• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.86-87
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• 2003

단일 소자로 외부의 제어회로를 통해 여러 파장으로 발진파장을 제어할 수 있는 파장가변 레이저 다이오드는 고정된 파장으로 발진하는 레이저 다이오드에 비해 여러 경제적 이점을 가지며 보다 유연한 광 네트워크의 구성이 가능하게 한다. 이러한 이유로 현재까지 다양한 구조의 파장가변 레이저 다이오드가 제안되고 개발되어 왔다. 본 논문에서는 새로운 구조의 광대역 파장가변 레이저 다이오드를 제안하였다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.11-17
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• 1995

반절연 InP를 전류 차단층으로 사용하는 초고속 변조 Distributed Feedback (DFB) 레이저의 다이오드를 제작 하였다. Grating이 형성된 InP 기판에 유기금속 증착법 (MOVPE)을 사용하여 다중 양자 우물 구조 성장 시켜 메사구조를 연성 한후, 전류 차단층으로 반절연 InP를 성장 하였다. 제작된 레이저 다이오드는 평균 문턱전류 10 mA, 기울기효율 14%이며, 30mA 구동 전류에서 10GHz 이상의 3dB 대역폭 특성을 보였다.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.154-155
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• 2002

완전 광 3R(Retiming, Reshaping, Reamplification) 재생기는 WDM 시스템과 광 네트워크의 크기를 확장시키기 위하여 필요한 매우 중요한 소자이다. 완전 광 3R 재생기의 구현에서 입력 광 신호로부터 광 클락 추출은 가장 핵심적인 요소이다. 이러한 광 클락 추출을 위하여 모드락 레이저 다이오드와 다중 전극 DFB 레이저에서 self-pulsating 현상을 이용하는 방법이 많이 연구되고 있다. 독일의 HHI는 다중 전극 DFB 레이저에서 self-pulsating 현상을 이용하여 80 GHz 초고속 광 클락 추출과 25-82 GHz 전기적 튜닝 특성을 보였다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.160-161
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• 2003

완전 광 3R(Retiming, Reshaping, Reamplification) 재생기는 WDM 시스템과 광 네트워크의 크기를 쉽게 확장시키기 위하여 필요한 매우 중요한 소자이다. 완전 광 3R 재생기의 구현에서 입력 광 신호로부터 광 클락을 추출하는 기술은 매우 중요한 기술이다. 이러한 광 클락 추출기술을 구현하기 위하여 모드락 레이저 다이오드와 다중 전극 OFB 레이저에서 self-pulsation 현상을 이용하는 방법이 많이 연구되고 있다. 모드락 레이저 다이오드를 이용한 방법은 모드 락킹 주파수가 레이저의 공진기의 길이에 의해서 결정되기 때문에 공진기의 길이를 정확하게 조절해야 한다는 단점을 가지고 있는 반면에 다중 전극 DFB 레이저의 경우 self-pulsation 주파수를 전기적으로 튜닝할 수 있다는 장점을 가지고 있다. (중략)

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.149-157
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• 2004

We have calculated the power extraction efficiency and the lasing wavelength distribution of complex-coupled(CC) DFB lasers above threshold for various｜$\chi$L｜ and facet reflectivity combinations, and we have compared the results with those at threshold. Also, we have investigated the effect of coupling coefficient ratio(CR) and the reflectivity of AR facet on the power extraction efficiency and the lasing wavelength distribution. At threshold, the single mode yield as a function of power extraction efficiency of in-phase(IP) CC DFB lasers is the same as that of anti-phase(AP) CC DFB lasers. Above threshold, however, the single mode yield as a function of power extraction efficiency of IP CC DFB lasers is much larger than that of AP CC DFB lasers. For IP CC DFB lasers, AR-HR combination has high single mode yield and large power extraction efficiency compared to other facet combinations. IP CC DFB laser with AR-HR combination for ｜$\chi$L｜of 0.8 has the highest single mode yield and largest power extraction efficiency above threshold among the cases considered. For AR-HR combination, as CR increases and the reflectivity of AR facet decreases, both single mode yield and power extraction efficiency increase due to the reduction of the spatial hole burning effect. For AR-HR combination, the lasing wavelength of CC DFB laser has distributed over the stopband of DFB. As CR increases, the lasing wavelength concentrates on the long wavelength side for IP CC DFB laser, while on the short wavelength side for AP CC DFB laser. As ｜$\chi$L｜ increases, the width of the wavelength distribution decreases and the lasing wavelength moves to the long wavelength side.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2426-2438
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• 1994

