Submicron free space optical interferometer

We propose a novel submicron optical interferometer for free space applications. A beam is split into two narrow beams by wavefront division. After going through different phase shift, the two beams merge by themselves due to diffraction effect. Because of the self-mixing effect, lens and other discrete components are no longer needed, which enables a simple and ultra-compact structure and a manufacturing process compatible with the semiconductor technology. We use finite-difference time-domain (FDTD) simulations to demonstrate principles of the interferometer and make estimate of the signal-to-noise ratio.