DeGui Sun

BUTTERFLY INTERCONNECTION IMPLEMENTATION FOR AN N-BIT PARALLEL FULL ADDER SUBTRACTOR

Free-space optical interconnections are important in both massive digital optical computing and communication systems. The architectural features of three interconnection networks are analyzed and compared, and the optical butterfly interconnection is shown to have many advantages over other interconnections in implementing various basic logic functions such as addition, subtraction, multiplication, and fast Fourier transforms (FFTs). Starting with conventional Karnaugh maps and Boolean algebra, the characteristics of full addition and full subtraction are analyzed and compared. An n-bit parallel calculator that can implement both ripple carry full additions and ripple borrow full subtractions using multilayer butterfly interconnection networks is designed. Then the schematic and architecture of the full adder/subtractor, interconnection networks, and the patterns of key devices such as masks to implement AND and OR operations in this calculation are described in detail. The correct simulation results of several groups of multibit digits are provided. Finally, the development of the interconnections in implementing logic operations is discussed.

INTRAPLANE TO INTERPLANE OPTICAL INTERCONNECTS WITH A HIGH DIFFRACTION EFFICIENCY ELECTRO-OPTIC GRATING

We report on a new optical interconnect architecture for three-dimensional, multiple electro-optic gratings with LiNbO(3) used in conjunction with substrate guided waves. First the operating mechanism of the system is studied in detail, and the momentum mismatch in the operating process of the system is also demonstrated. We then derive a new method for calculating coupling efficiency by introducing a compensation for the mismatch. This theoretical research allows the new optical interconnect architecture to provide a higher design accuracy and an optimized coupling efficiency, even though it is under the case of momentum mismatch. We achieve this result by introducing a substrate guided wave with 45 degrees bouncing angle and 100-V applied voltage. The successful design and its theoretical analysis will be helpful for research on the grating coupler.

Demonstration of an optoelectronic interconnect architecture for a parallel modified signed-digit adder and subtracter

A space-position-logic-encoding scheme is proposed and demonstrated, This encoding scheme not only makes the best use of the convenience of binary logic operation, but is also suitable for the trinary property of modified signed-digit (MSD) numbers. Based on the space-position-logic-encoding scheme, a fully parallel modified signed-digit adder and subtracter is built using optoelectronic switch technologies in conjunction with fiber-multistage 3-D optoelectronic interconnects, Thus an effective combination of a parallel algorithm and a parallel architecture is implemented. In addition, the performance of the optoelectronic switches used in this system is experimentally studied and verified. Both the 3-bit experimental model and the experimental results of a parallel addition and a parallel subtraction are provided and discussed. Finally, the speed ratio between the MSD adder and binary adders is discussed and the advantage of the MSD in operating speed is demonstrated

Analysis of one-way coupling between asymmetric highly multimode waveguides

In this paper, a unidirectional electrooptic modulator based on an asymmetrical highly multi-mode wavedguide coupler is proposed. The energy distribution of all the guided modes within a highly multi-mode waveguide is studied and a new conclusion is obtained. Furthermore, the whole coupling process among all the guided modes between two nonidentical highly multi-mode waveguides is analyzed and the total coupling efficiency is calculated. To achieve high switching performance in a guided-wave coupler, a larger guide is made to have a dumping effect, which can be implemented by using an absorbing material or a grating. Based on the dumping effect, the dumping process is theoretically modeled and the dumping efficiency is simulated. Not only can a high dumping efficiency of 100 percent be achieved, but a high electrooptic modulation depth more than 90 percent can also be implemented.

Novel poling and electro-optic measurement methods of cladded nonlinear-optical polymer films

We use high temperature liquid-contact poling as a method to pole efficiently cladded nonlinear optical polymer films. Poling voltage as high as 400 volts is applied to planar waveguides which have a nonlinear optical film of 1.2 im thick. The lack of a quick method to characterize the poled cladded nonlinear optical films inspires us to devise a new electrooptic measurement method. This method can determine r33 and r13 separately because it uses light of single polarization state to probe the nonlinear optical film. The interference between the modulated light and the unmodulated light in the reflected beam is used to extract electro-optic coefficients. Theoretical analysis of the relationship between the reflected light intensity and the electro-optically modulated signal is consistent with the experimental results. Formulae to calculate electro-optic coefficients are deduced. This method uses an even simpler experimental setup than that of the widely used ellipsometric method.

Intraplane to interplane optical interconnects using LiNbO3-based electro-optically modulated switch array for high-density holographic memory

A ne optical interconnect architecture for a 3D switch array using multiple LiNbO3-based electro-optically modulated gratings in conjunction with substrate guided waves is reported. First the operating mechanism of the system is studied in detail, and the momentum mismatch in the operating process of the system is also demonstrated. Then, a new method for calculating coupling efficiency is derived by introducing a compensation for the mismatch. With the new calculation method and by introducing a substrate guided wave with 45 degree bouncing angle and 100-V applied voltage, an optimized coupling efficiency is obtained even though it is under the case of momentum-mismatch. Finally, the experimental result of coupling efficiency of the electro-optically modulated grating is provided, and agreements between the experimental results and the theoretical prediction are obtained.

Combination of free-space and guided-wave optical interconnects for angularly multiplexed multiwavelength holographic memory

We propose and test experimentally a new scheme to implement spatially multiplexed multiwavelength holographic memory. An electro-optically modulated phase grating array on LiNbO(3) substrate is used as a guided-wave interconnect to activate the reconfigurable reference beam. The object beam is provided by free-space interconnect. An electro-optic modulation efficiency of 18 +/- 2.5% is achieved with an applied voltage of 100 V. The reference beams with different diffraction angles can implement the angle-multiplexing holographic recording. We believe this is the first report of the implementation of guided-wave electro-optic interconnect together with free-space interconnect in holographic memory applications.

Implemented optical Perfect Shuffle with a planarized architecture

In this paper, a substrate-guided-wave-based perfect shuffle (PS) having an 8-to-8 interconnection is demonstrated at 632.8 nm wavelength. Sixteen waveguide holograms are fabricated on a planar waveguiding plate with the full functionality of the PS. The diffraction efficiencies of the waveguide hologram are all within 80 percent +/- 5 percent. The planar architecture combined with the surface-normal configuration of the demonstrated PS makes the integration with vertical cavity surface emitting lasers and other surface mountable processing elements highly feasible.

High-density photopolymer-based spatially multiplexed multiwavelength programmable memory

In this paper, a new scheme to implement high-density photopolymer-based spatially multiplexed multiwavelength programmable holographic memory is proposed. Two approaches are considered. The first is to implement programmable massive fanout beams based on an electrooptic grating array and the second is aimed at providing a multiwavelength high density memory by obtaining a smaller holographic memory spot at the proposed off- focal plane location. In the first approach, the diffraction efficiency of the electrooptically modulated grating is optimized, and 32.5% +/- 2.5% modulation efficiency is achieved under an applied voltage of 100 volts. In the second approach, the storage density is improved by 100 approximately 110% when compared with that obtained at the focal plane after Fourier transform. All the experimental results agree well with the theoretical predictions. A memory density of 100 pages/mm2 is feasible using the reported scheme.