Grating Based Polarization Filter And Inter-Layer Equal Coupler

In the times of information,massive data are generated every-day around the world.Those information data are needed to be processed efficiently and expeditiously,which requires high performance computing systems and puts forward a very high demand on interconnection technology.Traditional electrical interconnection chips,whose performance and integration depends on the reduction of feature size of the wire.However,this technology is gradually encountering bottlenecks and is unsustainable due to the electromagnetic interference.Using photons instead of electrons to achieve integrated chip has become a recognized effective solution,especially optical interconnection chips based on silicon waveguides.Since the refractive index of silicon is much higher than quartz,the device size can be further reduced.However,the high refractive index difference waveguide structure of the silicon-based photonic integrated device not only increases the integration degree but also brings the problem of polarization sensitivity.In addition,the distribution of photonic devices with different functions in different layers is conducive to the design of light path and signal processing,furthermore,it improves the integration of devices and reduces the use of optical fiber.Thus,the interconnection between different layers is a future development direction.In order to solve the above problems,we innovatively proposed a grating waveguide polarization filter and an interlayer equal coupler.The main contents of this paper are as follows:(1)The development of silicon based photonics is introduced.The principle and the performance of various polarizers based on silicon waveguides are surveyed,and the research progress of inter-layer optical interconnection is expounded.(2)Theories about grating,slab waveguide and numerical calculation methods involved in the device design process are introduced.(3)Polarization filters based on grating waveguide are proposed.Using a sub-wavelength grating diffraction coupling mechanism,the conversion between the different modes of a specific polarization is realized.The mode is changed from the forward transmission mode to the backward transmission mode by grating diffraction.However,the transmission mode of the other polarized light is directly transmitted without being influenced.By this way,the polarization filter to achieve.In this paper,the setting of the parameters in the design of the device is discussed in detail.This device has excellent characteristics such as wide band width,high extinction ratio,low insertion loss,large structure tolerance and so on,which makes the practical application of the photonic integrated chip go a step further.(4)Interlayer equal couplers based on grating waveguide structure are proposed.Utilizing the principle of grating diffraction coupling and optical resonator,we achieve a wideband of upward and downward equal diffraction coupling.The diffraction output for different wavelengths at different positions is realized by designing the grating height,and the reflectivity of the device is reduced by the adjusting the grating duty ratio.In this paper,the design of the device parameters is discussed in detail.The device features wide bandwidth,low insertion loss,and up and down diffraction efficiency controllable.Which provides a way for the flexible networking of 3-D interlayer optical interconnection.