• Korean Journal of Optics and Photonics
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• v.5 no.3
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• pp.394-403
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• 1994

Chaos characteristics of laser diodes with external optical feedback is investigated. For a FabryPerot resonator laser, optical feedback by external mirror is assumed. The simulation is performed in such a way that a current of $1.3J_{th}$ is injected into the $1.3{\mu}m$wavelength "InGaAsP" buried hetero structure laser. With the increment of K, the system shows the evolution of four steps as follows: i) When the optical feedback coefficient K is very small, the relaxation oscillation is damped and the system reaches the steady state showing the stable operation characteristics. ii) As K increases a little bit, the relaxation oscillation is not damped any more and the system begins to maintain the periodic oscillation. iii) When K is increased further, the oscillation shows the larger amplitude and the long periodic length. iv) When K is increased very large, the system gets unstable and enters into the coherejlce collapse state. state.

• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.38-39
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.260-261
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.166-167
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• 2001

과장 변환기는 WDM (wavelength division multiplexing) 시스템에서 wavelength relocation을 가능하게 하여 시스템의 유연성과 효율성을 향상시킨다는 측면에서 매우 중요한 기능을 갖는다. WDM 시스템의 채널의 수가 점차 증가함에 따라 채널의 간격이 100 GHz에 이르고 있으며 향후 더욱 조밀해 질것이다. 이러한 DWDM (Dense WDM)시스템에서 사용될 수 있는 파장변환기는 100 GHz단위의 파장변환 기능과 광대역 가변 변위가 필수적이다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.315-316
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• 2006

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.313-314
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• 2006

• Korean Journal of Optics and Photonics
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• v.9 no.2
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• pp.96-99
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• 1998

In this study, a novel long term stabilization method of optical feedback for the resonant cavity coupled semiconductor lasers is proposed, and its utility was shown experimentally. The proposed method is realized by using the pahse discriminator of optical feedback with high gain. The phase discriminating signal was obtained by the polarization spectroscopic technique using reflection light from the external reflector, which is a confocal Fabry-Perot cavity. Experimental result shows that stable control state can be maintained up to 20 hours. The period can be increased by reducing size of the system and/or fixing position stably of optical parts used, which were arranged on an optical table by using magnetic bases in this experiment. The proposed long-term stabilization method of optical feedack of a resonant external cavity coupled semiconductor laser is very useful for the field of high sensitivity measurement, and for the use in the laboratory level in particular.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.296-301
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• 1995

A single-mode erbium-doped fiber laser is constructed by using a intracore fiber Bragg grating and a unidirectional fiber loop mirror. The laser cavity is designed in such a way that the laser beam forms a travelling wave in the gain medium by placing the erbium-doped fiber inside the unidirectional loop and that the wavelength-selective feedback is made from the outside of the loop by a fiber grating with 0.2 nm reflection linewidth. An additional fiber ring resonator is constructed and used as an optical spectrum analyzer to observe the variation of the laser mode spectra. As the result, relatively stable single mode, single polarization output is observed for the most of the time except some mode hoppings in minute scale due to enviommental temperature variations. tions.

• Korean Journal of Optics and Photonics
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• v.4 no.3
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• pp.330-337
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• 1993

Figure '8' type, passively-mode-locked erbium-doped-fiber ring laser was developed, incorporating a nonlinear loop mirror. Transmittance of the loop mirror was found to be dependent on the incident light intensity due to the non-reciprocal nonlinear phase shift, which enables the passive mode locking of the laser. Self-starting of stable mode locking was possible with only controlling the polarization controllers inside the cavity without any help of external perturbation or modulation. The mode-locked output pulse shape was discussed in relation with the transmission characteristics of nonlinear loop mirror.

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.66-72
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• 1993

Additive-pulse mode-locking (APM) was performed in a $1.053{\mu}m$ cw Nd:YLF laser by coupling a nonlinear external external cavity to the main cavity. The APM pulsewidth was 4.5 ps and the average output power was 1.5 W. This APM pulse was compressed by an optical fiber and a grating pair to be as short as 210 fs with a peak power of 17 kW.