• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.5
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• pp.46-53
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• 2002

A novel ultra-narrow linewidth single longtudinal mode DFB semiconductor laser in the extended FBG cavity is proposed. The 3㏈ linewidth of 20KHz was demonstrated by using self-heterodyne measurement set-up with a fiber delay line of 63km. And this linewidth was further compressed to less than 3KHz, which is resolution limited performance, by inserting E $r^{+3}$ doped fiber saturable absorber. This is equivalent to 3㏈ linewidth of 2$\times$10$^{-8}$ nm.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.10
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• pp.806-813
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• 1991

In this paper, we suggested the diagnosis of the optical FSK transmitter output characteristics using the Micheloson interferometer. The transmitter is designed by the direct frequency modulation effect of a semoconductor laser diode. The optical FSK transmitter consists of a temperature stabilized semiconductor laser diode and an optimally designed equalizer. It is modulated by 100Mbit/s PRBS Generator to diagonosis of Optical FSK transmitter output characteristics. The Michelson Interferometer is used for the optical frequency discriminator which transforms the output frequency of the transmitter to the amplitude of light. The measurement of the performance of the transmitter to the amplitude of light. The measurement of the performance of the transmitter computer the transmitted data and their eye pattern with the simulation results, the received data and their eye pattern. As the result of experiment, the data transfer rate of the transmitters is 100Mbit/s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.203-205
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• 2003

레이저 다이오드를 p-side-down 방식으로 본딩하기 위하여 AuSn 솔더합금을 증착한 후 온도와 압력, 시간을 변화시켜 본딩상태를 조사하였다. CuW위에 adhsion layer와 확산방지층을 각각 $500{\AA}$과 $2000{\AA}$을 증착하였으며 솔더층으로 AuSn을 $2.6{\mu}m$ 증착 하였다. 열처리는 질소 분위기에서 행하였으며, 표면의 거칠기는 AFM으로 측정하였다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.2
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• pp.103-106
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• 2000

ZnO is a wide-bandgap II-IV semiconductor and has a variety of potnetial applications. ZnO exhibits good piezoelectric, photoelectric and optical properties, and is a good candidate for an electroluminescence device. ZnO films have been deposited on (001) sapphire by PLD technique. Nd:YAG pulsed laser was operated at a wavelength of $\lambda=355nm$. The ZnO films were deposited at oxygen pressures from base to 500 mTorr. The substrate temperatures was increased from $200^{\circ}C\; to\;700^{\circ}C$ films showed strong UV emission by increasing the partial oxygen pressure. We have investigated the relationship between partial oxygen pressure and the intensity of UV emission.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.9
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• pp.1068-1073
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• 1988

PIN-Photodiodes were fabricated with CO2 laser annealed SOI and their electric characteristics were measured. Dark current decreased and photocurrent-dark current ratio increased as the grain size of polycrystalline silicon in intrinsic region increased. In case of the largest grain, 10-20um, dark current was 30 n A (at - 4V) and photocurrent was proportional to light intensity.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1727-1729
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• 2000

We has investigated the birefringence by the assisted electric field effect on $As_{40}Ge_{10}Se_{15}S_{35}$ thin films. Photoinduced birefringence has been studied in a chalcogenide material. We induced this thin films using linearly polarized He-Ne laser light(633nm) and detected polarized semiconductor laser light(780nm). To investigate the effect of electric field, various bias voltages applied. The result is shown that the birefringence has a higher value in +2V than others. We obtained the birefringence in the electric field effects by various voltages.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.364-369
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• 2005

In the semiconductor and optical industry the non-contact transportation is required for reducing the damages. The ultrasonic levitation is the solution of the problem. In this paper, the ultrasonic levitation system and 3 disk-type stator for levitation various object are proposed. The vibration modes of disks are analyzed with FEM and designed with the analysis results. The 3D vibration profiles of the disks are measured by Laser scanning vibrometer for verifying the vibration characteristics of the system. The amplitudes of the disks and the levitation heights of object are measured for evaluating the performance.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.399-404
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• 1996

We developed a non-contact shape measuring device using computer image processing technology. We present a method of calibrating a CCD video camera and a laser range finder which is the most important step toward making an accurate shape measuring system. An artificial neural network is used for the calibration. Our measurement system is composed of a semiconductor laser. a CCD video camera, a personal computer, and a linear motion table. We think that the developed system could be used for measuring the change in shape of the spent nuclear fuel rod before and after irradiation which is one of the most important tasks for developing a better nuclear fuel. A radiation shield is suggested for the possible utilization of the range finder in radioactive environment.

• Journal of the Optical Society of Korea
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• v.12 no.4
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• pp.303-308
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• 2008

Directly modulated fiber-optic links generally suffer higher link loss and larger signal distortion than externally modulated links. These result from the electron-photon conversion loss and laser modulation dynamics. As a method to overcome the drawbacks, we have experimentally demonstrated the RF performance of directly modulated, ultra-strong injection-locked gain-lever distributed Bragg reflector (DBR) lasers. The free-running DBR lasers exhibit an improved amplitude modulation efficiency of 12.4 dB under gain-lever modulation at the expense of linearity. By combining gain-lever modulation with ultra-strong optical injection locking, we can gain the benefits of both improved modulation efficiency from the gain-lever effect, plus improved linearity from injection locking. Using an injection ratio of R=11 dB, a 23.4-dB improvement in amplitude response and an 18-dB improvement in spurious-free dynamic range have been achieved.

• Korean Journal of Optics and Photonics
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• v.23 no.1
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• pp.42-51
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• 2012

In this paper, injection-locking characteristics versus active layer structures in Fabry-Perot laser diodes (FP-LD) are compared. TE and TM gain spectra and peak gains versus carrier density in polarized and unpolarized multiple quantum well structures and in an unpolarized bulk structure are calculated. The calculated gain parameters are applied to a time-domain large-signal model to simulate the injection-locking characteristics. The results show that RIN in unpolarized FD-LDs is about 3 dB lower than that in a polarized FP-LD and that the eye characteristics of the unpolarized FP-LD are much better than those of the polarized FP-LD.