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Featured researches published by Kyoung-Youm Kim.


IEEE Photonics Technology Letters | 2007

High-Performance Blue InGaN Laser Diodes With Single-Quantum-Well Active Layers

Han-Youl Ryu; K.H. Haleem; Sung-Yung Lee; T. Jang; J. K. Son; H. S. Paek; Y.J. Sung; H.K. Kim; Kyoung-Youm Kim; Okhyun Nam; Y.J. Park; Jong-In Shim

The authors report on the high-performance blue laser diodes (LDs) with an emission wavelength of ~448 nm employing InGaN single-quantum-well (QW) active layers. At 100-mW continuous-wave (CW) output power, operation current and voltage are, respectively, 150 mA and 5.3 V, corresponding to the wall plug efficiency of >12%, a record value for the single-mode InGaN LDs with blue wavelengths. The single QW blue LD showed normal temperature dependence of light output-current curves with the characteristic temperature of 170 K. In addition, we demonstrate a high level of catastrophic optical damage of >300 mW and long device lifetime under CW operation condition at room temperature.


IEEE Photonics Technology Letters | 2005

Bragg grating-assisted WDM filter for integrated optical triplexer transceivers

Jeong Hwan Song; Jong Hoon Lim; Ryun Kyung Kim; Kyung Shik Lee; Kyoung-Youm Kim; Jae-Geol Cho; Dongkyoon Han; Sun-tae Jung; Yun-Kyung Oh; Dong-Hoon Jang

We designed and experimentally demonstrated a Bragg grating-assisted wavelength-division-multiplexing filter for the three-wavelength multiplexing on a planar-lightwave-circuit platform. The 1310- and 1550-nm lights were designed to be separated after passing the directional coupler by a half-cycle and a full-cycle coupling actions with losses of 0.07 and 0.19 dB, respectively. The 1492-nm light was reflected back by a Bragg grating fabricated on the directional coupler and its loss was less than 2.0 dB. We also introduced and discussed the new concept of an integrated optical triplexer transceiver using this filter.


IEEE Photonics Technology Letters | 2005

Thin film filter-embedded triplexing-filters based on directional couplers for FTTH networks

Jeong Hwan Song; Kyoung-Youm Kim; Jae-Geol Cho; Dongkyoon Han; Joo-Hoon Lee; Yu Sheop Lee; Sun-tae Jung; Yun-Kyung Oh; Dong-Hoon Jang; Kyung Shik Lee

We designed and experimentally demonstrated a thin film filter (TFF)-embedded directional coupler-type triplexing-filter on the planar-lightwave-circuit platform. The triple-play multiplexing was significantly simplified by using one TFF. The 1.31- and 1.55-/spl mu/m lights were designed to be divided after passing the directional coupler by half-cycle and full-cycle coupling actions, respectively. The 1.49-/spl mu/m light was reflected by a TFF inserted in a trench on the directional coupler. The insertion losses of fabricated triplexing-filters were less than 2.0 dB with bandwidths of 20 nm. The newly proposed triplexing-filter provides a cost-effective high-performance solution for fiber-to-the-home networks.


IEEE Photonics Technology Letters | 2006

Single-mode blue-violet laser diodes with low beam divergence and high COD level

Han-Youl Ryu; Kyoung-ho Ha; Sung-Yung Lee; Kwon-Young Choi; T. Jang; J. K. Son; J. H. Chae; Su-hee Chae; H. S. Paek; Y.J. Sung; Tan Sakong; Hyoung-Joo Kim; Kyoung-Youm Kim; Yong-Hoon Kim; Okhyun Nam; Y.J. Park

We demonstrate GaN-based high-power single transverse-mode laser diodes (LDs) emitting at 405 nm. LD structures are designed to exhibit a high level of catastrophic optical damage and small beam divergence angle. By the control of refractive index profiles, we achieved a vertical beam divergence angle of as low as 17.5/spl deg/ and maximum output power of as high as 470 mW under continuous-wave operation condition. In addition, nearly fundamental transverse-mode operation is demonstrated up to 500-mW pulsed output power by far-field investigation.


