Open Access
Polarization diversity scheme for BOTDA sensors based on a double orthogonal pump interaction
(IEEE, 2015) Urricelqui Polvorinos, Javier; López Fernandino, Felipe; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We introduce a Brillouin optical time domain analysis (BOTDA) sensor deploying a novel polarization diversity technique based on the use of two orthogonal pump pulses which simultaneously interact with a phase modulated probe wave. The orthogonallity of the two pump pulses guarantees that two complementary Brillouin interactions take place at each position of the fiber, so that polarization independent measurements are performed throughout the fiber even if no averaging is applied. This feature can be exploited in dynamic distributed BOTDA sensors to reduce the measurement time, as no extra averaging is required to compensate the polarization dependence of Brillouin interaction. Proof of concept experiments demonstrate the feasibility of the technique by employing a completely passive scheme to generate the orthogonal pump pulses. Furthermore, the technique is stable and easy to implement, making it a perfect candidate for practical sensor implementations.
Open Access
Brilloun optical time domain analysis sensor assisted by a Brillouin distributed amplifier
(SPIE, 2015) Urricelqui Polvorinos, Javier; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate the extension of the measurement range of Brillouin optical time-domain analysis (BOTDA) sensors using a distributed Brillouin amplifier (DBA). The technique is based on injecting a DBA pump wave in the fiber to generate an additional Brillouin interaction that amplifies the BOTDA pump pulses. Furthermore, the differential pulse-width pair method is used to counteract the detrimental effects of the DBA amplification on the temporal shape of the pulses. Experimental proof-of-concept results in a 50-km fiber link demonstrate full compensation of the fiber’s attenuation with no penalty on the signal-to-noise ratio of the detected probe wave.
Open Access
Dynamic BOTDA measurements based on Brillouin phase-shift and RF demodulation
(Optical Society of America, 2012) Urricelqui Polvorinos, Javier; Zornoza Indart, Ander; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate a novel dynamic BOTDA sensor based, for the first time to our knowledge, on the use of the Brillouin phase shift in addition to the conventional Brillouin gain. This provides the advantage of measurements that are largely immune to variations in fiber attenuation or changes in pump pulse power. Furthermore, the optical detection deployed leads to an enhanced precision or measurement time and to the broadening of the measurement range. Proof of concept experiments demonstrate 1.66 kHz measurement rate with 1 m resolution over a 160 m sensing fiber length. Moreover, a measurement range of 2560 µε with a precision of 20 µε is successfully proved.
Open Access
Polarization diversity for Brillouin distributed fiber sensors based on a double orthogonal pump
(SPIE, 2014) Urricelqui Polvorinos, Javier; López Fernandino, Felipe; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate a novel Brillouin optical time domain analysis sensor deploying a polarization diversity technique which eliminates the need for polarization scrambling, providing measurements that are largely immune to the state of polarization of the probe wave and the pump pulses throughout the sensing fiber. This can be exploited to reduce the measurement time or can lead to an enhanced precision. Proof of concept experiments demonstrate a 651 Hz sampling rate with 1m resolution over a 930m sensing fiber.
Open Access
Phasorial DPP-BOTDA sensor tolerant to non-local effects
(SPIE, 2014) Urricelqui Polvorinos, Javier; Mariñelarena Ollacarizqueta, Jon; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We introduce a modification of the differential pulse width pair technique in a BOTDA sensor based on a phase modulated probe wave and RF demodulation. This provides a differential Brillouin phasorial signal with high spatial and spectral resolution in both components (magnitude and phase shift). Moreover, the use of a phase modulated probe wave provides RF phase shift measurements tolerant to the emergence of non local effects. The combination of both techniques can lead to the development of long range BOTDA sensors. Proof of concept experiments demonstrate RF phase shift measurements with 1m spatial resolution over 50km and an uncertainty of 1.3ºC at the worst contrast position.
Open Access
Overcoming non-local effects and Brillouin threshold limitations in Brillouin distributed sensors
(SPIE, 2015) Urricelqui Polvorinos, Javier; Ruiz Lombera, Rubén; Sagüés García, Mikel; Mirapeix, Jesús; López Higuera, José Miguel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
We demonstrate, for the first time to our knowledge, a Brillouin optical time domain analysis sensor that is able to operate with a probe power larger than the Brillouin threshold of the deployed sensing fiber and that is free from detrimental non-local effects. The technique is based on a dual-probe-sideband setup in which a frequency modulation of the probes waves along the fiber is introduced. This makes the frequency of maximum interaction between pump and probes to vary along the fiber, thus mitigating the pump pulse depletion and making it possible to use very large probe power, which brings an improved signal-to-noise ratio in detection.
