斜入射液晶空间光调制器的特性

用读出光斜入射到液晶空间光调制器(LC-SLM)的读出面,是一种有效的提高空间光调制器(SLM)读出效率的方法。测量了读出光以不同角度入射到液晶空间光调制器的读出面上时,相位调制深度与写入光强的关系、衍射效率与二值光栅对比度的关系。得到随着入射角度的增加,最大相位调制深度减小,而衍射效率变化并不明显。在45°时有最大相位调制深度2.0936π和35.4%的正一级衍射效率。     

Compact and low-loss arrayed waveguide grating module with tolerance-relaxed spot-size converter

A compact, low-loss arrayed waveguide grating (AWG) module was achieved by adopting a novel optical spot-size converter (SSC) to planar lightwave circuits (PLCs). The SSC is a laterally tapered waveguide that can be fabricated simply by the conventional fabrication process. The structure is composed of a core width converting region where the spot-size is converted efficiently, and a core width fine-tuning region where the cut-position tolerance is relaxed. We have applied this structure to a 1.5%-/spl Delta/ silica-based waveguides and reduced the single-mode fiber coupling loss to less than 0.5 dB/point. The SSC provides a large cut-position tolerance that enables angle polishing of the PLC endfaces to prevent reflection and low-loss connection of pigtail fibers. The center channel insertion loss of the AWG module was reduced from 4.2 to 2.2 dB, and the reflection was less than -60 dB.     

A 100-MHz 2-D discrete cosine transform core processor

A 100-MHz two-dimensional discrete cosine transform (DCT) core processor applicable to the real-time processing of HDTV signals is described. An excellent architecture utilizing a fast DCT algorithm and multiplier accumulators based on distributed arithmetic have contributed to reducing the hardware amount and to enhancing the speed performance. A layout scheme with a column-interleaved memory and a new ROM circuit are introduced for the efficient implementation of memory-based signal processing circuits. Furthermore, mean values of errors generated in the core were minimized to enhance the computational accuracy with the word-length constraints. Consequently, it features the fastest operating speed and the smallest area with sufficient accuracy to satisfy the specifications in CCITT recommendation H.261. The core integrates about 102 K transistors and occupies 21 mm² using 0.8-μm double-metal CMOS technology     

Wavelength conversion using a light injected DFB-LD and aMach-Zehnder filter with a ring resonator

Wavelength conversion using a light injected DFB-LD and a Mach-Zehnder filter with a ring resonator (r-MZ) is described. It utilizes frequency modulation of the DFB-LD induced by an external light and the FM/IM conversion function of the r-MZ filter. Owing to a unique characteristic of the r-MZ filter, the converter has good tolerance for input signal level and an effect of suppressing signal fluctuation, compared with a conversion scheme using a conventional MZ filter     

A subnanosecond clock cryogenic system for Josephson computers

Using Josephson chips maintained at 4.4 K by a closed-cycle 3-W desk-size refrigerator, the authors verified the correct operation of a 4-b Josephson microprocessor up to 1.1 GHz. Room temperature and liquid He temperature regions are connected with a 130-ps delay using I/O cables passing through sidewalls of a vacuum vessel. It is proposed that both semiconductor and Josephson devices can coexist on circuit boards that constitute the equivalent of a single board     

Carrier-injection type optical S3 switch withtraveling-wave amplifier

A carrier-injection-type semiconductor optical switch for photonic switching in which a traveling-wave optical amplifier is integrated in the optical single-slip structure (S³) switch to improve insertion loss and crosstalk is discussed. Preliminary experimental results are described. These results suggest that the carrier-injection-type optical S³ switch with traveling-wave amplifier has the potential to realize a small-size but large-capacity optical switch array for photonic switching     

Test structure measuring inter- and intralayer coupling capacitance of interconnection with subfemtofarad resolution

We present a new test structure measuring inter- and intralayer coupling capacitance parasitic to the same target interconnection with subfemtofarad resolution. The coupling capacitance as well as fringing capacitance measured by the test structure are demonstrated for two-level copper interconnections used in 90-nm technology node. In addition, we demonstrate that the accuracy of layout parameters extraction is improved by nondestructive inverse modeling of a copper interconnect cross-sectional structure, which reproduces the pitch dependence of the measured inter- and intralayer coupling capacitance within about a 1% error.     

Fast extraction of defect size distribution using a single layershort flow NEST structure

Defect inspection is required for process control and to enhance chip yield. Electrical measurements of test structures are commonly used to detect faults. To improve accuracy of electrically based determination of defect densities and defect size distributions, we present a novel NEST structure. There, many nested serpentine lines will be placed within a single layer only. This mask will be used as a short flow to guarantee a short turn around time for fast process data extraction. Data analysis procedures will provide densities and size distributions of killer defects that will have an impact on product chip yield     

一种基于低温多晶硅TFT技术的柔性8位异步微处理器

介绍基于低温多晶硅TFT技术和采用激光退火表面刻蚀技术的柔性8位异步微处理器,并且给出了异步电路描述语言Verilog 。32,000个晶体管的微处理器在500kHz,5V的条件下消耗电流180mA,功耗是同步微处理器的30%。     

Coupling properties in a 2-D photonic crystal slab directional coupler with a triangular lattice of air holes

Two-dimensional (2-D) photonic crystal (PC) directional couplers (DCs) that have a triangular lattice pattern of air holes in a planar dielectric slab are theoretically and experimentally analyzed. Unlike the 2-D PC DC structure with a dielectric rod in air, which is frequently used in theoretical studies, more practical PC DCs tend to be multimode in nature and exhibit a large group velocity dispersion, thus creating decoupling points in the dispersion relation without any additional modifications to the structure. The multimode nature and large dispersion lead to interference which degrades the coupling properties. By inserting three rows of air holes between neighboring line-defect waveguides in order to separate them, we have successfully reduced the multimode region and obtained a single-mode region. In this case, the large dispersion allows the creation of a PC DC with wavelength selectivity and a coupling length as short as 30 a,/spl sim/10 /spl mu/m for a=345 nm, where a is the lattice constant. The transmission spectra obtained experimentally showed good agreement with the theory whereas their transmission ranges were restricted to those of bent waveguides. These results are encouraging for practical application to optical communications.