김석관 교수

The beating between the eigenpolarization modes from a fiber laser is used to demonstrate an active, polarimetric sensor with direct frequency output. For the measurement of lateral stress applied to the jacketed Nd-doped fiber laser, a sensitivity of 4.8 kHz/g with a good linearity is obtained.

Abstract For the determination of lipid oxidation in oils, electrical, optical, spectroscopic and extraction methods were investigated using rice bran oil and doubly‐fractionated palm olein as model systems. The oxidized polar components and dielectric constant of rice bran oil increased very similarly with those of double‐fractionated palm olein. In the case of rice bran oil, all of the test methods were shown to possess good statistical correlations. Polar components, dielectric constant, refr

Methods of polarization control for optimum operation of the fiber laser as polarimetric fiber-laser sensors are proposed and demonstrated. The fiber-laser cavity consisted of two sections of equal length of polarization-maintaining fiber with a splice rotated by 90°. Temperature change and longitudinal strain applied to the fiber produced the slope coefficients of 30 kHz/(°C cm) and 43 kHz/μm, respectively. We also demonstrate single-polarization operation of the fiber laser by simply bending t

The characteristics of the output polarization angle and the polarization-mode beat frequency of a twisted fiber laser are investigated. A theoretical model is used to describe successfully the polarization properties.

It is found that a properly tuned segmented coil system allows external control of the radial plasma density profile in an inside-type, large-area inductively coupled plasma. This coil system is composed of inner and outer coil segments and an external variable inductor. The external variable inductor is used to balance coil currents between the two coil segments for plasma uniformity control. The measured results indicate that radial plasma spread can be controlled and optimized with this exter

We present a thermally tunable microring resonator (MRR) implemented on a Ge-on-insulator (Ge-OI) photonic platform tailored for mid-infrared spectrometer applications. Thanks to the favorable thermo-optic effect of Ge, we characterized the optical and thermal properties of the thermally tunable Ge-OI MRR through rigorous optical and thermal numerical analyses. Building upon the simulation, a ring-shaped Au heater was successfully integrated into the Ge-OI MRR that was fabricated by using a dire

Recent years, the photonic crystal laser device has matured from a theoretical interest to real experimental problems. This custom-made crystal opens up the possibility of the photon control: it can be designed to guide photons, to localize photons, or to modify the dispersion relation of photons. Especially the potential of the photon confinement in multi-dimensions has attracted scientists working in the filed of ultra-small lasers.