Won-Taek Han

Large temperature sensitivity of Sagnac loop interferometer based on the birefringent holey fiber filled with metal indium

The large temperature sensitivity of the Sagnac loop interferometer based on the birefringent holey fiber filled with metal indium was experimentally demonstrated. The temperature sensitivities of the wavelength shift of the interferometer and the birefringence the fiber with indium were measured to be -6.3 nm/K and -3.3x10(-6) /K, respectively. The large temperature sensitivity of the fiber was explained by introduction of the fiber birefringence change originated from the large thermal expansion property of the metal indium at the elevated temperature.

Enhanced current sensitivity in the optical fiber doped with CdSe quantum dots

A new optical fiber current sensor using a CdSe quantum dots doped optical fiber has been demonstrated with high Faraday rotation for remote sensing of current from 0 to 40 Amperes. It showed enhancement in the current sensitivity by about 2 times than that of the single mode optical fiber current sensor at 632 nm.

Effect of filler metals on the temperature sensitivity of side-hole fiber

Effect of filler metals (Bi, 80Au-20Sn alloy, Sn, and In) on the temperature sensitivity of a birefringent side-hole fiber was investigated. The temperature sensitivity of the fiber was found to increase by introduction of the filler metals and the sensitivity gradually increased with the increase of the thermal expansion coefficient of metals. The sensitivity was larger for the filler metals with the larger thermal expansion coefficient.

Design and development of a trenched optical fiber with ultra-low bending loss

We have designed and experimentally demonstrated a single mode optical fiber with a very low bending loss of about 0.014 dB/loop at 1550 nm for a bending radius of 5 mm.

All-optical switching application of germano-silicate optical fiber incorporated with Ag nanocrystals

Ag-nanocrystal-incorporated germano-silicate optical fiber with high resonant nonlinearity was fabricated by using modified chemical vapor deposition and solution doping techniques. An all-optical signal switching application based on cross-phase modulation was demonstrated in the cascaded long-period fiber gratings. Pumped with 499 nm argon laser, all-optical signal gating of the pi-phase shift was achieved with low pump intensities of less than 7.64 GW/cm2.

Near zero bending loss in a double-trenched bend insensitive optical fiber at 1550 nm

We have developed a new single-mode optical fiber (SMF) which exhibits ultra low bend sensitivity over a wide communication band. The measured mean bending loss at 1550 nm was about 0.0095 dB for a loop of 10 mm diameter.

Linear and Nonlinear Optical Properties of Si Nanoparticles/ Er-Ions Doped Optical Fiber

An alumino-germano-silica glass fiber doped with silicon nanoparticles and erbium ions was fabricated using the modified chemical vapor deposition (MCVD) method. Optical properties of the glass fiber were investigated using a Judd-Ofelt analysis. It was found that incorporating silicon nanoparticles with erbium ions did not alter Er-related optical properties of the silica glass fiber. The incorporation of silicon particles in a fiber core caused wide band absorption from 480 nm to 1200 nm. A third order optical nonlinearity of the Si-Er-doped alumino-germano-silica glass fiber was measured to be about 3.8 x 10-15 m2/W.

Tellurium-enhanced nonresonant third-order optical nonlinearity in a germanosilicate optical fiber

A tellurium-doped germanosilicate optical fiber was developed by modified chemical vapor deposition and solution doping techniques. Using the continuous-wave self-phase modulation method, the nonresonant nonlinear refractive index, n2, was measured to be 5.52 x 10(-20) m2/W, which is 2 to 3 times that of the undoped germanosilicate glass fiber. Polyhedron structures TeO3 and TeO4 with GeO4 and SiO4 are believed responsible for lower phonon energy, more nonbridging oxygens, and a larger hyperpolarization, leading to the observed higher nonresonant optical nonlinearity.

Highly sensitive temperature sensor using fiber Bragg grating on Pb/Ge-codoped fiber

A highly sensitive fiber Bragg grating temperature sensor using a temperature-sensitive Pb/Ge-codoped fiber was demonstrated experimentally with the average temperature sensitivity of the resonance wavelength shift about 0.0176 nm/°C.

Ultra-low bending loss of 0.007 dB/loop for 10 mm of bending diameter at 1550 nm in the double trenched bend insensitive optical fiber

The increase in the usage of FTTH in the optical communication has drawn much attention among the fiber optics engineers to face the challenges of sharp bends that are unavoidable at city apartment corners [1–2]. In the current communication, we report experimental demonstration of the ultra-low bending loss in the single mode optical fiber. The optical fiber was fabricated using the modified chemical vapour deposition (MCVD) process. The optical fibers core was surrounded by five cladding layers: innermost being the silica cladding followed by the first low-index trench, then the second silica cladding, the second low-index trench, and finally the third silica cladding. The double trenched bend insensitive optical fiber had the LP11 cutoff wavelength at 1190 nm. Its mode field diameter was determined using the lateral splice loss measurement technique and it was found to be about 8.5–9.5 µm at 1550 nm.