Research In The Polarization Control Based On Array Waveguide Grattings (AWG)

Array Waveguide Grating(Arrayed Waveguide Grating: AWG) is now becoming more and more popular in the large capacity WDM(Wavelength-Division Multiplexing: WDM) systems due to its unique advantages, such as flexible design, ease of integration and so on. In In general, the transmission characteristics of AWGs can be easily affected by different polarizations. On the one hand, AWGs can be used in the polarization multiplexing systems due to its multi-functions. On the other hand, AWGs’ sensitivity of polarization can further affect the systems of no difference on the polarization. Therefore, there is a great significance in the research of polarization characteristics of AWGs.In this paper, the main work is to study and analyze the AWG polarization control technologys, which mainly include polarization splitting/mixing based on AWGs and eliminating the polarization sensitivity of AWGs. Therefore, this paper first briefly introduces the basic principle of AWGs, performance parameters and the current situation of the development. At the same time, based on the theory of optical waveguide, the AWG transfer function is verified and derived, which provides the theoretical foundation for the polarization control.At first, the technology of polarization splitting/mixing based on AWGs is theoretically discussed in detail. Through the transfer function and the optical software simulation analysis, the parameters of the device performance are analyzed.The polarization sensitivity always restricts the applications of AWGs. Based on the relation between birefringence and the waveguide structure, a method of compensating the polarization sensitivity caused by the structures is put forward. On this basis, developed from the grating equation, a novel method of using asymmetric slab waveguide completely to eliminate the residual polarization sensitivity of AWGs with an embedded half wave plate is proposed.Given the shortcomings of the half wave plate, using polarization rotator to instead of half wave plate is dicussed in this paper. The polarization rotator based on SPPs waveguides is introduced in detail. Furthermore, a new type of polarization rotator with low insertion loss and the compact structure is presented, which has a positive influence on the study of rotating different polarizations and eliminating the polarization sensitivity of AWGs in the fulture.