The physical optical solution to the E-polarized diffraction by a composite wedge consisting of perfect conductor and lossless dielectric cannot sayisfy not only the boundary conditions at the wedge interfaces but also the edge condition at the wedge tip. Its diffraction coefficients are extended outside the composite wedge to become the exact solution to the perfectly conducting wedge as its relative dielectric constant increases to infinite or decreases to 1. It is assured that the extended diffraction coefficients approach zero in the arificially complementary region of the composite wedge.

The phusical optics approximation to an E-polarized diffraction by a composite wedge provides its diffraction coefficients in terms of finite series of cotangent functions. In this paper, its diffraction coefficients inside the dielectric part are extended to become the exact solution to the perfectly conducting wedge as its relative dielectric constant increases to infinite or decreases to 1. It is assured that the extended diffraction coefficients satisfy the boundary condition at th econducting interface and become zero in the artificially complementary region of the composite wedge.

A 10Gbit/s limiting amplifier IC for optical transmission system was implemented with AlGaAs HBT (heterojunction bipolar transistor) technology. HBTs with 2x10.mu. $m^{2}$ and 6x20.mu. $m^{2}$ emitter size were used. The HBT structures are based on metal-organic chemical vapor deposition (MOCVD) epitxy and employ a mesa structure with self-aligned emitter/base and sidewall dielectric passivation. IC was designed to support differnetial input and output. Small signal performance of the packaged IC showed 26dB gain and $f_{3dB}$ of 8GHz. A single ouput has 800m $V_{p-p}$ swing with more than 26dB dynamic range. The performance of the limiting amplifier was verified through single mode fiber320km transmission link test.est.

The performance degradation of CMOS differential amplifiers due to hot carrier effect has been measured and analyzed. Two-state CMOS amplifiers whose input transistors are PMOSFETs were designed and fabriacted using the ISRC CMOS 1.5.mu.m process. It was observed after the amplifier was hot-carrier stressed that the small-signal voltage gain and the input offset voltage increased and the phase margin decreased. The performance variation results from the increase of the transconductances and gate capacitances of the PMOSFETs used as input transistors in the differential input stage and the output stage and also resulted from the decrease of their output conductances. After long-term stress, the amplifier became unstable. The reason might be that its phase margin was reduced due to hot carrier effect.

Bump bonded piezoesistive silicon accelerometer was fabricated by the porous silicon micromachining and th eprocess technique of integrated circuit. The output voltage of the accelerometer fabricated on (111)-oreiented Si substrates with n/n$^{+}$n triple layers showed good linear characteristic of less than 1%. The measured sensitivity and the resonant frequency was about 743 .mu.V/g and 2.04 kHz, respectively. And the transverse sensitivity of 5.2% was measured from the accelerometer. Also, to investigate an influence on the output characteristics of the sensor due to bump bonding, the values of the piezoresistors were measured through thermal-cycling test in the temperature variation form -50 to 120.deg. C. Then, there was 0.014% resistance changes about 3.61 k.ohm., so sthe output charcteristics of the sensor was less affected by bump bonding.g.

A dadaptive refinement tetrahedron mesh has been presented for using in full band GaAs monte carlo simulation. A uniform tetrahedron mesh is used without regard to energy values and energy variety in case of the past full band simulation. For the uniform tetrahedron mesh, a fine tetrahedron is demanded for keeping up accuracy of calculation in the low energy region such as .GAMMA.-valley, but calculation time is vast due to usin gthe same tetrahedron in the high energy region. The mesh of this study, thererfore, is consisted of the fine mesh in the low energy and large variable energy region and rough mesh n the high energy. The density of states (DOS) calculated with this mesh is compared with the one of the uniform mesh. The DOS of this mesh is improved th efive times or so in root mean square error and the ten times in the correlation coefficient than the one of a uniform mesh. This refinement mesh, therefore, can be used a sthe basic mesh for the full band GaAs monte carlo simulation.

Electircal characteristics of HgCdTe photodiodes with a heterostructure to achieve high performance are analyzed numerically. A two-dimensional device simulator which can handle a HgCdTe heterostructure, was developed for this work. The effects of band nonparabolicity, carrier degeneracy, and band-offset of heterointerace are included in a carrier transport model. A unified generation-recombination model includes simultaneously phonon-assisted tunneling and pure tunneling of carriers via traps is newly employed for describing the electric field and temperature dependency of dark current effectively. Furthermore, to accurately predict the effect mole fraction variations on genration rates, ray-trace algorithm is incorporated in the our simulator. Under the various circumstances such as dark, illumination, and surface states, electrical properties of planar heterostructure photodiode are presented and those of homojunction are compared. These results serve as a explanation of cap layer's role on performance.

