Hyunseo Kang

Highly efficient, wavelength-selective out-coupling of cladding mode using tilted fiber grating and micro-etched cladding

A highly efficient, wavelength-selective detection through micro-etched groove on cladding of tilted fiber gratings (TFGs) is proposed and experimentally demonstrated. More than 88% power of the cladding mode is out-coupled into an optical power detector

Effects of postbake on the microstructure and whisker growth of matte Sn finish

The effects of postbake treatment on a pure matte Snplated copper leadframes under high temperature and humidity conditions were investigated. The samples were divided into two categories: those without postbake treatment (WOPB) and those with postbake treatment (WPB), which exposed at 125□ for 1 hour. The X-ray intensity decreased through all crystal orientations after the postbake treatment. For matte Sn-plated Cu leadframes stored at 55°C/85%RH for 1800 hours, nodule-shaped whiskers were observed on samples WOPB, while none were on samples WPB. The WPB samples have a regular layer of IMCs approximately 27% narrower than the WOPB samples. The IMCs had two distinct layers divided into large-grains and small-grains. The large-grain layers located on the Sn side grew before the small-grain layers. The IMCs in the WOPB and WPB samples were identified as Cu6Sn5 and η-Cu6.26Sn5. IMC precipitates were also observed at the grain boundaries and some IMC precipitates were embedded at the Sn matrix. No Cu3Sn or Kirkendall voids were observed at the interface between the Sn and Cu.

Analysis of wavelength effects on a spherical-end fiber lens

The wavelength of light affects the working distance to the beam waist and the mode field diameter in a spherical-end fiber lens. The compensation effects of the chromatic aberration in the fiber lens are shown, and the predicted results are found to be in good agreement with the experimental values.

Wavelength-Switching Erbium-Doped Fiber Laser with a Multimode Fiber Bragg Grating and Faraday Rotator Mirror

Without polarization dependent gain, a multimode fiber Bragg grating (MMFBG)-based wavelength-switching erbium-doped fiber laser (EDFL) as a case of optical source in WDM communication system is demonstrated. By varying spatial-launching position of the single-mode fiber against the MMFBG, discrete single-wavelength lasing are obtained.

Optimization of tilted fiber Bragg grating and micro-etched cladding for high efficient out-coupling of cladding mode

The cladding mode generated by the tilted fiber Bragg grating is out-coupled to optical power detector by the total internal reflection at the micro-etched cladding. Optimization of the tilted fiber Bragg grating and micro-etched cladding for high efficient out-coupling of cladding mode was discussed theoretically. Over 32 % power of the cladding mode is out-coupled by the micro-etched cladding. In addition, as much as 90 % power of the input power is experimentally detected using the avalanche photodiode.