We report a high-speed phase-sensitive optical coherence reflectometer (OCR) with a stretched supercontinuum source.
Firstly, supercontinuum source has been generated by injecting an amplified fiber laser pulses into a highly nonlinear
optical fiber. The repetition rate and pulse duration of the generated supercontinuum source are 10 MHz and 30 ps
respectively. The supercontinuum pulses are stretched into 70 ns pulses with a dispersion-compensating fiber (DCF).
This pulse stretching technique enables us to measure the spectral information in the time domain. The relationship of
time-wavelength has been measured by modified time-of-flight method. We have built a phase-sensitive OCR with this
stretched pulse source and a two-dimensional (2D) scanning system. The displacement sensitivity of our proposed
system has been investigated. We have demonstrated high-speed 2D imaging capability and single-point dynamics
measurement performance of our proposed system.
We report a scheme for controlling pulse width in a robust self-starting mode-locked ytterbium fiber laser using a
semiconductor saturable absorber mirror (SESAM). We demonstrate that the pulse width in a mode-locked laser made
of all-normal-dispersive fiber can be adjusted by changing ump power to the laser or by adjusting the axial position of
the SESAM with respect to a focusing beam. We have obtained optical pulse width of 7.4 ps and the adjustable range
was 2 ps without dispersion compensators in the all-normal-dispersive cavity and provides a high reliability of turn-key
operation. We have explained that the principle of position dependent pulse width change in a mode-locked laser with a
SESAM and verified with numerical simulations.
Using a fiber-type confocal scanning optical microscope system, we have obtained a stable refractive index profile
measurement system of good performance. We could acquire excellent index precision and good spatial resolution by
using a fiber-optic system for the majority part instead of a bulk-optic system and a single mode fiber at visible region
with a 4 &mgr;m core diameter instead of a pinhole structure. Also, using a power detection system that is synchronous with
fiber-coupled detector, we have improved system stability by reducing noise generated by the roughness of a sample
surface because of using the optical fiber as a pinhole system. The light reflected by the sample surface was divided by a
beam splitter; one ray passed back through the optical fiber in order to detect a confocal point and another ray entered
the synchronous power detector in order to detect reflected power. The power detected by the synchronous power
detector without a pinhole is less sensitive to the surface roughness than the power detected by the fiber-coupled
detector. We could implement the simple and robust index measurement system by using a fiber-optic system and a
synchronous detection system, and a single mode fiber was measured to demonstrate the effectiveness of our proposed