• Journal of the Optical Society of Korea
• /
• v.15 no.2
• /
• pp.124-127
• /
• 2011

Quantum dots were designed within a GRIN-SCH(Graded index - Separate confinement Heterostructure) heterostructure to create a high power InAlAs/AlGaAs laser diode. 808 nm light emission was with a quantum dot composition of In0.665Al0.335As and wetting layer composition of Al0.2Ga0.8As by LASTIP simulation software. Typical characteristics of GRIN structures such as high confinement ratios and Gaussian beam profiles were shown to still apply when quantum dots are used as the active media. With a dot density of 1.0x1011 dots/cm2, two quantum dot layers were found to be good enough for low threshold, high-power laser applications.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.122-122
• /
• 2013

In this talk, some optical properties of quantum dot based mode-locked diode lasers and photonic crystal nano lasers will be discussed. Linewidth enhancement factor, chirp and interband injection locking technique of quantum dot mode-locked lasers will be presented. Also various types of photonic crystal buried heterostructure lasers toward coherent nano laser will be covered as well.

• Journal of the Korean Vacuum Society
• /
• v.16 no.5
• /
• pp.371-376
• /
• 2007

We have investigated the lasing characteristics of the InGaAs quantum dot laser diode (QD-LD) and InGaAs quantum well laser diode (QW-LD) operated at the 980 nm wavelength range. The 980-nm lasers are used as a pumping source for a erbium-doped fiber amplifier (EDFA) and it shows high efficiency in long-haul optical fiber network. We have compared the threshold current density, the characteristic temperature, the optical power and the internal efficiency of QD-LD and QW-LD under a pulsed current condition. The QD-LD shows superior performances to the QW-LD. Further optimization of a LD structure is expected to the superior performances of a QD-LD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.477-478
• /
• 2006

Characteristics of InAs/GaAs quantum dot (QD) ridge laser diodes (LDs) are investigated for high-power $1.3\;{\mu}m$ applications. For QD ridge LDs with a $5-{\mu}m$-wide stripe and a 1-mm-long cavity, the emission wavelength of 1284.1 nm, the single-uncoated-facet CW output power as high as 90 mW, the external efficiency of 0.31 W/A and the threshold current density of $800\;mA/cm^2$ are obtained. The linewidth enhancement factor ($\alpha$-factor) is successfully measured to be between 0.4 and 0.6, which are about four times as small values with respect to conventional quantum well structure. It is possible that this result significantly reduce the filamentation of far-field profiles resulting in better beam quality for high power operation.

• Journal of the Korean Vacuum Society
• /
• v.17 no.6
• /
• pp.555-559
• /
• 2008

Junction temperature of quantum dot laser diodes is investigated by utilizing forward voltage-temperature method. In the case of ridge type laser diodes with deep mesa the increasing rate of junction temperature to current is about 0.05 K/mA, while in the case of shallow mesa the increasing rate is about 0.07 K/mA. It is explained that the relatively low increasing rate in the deep mesa results from the heat expansion to the lateral direction of mesa.

• Korean Journal of Optics and Photonics
• /
• v.24 no.2
• /
• pp.71-76
• /
• 2013

Using fluorescence correlation spectroscopy, we analyzed the change of effective focal volume of a confocal system with light intensity. The fluorescence correlation spectroscopy system was home-built in accordance with the He-Ne laser with a wavelength of 632.8 nm, and two kinds of samples (AlexaFluor657 and Quantum dot655) suitable for the wavelength of the laser beam were used. For each sample, we analyzed and compared the correlation functions obtained while changing the intensity of the light source in a range of 1~50 ${\mu}W$. The result shows that the radius of the focal area increases linearly through the increase of particle number and diffusion time in response to an intensity change in weak light below 10 ${\mu}W$. In the higher intensity region (>10~15 ${\mu}W$), the increasing rate of particle number and diffusion time keep increasing but at a much slower rate. Through this result, it was also found that the radius increasing rate of the focal area was reduced however, the radius still increased slightly.

• Journal of the Korean Vacuum Society
• /
• v.18 no.4
• /
• pp.266-271
• /
• 2009

We have investigated the lasing characteristics of GaAs-based 1300 nm wavelength region InAs Quantum Dot Laser Diode grown by Migration Enhanced Molecular Beam Epitaxy. Under a pulsed and CW operation, we observed the state switching of lasing wavelength from ground state (1302 nm) to excited state (1206 nm) due to the gain saturation of ground state. Under a pulsed operation, $J_{th}=92A/cm^2$, $\lambda_L=1311\;nm$ and under a CW operation, $J_{th}=247A/cm^2$, $\lambda_L=1320\;nm$.

• Journal of Powder Materials
• /
• v.31 no.2
• /
• pp.169-179
• /
• 2024

Colloidal quantum dot (QDs) have emerged as a crucial building block for LEDs due to their size-tunable emission wavelength, narrow spectral line width, and high quantum efficiency. Tremendous efforts have been dedicated to improving the performance of quantum dot light-emitting diodes (QLEDs) in the past decade, primarily focusing on optimization of device architectures and synthetic procedures for high quality QDs. However, despite these efforts, the commercialization of QLEDs has yet to be realized due to the absence of suitable large-scale patterning technologies for high-resolution devices., This review will focus on the development trends associated with transfer printing, photolithography, and inkjet printing, and aims to provide a brief overview of the fabricated QLED devices. The advancement of various quantum dot patterning methods will lead to the development of not only QLED devices but also solar cells, quantum communication, and quantum computers.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2007.02a
• /
• pp.181-181
• /
• 2007

• Proceedings of the Korean Vacuum Society Conference
• /
• 2006.02a
• /
• pp.203-203
• /
• 2006