solitons is computed. In addition, the light distribution of the optical soliton cross-section when parameters are different can be simulated according to above equations.
In our experiments, we have prepared different concentrations of liquid crystal samples incorporating the CNT, as well as different thicknesses of liquid crystal cell (planar). We structured the optical path of the experiments, with the DPSS laser (532nm) as light source observe the forming process of spatial optical solitons and its variation when changing different factors, using CCD took all of the results of the experiment and comparing the spatial optical solitons of the experiments to the spatial optical solitons of the pure liquid crystal.
Finally, for the influencing factors of the spatial optical solitons, we analyzed and compared from the thickness of liquid crystal cell, the power of incident light, the dosage concentration of carbon nanotubes, the applied voltage and the polarization orientation of incident light. We made detail analysis and conclusion to the properties of the spatial optical solitons in carbon nanotubes doped nematic liquid crystal.
理论上,分析了掺入碳纳米管的向列相液晶中重新取向角的影响因素,对向列相液晶中的光波演化方程进行了适当的简化和修正,推导出了掺杂碳纳米管的液晶中的空间光孤子的演化方程并给出了亮、暗空间光孤子的解和孤子宽度的表达式;另外,根据上述的方程模拟了不同参数时孤子的横截面光强分布。
实验中,配制了不同浓度碳纳米管掺杂的液晶样品,制备了不同厚度的平行取向的液晶盒,搭建了观测空间光孤子的实验光路,使用532 nm的DPSS激光器作为光源观测了空间光孤子的形成过程以及变化不同因素时对空间光孤子的影响,使用CCD拍摄了全部的实验结果,并将实验中观测的空间光孤子与纯液晶中的空间光孤子进行了对比。
最后,详细地分析了液晶盒的厚度、入射光的功率、碳纳米管的掺杂浓度、外加电压以及入射光的偏振方向对空间光孤子的影响,对掺杂碳纳米管的向列相液晶中空间光孤子的性质进行了分析和总结。
For spatial optical solitons research, nematic liquid crystal is the ideal material. It has been found that pure liquid crystal also exist shortcomings when observe the spatial optical solitons, in order to improve the pure liquid crystal, researchers found that the shortcomings would be eliminated when other materials was incorporated in the pure liquid crystals. The CNT(carbon nanotube)is a tubular structure with spiralization cycle, which is twisted from graphene sheet. There are a large number of unpaired electrons moving about around the tube wall. The carbon nanotube has both the conductivity of metal and the properties of semiconductor. There are helical angles in the CNT, which will be positive or negative, so the CNT has optical activity. In consideration of the good optical and electrical properties of the CNT, this paper will analyze and discuss the spatial optical solitons in the liquid crystal incorporating the CNT in both theory and experiment.
In theory, we analyzed the factors influencing the reorientation angle of the nematic liquid crystals incorporating the CNT, so as to get the concrete expression of the angle since the molecular reorientation. Then according to the proper simplification and correction of the light wave evolution equation in the nematic liquid crystal, the equation of the spatial optical solitons in the liquid crystal incorporating the carbon nanotubes is deduced and the solution of the bright、dark solitons are gave, the width of the spatial optical solitons is computed. In addition, the light distribution of the optical soliton cross-section when parameters are different can be simulated according to above equations.
In our experiments, we have prepared different concentrations of liquid crystal samples incorporating the CNT, as well as different thicknesses of liquid crystal cell (planar). We structured the optical path of the experiments, with the DPSS laser (532nm) as light source observe the forming process of spatial optical solitons and its variation when changing different factors, using CCD took all of the results of the experiment and comparing the spatial optical solitons of the experiments to the spatial optical solitons of the pure liquid crystal.
Finally, for the influencing factors of the spatial optical solitons, we analyzed and compared from the thickness of liquid crystal cell, the power of incident light, the dosage concentration of carbon nanotubes, the applied voltage and the polarization orientation of incident light. We made detail analysis and conclusion to the properties of the spatial optical solitons in carbon nanotubes doped nematic liquid crystal.
引文
[1] Shen Y R. Soliton Made Simple[J]. Science. 1997, 276(6): 1520~1520.
