Analysis of the fiber-waveguide coupling efficiency and the resulting polarization dependent loss

In both science research and product development of waveguides based chips fiber-waveguide coupling is a mandatory stage. In this work, the universal fiber-waveguide coupling efficiency is analyzed based on the overlap model of fiber and waveguide profiles. Furthermore, the systematic numerical simulations with gap size, matching material and birefringence show that the waveguide-gap interface reflection plays a dominant role in polarization dependent loss (PDL). For the two cases: this interface reflection is (i) involved and (ii) eliminated, the resulting numerical PDL values are 1.08dB and 0.06dB, respectively. The simulations from the professional simulators are sustainable to the above numerical results.