I $n_{0.53}$G $a_{0.47}$As/I $n_{0.52}$A $l_{0.48}$As pseudomorphic high electron mobility transistor (P-HEMT) structures were grown on semi-insulating InP substrates by molecular beam epitzxy method. The hall effect measuremetn was used to measure the electrical properties and the photoluminescence (PL) measurement was used to measure the electrical properties and the photoluminescence(PL) measurement for optical propety. By the cross-sectional transmission electron microscopy (XTEM) investigation of the V and X shape defects including slip with angle of 60.deg. C and 120.deg. C to surface in the sampel, the defects formation mecahnism in the I $n_{0.52}$A $l_{0.48}$As epilayers on InP substrates could be explained with the different thermal expansion coefficients between I $n_{0.52}$A $l_{0.48}$As epilayers and InP substrate.d InP substrate.

In this paper, the optical conditins of a reflective multi-color STN-LCD based on electrical control of birefringence is designed on the poincare sphere. First of all, the angles of polarizer and analyzer for the best color purity are decided in the configuration without a retardation film. A retardation film is introduced for a bright white in the range of the applied voltage. The sretardation and the angle of the retardation film are also decided on the poincare shpere. The test cell is farbricated and its measured spectral transmittance and the CIE chromaticity diagram agree well with simulations.

In this paper, we analyzed the crosstalk characteristics of LD array modules for WDM and improved the crosstalk levels using a screening line between access lines. From the calculation resutls, we have found that inductive crosstalk of access lines is dominant for the low impedance LD arrays with short bondwire interconnections. The proposed array interconnecton with the screening line and ouble bondwires, rduces the crosstalk level about 10dB compared to conventional interconnections using simple access lines and a single bondwire. This proposed structure also can be easily imlemented with transmission reliability.

Untill now, the most well-known cofiguration for waveguide grating router(WGR) is composed of radiative star couplers and arrayed waveguide grating(AWG), which usually suffer form the rdiation loss of around 3dB or more. Therefore, te improved design of WGRs is needed to reduce the loss. In ths paper, we propose a novel WGR composed of multimode interference couplers which have good unifiormity, fabrication tolerance, and very low excess loss, and suggest the efficient algorithm to find the proper path length differences of AWG for given channel spacing and channel assignment to each output prot. The simulated spectral responses of the proposed WGR using the finite difference beam propagation method (BPM) show that the excess loss is less than 0.3dB and the crosstalk less than -25dB in case of 4x4 WGR, and the excess loss less than 0.4dB and the crosstalk less than -25dB in case of 8x8 WGR for all the channel wavelengths.

As the need of automatized system has been increased recently together with the development of industrial and military technologies, the adaptive real-time target detection technologies that can be embedded on vehicles, planes, ships, robots and so on, are hgihly demanded. Accordingly, this paper proposes a novel approach to detect and segment the moving targets using the binary phase extraction joint transform correlator (BPEJTC), the advanced image subtraction filter and convex hull processing. The BPEJTC which was used as a target detection unit mainly for target tracking compensating the camera movement. The target region has been detected by processing the successful three frames using the advanced image subtraction filter, and has become more accurate by applying the developed convex hull filter. As shown by some experimental results, it is expected that the proposed approaches for compensation of the camera movement and segmentationof of target region, can be used for th emissile guiddance, aero surveillance, automatic inspectin system as well as the target detection unit of automatic target recognition system that request adaptive real-time processing.

Using the ray optics technique, we derive the analytic expressions of TE mode coupling coefficient for five-layer distributed feedback (DFB) structure devices. We compare the coupling coefficient calculated by the ray optics technique with those calulated by the extended additional layer method (EALM) which may be a most accurate method of calculating the coupling coefficient. The difference between the results of the ray optics technique and those of the EALM is small for most cases of grating depth and forms being practically made. In the case of rectangular gratings, the difference increases as the duty cycle of graing deviates from 0.5. In the case of the trapezoidal grating, the difference increases as the ratio of the top to the period of grating deviates from 0.5 and as the length of the top becomes longer than that of the base. The difference of theree-layer DFB structures is smaller than that of five-layer DFB structures.