Open Access
Phasorial differential pulse-width pair technique for long-range Brillouin optical time-domain analysis sensors
(Optical Society of America, 2014) Urricelqui Polvorinos, Javier; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We introduce a novel phasorial differential pulse width pair (PDPP) method for Brillouin optical time domain analysis (BOTDA) sensors that combines spatial resolution enhancement with increased tolerance to non local effects. It is based on the subtraction of the complex time domain traces supplied by a sensor configuration that uses a phase modulated probe wave and RF demodulation. The fundamentals of the technique are first described theoretically and using numerical simulation of the propagating waves. Then, proof of concept experiments demonstrate the measurement of the Brillouin frequency shift distribution over 50 km. The system is shown to withstand large variations of the pump power generated by its interaction with a powerful probe wave along the fiber; hence, highlighting the potential of the PDPP technique to increase the detected signal to noise ratio in long range BOTDA. Moreover, the PDPP is also shown to increase the measurement contrast by allowing the use of relatively long duration pulses while retaining 1 m spatial resolution.
Open Access
Overcoming non-local effects and Brillouin threshold limitations in Brillouin optical time domain sensors
(IEEE, 2015) Ruiz Lombera, Rubén; Urricelqui Polvorinos, Javier; Sagüés García, Mikel; Mirapeix, Jesús; López Higuera, José Miguel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate, for the first time to our knowledge, a Brillouin optical time domain analysis (BOTDA) sensor that is able to operate with a probe power larger than the Brillouin threshold of the deployed sensing fiber and that is free from detrimental non-local effects. The technique is based on a dual-probe-sideband setup in which an optical frequency modulation of the probe waves along the fiber is introduced. This makes the optical frequency of the Brillouin interactions induced by each probe wave on the pump to vary along the fiber so that two broadband Brillouin gain and loss spectra that perfectly compensate are created. As a consequence, the pulse spectral components remain undistorted avoiding non-local effects. Therefore, a very large probe power can be injected, which improves the signal-to-noise ratio in detection for long-range BOTDA. Moreover, the probe power can even exceed the Brillouin threshold limit due to their frequency modulation, which reduces the effective amplification of spontaneous Brillouin scattering in the fiber. Experiments demonstrate the technique in a 50-km sensing link in which 8 dBm of probe power is injected.
Open Access
Synthesis of Brillouin frequency shift profiles to compensate non-local effects and Brillouin induced noise in BOTDA sensors
(Optical Society of America, 2014) Urricelqui Polvorinos, Javier; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We present a novel technique for Brillouin optical time domain analysis (BOTDA) sensors that simultaneously compensates non local effects and reduces Brillouin noise. The technique relies on the wavelength modulation of the optical source to modify the Brillouin interaction between probe and pump waves during their propagation. The resulting Brillouin distribution mimics the wavelength modulation, creating a virtual Brillouin frequency shift profile along the sensing fiber. The fundamentals of the technique are first described theoretically and using numerical simulations. Then, proof of concept experiments demonstrate the capabilities of the system to reduce large variations of the pump power resulting from the interaction with high probe powers and to decrease the Brillouin induced noise enhancing the signal to noise ratio (SNR) of the system. Furthermore, we show, for the first time to our knowledge, measurements of the Brillouin distribution using an injected optical power higher than the Brillouin threshold of the fiber.
Open Access
Phase-shift based BOTDA measurements tolerant to non-local effects
(SPIE, 2013) Urricelqui Polvorinos, Javier; Sagüés García, Mikel; Loayssa Lara, Alayn; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
We demonstrate a BOTDA sensor based on the use of the Brillouin phase shift that performs measurements tolerant to non local effects. This technique raises opportunities to increase the distance covered by these sensors and the maximum optical power of the probe wave injected to the fiber. As a result, the system has the potential to increase the SNR achieved at the last meters of the fiber. Proof-of-concept experiments demonstrate unaltered measurements of the phase shift spectrum in a 20Km long fiber for large frequency-dependent distortions of the pump pulse.