[1] [1] HE Y, WANT Y, XU D, et al. High-energy and ultra-wideband tunable terahertz source with DAST crystal via difference frequency generation[J]. Applied Physics B, 2018, 124(1): 1-8.

[2] [2] LIN C T, SHIH P T, JIANG W J, et al. Photonic vector signal generation at microwave/millimeter-wave bands employing an optical frequency quadrupling scheme [J]. Optics Letters, 2009, 34(14): 2171-2173.

[4] [4] GAO F, LI Y, CONG Z, et al. Injection-seeded terahertz parametric oscillator with a ring-cavity configuration[J]. Crystals, 2020, 10(9): 732-739.

[5] [5] WANG W, ZHANG X, WANG Q, et al. Multiple-beam output of a surface-emitted terahertz-wave parametric oscillator by using a slab MgO: LiNbO3 crystal[J]. Optics Letters, 2014, 39(4): 754-757.

[6] [6] YANG Z, WANG Y, XU D, et al. High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration[J]. Optics Letters, 2016, 41(10): 2262-2265.

[7] [7] LIU P, ZHANG X, YAN C, et al. Widely tunable and monochromatic terahertz difference frequency generation with organic crystal 2-(3-(4-hydroxystyryl)-5, 5-dime-thylcyclohex- 2-enylidene) malononitrile[J]. Applied Physics Letters, 2016, 108(1): 011104-1-011104-3.

[8] [8] PAN S L, YAO J P. Photonics-based broadband microwave measur-ement [J]. Journal of Lightwave Technology, 2017, 35(16): 3498-3513.

[9] [9] GENG H J, HAO S Q, ZHAO Q S, et al. Research on the technology of microwave generation with photonic frequency sextupling by cascaded external modulators[J]. Journal of Optoelectronics Laser, 2015, 26(2): 272-276.

[10] [10] ZHOU W, ZOU X H, PAN W, et al. Photonic generation of microwave signals with a 24 multiplied frequency using cascaded Mach-Zehnder modulators and four-wave mixing [J]. Journal of Optoelectronics Laser, 2013, 24(12): 2332-2337.

[11] [11] YING X Y, XU T F, LIU T J, et al. Photonic generation of millimeter-wave signal via frequency 24-tupling based on dual-parallel MZM and four-wave-mixing in HNLF [J]. Journal of Optoelectronics Laser, 2016, 27(8): 814-818.

[12] [12] LIN C T, DAI S P, CHEN J, et al. A novel direct detection microwave photonic vector modulation scheme for radio-over-fiber system [J]. IEEE Photonics Technology Letters, 2008, 20(13): 1106-1108.

[13] [13] LIN C T, WONG E Z, JIANG W J, et al. 28 Gb/s 16QAM OFDM radio-over-fiber system within 7 GHz license-free band at 60 GHz employing all-optical up-conversion[EB/OL]//[2021-08-09]. https://www.osapublishing.org/viewmedia.cfm?uri=CLEO-2009-CPDA8&seq=0.

[14] [14] SHIH P T, LIN C T, JIANG W J, et al. Transmission of 20 Gb/s OFDM signals occupying 7 GHz license-free band at 60 GHz using a RoF system employing frequency sextupling optical up-conversion, Optics Express, 2010, 18(12): 12748-12755.

[15] [15] CHARLES M, MICHAEL B, JEFF W, et al. Measurement of SFDR and noise in EDF amplified analog RF links using all-optical down-conversion and balanced receivers[C]// SPIE. Proceedings of Defense and Security Symposium, International Society for Optics and Photonics. Florida: SPIE, 2008: 69750Q-1-69750Q-12.