[1] [1] Gawith C B E, Shepherd D P, Abernethy J A, et al. Second-harmonic generation in a direct-bonded periodically poled LiNbO3 buried waveguide[J]. Opt Lett, 1999, 24(7): 481-483.

[2] [2] Miller G D, Batchko R G, Tulloch W M, et al. 42%-effective single-pass cw second-harmonic generation in periodically poled lithium niobate[J]. Opt Lett, 1997, 22(24): 1834-1836.

[3] [3] Pruneri V, Koch R, Kazansky P G, et al. 49 mW of cw blue light generated by first-order quasi-phase-matched frequency doubling of a diode-pumped 946-nm NdYAG laser[J]. Opt Lett, 1995, 20(23): 2375-2377.

[4] [4] Myers L E, Eckardt R C, Fejer M M, et al. Quasi-phase-matched optical parametric oscillation in bulk periodically poled LiNbO3[J]. J Opt Soc Am B, 1995, 12(11): 2101-2116.

[5] [5] Yang S T, Velsko S P. Frequency-agile kilohertz repetition optical parametric oscillator based on periodically poled lithium niobate[J]. Opt Lett, 1999, 24(3): 133-135.

[6] [6] Li Weifan, Guo Baoshan, Shi Wei. Progress of terahertz parametric oscillator[J]. Laser & Optoelectronics Progress, 2014, 51(9): 090005.

[7] [7] Franken P A, Hill A E, Peters C W, et al. Generation of optical harmonics[J]. Phys Rev Lett, 1961, 7(4): 118-120.

[8] [8] Shi Shunxiang, Chen Guofu, Zhao Wei. Nonlinear optics[M]. Xi′an: Xidian University Press, 2003: 177.

[9] [9] Armstrong J A, Bloembergen N, Ducuing J, et al. Interactions between light waves in a nonlinear dielectric[J]. Phys Rev, 1962, 127(6): 1918-1939.

[10] [10] Bloembergen N, Pershan P S. Light waves at the boundary of nonlinear media[J]. Phy Rev, 1962, 128(2): 606-622.

[11] [11] Lifshita R, Arie A, Bahabad A. Photonic quasicrystals for nonlinear optical frequency conversion[J]. Phys Rev Lett, 2005, 95(13): 133901.

[12] [12] Gu B Y, Dong B Z, Zhang Y, et al. Enhanced harmonic generation in aperiodic optical superlattices[J]. Appl Phys Lett, 1999, 75(15): 2175-2177.

[13] [13] Arbore M A, Marco O, Fejer M M. Pulse compression during second-harmonic generation in aperiodic quasi-phase-matching gratings[J]. Opt Lett, 1997, 22(12): 865-867.

[14] [14] Chen X F, Wu F, Zeng X L, et al. Multiple quasi-phase-matching in a nonperiodic domain-inverted optical superlattice[J]. Phys Rev A, 2004, 69(1): 013818.

[15] [15] Li Hong, Feng Jinxia, Wan Zhenju, et al. Low noise continuous-wave single frequency 780 nm laser high-efficiently generated by extra-cavity-enhanced frequency doubling[J]. Chinese J Lasers, 2014, 41(5): 0502003.

[16] [16] Li Keyu, Feng Bin, Wang Fang, et al. Harmonic conversion rule for Gauss pulse with nonideal conditions[J]. Acta Optica Sinica, 2014, 34(8): 0819001.

[17] [17] Zhu S N, Zhu Y Y, Ming N B. Quasi-phase-matched third-harmonic generation in a quasi-periodic optical superlattice[J]. Science, 1997, 278(5339): 843-846.

[18] [18] Zhu S N, Zhu Y Y, Qin Y Q, et al. Experimental realization of second harmonic generation in a Fibonacci optical superlattice of LiTaO3[J]. Phys Rev Lett, 1997, 78(14): 2752-2755.

[19] [19] Zhao L M, Yue G K, Zhou Y S, et al. A promising nonlinear conjugate-gradient method proposed to design nonlinear domains with a disordered distribution[J]. Mod Phy Lett B, 2015, 29(9): 1550030.

[20] [20] Hestenes M R, Stiefel E. Methods of conjugate gradients for solving linear systems[J]. J Res Nat Bur Standards, 1952, 49(6): 409-436.

[21] [21] Fletcher R, Reeves C. Function minimization by conjugate gradients[J]. Computer J, 1964, 7(2): 149-154.

[22] [22] Chen Yunlin, Guo Juan, Liu Xiaojuan, et al. Continuous-wave quasi-phase-matched second harmonic generation at 490 nm in periodically poled MgOLiNbO3[J]. Acta Photonica Sinica, 2005, 34(1): 29-31.

[23] [23] Zhang Yuantao, Qu Qiuzhi, Qian Jun, et al. Thermal effect analysis of 1560 nm laser frequency doubling in a PPLN crystal[J]. Chinese J Lasers, 2015, 42(7): 0708002.

[24] [24] Dmitriev G, Gurazdyan G G, Nikogosyan D N. Handbook of nonlinear optical crystals[M]. Berlin: Springer-Verlag Berlin Heidelberg, 1999.

[25] [25] Zhao L M, Yue G K, Zhou Y S, et al. Effect of pump depletion on second harmonic generation in multiple quasi-phase-matching gratings[J]. Opt Express, 2013, 21(15): 17592-17601.