In this paper we present for the first time the electric circuit model for direct frequrncy modulation(FM) response of the conventional distributed-feedback(DFB) semiconductor laser diodes. Especially, in this paper, the proposed model includes not only the carrier density modulation effect, but also the temperature modulation effect determining the DFM characteristics of DFB characteristics of DFB semiconductor lasers. The DFM response due to injection current modulation was obtained as a function of modulation frequency from DC to a few GHz. The circuit model representing the temperature modulation effect is obtained from the structure of DFB LD chip and the simulation results are compared with the published experimental results. The circuit model representing the temperature modulation effect is obtained from the structure of DFB LD chip and the simulation results are compared with the published experimental results. The circuit model representing carrier density modulation effect is obtained from the rate equations of DFB lasers and the simulation results are compared with the results that were obtained by the conventional numerical analysis approach. The results showed good agreements.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.483-488
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• 2022

In this paper, when a gain grating and a refractive index grating exist simultaneously in a DFB laser diode having a wavelength of 1.55 ㎛, an anti-reflection coating is applied to the right mirror surface so that ρ_r=0. In case of δL<0, the characteristics of the oscillation frequency and oscillation gain have been analyzed. Whenever the phase of the grating on the left side of the mirror continuously decreases by π/2, the δL value of each oscillation mode decreases by about 0.6 to the left of the graph lines of each oscillation mode. The case of the oscillation mode having the lowest threshold gain is the case of κL=10, and in this case, the mode selectivity is relatively low compared to the case of other values of κL. From κL=0.1 to κL=6, the mode selectivity and the frequency stability are excellent. As the mode selectivity is excellent, the frequency stability is excellent. Compared to the case with two cleaved mirrors, the DFB laser diode with anti-reflection coating increases the threshold gain of the oscillation mode by about 2 times, but the mode selectivity becomes about 2 times better.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.327-332
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• 1997

We fabricated the high speed 1.55${\mu}{\textrm}{m}$ distributed feedback laser diodes (DFB-LD) using both two-step mesa etching process and semi-insulating InP current blocking layers. The devices characteristics were threshold current of ~15mA, slope efficiency of ~0.13mW/mA, and dynamic resistance of ~6.0Ω, with as-cleaved facets. The fabricated DFB-LD showed the single longitudinal mode with more than 40dB up to 6 $I_{th}$(CW condition), emitting at the wavelength of 0.546${\mu}{\textrm}{m}$. The -3dB bandwidth was >10㎓ at the driving current of 27mA, and the maximum -3dB bandwidth was ~18㎓ at 90 mA current, showing the superior frequency response of SI-PBH DFB-LD. In the 10Gb/s transmission experiment for 1.55${\mu}{\textrm}{m}$ DFB-LD module, maximum 10 km of single mode fiber(SMF) or 80 km of dispersion shifted fiber (DSF) could be transmitted with error free.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.7
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• pp.17-28
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• 2000

A novel and efficient approach for the numerical solution of time-dependent coupled-wave equations, which are frequently used for the modeling of DFB(Distributed Feedback), DBR(Distributed Bragg Reflector), and FP(Fabry Perot) laser diodes, is proposed. In this approach, the coupled wave equations are split into two sets of equations. One of two sets of equations contains only the phase factors and the other contains only the coupling terms. The separate equations are solved exactly in their split form successively. This new numerical scheme, which we call the SS-TDM(Split-Step Time Domain Model), is found to require an order of magnitude smaller number of subsections to get accurate results than the previous methods while the computation time for each time step is comparable to the previous methods.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.521-529
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• 2003

For complex-coupled (CC) DFB lasers, we found that there might be little correlation between the single mode yields at threshold and above threshold. At threshold, the single mode yield considering f number of in-phase (IP) CC DFB lasers is the same as that of anti-phase (AP) CC DFB lasers. However, the single mode yield as a function of injection current above threshold of IP CC DFB lasers is much different from that of AP CC DFB lasers. In the case of IP CC DFB lasers, the single mode yield increases as the coupling coefficient ratio (CR) increases, while, in the case of AP CC DFB lasers, the single mode yield decreases rapidly regardless of CR as the injection current increases. In the case of AR-HR combinations, the effect of AR ref1ectivity on the single mode yield increases as the coupling strength decreases. As the coupling strength decreases, the CR at which the increase rate of the single mode yield starts to decrease, increases, and the maximum single mode yield increases. Single mode yields of AR-HR and AR-AR combinations are larger than those of AR-CL and CL-CL combinations.