Broadband image-reject mixing using a dual-channel polarization-modulated photonic microwave phase shifter is proposed and experimentally demonstrated. The polarization-modulated photonic microwave phase shifter is realized by an orthogonal circularly-polarized wavelength generator, an optical coupler, two polarizers, and two photodetectors (PDs). When a local oscillator (LO) signal, a radio-frequency (RF) signal, and an image interference are supplied to the polarization-modulated phase shifter, opposite phase shifts would be introduced to the RF- and image-induced intermediate frequency (IF) signals. By carefully adjusting the polarizers to make the two channels of the phase shifter quadrature, a phase difference of −90 degree is introduced to the RF-induced IF signals in the two channels, while 90-degree phase difference between the image-induced IF signals is produced. With an electrical 90 degree hybrid to combine the two channels, the two RF-induced IF signals will be in phase while those from the image are out of phase. As a result, the image in the downconverted signal is cancelled. An experiment is carried out. An image-reject mixer (IRM) with an image rejection ratio of ∼60 dB for a single-frequency signal and 23 dB for a 4-GHz linear frequency-modulated signal is obtained.

中文翻译：

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基于偏振调制双通道光子微波移相器的宽带镜像抑制混频

提出并实验证明了使用双通道偏振调制光子微波移相器的宽带镜像抑制混合。偏振调制光子微波移相器由正交圆偏振波长发生器、光耦合器、两个偏振器和两个光电探测器（PD）实现。当本地振荡器 (LO) 信号、射频 (RF) 信号和镜像干扰被提供给偏振调制移相器时，相反的相移将被引入到射频和镜像感应中频 (IF) ) 信号。通过仔细调整偏光片，使移相器的两个通道正交，在两个通道中的射频感应中频信号中引入了-90度的相位差，同时产生图像感应中频信号之间的 90 度相位差。使用 90 度电混合器组合两个通道，两个射频感应 IF 信号将同相，而来自图像的信号则异相。结果，下变频信号中的图像被消除。进行了一项实验。获得了镜像抑制混频器 (IRM)，其镜像抑制比对于单频信号为 60 dB，对于 4 GHz 线性调频信号为 23 dB。