Ho Jin Jeong

Suppression of polarization dependence in a two-mode-fiber acousto-optic device.

We present a theoretical and experimental analysis of the polarization dependence of a two-mode-fiber acoustooptic device, taking into account the residual stress in the fiber and the ellipticity of the core. We successfully demonstrate the suppression of the polarization dependence by relieving the residual stress, using thermal annealing.

Mode-locked fiber laser gyroscope

We describe a new form of an all-fiber-optic gyroscope that utilizes a fiber laser. The Sagnac interferometer is used as a loop reflector with a modulated reflectivity to produce actively mode-locked optical pulses. The rotation-induced phase shift is obtained from the timing shift of the pulses. Experimental results compare well with the theoretical predictions.

High-sensitivity mode-locked fiber laser gyroscope

We report significant performance improvement of a mode-locked fiber laser gyroscope. A Fabry-Perot cavity GaAlAs laser diode whose front facet was antireflection coated was used as a gain medium. The rms noise equivalent rotation rate measured with a time-interval counter was improved to 0.06deg/ radicalh. The long-term drift of the gyroscope signal was reduced to 100deg/ radicalh after a polarizer was inserted into the laser cavity formed with a polarization-maintaining fiber.

Analysis of polarization properties of a mode-locked fiber laser gyroscope

We investigated the polarization characteristics of a mode-locked fiber laser gyroscope (MLPLG) formed with a Nd-doped fiber as an optical gain medium and a Sagnac loop mirror. The output pulse patterns and the polarization states were found to be determined by fiber birefringence in the different sections of the MLPLG. We describe the conditions for the MLPLG to operate with automatic reciprocity leading to the possibility of phase-error-free operation.

Polarization characteristics of mode-locked fiber laser gyroscope

A mode locked fiber laser gyroscope (MLFLG) [1] has a laser cavity formed with a fiber amplifier with a planar mirror at one end and a Sagnac loop interferometer at the other end, as shown in figure 1. The Sagnac interferometer functions as a loop mirror, and a phase modulator in the interferometer is used to modulate the reflectivity of the loop mirror.

Simple all-fiber-optic component for first-order polarization mode dispersion compensation

A simple and reliable all-fiber-optic component for a first-order polarization mode dispersion compensator is presented and tested in a 10-Gbit/s transmission system. The proposed component incorporates tunable differential group delay (DGD) provided by several pieces of polarization maintaining (PM) fibers of different DGD that were spliced together with short lengths of single-mode fibers between them. The total DGD of the compensator is determined by the alignment of fast and slow axes of the PM fiber sections. Applying this component as a first-order polarization mode dispersion (PMD) compensator, we demonstrate that a component with seven pieces of PM fiber segments could possibly compensate the first-order PMD up to 63.5 ps with 1-ps steps and a switching time of 300 ms. We also optimize the number of PM fiber sections in this component for a first-order PMD compensation in a 10Gbit/s system based on experimental results.

Mode-locked fiber laser gyroscope using an antireflection-coated laser diode

An anti-reflection coated GaAlAs laser diode was used as a gain medium in a mode-locked fiber laser gyroscope to obtain stable mode-locked optical pulses without gain competition. The time intervals between the pulses could be measured with much improved accuracy using an electronic counter. The rms noise equivalent rotation rate was 3.4 deg/hr/(root)Hz and the long-term drift was less than 200 deg/hr.