Seok-Ho Song

Planar optical implementation of crossover interconnects.

We propose a planar optical configuration for implementation of crossover interconnects. The planar overlay allows two-dimensional pixel arrays located on a wafer-scale integrated circuit to be interconnected in a compact and vibrationally robust configuration. By using an acute-angle microprism array with apex angles of 70.52 deg fabricated on a silicon substrate, we show the experimental result of the crossover interconnections. Some practical limits of the planar optical crossover interconnections are also discussed.

Focusing-grating-coupler arrays for uniform and efficient signal distribution in a backboard optical interconnect.

Several one-dimensional arrays of focusing grating couplers are designed for uniform distribution of incident optical powers to several processing boards in a backboard interconnection scheme. As main design parameters, both the length and the duty cycle of each focusing grating coupler are determined on the bases of ray-optic propagation-mode analysis in a slab waveguide and of rigorous coupled-wave diffraction analysis for out-coupled radiation modes. The backboard interconnection scheme incorporating the one-dimensional focusing-grating-coupler arrays, when used to distribute a guided optical power of TE(0) mode to several converging waves radiated only toward a glass substrate, displayed a power uniformity of 5% and a total coupling efficiency of 99.1%, which can be highly acceptable in practical use.

Beam-array combination with planar integrated optics for three-dimensional multistage interconnection networks.

We propose a configuration of planar integrated optics for three-dimensional multistage interconnection networks. To show the feasibility of cascading operations in the planar integrated optics, we present experimental results on the beam combination of signal- and power-beam arrays at a node stage. The beam-combination efficiency measured in the experiment is ~42% of the theoretical limit.

Optical perfect-shuffle interconnection using a computer-generated hologram

We propose the use of a computer-generated hologram that combines a fanout and focusing element that can be used to perform an optical perfect-shuffle interconnection. The hologram is designed by calculation of the interference fringes between diverging waves from four point sources and a reference plane wave. With this element we show experimentally the resulting perfect-shuffle pattern. The use of the computer-generated hologram makes it easy to implement a planar optical perfect-shuffle interconnect, which is compact, has low aberration, and is easy to align. The planar optics configuration for a perfect-shuffle interconnection network is also discussed.

Planar optical implementation of multichannel fractional Fourier transforms

Abstract A planar integrated optics for multichannel fractional Fourier transform (FRT) is demonstrated. Experimental results obtained from four channels with four different fractional orders show a good agreement with calculation results. It is found that the planar integrated optics offers a great potential to implement FRT-based optical systems for optical processing with high accuracy in transformation.

Planar optical implementation of fractional correlation

Abstract A fractional correlation operation has been implemented by using a planar optics configuration which consists of all optical components integrated on a single glass substrate. The fractional correlation filter and Fresnel lenses with continuous surface-relief structures have been fabricated directly on the glass substrate using the same laser-beam writing process. Excellent agreement between the experimental and calculated results shows that planar optics is very appropriate for space-variant operations, like fractional correlation, because of its accurate determination of fractional orders and high stability in optics alignment.

Optical implementation of a quadratic associative memory by using the polarization-encoding process

As a higher-order associative memory of a neural network, the quadratic associative memory is implemented holographically by using the polarization-encoding process. The use of polarization encoding to represent sign in the quadratic associative memory tensor is made by twisted nematic liquid-crystal light modulators. Experimental results of retrieving the stored objects from an incomplete input are presented.

Diffractive polarizing beam splitter based on surface plasmon resonance

Diffracive optical polarizing-beam-splitter by using surface plasmon resonance is proposed. Interaction between surface plasmon and diffractive grating structure is calculated by use of rigorous coupled wave theory. The optimum thickness of diffractive grating for very high extinction ratios of polarization are obtained above 30dB.

Parallel Optical Packet Address Detection Using Planar Optical Interconnections

We propose a novel planar optical interconnection scheme for 100 Gb/s optical packet address detection, which consists of wave guide grating couplers and a diffractive microlens integrated on a glass substrate 3-dimensionally. Length and duty cycle of the grating couplers have been determined on the bases of ray-optic propagation-mode analysis in a slab waveguide and of rigorous coupled-wave diffraction analysis for out-coupled radiation-modes. The 3-dimensionally integrated planar optics makes it possible to connect each address bit-signal of the TE0-waveguide mode to the detector with a power uniformity of 6.4% and a total coupling efficiency of 72.3%.

Sulfonation as a new technique of fabricating polymeric gradient-index lenses

Gradient-index (GRIN) lenses, whose refractive index varies continuously within the medium, have been useful as focusing elements, such as a connector and coupler of optical fibers, in optical communication systems. Glasses and polymers have been widely used in forming GRIN media, of which the polymers have milder processing condition and wider versatility in materials. Various copolymerization techniques have been used to form the gradient profiles of refractive index. Here, we report a new technique of fabricating GRIN medium in aromatic polymers using sulfonation method.