Incorporation of a fiber Bragg grating to improve the efficiency of a 1580-nm-band tunable fiber ring laser

Strong tunable slow and fast lights using a gain-clamped semiconductor optical amplifier

Previously demonstrated slow light is still far from applications, particularly due to the limited bandwidth and control speed. Although semiconductor-based slow light has the high bandwidth and sub-nanosecond control speed, slow light was observed only in the absorption regime with attenuation, while fast light observed in the gain regime with amplification. The large power difference in two regimes makes the use of the optical delay impractical. We report novel slow light in the gain regime, with a high power comparable to that of fast light, utilizing the anomalous gain characteristic in a gain-clamped semiconductor optical amplifier. The slow light is tunable to fast light with the current as the only variable. Additional high speed operation, fast delay control, and wide range of operation wavelength make the present approach practical.

Monitoring and multiplexing technique for interferometric fiber optic sensors with a linearly chirped Er:fiber laser

The monitoring of interferometer fiber optic sensors using a laser that is scanned over a wide frequency range is investigated. The interrogation technique is based on the principle that if the light-source frequency varies linearly with time, the optical signal reflected or transmitted is intensity modulated at a frequency that is proportional to the optical path difference (OPD) in the interferometer. Fourier components in the detected optical output signal then correspond to the OPDs of any interferometers that have contributed to this modulation. The temporal position of a peak in the power spectrum of this signal is proportional to the OPD of the interferometer that is responsible for that peak. A fine tuning of the OPD value is determined from the phase of the corresponding Fourier component. Experimentally, an Er:fiber laser scanned over a 48-nm range centered at 1540 nm was used to monitor intrinsic fiber Fabry-Perot interferometers (FFPIs). Variations in the laser scan rate were compensated with the optical signal modulated by a reference FFPI held at a constant temperature. The OPD measurement resolution was 3.6 nm, and the dynamic range was 1.3 x 10(7). The temperature was measured from 20 degrees C to 610 degrees C with a 0.02 degrees C resolution, and multiplexing of three of the sensors arranged in series was demonstrated.