[2]侯春风,李师群,李斌,等.有外加电场的光伏光折变晶体中的非相干耦合亮-暗屏蔽光伏孤子对[J].物理学报. 2001, 50(9): 1709~1711.
[3]谷超豪.孤立子理论与应用[M].浙江:浙江科学技术出版社,1990:1~5.
[4] Zabusky N J, Kruskal M D. Interaction of“Solitons”in a Collisionless Plasma and the Recurrence of Initial States[J]. Phys. Rev. Lett. 1965, 15(6): 240~243.
[5]张冰志,崔虎,佘卫龙.光折变空间孤子研究进展[J].光学前沿专题. 2008, 37(3): 152~161.
[6] Ducharme S, Scott J C, Twieg R J, et al. Observation of the Photorefractive Effect in a Polymer[J]. Phys. Rev. Lett. 1991, 66(14): 1846~1849.
[7]万长虹,王天科.液晶及其显示器原理分析[J].微处理机. 2005, (1): 61~64.
[8]沈曼,郭丽丽,刘建军.液晶的研究进展[J].河北师范大学学报(自然科学版). 2005, 29(2): 154~157.
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[10]张勇,朱海哲.碳纳米管[J].炭素技术. 1995, (6): 21~26.
[11]王敏炜,李凤仪,彭年才.碳纳米管——新型的催化剂载体[J].新型炭材料. 2002, 17(3): 75~78.
[12] Assanto G, Peccianti M, Rossi A D. Spatial Solitons in Voltage-Biased Nematic Liquid Crystals[J]. IEEE. 2000: 195~196.
[13] Peccianti M, Brzdakiewicz K A, Assanto G. Nonlocal Spatial Soliton Interactions in Nematic Liquid Crystals[J]. Optics Letters. 2002, 27(16): 1460~1462.
[14] Karpierz M A, Brzdakiewicz K A, Nguyen Q V. Modeling of Spatial Solitons in Twisted Nematics Waveguides[J]. Acta Physica Polonicaa. 2003, 103(2-3): 169~175.
[15] Beeckman J, Neyts K. Simulations and Experiments on Self-focusing Conditions in Nematic Liquid-Crystal Planar Cells[J]. Optics Express. 2004, 12(6): 1011~1018.
[16] Karpierz M A, Assanto G, Brzdakiewicz K A, et al. Discrete Solitons in Nematic Liquid Crystals[J]. IEEE. 2004: 167~170.
[17] Makris K G, Sarkissian H, Christodoulides D N. Nonlocal Incoherent Spatial Solitons in Liquid Crystals[J]. J. Opt. Soc. Am. B. 2005, 22(7): 1371~1377.
[18] Alberucci A, Peccianti M, Assanto G, et al. Self-healing Generation of Spatial Solitons in Liquid Crystals[J]. Optics Letters. 2005, 30(11): 1381~1383.
[19] Henninot J F, Blach J F, Warenghem M. Experimental Study of the Nonlocality of Spatial Optical Solitons Excited in Nematic Liquid Crystal[J]. J. Opt. A: Pure Appl. Opt. 2006, 9: 20~25.
[20] Beeckman J, Neyts K, Haelterman M. Patterned Electrode Steering of Nematicons[J]. J. Opt. A: Pure Appl. Opt. 2006, 8: 214~220.
[21] Hu Wei, Zhang Tao, Guo Qi. Nonlocality-controlled Interaction of Spatial Solitons in Nematic Liquid Crystals[J]. Applied Physics Letters. 2006, 89 (071111): 071111-1~071111-3.
[22] Lucaa A D, Veltri A, Pezzi L, et al. Assanto. Nematic Liquid Crystal Cells for Optical Spatial Solitons (Nematicons)[J]. Proc. of SPIE. 2007, 6487: 64870R-1~64870R-8.
[23] Peccianti M, Assanto G. Nematicons across Interfaces: Anomalous Refraction and Reflection of Solitons in Liquid Crystals[J]. Optics Express. 2007, 15(13): 8021~8028.
[24] Henninot J F, Blach J F, Warenghem M. The Investigation of an Electrically Stabilized Optical Spatial Soliton Induced in a Nematic Liquid Crystal[J]. J. Opt. A: Pure Appl. Opt. 2008, 10: 1~7.
