Taper is a basic device widely used in photonics technology which transmits light between the waveguides with different widths. Tapers are usually designed to be trapezoidal in shape, which is simple but has many limits. If the taper is designed to be too short, the broken lines at the junction positions between the strip waveguides (SWGs) and the taper will excite high-order modes and cause high fundamental mode loss. As a result, the traditional tapers are always with a long length which limits the miniaturization of photonic systems. To solve this problem, we proposed a method based on forth-order Bezier curve that made the taper has both small size and good performances on the transmission loss of fundamental mode and the mode excitation ratios (MERs) of high-order modes. According to the obtained results, the proposed Bezier curve method decreased the length of a taper from 100μm to 30μm on the premise of maintaining the performances.
KEYWORDS: Holograms, Holography, 3D image reconstruction, Near field diffraction, 3D displays, Fourier transforms, 3D image processing, Tomography, Diffraction, Reconstruction algorithms
A rapid algorithm of multi-plane holographic display is given. A proper thin lens phase factor was combined with fast Fourier transform (FFT) in this algorithm to move the reconstructed image of Fourier transform hologram to specify depth from infinity and the imaging effect of this algorithm is identical with Fresnel diffraction. Using this simple operation replaced complicated Fresnel diffraction integral in the Ping-Pong iteration algorithm, the computational load of multi-plane hologram was reduced and computational speed was significantly increased. Moreover, the hologram of a 3-D object consists of two pictures at different depths was computed by this modified Ping-Pong algorithm. The reconstructing of this obtained hologram was also simulated in MATLAB. The result showed the new algorithm is feasible and effective.
KEYWORDS: Holograms, Holography, 3D image reconstruction, Near field diffraction, 3D displays, Fourier transforms, 3D image processing, Tomography, Diffraction, Reconstruction algorithms
A rapid algorithm of multi-plane holographic display is given. A proper thin lens phase factor was combined with fast Fourier transform (FFT) in this algorithm to move the reconstructed image of Fourier transform hologram to specify depth from infinity and the imaging effect of this algorithm is identical with Fresnel diffraction. Using this simple operation replaced complicated Fresnel diffraction integral in the Ping-Pong iteration algorithm, the computational load of multi-plane hologram was reduced and computational speed was significantly increased. Moreover, the hologram of a 3-D object consists of two pictures at different depths was computed by this modified Ping-Pong algorithm. The reconstructing of this obtained hologram was also simulated in MATLAB. The result showed the new algorithm is feasible and effective.
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