[1] [1] Li P P, Zheng N, Kang P C, et al. Overview and inspiration of global 5G spectrum researches［J］. Telecommunication Engineering, 2017, 57(6): 734-740.

[2] [2] Liu G P. Research on development strategy of radio spectrum resource management［D］. Jinan: Shandong University of Finance and Economics, 2016: 1-6.

[3] [3] Xi Y J. Radio spectrum resources［J］. GNSS World of China, 2002, 27(5): 40-43.

[4] [4] Huang Z J. Optical carried microwave/millimeter-wave transmission technology［D］. Hangzhou: Zhejiang University, 2012: 1-3.

[5] [5] Tonda-Goldstein S, Dolfi D, Monsterleet A, et al. Optical signal processing in Radar systems［J］. IEEE Transactions on Microwave Theory & Techniques, 2006, 54(2): 847-853.

[6] [6] Chen J, Zhu H, Xia W, et al. Self-mixing birefringent dual-frequency laser Doppler velocimeter［J］. Optics Express, 2017, 25(2): 560-572.

[7] [7] Huo J W. All-Optical frequency up and down-conversion for millimeter-wave over fiber systems［D］. Beijing: Beijing University of Posts and Telecommunications, 2011: 1-6.

[8] [8] Danion G, Hamel C, Frein L, et al. Dual frequency laser with two continuously and widely tunable frequencies for optical referencing of GHz to THz beatnotes［J］. Optics Express, 2014, 22(15): 17673-17678.

[9] [9] Rolland A, Frein L, Vallet M, et al. 40-GHz photonic synthesizer using a dual-polarization microlaser［J］. IEEE Photonics Technology Letters, 2010, 22(23): 1738-1740.

[10] [10] Pillet G, Morvan L, Ménager L, et al. Dual-frequency laser phase locked at 100 GHz［J］. Journal of Lightwave Technology, 2014, 32(20): 3824-3830.

[11] [11] Hu M, Zhang H, Zhang F, et al. Thermally induced frequency difference characteristics of dual-frequency microchip laser used optical generation millimeter-wave［J］. Acta Physica Sinica, 2013, 62(20): 204205.

[12] [12] Mckay A, Dawes J M. Microwave generation using a dual-helicoidally-polarized ceramic microchip laser［C］∥International Topical Meeting on Microwave Photonics Jointly Held with the 2008 Asia-Pacific Microwave Photonics Conference, September 09-October 03, 2008, Gold Coast, Qld, Australia. New York: IEEE, 2008: 263-266.

[13] [13] Wang R Y, Li Y F. Dual-polarization spatial-hole-burning-free microchip laser［J］. IEEE Photonics Technology Letters, 2009, 21(17): 1214-1216.

[14] [14] Hu M, Huang Q F, Zhang H, et al. Spectral and frequency difference characteristics of the LD-pumped dual-frequency solid-state laser［J］. Journal of Optoelectronics·Laser, 2014, 25(3): 472-477.

[15] [15] Dai R, Hu M, Cai M L, et al. Experimental study of thermally induced frequency difference tuning of Nd∶YVO4 microchip dual frequency lasers［J］. Chinese Journal of Lasers, 2017, 44(1): 0101003.

[16] [16] Huang Y J, Cho H H, Su K W, et al. Exploring a diffusion-bonded Nd∶YVO4/Nd∶GdVO4 crystal for generating an efficient diode-end-pumped dual-spectral-band laser［C］∥Advanced Solid State Lasers, October 04-09, 2015, Berlin, Germany. Washington: Optical Society of America, 2015: ATu1A.7.

[17] [17] Délen X, Balembois F, Georges P. Temperature dependence of the emission cross section of Nd∶ YVO4 around 1064 nm and consequences on laser operation［J］. Journal of the Optical Society of America B, 2011, 28(5): 972-976.

[18] [18] Cai M L, Hu M, Dai R, et al. Experimental study of emission cross section spectra and microchip laser spectra of Nd∶ GdVO4 and Nd∶ YVO4 crystals［J］. Chinese Journal of Lasers, 2017, 44(11): 1101004.