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半導體 레이저 다이오드의 位相雜音과 스펙트럼 線狀에 關한 硏究
洪玩熹 서울市立大學校 1984 論文集 Vol.18 No.-
Phase noise phenomena in semiconductor lasers is of primary importance when employing these devices as sources in cherent/heterodyne optical communication systems. This kind of noise is responsible for the source spectrum linewidth in single mode semiconductor lasers. In Section Ⅱand Ⅲ, we calculate <Δφ²(t)> due to spontaneous emission and explain and derive the spectral linewidth in semiconductor lasers. In Section Ⅳ and Ⅴ, we relate the power spectrum of the laser to <Δφ²(t)> and present the results. In conclusion, the linewidth and line shape of the semiconductor laser power spectrum can be estimated.
洪玩憙 서울市立大學校 1992 論文集 Vol.26 No.-
In this paper, the method to realize the coherent/heterodyne optical BFSK(Binary Frequency Shift Keying) transmitter is suggested by using the DFM(Direct Frequency Modulation) characteristics of LD(Laser Diode). DFM characteristics of LD are measured with in the 10KHz-100MHz by F-P(Fabry-Perot) interferometer. The optimized equalizers that can make the LD's DFM transfer function uniform were designed by use of a simple passive network. The BFSK transmitter consists of temperature stabilized laser diode and optimally designed equalizer. It is modulated by 100Mbit/s PRBS(Pseudo Random Bit Sequence) generator to diagonosis of optical BFSK transmitters output characteristics. To evaluate the performance of the transmitter, the transmitted data and their pattern are compared with the received data and their eye pattern. As the results, the data transfer rate is more than 100Mbit/s.
洪玩熹 서울市立大學校 1989 論文集 Vol.23 No.-
The influence of device circuit interactions on the dynamic response of a direct modulated semiconductor laser. can be evaluated using a circuit modeling approach. In this paper, small signal circuit models for IM and FM of semiconductor laser(HLP1400) are proposed and evaluated. Especially, we describe a new circuit modeling techniques for obtaining the small signal frequency modulation response, which includes the effect of the temperature and the carrier density in the active region. The simulation results with these models are compared with published experimental results of IM and FM in the range from DC to 3GHz, and show good agreements.
헤테로다인 광통신 방식을 위한 반도체 레이저의 주파수-출력 안정화에 관한 연구
홍완희,반재경,박한규 한국통신학회 1986 韓國通信學會論文誌 Vol.11 No.3
In this paper, a new method is suggested to stabilize the frequency of semiconductor laser diode for heterodyne optical communication systems. In order to stabilize the frequency of semiconductor laser, the method of the injection current controal has been widely used, in which the laser frequency is locked to a F-P interferometer. By adding another servoloop to stabilize the output power of semiconductor laser, we could stabilize the laser frequency and the output power simultaneously and the frequency stability is improved by a factor of fice times. 本 論文에서는 半導體 레이저를 使用하여 헤테로다인 光通信 方式을 具現시키기 爲하여 必要한 半導體 레이저의 發振周波數 安定化 시스템을 이제까지의 周波數 安定化만을 考慮한 方式에서 光出力 安定化를 爲한 歸還回路를 追加하므로서 旣存의 周波數 安定化만을 考慮한 方式에서보다 周波數安定度를 約5倍 改善시켰다.
VLSI의 收率增大를 위한 PMOS IC 프로세스 진단에 관한 연구
홍완희,김창민,김철주,노승용,김성환 서울市立大學校 1987 論文集 Vol.21 No.2
In this paper, the PMOS IC process check through various fabrication processes were dicussed. The Si water used process was estimated by the surface cleanness and bulk crystalline properties. For the photolihography process and photomask fabrication, the process cleanness was estimated. The control technology of process parameters from process cleanness in oxidation, CVD(chemical vapor diposition), diffusion and Al evaporation process was described. To estimate synthetically the process, the MOS and planar diode and PMOS transistor array were fabricated, and then the maximun yield of IC was assumed by the minimum number of bad transistor and diode.
F-P 간섭계를 이용한 반도체 레이저의 출력-주파수 동시 안정화에 관한 연구
홍완희,홍기룡,황문수,전광석 서울市立大學校 1987 論文集 Vol.21 No.2
본 논문에서 최근 반도체 레이저를 광산업분야에 특수 분야인 공해 모니터 시스템, 레이저 자이로스코우프, 정밀도량형기, 코히어런트 광통신 시스템의 발광소자로 사용하기 위해 요구되고 있는 주파수 안정도를 개선하기 위한 새로운 방법을 제시하였다. 반도체 레이저의 주파수 안정도를 개선하기 위하여 이제까지 광출력이 안정하다는 가정하에 광출력을 기준으로 F-P간섭계에 레이저 주파수를 고정시키는 주입전류 제어 방식이 널리 쓰여 왔으나 주파수 안정시에도 광출력은 미세하나마 드리프트 하는 현상을 나타낸다. 이는 주파수 안정시 기준 변동 요인이 되어 주파수 안정도를 저해하므로 높은 안정도를 얻기 위하여 광출력을 안정시키기 위한 출력 안정화 궤환제어기를 부가하므로 기존의 안정화만을 고려한 방식에서 보다 주파수 안정도를 약 5배 개선 시켰다.
散亂行列을 利用한 超高周波 트란지스터 增幅器의 安定度 및 設計方式에 對한 硏究
洪玩憙,金昌敏,金興洙 서울市立大學校 1983 論文集 Vol.17 No.-
Scattering parameters make it easy to characterize the high frequency performance of transistors. Stability is most important in amplifier design and is determined from the S-parameters and the synthesized source and load impedances. This article described the properties of microwave amplifiers using scattering matrices and explains a procedure used to design amplifiers with the aid of the computer. This program is very simple and useful to all designers. The amplification characteristics of the realized amplifier using this program are in good agreement with the theoretical ones.
Noncommensurate line을 이용한 Microstrip elliptic function bandstop filter에 관한 연구
김창민,홍완희,배명진 서울市立大學校 1984 論文集 Vol.18 No.-
In realizing a elliptic function filter, the procedure of a resonant type filter using the λ/8 commensurate line was formerly reported. In this paper, the author tries another method, that is, "non-commensurate line filter synthesis", which is the approximation method of a resonant type-filter. The result shows a satisfactory characteristics of elliptic function the edge skirt of which rises up very sharply. Center frequency of a bandstop filter is a 2.1 GHz, B.W. is 8%, and minimum attenuation shows 25 dB.