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High-power SLD-based BLS Module for WDM-PON Applications
허두창,윤인국,이정석,이재훈 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.3
We developed polarization-independent high-power superluminescent diode (SLD)-based broadband light sources for low-cost wavelength-division multiplexed-passive optical network (WDMPON) applications. We used an angled, facet-flared waveguide structure to obtain high optical power and low spectral ripple. An active layer with tensile strain was used to ensure the polarization insensitivity of the optical output. The output power from the SLD device was 150 mW, and the output power at the fiber’s end was 68 mW after butterfly packaging at a current of 1.47 A at a temperature of 25 →. The BLS module had a spectral bandwidth of 40 nm, a polarizationdependent power variation of less than 1 dB, and a spectral ripple of less than 3 dB.
30-W Fiber-coupled Laser-diode Optical Module for Medical Applications
허두창,이대식,김광훈,강욱 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61
We developed the fiber-coupled optical module using two laser diode arrays (LDAs) at the wavelength of 1460 nm for medical applications because the wavelength of around 1460 nm has an absorption peak for fat and water simultaneously. We combine two beams from the two LDAs by spatial multiplexing. The two beams of the LDAs vertically collimated and rotated by micro optics, called a beam-transformation system (BTS), are collimated to be parallel by using a cylindrical lens and are combined by using a folding mirror carefully with different height. Then, the parallel beams are focused by using an aspheric lens and are coupled to a fiber with a core diameter of 600 um and a numerical aperture of 0.37. The maximum optical power is 31 W at the end of the fiber. The corresponding coupling efficiency is 82.4% at a current of 50 A and at a temperature of 20 ℃. The result shows a total optical system efficiency of 77% from 2 LDAs to the end of fiber.
Fabrication of Optical Sources Using InGaAs Quantum Dots Grown by Atomic Layer Epitaxy
허두창,송진동,최원준,이정용,정지채,한일기 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.1
We report that the characteristics and the device applications of InGaAs quantum dots (QD's) grown by using the atomic layer epitaxy (ALE) technique. The measured average diameter and height of the QD's are about 45 nm and 7 nm, respectively. The typical density of QD's is 1.4 $\times$ 10$^{10}$/cm$^2$ for a single layer. Optical sources, like laser diodes (LD's) and superluminescent diodes (SLD's), are fabricated on epi-structures with an active medium consisting of InGaAs QD's. In the case of LD's, the lasing wavelength is about 1.02 $\mu$m, which reflects lasing at high-energy states. The internal quantum efficiency and the internal loss is about 66 \% and 45 cm$^{-1}$, respectively. In the case of SLD's, the output power is about 0.9 W, and the spectral bandwidth is 93 nm. Procedures to further improve device performances are also discussed.
대면적 레이저 다이오드의 필라멘테이션과 α-factor
한일기,허두창,이정일,이주인,Han, Il-Ki,Her, Du-Chang,Lee, Jung-Il,Lee, Joo-In 한국광학회 2002 한국광학회지 Vol.13 No.4
Linewidth enhancement factor ($\alpha{-factor}$) 값이 2와 4인 두 종류의 1.55${\mu}m$ 다층양자우물(Multi-Quantum Well; MQW) 대면적 레이저 다이오드를 제작하였다. 제작된 레이저 다이오드의 far-field 측정 결과 $\alpha{-factor}$ 값이 4일 때 보다 2인 구조에서 반폭치(Full Width at Half Maximum; FWHM)와 필라멘테이션(filamentation)이 감소되었다. 주입전류의 증가에 따라 두 종류 모두 far-field의 FWHM의 증가 현상이 나타났고 이는 filament spacing이 감소하였기 때문으로 설명된다. 1.55 ${\mu}m$multi-quantum well (MQW) broad area laser diodes with different linewidth enhancement factors ($\alpha{-factor}$) of 2 and 4 were fabricated. The far-fields of the laser diodes were measured. It was observed that the full width at half maximum (FWHM) of the far-fields and the filamentations were reduced in the laser diodes for which the value of the $\alpha{-factor}$ was small. As injection current increased, the FWHM of the far-field also increased regardless of the a-factor. This phenomenon was explained by reduction of filament spacing as injection current increased.