[25] Piccardi A, Peccianti M, Assanto G. Non-linear Control of Soliton Spiraling in Nematic Liquid Crystals[J]. IEEE. 2008: 117~118.
[26] Alberucci A, Assanto G, Buccoliero D, et al.Modulation Analysis of Boundary-induced Motion of Optical Solitary Waves in a Nematic Liquid Crystal[J]. Physical Review A. 2009, 79(4): 043816-1~043816-8.
[27] Zhong Weiping, Yang Zhengping, Xie Ruihua, et al. Two-Dimensional Spatial Solitons in Nematic Liquid Crystals[J]. Commun. Theor. Phys. (Beijing, China). 2009, 51(2): 324~330.
[28] Beeckman J, Neyts K, Vanbrabant P J M, et al. Finding Exact Spatial Soliton Profiles in Nematic Liquid Crystals[J]. Optics Express. 2010, 18(4): 3311~3321.
[29] Izdebskaya Y V, Shvedov V G, Desyatnikov A S, et al. Soliton bending and routing induced by interaction with curved surfaces in nematic liquid crystals[J]. Optics Letters. 2010, 35(10): 1692~1694.
[30] Henninot J F, Blach J F, Warenghem M. Enhancement of Dye Fuorescence Recovery in Nematic Liquid Crystals Using a Spatial Optical Soliton[J]. J. Appl. Phys. 2010, 107(11): 113111-1~113111-6.
[31] Derrien F, Henninot J F, Warenghem M, et al. A Thermal (2D+1) Spatial Optical Soliton in a Dye Doped Liquid Crystal[J]. J. Opt. A: Pure Appl. Opt. 2000, 2: 332~337.
[32] Henninot J F, Debailleul M, Derrien F, et al. In Situ Intensity Profile Measurements of Spatial Quasi-solitons in Thick Dye-doped Liquid Crystal Samples[J]. J. Opt. A: Pure Appl. Opt. 2003, 5: 250~255.
[33] Hutsebaut X, Cambournac C, Haelterman M, et al. Single-component Higher-order Mode Solitons in Liquid Crystals[J]. Optics Communications. 2004, 233: 211–217.
[34] Henninot J F, Debailleul M, Asquini R, et al. Self-waveguiding in an Isotropic Channel Induced in Dye Doped Nematic Liquid Crystal and a Bent Self-waveguide[J]. J. Opt. A: Pure Appl. Opt. 2004, 6: 315~323.
[35]郝利丽.掺杂甲基红的向列相液晶中空间孤子及其诱导波导的研究[D].哈尔滨:哈尔滨工业大学光学学科硕士学位论文,2007:1~50.
[36] Piccardi A, Assanto G, Lucchetti L, et al. All-optical Steering of Soliton Waveguides in Dye-doped Liquid Crystals[J]. Applied Physics Letters. 2008, 93(17): 171104-1~171104-3.
[37] Laudyn U A, Kwasny M, Jaworowicz K, et al. Self-focusing and Nematicons in Chiral Nematic Liquid Crystals[J]. Proc. of SPIE Vol. 2008, 7141: 71410F-1~71410F-5.
[38]孙祥宇.掺杂C60的向列相液晶中空间光孤子的研究[D].哈尔滨:哈尔滨工业大学光学学科硕士学位论文,2009:1~45.
[39] Assanto G, Peccianti M. Spatial Solitons in Nematic Liquid Crystal. IEEE Journal Of Quantum Electronics[J]. 2003, 39(1): 13~21.
[40] Chen Huiyu, Lee Wei. Effects of Single-walled and Multi-walled Carbon Nanotubes on the Transient Current in Doped Nematic Cells in a Polarity-reversed Field. Liquid Crystals: Optics and Applications[J]. 2005, 59470T-1~ 59470T-8.
[41]王玉芳,蓝国祥.碳纳米管的结构、对称性及晶格动力学[J].光散射学报. 1999, 11(1): 36~45.
[42]展凯云,裴延波,侯春风.向列相液晶中空间光孤子的观测[J].物理学报,2006,55(9):4686~4690.
