RESUMEN

An innovative optical frequency-domain reflectometry (OFDR)-based distributed temperature sensing method is proposed that utilizes a Rayleigh backscattering enhanced fiber (RBEF) as the sensing medium. The RBEF features randomly high backscattering points; the analysis of the fiber position shift of these points before and after the temperature change along the fiber is achieved using the sliding cross-correlation method. The fiber position and temperature variation can be accurately demodulated by calibrating the mathematical relationship between the high backscattering point position along the RBEF and the temperature variation. Experimental results reveal a linear relationship between temperature variation and the total position displacement of high backscattering points. The temperature sensing sensitivity coefficient is 7.814 µm/(m·°C), with an average relative error temperature measurement of -1.12% and positioning error as low as 0.02 m for the temperature-influenced fiber segment. In the proposed demodulation method, the spatial resolution of temperature sensing is determined by the distribution of high backscattering points. The temperature sensing resolution depends on the spatial resolution of the OFDR system and the length of the temperature-influenced fiber. With an OFDR system spatial resolution of 12.5 µm, the temperature sensing resolution reaches 0.418 °C per meter of RBEF under test.

Asunto(s)

RESUMEN

We propose and experimentally demonstrate an all-fiber-based approach to generate microwave signals with tunable frequency and pulse width. The adjustable optical power spectrum can be achieved using a spectrum shaper, consisting of a variable differential-group-delay element and a bandwidth-tunable optical filter. Through the frequency-to-time conversion in the dispersive fiber, the frequency and pulse width of the obtained microwave signals can be user defined by modifying the optical spectrum shape.