Fabrication and characterization of fiber gratings
Developing and analyzing Photonic Crystal Fibers (PCF)
Optical 3-D Medical Imaging based on photonics, especially OCT (Optical Coherence Tomography)
Sensor and sensor systems based on fiber gratings
Novel fiber devices for optical fiber communications
1996 University of Colorado at Boulder (Ph.D.-Physics, Optics)
1989 Seoul National University (M.S.-Physics, Optics)
1984 Seoul National University (B.S.-Physics)
2017 - 2018 Director of Advanced Photonics Research Institute (APRI)
2007 - present Professor
2004 - 2005 BLI (Beckman Laser Institute), UCI (University of California at Irvine), USA, Visiting Professor
2003 - 2006 Associate Professor
2000 - 2002 GIST, Assistant professor
1999 - 2000 GIST, Research Professor
1997 - 1999 Osaka National Research Institute, STA Fellow (Japan)
1997 - 1997 KIST, Research Associate
1989 - 1991 Advent Co., Senior Researcher
1983 - 1987 LG Cable Laboratory, Researcher
Fiber Grating for Tele-Communications
Optical Fiber Grating is a very interesting and versatile device, where a diffractive grating is made along the length of a hair-like optical fiber. The mode-coupling phenomenon induced by the fiber grating enables us to implement various fiber devices for high-speed optical fiber communication systems or advanced sensor systems. We are struggling to be able to design, analyze, and fabricate state-of-art fiber gratings by utilizing apodizing, chirping, and cascading techniques. With the fiber gratings, we measure various properties of fibers and fiber modes. We fabricate the fiber monitoring sensor system that can measure more than 100 points simultaneously through a single piece of fiber. Recently, a novel optical CDMA system was implemented by using the true time delay associated with a fiber cladding mode.
The optical properties of an optical fiber are sensitive to strain, temperature, and pressure applied on the fiber through the refractive index variation and/or mechanical deformation of the fiber. The resonance wavelength of a fiber grating is determined by the index profile of the fiber. Therefore, the amount of the measurand applied on the fiber can be detected by measuring the variation of the resonance wavelength of the fiber grating. We are developing various sensor systems based on fiber gratings, and studying novel interrogating methods based on tunable matched fiber gratings.
Fabricating, modeling and applying Photonic Crystal Fibers (PCF) are also our major interesting fields. The fiber composed of many tiny air holes running along the length of a fiber shows very peculiar properties that can overcome the inherent limit of solid core-cladding based conventional optical fibers.
Optical 3-D tomographical Imaging became included in our research scope. Combining all the technologies developed and accumulated in the field of fiber optics, we are building the OCT (Optical Coherence Tomography) system that can give the cross-sectional images of living objects in real-time and in-vivo. OCT system is similar to an advanced fiber communication system. Only the scale and aim are different. Developing novel devices for OCT systems is also in the main stream of our laboratory.