[2]侯春风,李师群,李斌,等.有外加电场的光伏光折变晶体中的非相干耦合亮-暗屏蔽光伏孤子对[J].物理学报. 2001, 50(9): 1709~1711.
[3]谷超豪.孤立子理论与应用[M].浙江:浙江科学技术出版社,1990:1~5.
[4] Zabusky N J, Kruskal M D. Interaction of“Solitons”in a Collisionless Plasma and the Recurrence of Initial States[J]. Phys. Rev. Lett. 1965, 15(6): 240~243.
[5]张冰志,崔虎,佘卫龙.光折变空间孤子研究进展[J].光学前沿专题. 2008, 37(3): 152~161.
[6] Ducharme S, Scott J C, Twieg R J, et al. Observation of the Photorefractive Effect in a Polymer[J]. Phys. Rev. Lett. 1991, 66(14): 1846~1849.
[7]万长虹,王天科.液晶及其显示器原理分析[J].微处理机. 2005, (1): 61~64.
[8]沈曼,郭丽丽,刘建军.液晶的研究进展[J].河北师范大学学报(自然科学版). 2005, 29(2): 154~157.
[9]孙康宁,李爱民.碳纳米管符合材料[M].北京:机械工业出版社,2010:1~20.
[10]张勇,朱海哲.碳纳米管[J].炭素技术. 1995, (6): 21~26.
[11]王敏炜,李凤仪,彭年才.碳纳米管——新型的催化剂载体[J].新型炭材料. 2002, 17(3): 75~78.
[12] Assanto G, Peccianti M, Rossi A D. Spatial Solitons in Voltage-Biased Nematic Liquid Crystals[J]. IEEE. 2000: 195~196.
[13] Peccianti M, Brzdakiewicz K A, Assanto G. Nonlocal Spatial Soliton Interactions in Nematic Liquid Crystals[J]. Optics Letters. 2002, 27(16): 1460~1462.
[14] Karpierz M A, Brzdakiewicz K A, Nguyen Q V. Modeling of Spatial Solitons in Twisted Nematics Waveguides[J]. Acta Physica Polonicaa. 2003, 103(2-3): 169~175.
[15] Beeckman J, Neyts K. Simulations and Experiments on Self-focusing Conditions in Nematic Liquid-Crystal Planar Cells[J]. Optics Express. 2004, 12(6): 1011~1018.
[16] Karpierz M A, Assanto G, Brzdakiewicz K A, et al. Discrete Solitons in Nematic Liquid Crystals[J]. IEEE. 2004: 167~170.
[17] Makris K G, Sarkissian H, Christodoulides D N. Nonlocal Incoherent Spatial Solitons in Liquid Crystals[J]. J. Opt. Soc. Am. B. 2005, 22(7): 1371~1377.
[18] Alberucci A, Peccianti M, Assanto G, et al. Self-healing Generation of Spatial Solitons in Liquid Crystals[J]. Optics Letters. 2005, 30(11): 1381~1383.
[19] Henninot J F, Blach J F, Warenghem M. Experimental Study of the Nonlocality of Spatial Optical Solitons Excited in Nematic Liquid Crystal[J]. J. Opt. A: Pure Appl. Opt. 2006, 9: 20~25.
[20] Beeckman J, Neyts K, Haelterman M. Patterned Electrode Steering of Nematicons[J]. J. Opt. A: Pure Appl. Opt. 2006, 8: 214~220.
[21] Hu Wei, Zhang Tao, Guo Qi. Nonlocality-controlled Interaction of Spatial Solitons in Nematic Liquid Crystals[J]. Applied Physics Letters. 2006, 89 (071111): 071111-1~071111-3.
[22] Lucaa A D, Veltri A, Pezzi L, et al. Assanto. Nematic Liquid Crystal Cells for Optical Spatial Solitons (Nematicons)[J]. Proc. of SPIE. 2007, 6487: 64870R-1~64870R-8.
[23] Peccianti M, Assanto G. Nematicons across Interfaces: Anomalous Refraction and Reflection of Solitons in Liquid Crystals[J]. Optics Express. 2007, 15(13): 8021~8028.
[24] Henninot J F, Blach J F, Warenghem M. The Investigation of an Electrically Stabilized Optical Spatial Soliton Induced in a Nematic Liquid Crystal[J]. J. Opt. A: Pure Appl. Opt. 2008, 10: 1~7.
