OFF-PLANE COMPUTER-GENERATED WAVE-GUIDE HOLOGRAM

We present the theory, design, fabrication and evaluation of off-plane computer-generated waveguide holograms (OP-CGWH's), The hologram stru cture is composed of an array of rectangular elements each containing a waveguide grating coupler, The function of the rectangular elements is twofold: outcoupling the guided optical wave, and introducing phase shift. The phase shift of each rectangular element can be determined by controlling the dislocation of the grating grooves along the guided wave propagation direction, In addition, the phase pattern of the OP- CGWH can be designed using many existing algorithms for computer-gener ated holograms (CGH), such as the iterative Fourier transform algorith m (IFTA), A design example is presented for a waveguide array generato r, which outcouples a Gaussian-like incident guided wave and simultane ously produces an array of spots in free space, Such an OP-CGWH device , based on an AlGaAs-GaAs waveguide, was fabricated using electron-bea m lithography and reactive ion beam etching, Experimental results are presented that demonstrate the effectiveness of the proposed idea, The uniformity error and the power efficiency of the fabricated OP-CGWH a rray generator were measured to be approximately 8% and 30%, respectiv ely.