综合利用锂酸铌(LiNbO3)晶体的双折射效应和电光效应，设计了一种适用于相干光通信系统的新型空间光桥接器。其由4块结构相同的具有电极控制的晶片和一块检偏双折射元件所组成，两对双折射晶体光学平板利用双折射效应分别实现信号光和本振光的偏振分离和合束，电光调制则产生所需的相移。通过调整晶片的控制电压，可从检偏双折射元件输出四通道的相对相位差为90°的信号/本振合成光。与以往的空间光桥接器相比，该桥接器具有结构紧凑、损耗小和相栘性能稳定的优点。

A new 90° 2×4 hybrid for coherent optical communication systems was designed based on the birefringence effect and the electro-optic effect of crystal. It consists mainly of four pieces LiNbO₃ crystal plates with the same sizes which are modulated by the electric fields and a polarization analyzer. Two of LiNbO₃ crystal plates split respectively incoming signal beam E_S and local oscillator beam E_LO into four beams of laser lights and another LiNbO₃ crystal plates mix them into two synthetic beams by birefringence effects. The desired phase relations between the respective output ports can be obtained by the electro-optic effect. By adjusting the applied voltages on the LiNbO₃ crystal plates, 4 output ports from the polarization analyzer give the mixed beams which are phase shifted by 90° relatively to each other. Compared with traditional optical hybrids, the optical hybrid has the advantage of low losses and good stability of the phase shift.