IEEE Photonics Technology Letters | 2005

Polarization-dependent waveguide coupling utilizing single-negative materials

Kyoung-Youm Kim

It is shown that if a single-negative (SNG) material layer is included between two parallel waveguides of a directional coupler, we can obtain such supermodes that the symmetric mode propagates faster than the antisymmetric mode for one polarization component of input waves while the antisymmetric mode travels faster than the symmetric mode for the other polarization component. Utilizing this feature, we propose a new kind of polarization beam splitter whose polarization-dependent characteristics are originated not from the material birefringence, but from polarization-dependent continuity conditions at media interfaces between conventional materials and the SNG media.


Optics Letters | 2005

Properties of photon tunneling through single-negative materials

Kyoung-Youm Kim

The photon tunneling phenomena in the composite barriers of single-negative materials were analyzed. It was found that the tunneling through such a barrier shifts TE- and TM-polarization light waves laterally (parallel to the material interface) in two opposite directions, causing them to be divided into two waves after tunneling. This property could not be obtained with double-positive and (or) double-negative materials.


IEEE Photonics Technology Letters | 2005

Reduction of insertion loss of thin film filters embedded in PLC platforms

Kyoung-Youm Kim; Jeong Hwan Song; Joo-Hoon Lee; Se Yoon Kim; Jae-Geol Cho; Yu Sheop Lee; Dongkyoon Han; Sun-tae Jung; Yun-Kyung Oh

We propose and experimentally demonstrate a method of reducing insertion loss of a thin-film-filter-embedded planar-lightwave-circuit platform for a triplexer transceiver module. Significant loss reduction was achieved by adding horn waveguide elements at the interfaces between the thin film filter and the output-port (transmission and reflection) waveguides.


Journal of Lightwave Technology | 2005

Development of compact and low-crosstalk PLC-WDM filters for hybrid-integrated bidirectional optical transceivers

Kyoung-Youm Kim; Se Yoon Kim; Myoung Won Kim; Sun-tae Jung

This paper reports on the development of planar-lightwave-circuit wavelength-division-multiplexing (PLC-WDM) filters based on double polynomial curve directional couplers, which will be integrated into compact and low-cost bidirectional optical transceivers for FTTx systems. Silica-based PLC-WDM filters smaller than 5 mm/spl times/100 /spl mu/m for Ethernet passive optical network (E-PON) applications were designed and fabricated to have low bidirectional crosstalk (lower than -40 dB) as well as low insertion losses (lower than 1 dB) within the operating temperatures of -40 to 80/spl deg/C. Several features and design guides that can reduce the size of directional couplers and improve the level of bidirectional crosstalk are discussed.


Integrated optics : devices, materials, and technologies. Conference | 2005

Waveguide design and fabrication of trench for hybrid integrated optic devices

Sun-tae Jung; Jeong Hwan Song; Kyoung-Youm Kim; Yun-Kyung Oh

The hybrid integration of passive and optoelectronic devices has been widely researched. One of the main applications of this technique is for the fiber to the home (FTTH) network. In bi-directional transceivers, integrated WDM filters have been used to separate or combine the optical signals. Thin film filter (TFF) embedded waveguide type is effective for an application requiring wide bandwidth and low loss. Although the insertion loss of TFF itself is quite low, significant loss occurs at the trench and it depends on the geometrical structure and fabrication errors of the trench waveguide. The conventional sawing method and deep reactive ion etching technique were used for trench fabrication. In the case of using DRIE process, fabrication error was reduced and position error of the trench was controlled within 1um. This method could also enhance the platform design flexibility. To reduce the coupling loss between input and reflection waveguides with high tolerance of filter position, a few mode waveguide and horn waveguide were proposed. The insertion losses of transmission and reflection were less than 0.5dB and 0.7dB respectively. The 1dB tolerance of filter position was improved to be nearly twice than that of the conventional waveguide.


Archive | 2007

Keypad and keypad assembly

Joo-Hoon Lee; Sun-tae Jung; Kyoung-Youm Kim; Byung-Duck Cho; Dong-Hoon Jang

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