[1] [1] Pan S, Zhang Y. Microwave photonic radars［J］. J. Lightwave Technol., 2020, 38(19): 5450-5484.

[2] [2] Marpaung D, Yao J, Capmany J. Integrated microwave photonics［J］. Nat. Photonics, 2019, 13(2): 80-90.

[3] [3] Cao Z, Tessema N, Latkowski S, et al. Integrated remotely tunable optical delay line for millimeter-wave beam steering fabricated in an InP generic foundry［J］. Opt. Lett., 2015, 40(17): 3930-3933.

[4] [4] Shan W, Lu L, Wang X, et al. Broadband continuously tunable microwave photonic delay line based on cascaded silicon microrings［J］. Opt. Express, 2021, 29(3): 3375-3385.

[5] [5] Zhu C, Lu L, Shan W, et al. Silicon integrated microwave photonic beamformer［J］. Optica, 2020, 7(9): 1162-1170.

[6] [6] Liu Y, Wichman A R, Isaac B, et al. Ultra-low-loss silicon nitride optical beamforming network for wideband wireless applications［J］. IEEE J. Sel. Top. Quantum Electron., 2018, 24(4): 1-10.

[7] [7] Tsokos C, Andrianopoulos E, Raptakis A, et al. True time delay optical beamforming network based on hybrid InP-silicon nitride integration［J］. J. Lightwave Technol., 2021, 39(18): 5845-5854.

[8] [8] Roeloffzen C G H, Hoekman M, Klein E J, et al. Low-loss Si3N4 TriPleX optical waveguides: Technology and applications overview［J］. IEEE J. Sel. Top. Quantum Electron., 2018, 24(4): 1-21.

[9] [9] Hansen R C. Phased Array Antennas［M］. New York: John Wiley & Sons, 2009.

[10] [10] Zhou L, Wang X, Lu L, et al. Integrated optical delay lines: A review and perspective［J］. Chin. Opt. Lett., 2018, 16(10): 101301.

[11] [11] Urick V J, Williams K J, McKinney J D. Fundamentals of Microwave Photonics［M］. New York: John Wiley & Sons, 2015.

[12] [12] Hu G, Cui Y, Yang Y, et al. Optical beamformer based on diffraction order multiplexing (DOM) of an arrayed waveguide grating［J］. J. Lightwave Technol., 2019, 37(13): 2898-2904.

[13] [13] Zhang X, Zhao M, Jiao Y, et al. Integrated wavelength-tuned optical mm-wave beamformer with doubled delay resolution［J］. J. Lightwave Technol., 2020, 38(8): 2353-2359.

[14] [14] Ye X, Zhang F, Pan S. Compact optical true time delay beamformer for a 2D phased array antenna using tunable dispersive elements［J］. Opt. Lett., 2016, 41(17): 3956-3959.

[15] [15] Kumar R, Raghuwanshi S K. Efficient 2D optical beamforming network with sub partitioning capability based on raised cosine chirped fiber grating and Mach-Zehnder delay interferometer［J］. IEEE Photonics J., 2021, 13(3): 1-11.

[16] [16] Soref R A, De Leonardis F, Passaro V M N. Integrated on-chip Bragg time-delay system for thermo-optical control of a microwave antenna［J］. J. Lightwave Technol., 2018, 36(24): 5849-5856.

[17] [17] Zhang J, Yao J. Photonic true-time delay beamforming using a switch-controlled wavelength-dependent recirculating loop［J］. J. Lightwave Technol., 2016, 34(16): 3923-3929.

[18] [18] Xiang C, Davenport M L, Khurgin J B, et al. Low-loss continuously tunable optical true time delay based on Si3N4 ring resonators［J］. IEEE J. Sel. Top. Quantum Electron., 2018, 24(4): 1-9.

[19] [19] Liu Y, Wichman A, Isaac B, et al. Tuning optimization of ring resonator delays for integrated optical beam forming networks［J］. J. Lightwave Technol., 2017, 35(22): 4954-4960.

[20] [20] Cardenas J, Foster M A, Sherwood-Droz N, et al. Wide-bandwidth continuously tunable optical delay line using silicon microring resonators［J］. Opt. Express, 2010, 18(25): 26525-26534.

[21] [21] Khurgin J B, Morton P A. Tunable wideband optical delay line based on balanced coupled resonator structures［J］. Opt. Lett., 2009, 34(17): 2655-2657.

