Development of pulling interferometer with geometric phase modulation

调零干涉仪是对极亮恒星光进行相消干涉的一种直接探测太阳系外行星的方法。在第一个实验中，一个线偏振光被认为是两个正交的线偏振光的合成和这些分解的偏振分量相消干涉使用偏振。然而，这种情况并不能完全模拟实际的牵引干涉仪。在接下来的实验中，用马赫-曾德尔干涉仪产生两束独立的光束，并在每一臂上施加几何相位调制，从而实现拉干涉。几何相位或Pancharatnam相位本质上与波长无关，并且相移值是可调的。这些几何相位特性对于多元望远镜牵引干涉仪的设计是非常有用的，实验结果表明，在牵引干涉仪中可以实现任意弧度（小于2π）的独立相位调制，消光比可达0.8 × 10^4。

To directly detect extrasolar planets nulling interferometer gains wide attention, where extremely bright star-light is destructively interfered. In the first experiments, one linearly polarized light beam is considered as the synthesis of two orthogonal linearly polarized light and these decomposed polarization components are destructively interfered by use of a polarizes. However, this situation does not fully simulate a practical pulling interferometer. In the next experiments two separate beams are generated with a Mach-Zehnder interferometer and geometric phase modulation is exerted in each arm so as to perform pulling interference. Geometric phase or Pancharatnam phase is independent of wavelength in nature and the phase shift value is adjustable. These characteristics of geometric phase are very useful for pulling interferometer with multi-element telescopes.Experimental results reveal the feasibility of separate phase modulation of an arbitrary amount of radians (less than 2π) in pulling interferometer and the extinction ratio of 0.8x10^4 is achieved.