• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.178-179
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• 2003

단일기본모드 수직공진표면광레이저(VCSELs)는 광네트워크, 광연결, 광저장 및 레이저 프린팅 등 다양한 분야에 응용이 가능한 소자로서 많은 관심과 연구가 증대되고 있다. 일반적으로 VCSELs은 공간홀버닝(spatial hole burning)과 열 렌즈효과(thermal lensing)로 인하여 단일기본모드로 동작하기가 쉽지 않다. 지금까지 여러 가지 연구가 진행되고 있는데 대표적인 예로서 VCSEL의 공진기를 길게 하거나 출력경 표면을 정교하게 식각하는 방법, 그리고 이온 주입구경과 산화막을 함께 사용한 것들이 있다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.24-25
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• 2001

광 밴드 갭(photonic band gap)을 가지는 광 결정(photonic crystal)을 이용하여 만들어진 미세 공진기(micro-resonator)를 통해 상온 연속 동작하는 레이저가 최근 개발되었다. 이 미세 공진기는 이득매질(gain medium)이 성장된 반도체의 기판방향과 기판에 수직한 방향을 각각 이차원 광 결정과 판 도파로(slab waveguide) 구조의 전반사를 이용하여 제한하는 구조이다 이러한 광 밴드 갭 공진기의 공진 모드는 그 동안 계산적인 방법을 통해 이론적으로 연구되어 왔으며, 직접 모드의 특성을 측정하는 실험의 필요성이 크게 대두되고 있다. 본 연구에서는 광 밴드 갭에 의해 형성된 2차원 미세 공진기내에서 레이저 발진된 모드의 특성을 먼장 영역(far-field regime)에서 측정 분석한 결과를 보고한다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.52-53
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• 2005

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.31-36
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• 2004

In comparison with in-plane lasers, predicting the output power and differential quantum efficiency of Vertical-Cavity Surface-Emitting Lasers(VCSELs) is very difficult due to the distributed Bragg reflector(DBR) layers. Therefore, effective cavity model and transfer matrix method have been adapted in order to calculate the output power and differential quantum efficiency The effective cavity model is inappropriate to calculate output power and differential quantum efficiency while it is practically adequate to calculate the threshold gain and threshold current density The reason is that the effective cavity model can not take account of the absorption in GaAs stack layer right below the metal aperture. In this paper, we have compared the threshold current and differential quantum efficiency calculated by using transfer matrix method with effective cavity model and we have made a study of the validity of the effective cavity model. Finally, we have confirmed the versatility of the transfer matrix method with these studies.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.62-63
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• 2002

파장가변 색소 레이저 발진기는 반사형 회절격자에 비스듬히 입사하는 Grazing Incidence형 공진기 구조로 설계되었다.[1-2] 색소용액이 고속으로 순환되는 색소 셀에 여기광인 레이저 광원을 입사시키는 방법은 색소 셀과 색소 용액 순환방향 및 펌핑 광의 방향이 서로 수직을 이루도록 구성되어 있다. 또한, 두 개의 펌핑 광을 양방향에서 동시에 입사시킬 수 있도록 함으로써, 색소 셀 내부의 색소 용액이 여기 광을 균일하게 흡수하도록 설계하였다. (중략)

• The Journal of Natural Sciences
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• v.8 no.1
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• pp.23-26
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• 1995

Operating characteristics of a $Cr^3+$:LiASF laser pumped by 640 nm and pulsed DCM dye laser are observed. The laser consists of a 93% reflectivity of half mirror and a total reflector, and the length between two mirrors is 3cm. Maximum efficiency is 10% for 22 mJ of pumping energy and the maximum slope efficiency is 19%.

• Journal of the Korean Institute of Telematics and Electronics
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• v.3 no.4
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• pp.16-24
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• 1966

The LASER Amplifier is treated in the manner of a Fabry-Perot Resonator with an active media, five layers are considered: air, reflector, active medium(ruby), reflector and air. One dimensional scalar wave equations are derived using the method of boundary value probrems in which it is assumed that incident coherent radiation falls normally on the surface wall. All equations are treated from the transient analysis point of view using the Laplace transform nethods, and are arranged steady state region as an amplifier and transient region as a self excited oscillator. Also some remarks are given on the design problem of LASER amplifier in connection with the transient terms involved.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.1
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• pp.35-46
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• 2004

In comparison with edge-emitting lasers(EELs), predicting the output power and slope efficiency of Vertical-Cavity Surface-Emitting Lasers(VCSELs) is very difficult due to the absorption loss in DBR layers. However, by using transfer matrix method(TMM), we've made possible to calculate such parameters of multi-layer structures like VCSELs. In this paper, we've calculated the threshold gain, threshold current and slope efficiency through the methodology based on TMM. Also TMM is the way of customizing the VCSEL structure for the desired threshold current and slope efficiency by changing the number of DBR mirror layers.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.12
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• pp.19-26
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• 2005

We have studied the relationship between static mode behavior and dynamic characteristics of multiple transverse-mode VCSELs by measuring the modal L-I and I-V characteristics. Dependence of the resonance frequencies of RIN (relative intensity noise) spectra on the injection current can be understood by modal L-I characteristics and mode-coupling effects. Each transverse mode behaves as an independent diode laser with the different threshold current in large active-area VCSELs, and the multiple-step turn-on is observed when step-current input is applied. This multiple-step turn-on is a result of different turn-on delay times of the transverse modes. Since the multiple-step turn-on increases the rise-time significantly, the wide active-area VCSELs are not suitable for high-speed optical transmitters unless the input current is adjusted for single transverse-mode operation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.10-21
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• 2006

We have studied the characteristics of oxide VCSELS when their off-current and on-current are kept small in order to find out the possibility of low current operation. A large signal equivalent circuit model has been used. By comparing measured data and simulation results, the parameters of the large signal models are obtained including the capacitances. Using the large signal model, we have investigated the effects of capacitance and on/off currents upon the turn-on/turn-off characteristics and eye diagram. According to the experiment and simulation, the depletion capacitance, which has been neglected, is found to have significant influence on the him-on delay and eye-diagram. Therefore, for high speed and low current operation, the reduction of the depletion capacitance is essential.