[25] Piccardi A, Peccianti M, Assanto G. Non-linear Control of Soliton Spiraling in Nematic Liquid Crystals[J]. IEEE. 2008: 117~118.
[26] Alberucci A, Assanto G, Buccoliero D, et al.Modulation Analysis of Boundary-induced Motion of Optical Solitary Waves in a Nematic Liquid Crystal[J]. Physical Review A. 2009, 79(4): 043816-1~043816-8.
[27] Zhong Weiping, Yang Zhengping, Xie Ruihua, et al. Two-Dimensional Spatial Solitons in Nematic Liquid Crystals[J]. Commun. Theor. Phys. (Beijing, China). 2009, 51(2): 324~330.
[28] Beeckman J, Neyts K, Vanbrabant P J M, et al. Finding Exact Spatial Soliton Profiles in Nematic Liquid Crystals[J]. Optics Express. 2010, 18(4): 3311~3321.
[29] Izdebskaya Y V, Shvedov V G, Desyatnikov A S, et al. Soliton bending and routing induced by interaction with curved surfaces in nematic liquid crystals[J]. Optics Letters. 2010, 35(10): 1692~1694.
[30] Henninot J F, Blach J F, Warenghem M. Enhancement of Dye Fuorescence Recovery in Nematic Liquid Crystals Using a Spatial Optical Soliton[J]. J. Appl. Phys. 2010, 107(11): 113111-1~113111-6.
[31] Derrien F, Henninot J F, Warenghem M, et al. A Thermal (2D+1) Spatial Optical Soliton in a Dye Doped Liquid Crystal[J]. J. Opt. A: Pure Appl. Opt. 2000, 2: 332~337.
[32] Henninot J F, Debailleul M, Derrien F, et al. In Situ Intensity Profile Measurements of Spatial Quasi-solitons in Thick Dye-doped Liquid Crystal Samples[J]. J. Opt. A: Pure Appl. Opt. 2003, 5: 250~255.
[33] Hutsebaut X, Cambournac C, Haelterman M, et al. Single-component Higher-order Mode Solitons in Liquid Crystals[J]. Optics Communications. 2004, 233: 211–217.
[34] Henninot J F, Debailleul M, Asquini R, et al. Self-waveguiding in an Isotropic Channel Induced in Dye Doped Nematic Liquid Crystal and a Bent Self-waveguide[J]. J. Opt. A: Pure Appl. Opt. 2004, 6: 315~323.
[35]郝利丽.掺杂甲基红的向列相液晶中空间孤子及其诱导波导的研究[D].哈尔滨:哈尔滨工业大学光学学科硕士学位论文,2007:1~50.
[36] Piccardi A, Assanto G, Lucchetti L, et al. All-optical Steering of Soliton Waveguides in Dye-doped Liquid Crystals[J]. Applied Physics Letters. 2008, 93(17): 171104-1~171104-3.
[37] Laudyn U A, Kwasny M, Jaworowicz K, et al. Self-focusing and Nematicons in Chiral Nematic Liquid Crystals[J]. Proc. of SPIE Vol. 2008, 7141: 71410F-1~71410F-5.
[38]孙祥宇.掺杂C60的向列相液晶中空间光孤子的研究[D].哈尔滨:哈尔滨工业大学光学学科硕士学位论文,2009:1~45.
[39] Assanto G, Peccianti M. Spatial Solitons in Nematic Liquid Crystal. IEEE Journal Of Quantum Electronics[J]. 2003, 39(1): 13~21.
[40] Chen Huiyu, Lee Wei. Effects of Single-walled and Multi-walled Carbon Nanotubes on the Transient Current in Doped Nematic Cells in a Polarity-reversed Field. Liquid Crystals: Optics and Applications[J]. 2005, 59470T-1~ 59470T-8.
[41]王玉芳,蓝国祥.碳纳米管的结构、对称性及晶格动力学[J].光散射学报. 1999, 11(1): 36~45.
[42]展凯云,裴延波,侯春风.向列相液晶中空间光孤子的观测[J].物理学报,2006,55(9):4686~4690.