Yuh Tat Cho

Simultaneous temperature and strain measurement with combined spontaneous Raman and Brillouin scattering

We report on a novel method for simultaneous distributed measurement of temperature and strain based on spatially resolving both spontaneous Raman and Brillouin backscattered anti-Stokes signals. The magnitude of the intensity of the anti-Stokes Raman signal permits the determination of the temperature. The Brillouin frequency shift is dependent on both the temperature and the strain of the fiber; once the temperature has been determined from the Raman signal, the strain can then be computed from the frequency measurement of the Brillouin signal.

Comparison of the methods for discriminating temperature and strain in spontaneous Brillouin-based distributed sensors

A recently proposed method of measuring the two Brillouin frequencies in a multicompositional fiber core for unambiguously resolving temperature and strain in a distributed sensor is compared with the previously established technique of measuring the intensity and frequency of the single Brillouin peak in a standard single-mode fiber.

50-km single-ended spontaneous-Brillouin-based distributed-temperature sensor exploiting pulsed Raman amplification

We demonstrate enhanced performance of a single-ended spontaneous-Brillouin-intensity-based distributed-temperature sensor with a sensing length of 50 km and a spatial resolution of 15 m by use of Raman amplification of the probe pulse within the sensing fiber. The Raman amplification was achieved with a copropagating pump pulse at 1450 nm. The standard deviation error of the temperature resolution was 1 degree C at the front end and increased to less than 13 degrees C at 50 km with Raman pulse amplification.

Distributed Raman amplification combined with a remotely pumped EDFA utilized to enhance the performance of spontaneous Brillouin-based distributed temperature sensors

Enhanced performance of a distributed temperature sensor based on spatially resolving the temperature-dependent intensity of the spontaneous Brillouin scattered signal was accomplished by combining distributed Raman amplification and a remotely pumped erbium-doped fiber amplifier. A temperature resolution of 5.7/spl deg/C combined with a spatial resolution of 20 m was achieved at a range of 88 km.

Long-range distributed temperature and strain optical fibre sensor based on the coherent detection of spontaneous Brillouin scattering with in-line Raman amplification

We report an extended range distributed temperature and strain optical fibre sensor based on the coherent detection of spontaneous Brillouin scattering combined with Raman amplification. The Raman amplification was achieved within the sensing fibre using either co- or counter-propagating Raman pump configuration with respect to the probe pulse and experiments were conducted to investigate the optimum pump and probe power combination. Using Brillouin frequency shift measurements with co-propagating Raman pump configuration, a temperature resolution of 1.7°C with a 20m spatial resolution at 100km was achieved. With the counter-propagating pump configuration, a temperature resolution of 5°C with a 50m spatial resolution at 150km was achieved. Measuring both the power and frequency of the Brillouin signal, a simultaneous temperature and strain measurement was performed over 50km using co-propagating Raman pump. Temperature and strain resolutions of 3.5°C and 85 mu.epsilon with 5m spatial resolution were achieved.

A temperature-compensated high spatial resolution distributed strain sensor

We propose and demonstrate a scheme which utilizes the temperature dependence of spontaneous Raman scattering to provide temperature compensation for a high spatial resolution Brillouin frequency-based strain sensor.

Enhanced performance of long range Brillouin intensity based temperature sensors using remote Raman amplification

We report on the use of remote Raman amplification to improve the accuracy of spontaneous Brillouin measurements for long range distributed sensor applications. The enhancement of the signal to noise was demonstrated in a long range distributed temperature sensor exploiting the temperature dependence of the spontaneous Brillouin backscattered signal. A temperature resolution of 8 °C and a spatial resolution of 20 m were obtained at a sensing range of 100 km. The Brillouin signal was averaged 220 times.

Simultaneous distributed measurements of temperature and strain using spontaneous Raman and Brillouin scattering

We report on a novel method for simultaneous distributed measurement of the temperature and strain in an optical fiber based on spatially resolving the anti-Stokes signals of both the spontaneous Raman and Brillouin backscattered signals.

Comparison between standard SMF and non-zero dispersion shifted fibre LEAF for long range simultaneous temperature and strain measurements

The relative accuracy of temperature and strain determination using Brillouin frequency shift and power change in standard single-mode fiber and the frequency shifts of the two Brillouin peaks in large effective area fiber is reported.

Coherent detection of spontaneous Brillouin scattering combined with Raman amplification for long range distributed temperature and strain measurements

Brillouin intensity and frequency measurements achieved temperature and strain to be unambiguously resolved with resolutions of 3.5°C and 85 με at 50km. Frequency only measurements, achieved temperature or strain resolution of 1.7°C and 35 με at 100km.