• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
• /
• pp.1094-1097
• /
• 2003

In this paper, the cavity-length-dependent spectral and temporal characteristics of a V-groove AlGaAs-GaAs quantum wire (QWR) laser at each subband were investigated. At short cavity lasers less than $300{\mu}m$, a discrete wavelength switching from the n=1 to the n=2 subband occurred due to the increased threshold gain, resulting from the increased cavity loss. Using the characteristic of the wavelength shift from n=1 to the n=2 subband with shortening the cavity length, ultrafast lasing behaviors under gain switching at the n=1 and the n=2 subband transition were demonstrated and compared.

• 한국정보통신학회논문지
• /
• 제9권4호
• /
• pp.861-864
• /
• 2005

광위상변조기를 이용하여 OCT용 초고속 광지연단을 설계하고 수치해석을 수행하였다. 수치해석은 electro-optic 위상 변조기에 1310nm, 10ps의 펄스폭을 갖는 레이저 광원을 적용하여 수행하였다. 수치해석결과로 500MHz의 변조 주파수일때 19ps의 시간 지연을 얻었으며, 이는 기존의 기계적 검출 방식(수십kHz)의 OCT장치에 비해 1000배이상 빠른 검출이 가능할 것으로 예상된다.

• Journal of Photoscience
• /
• 제4권1호
• /
• pp.11-16
• /
• 1997

We measured, using femtosecond pump-probe experiment, the time evolution of transient absorption in aqueous CdS colloids. The signal rises within the time resolution (= 0.5 ps) of the experiment and decays with two exponential time constants, 4.8 ps and 132 ps. The ultrafast rise of the transient absorption is considered to be for shallowly trapped conduction band electrons after photoexcitation. The amplitude ratio of the two decaying components varies with the pump intensity and the decay times increase in the presence of hole scavengers. Even though a biexponential function fits the decay well, we object hat two independent first order processes (geminate and nongeminate recombinations) are responsible for the decay. A function with an integrated rate equation for second order nongeminate recombination plus a long background fits the decay well. The long background is considered to be for deeply trapped charges at the CdS particle.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
• /
• pp.54-55
• /
• 2001

Recently, there has been much interests in InGaN/GaN multiple-quantum-well (MQW) structures due to their applicability as optoelectronic devices such as light-emitting diodes (LEDs) and laser diodes [1]. Their ultrafast and physical properties are also of significant interests. Anomalously large acoustic phonon oscillations have been observed using ultrafast lasers in InGaN MQWs [2]. In this study, we have peformed femtosecond pump-probe experiments in the reflection geometry on 5 periods InGaN/GaN MQW LED structure with well width of 20$\AA$ and barrier width of 100$\AA$ at room temperature. (omitted)

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2005년도 춘계종합학술대회
• /
• pp.438-440
• /
• 2005

광위상변조기를 이용하여 OCT용 초고속 광지연단을 설계하고 수치해석을 수행하였다. 수치해석은 electro-optic 위상 변조기에 1310nm, 10ps의 펄스폭을 갖는 레이저 광원을 적용하여 수행하였다. 수치해석결과로 500MHz의 변조 주파수일때 19ps의 시간 지연을 얻었으며, 이는 기존의 기계적 검출방식(수십kHz)의 OCT장치에 비해 1000배이상 빠른 검출이 가능할 것으로 예상된다.

• 한국광학회:학술대회논문집
• /
• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
• /
• pp.55-58
• /
• 1989

The methods of recording transient phenomena with picosecond or better resolution fall into two basic categories: those in which the detector itself prossesses adequate time resolution for the task at hand, and those in which the response of the system is sampled by examining the characteristics of a second pulse ("the probe") delayed in time from the initiating pulse ("the pump") as a function of time delay between pump and probe cases. In this case the time resolution is only limited by the pump-and probe-pulse durations. As an application of this time-resolved spectroscopic technique, the ultrafast orientational relaxation phenomena of the dye molecules are currently under investigation in our laboratory. In this presentation the status of our experiment is summarized.iment is summarized.

• 한국전기전자재료학회논문지
• /
• 제35권4호
• /
• pp.322-332
• /
• 2022

Energy storage capacitors based on dielectric ceramics with superior polarization properties and dielectric constant can provide much higher output power density due to their very fast energy charging/discharging rates, which are particularly suitable for operating pulsed-power devices. For an outstanding energy storage performance of dielectric capacitor, a large recoverable energy density could be derived by introducing a slim polarization-electric field hysteresis loop into dielectric materials by various technical approaches. Many research teams have explored various dielectric capacitor technologies to demonstrate high output power density and ultrafast charging/discharging behavior. This article reviews the recent research progress in high-performance dielectric capacitors for pulsed-power electronic applications.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 추계학술대회 논문집
• /
• pp.749-750
• /
• 2008

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
• /
• pp.116.2-116.2
• /
• 2007

• 대한의용생체공학회:의공학회지
• /
• 제37권5호
• /
• pp.168-177
• /
• 2016

In this paper we present an implantable pressure sensor to measure real-time blood pressure by monitoring mechanical movement of artery. Sensor is composed of inductors (L) and capacitors (C) which are formed by microfabrication and direct bonding on two biocompatible substrates (quartz). When electrical potential is applied to the sensor, the inductors and capacitors generates a LC resonance circuit and produce characteristic resonant frequencies. Real-time variation of the resonant frequency is monitored by an external measurement system using inductive coupling. Structural and electrical simulation was performed by Computer Aided Engineering (CAE) programs, ANSYS and HFSS, to optimize geometry of sensor. Ultrafast laser (femto-second) cutting and MEMS process were executed as sensor fabrication methods with consideration of brittleness of the substrate and small radial artery size. After whole fabrication processes, we got sensors of $3mm{\times}15mm{\times}0.5mm$. Resonant frequency of the sensor was around 90 MHz at atmosphere (760 mmHg), and the sensor has good linearity without any hysteresis. Longterm (5 years) stability of the sensor was verified by thermal acceleration testing with Arrhenius model. Moreover, in-vitro cytotoxicity test was done to show biocompatiblity of the sensor and validation of real-time blood pressure measurement was verified with animal test by implant of the sensor. By integration with development of external interrogation system, the proposed sensor system will be a promising method to measure real-time blood pressure.