Characteristics Of Polarization-Independent Electro-Optical Switch

Nowadays, polarization-independent optical switches are playing a more and more important role in optical communication system. The polarization independent devices have advantages in many aspects. Using polarization-independent component in optical communication networks, polarization-maintaining fiber can be replaced with the ordinary single-mode fiber, which has no polarization dependence and can be applied in specific occasions. A free-space polarization-independent optical switch is discussed in this dissertation, which is mainly improved in cross talk.Firstly, we introduce some important applications of optical switches in optical networks. We overview the new progress in optical switches and analyze the properties together with the merits and demerits of different types of switches. Also, we discuss the development of electro-optic crystal.Then, based on the existing polarization-independent optical switches, we present a novel polarization-independent 2×2 electro-optical switch in free space. The characteristics of the scheme are described as follows:1 Two birefringent crystals and three electro-optic crystals are combined. Electro-optic crystals are used to transfer ordinary light to extraordinary light. Then there is a walkoff when extraordinary light passes through the birefringent crystal. Therefore most of crosstalk cannot exit in the output, which can reduce the crosstalk.2 The clear aperture of crystal is lmm and the Electro-optic crystal aspect ratio is 1.34, which can reduce the energy loss.3 Through theoretical analysis, the interchannel crosstalk is less than-52.6dB crosstalk. The insertion loss of the 2×2 optical switch architecture is less than 1dB. The drive voltage is about 160.4 V and the switch time is in nanosecond range.