[1] Nye J F, Berry M V. Dislocations in wave trains[C]. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 1974, 336: 165-190.
[2] Basistiy I V, Soskin M S, Vasnetsov M V. Optical wavefront dislocations and their properties[J]. Optics Communications, 1995, 119(5-6): 604-612.
[3] Coullet P, Gil L, Rocca F. Optical vortices[J]. Optics Communications, 1989, 73(5): 403-408.
[4] Allen L, Beijersbergen M W, Spreeuw R J C, et al. Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser modes[J]. Physical Review A, 1992, 45(11): 8185-8189.
[5] Padgett M, Courtial J, Allen L. Light′s orbital angular momentum[J]. Physics Today, 2004, 57(5): 35-40.
[6] Bernet S, Jesacher A, Furhapter S, et al. Quantitative imaging of complex samples by spiral phase contrast microscopy[J]. Optics Express, 2006, 14(9): 3792-3805.
[7] Padgett M, Bowman R. Tweezers with a twist[J]. Nature Photonics, 2011, 5(6): 343-348.
[10] Guo Jianjun, Guo Banghong, Cheng Guangming, et al. Research progress on photon orbital angular momentum in quantum communication applications[J]. Laser & Optoelectronics Progress, 2012, 49(8): 080003.
[11] Dai Maochun, Fan Daihe, Wang Yao, et al. Generation of high quality helical beams based on spatial light modulator[J]. Chinese J Lasers, 2016, 43(9): 0905004.
[12] Wang Zheng, Xin Jingtao, Wu Zhiqiang. Accurate measurement of photon orbital angular momentum carried by helical beams through spatial light modulator[J]. Laser & Optoelectronics Progress, 2015, 52(8): 080902.
[13] Beijersbergen M W, Coerwinkel R P C, Kristensen M, et al. Helical-wavefront laser beams produced with a spiral phaseplate[J]. Optics Communications, 1994, 112(5-6): 321-327.
[14] Bazhenov V Y, Soskin M S, Vasnetsov M V. Screw dislocations in light wavefronts[J]. Journal of Modern Optics, 1992, 39(5): 985-990.
[15] Ke Xizheng, Xu Junyu. Interference and detection of vortex beams with orbital angular mmentum[J]. Chinese J Lasers, 2016, 43(9): 0905003.
[17] Dholakia K, Simpson N B, Padgett M J, et al. Second-harmonic generation and the orbital angular momentum of light[J]. Physical Review A, 1996, 54(5): R3742- R3745.
[18] Shao G, Wu Z, Chen J, et al. Nonlinear frequency conversion of fields with orbital angular momentum using quasi-phase-matching[J]. Physical Review A, 2013, 88(6): 063827.
[19] Li S M, Kong L J, Ren Z C, et al. Managing orbital angular momentum in second-harmonic generation[J]. Physical Review A, 2013, 88(3): 035801.
[20] Zhou Z Y, Ding D S, Jiang Y K, et al. Orbital angular momentum light frequency conversion and interference with quasi-phase matching crystals[J]. Optics Express, 2014, 22(17): 20298-20310.
[21] Zhou Z Y, Li Y, Ding D S, et al. Highly efficient second harmonic generation of a light carrying orbital angular momentum in an external cavity[J]. Optics Express, 2014, 22(19): 23673-23678.
[22] Courtial J, Dholakia K, Allen L, et al. Second-harmonic generation and the conservation of orbital angular momentum with high-order Laguerre-Gaussian modes[J]. Physical Review A, 1997, 56(5): 4193-4196.
[23] Li Y, Zhou Z Y, Ding D S, et al. Sum frequency generation with two orbital angular momentum carrying laser beams[J]. Journal of the Optical Society of America B, 2015, 32(3): 407-411.
[24] Galvez E J, Smiley N, Fernandes N. Composite optical vortices formed by collinear Laguerre-Gauss beams[C]. SPIE, 2006, 6131: 613105.
[25] Ando T, Matsumoto N, Ohtake Y, et al. Structure of optical singularities in coaxial superpositions of Laguerre-Gaussian modes[J]. Journal of the Optical Society of America A, 2010, 27(12): 2602-2612.
[26] Indebetouw G. Optical vortices and their propagation[J]. Journal of Modern Optics, 1993, 40(1): 73-87.
[27] Beijersbergen M W, Allen L, Van der Veen H, et al. Astigmatic laser mode converters and transfer of orbital angular momentum[J]. Optics Communications, 1993, 96(1-3): 123-132.
[28] Zhou J, Zhang W, Chen L. Experimental detection of high-order or fractional orbital angular momentum of light based on a robust mode converter[J]. Applied Physics Letters, 2016, 108(11): 111108.