High efficiency volume grating coupler

The compact nature of grating couplers makes them ideal for integrated optics applications. The out-coupling efficiency of grating couplers is reduced by diffraction into undesired orders. To create a viable grating coupler preferential-order coupling must be produced, where preferential-order coupling is defined as concentrating the out-coupled power into a single diffracted order in either the cover or substrate regions. In addition, the out-coupled beam should be focused to increase the alignment tolerance between the coupler and a detector. Furthermore, to facilitate the integration with integrated electronics it is desirable to out-couple the light normal to the surface of the waveguide.; In this thesis volume gratings are used to produce a grating coupler with the desired features. The volume grating coupler is modeled using rigorous coupler wave analysis. Couplers with a volume grating recorded in both the cover and core of the waveguide are examined. Various simulations of both volume grating couplers configurations are performed. These simulations are used to develop a qualitative understanding of the affect of various design parameters on the coupler performance.; A holographic recording material based on monomer diffusion and polymerization is examined as a means of producing a preferential-order volume grating coupler. A design method is developed to record a specific grating pattern and compensate for variation in the holographic recording material due to processing. A method is developed for recording a specific variable grating pattern required to incorporate focusing in to the preferential-order coupler. A fabrication method is developed for recording volume grating in the cover of a single mode polyamide waveguide. The fabricated volume grating coupler is then tested to demonstrate a preferential-order volume grating coupler prototype with a beam out-coupled normal to the waveguide surface and focused to a line 25 mm above the grating.