[1] [1] MEHMET M, EBERLE T, STEINLECHNER S, et al. Demonstration of a quantum-enhanced fiber Sagnac interferometer［J］. Optics Le-tters, 2010, 35(10):1665-1667.

[2] [2] MEHMET M, VAHLBRUCH H, LASTZKA N, et al. Observation of squeezed states with strong photon-number oscillations［J］. Physical Review, 2010, A81(1): 013814.

[3] [3] EBERLE T, STEINLECHNER S, BAUCHROWITZ J, et al. Quantum enhancement of the zero-area Sagnac interferometer topology for gravitational wave detection［J］. Physical Review Letters, 2010, 104(25): 251102.

[4] [4] VAHLBRUCH H, MEHMET M, DANZMANN K, et al. Detection of 15dB squeezed states of light and their application for the absolute ca-libration of photoelectric quantum efficiency［J］. Physical Review Letters, 2016, 117(11): 11081.

[5] [5] HOFF U B, HARRIS G I, MADSEN L S, et al. Quantum-enhanced micromechanical displacement sensitivity［J］. Optics Letters, 2013, 38(9):1413-1415.

[6] [6] POOSER R C, LAWRIE B. Ultrasensitive measurement of microcantilever displacement below the shot-noise limit［J］. Optica, 2015, 2(5): 393-399.

[7] [7] KIMBLE H J. The quantum internet［J］. Nature, 2008, 453: 1023-1030.

[8] [8] POLZIK E S, CARRI J, KIMBLE H J. Spectroscopy with squeezed light［J］. Physical Review Letters, 1992, 68(20): 3020-3023.

[9] [9] TURCHETTE Q A, GEORGIADES N P, HOOD C J, et al. Squeezed excitation in cavity QED: Experiment and theory［J］. Phy-sical Review, 1998, A58(5): 4056-4077.

[10] [10] APPEL J, FIGUEROA E, KORYSTOV D, et al. Quantum memory for squeezed light［J］. Physical Review Letters, 2008, 100(9): 093602.

[11] [11] PASCHOTTA R, KüRZ P, HENKING R, et al. 82% efficient continuous-wave frequency doubling of 1.06μm with a monolithic MgO∶LiNbO3 resonator［J］. Optics Letters, 1994, 19(17): 1325-1327.

[12] [12] FENG J X, LI Y M, LIU Q, et al. High-efficiency generation of a continuous-wave single-frequency 780nm laser by external-cavity frequency doubling［J］. Applied Optics, 2007, 46(17): 3593-3596.

[13] [13] TIAN L, WANG Q W, YAO W X, et al. Experimental realization of high-efficiency blue light at 426nm by external frequency doubling resonator［J］. Acta Physica Sinica, 2020, 69(4): 044201(in Ch-inese).

[14] [14] HAN Y S, WEN X, BAI J D, et al. Generation of 130mW of 397.5nm tunable laser viaring-cavity-enhanced frequency doubling［J］. Journal of the Optical Society of America, 2014, B38(8): 1942-1947.

[15] [15] WEN X, HAN Y S, BAI J D, et al. Cavity-enhanced frequency doubling from 795nm to 397.5nm ultra-violet coherent radiation with PPKTP crystals in the low pump power regime［J］. Optics Express, 2014, 22(26): 32293-32300.

[16] [16] ZHAI Y Y, FAN B, YANG S F, et al. A tunable blue light source with narrow linewidth for cold atom experiments［J］. Chinese Phy-sics Letters, 2013, 30(4): 044209.

[17] [17] VILLA F, CHIUMMO A, GIACOBINO E, et al. High-efficiency blue-light generation with a ring cavity with periodically poled KTP［J］. Journal of the Optical Society of America, 2007, B24(3): 576-580.

[18] [18] DENG X, ZHANG J, ZHANG Y C, et al. Generation of blue light at 426nm by frequency doubling with a monolithic periodically poled KTiOPO4［J］. Optics Express, 2013, 21(22): 25907-25911.

[19] [19] TIAN J F, YANG C, XUE J, et al. High-efficiency blue light ge-neration at 426nm in low pump regime［J］. Journal of Optics, 2016, 18(5): 055506.

[20] [20] ZHANG Y, LIU J H, MA R, et al. Generation of quadrature squeezed vacuum light field for cesium D1 line［J］. Acta Optica Si-nica, 2017, 37(5): 0519001(in Chinese).

[21] [21] LUO G Z, ZHU SH N, HE J L, et al. Simultaneously efficient blue and red light generations in a periodically poled LiTaO3［J］. A-pplied Physics Letters, 2001, 78(20): 3006-3008.

[22] [22] LIAO J, HE J L, LIU H, et al. Simultaneous generation of red, green, and blue quasi-continuous-wave coherent radiation based on multiple quasi-phase-matched interactions from a single, aperiodically-poled LiTaO3［J］. Applied Physics Letters, 2003, 82(19): 3159.

[23] [23] ZHDANOV B V, SHAFFER M K, LU Y L, et al. Perfomance comparison of nonlinear crystals for frequency doubling of an 894nm Cs vapor laser［C］. Proceedings of the SPIE, 2010, 7846:32-39.

[24] [24] ZHANG Y, LIU J H, WU J Z, et al. Single-frequency tunable 447.3nm laser by frequency doubling of tapered amplified diode laser at cesium D1 line［J］. Optics Express, 2016, 24(17): 19769-19775.

[25] [25] ZHANG Y, LIU Ch, XIAO Ch Sh, et al. Comparison of frequency locking of 894.6nm frequency doubling cavity using intra-modulation technology and Pound-Drever-Hall technology［J］. Laser Technology, 2017, 41(1): 47-50(in Chinese).

[26] [26] ZHANG Y, MA R, LIU J H, et al. Locking the frequency of the external cavity diode laser at 894.6nm using polarization spectroscopy［J］. Journal of Quantum Optics, 2017, 23(1): 87-91(in Chin-ese).

[27] [27] TYMINSKI J K. Photorefractive damage in KTP used as second-harmonic generator［J］. Journal of Applied Physics, 1991, 70(10): 5570-5576.