[22] [22] Chen Z, Zhou L, Chen J. Analysis of a silicon reconfigurable feed-forward optical delay line［J］. IEEE Photonics J., 2013, 6(1): 1-11.

[23] [23] Xie J, Zhou L, Li Z, et al. Seven-bit reconfigurable optical true time delay line based on silicon integration［J］. Opt. Express, 2014, 22(19): 22707-22715.

[24] [24] Wang X, Zhou L, Li R, et al. Continuously tunable ultra-thin silicon waveguide optical delay line［J］. Optica, 2017, 4(5): 507-515.

[25] [25] Liu Y, Lu L, Chen J, et al. Silicon integrated low-loss 4-channel 5-bit optical true-time delay lines［C］// Proc. of the 26th Optoelectronics and Communications Conference(OECC), Optical Society of America, 2021: paper W3C.3.

[26] [26] Hong S, Zhang L, Wang Y, et al. Ultralow-loss compact silicon photonic waveguide spirals and delay lines［J］. Photonics Res., 2022, 10(1): 1-7.

[27] [27] Zheng P, Wang C, Xu X, et al. A seven bit silicon optical true time delay line for Ka-band phased array antenna［J］. IEEE Photonics J., 2019, 11(4): 1-9.

[28] [28] Melati D, Waqas A, Mushtaq Z, et al. Wideband integrated optical delay line based on a continuously tunable Mach-Zehnder interferometer［J］. IEEE J. Sel. Top. Quantum Electron., 2018, 24(1): 1-8.

[29] [29] Zhuang L, Roeloffzen C, Heideman R, et al. Single-chip ring resonator-based 1×8 optical beam forming network in CMOS-compatible waveguide technology［J］. IEEE Photonics Technol. Lett., 2007, 19(15): 1130-1132.

[30] [30] Burla M, Marpaung D A I, Zhuang L, et al. Multiwavelength-integrated optical beamformer based on wavelength division multiplexing for 2-D phased array antennas［J］. J. Lightwave Technol., 2014, 32(20): 3509-3520.

[31] [31] Cheng Q, Zheng S, Zhang Q, et al. An integrated optical beamforming network for two-dimensional phased array radar［J］. Opt. Commun., 2021, 489: 126809.

[32] [32] Duarte V C, Prata J G, Ribeiro C F, et al. Modular coherent photonic-aided payload receiver for communications satellites［J］. Nat. Commun., 2019, 10(1): 1984.

[33] [33] Reza M, Mohammad A, Serafino G, et al. Design of an integrated-photonics RF beamformer for multi-beam satellite synthetic aperture radar［C］// IEEE Proc. of the 2020 Inter. Topical Meeting on Microwave Photonics (MWP), 2020: 87-90.

[34] [34] Tsokos C, Kouloumentas C, Mylonas E, et al. Analysis of a multibeam optical beamforming network based on blass matrix architecture［J］. J. Lightwave Technol., 2018, 36(16): 3354-3372.

[35] [35] Xiang C, Jin W, Huang D, et al. High-performance silicon photonics using heterogeneous integration［J］. IEEE J. Sel. Top. Quantum Electron., 2022, 28(3): 1-15.

[36] [36] Dhillon A S, Radi B, Liboiron-Ladouceur O. An analysis of RF on-chip antennas in Si-based integrated microwave photonics［J］. IEEE Photonics J., 2021, 13(2): 1-18.

[37] [37] Pan B, Zheng S, Ren C, et al. A structure optimization for integrated binary reconfigurable true time delay lines［J］. Opt. Commun., 2022, 502: 127439.

[38] [38] Song L, Chen T, Liu W, et al. Toward calibration-free Mach-Zehnder switches for next-generation silicon photonics［J］. Photonics Res., 2022, 10(3): 793-801.

[40] [40] Choo G, Madsen C K, Palermo S, et al. Automatic monitor-based tuning of an RF silicon photonic 1×4 asymmetric binary tree true-time-delay beamforming network［J］. J. Lightwave Technol., 2018, 36(22): 5263-5275.

[41] [41] Duarte V C, Ribeiro C F, Prata J G, et al. Reconfigurable monitoring and control system for tunable optical delay lines［J］. Opt. Lett., 2018, 43(11): 2543-2546.