Fiber Bragg grating–based self-referencing technique for wavelength-multiplexed intensity sensors

Abad, Sílvia; López-Amo, Manuel; Araújo, F. M.; Ferreira, L. A.; Santos, J. L.

doi:10.1364/ol.27.000222

Cited by 40 publications

(31 citation statements)

References 6 publications

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“…Bus and star reflective topologies using FBG have been reported [24][25], employing optical amplification in order to compensate insertion losses of optical couplers; nevertheless, the noise associated to amplification is a limiting aspect. Partial optimizations of power budget using WDM devices at the reception stage have been demonstrated in self-referencing intensity networks [16], but the use of couplers leads to lossy distribution of lightwave channels. A scalable self-referencing sensor network with low insertion losses implemented in Coarse Wavelength Division Multiplexing (CWDM) technology is reported.…”

Section: Multiplexing Techniquesmentioning

confidence: 99%

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Self-referencing techniques in photonics sensors and multiplexing

et al. 2007

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A short review of self-reference techniques for remote fiber-optic intensity sensors and possible integration in multiplexing sensor networks is reported. Special focus is given to developments on radio-frequency (RF) source modulation techniques in interferometric configurations operating under incoherent regime. Experimental results on ring resonator (RR) configurations in transmission and reflection modes are included. Sensitivity, optimum insertion losses and robustness to intensity error fluctuations are reported. Sensors are interrogated at two sub carrier frequencies having a high rejection of interference from laser source intensity fluctuations and loss in the fiber lead. Dependence on source coherence is also analysed.Scalable self-referencing sensor networks with low insertion losses implemented in Coarse Wavelength Division Multiplexing (CWDM) technology are reported. The possibility of remote self-referenced measurements using a fullduplex fiber down-lead tenths of kilometers long with no need for optical amplification is also described. Fiber Bragg gratings (FBG) are used in the reflection configuration, thus increasing the sensitivity of the optical transducers. Lowcost off-the-shelf devices in CWDM and DWDM technology can be used to implement and scale the network.Applications to specific photonic sensors are also envisaged and these techniques can be used in networks of microfiber loop resonators, being the microfiber loop the sensing element itself.

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Section: Multiplexing Techniquesmentioning

confidence: 99%

“…So it is very important to be able to conjugate self-referencing and multiplexing [15][16]. This is one of the main reasons for migration to single-mode fiber (SMF) configurations in self-referenced intensity based sensors networks.…”

Section: Introductionmentioning

confidence: 99%

Self-referencing techniques in photonics sensors and multiplexing

et al. 2007

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“…FBG-based self-referencing configurations providing insensitivity to external power fluctuations, non-correlated to the sensor intensity modulation, have also been reported in reflective operation employing in the sensing points all-optical delay line filters [13], as well as Michelson and ring resonator configurations [14], [15]. Recently, we have reported a compact electro-optical design which avoids the need for fiber delay coils, thus achieving compact sensor heads, arbitrary modulation frequency and electronically reconfigurable operation in a single point [16].…”

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confidence: 99%

“…It is shown that the proposed multiplexing approach optimizes the power budget. The self-referenced measurement parameter is based on the optical configuration detailed in [13], but the Z-Transform technique is used for describing the new system with a doubled sensitivity, obtained by subtracting the output phase signals at two different modulation frequencies.…”

mentioning

confidence: 99%

Radio-Frequency Self-Referencing Technique With Enhanced Sensitivity for Coarse WDM Fiber Optic Intensity Sensors

Montalvo

Frazão

Santos

et al. 2009

J. Lightwave Technol.

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Abstract-A self-referenced passive optical network (PON) with coarse wavelength division multiplexing (CWDM) is reported for remotely addressing optical intensity sensors with enhanced sensitivity. The self-referencing remote configuration is described as a finite-impulse-response (FIR) filter in reflective operation using two fiber Bragg gratings (FBG) and a fiber delay line. The antisymmetrical phase response of the configuration permits to achieve a self-referencing measurement parameter two times more sensitive than reported previously. To enhance the power budget of the network, CWDM devices with low insertion losses are used for spectral splitting of a radio-frequency (RF) modulated broadband light source (BLS). The network topology and the sensor's interrogation technique are theoretically analyzed and experimental results validating the models are reported.Index Terms-Coarse wavelenght-division multiplexing (CWDM), digital filters, fiber Bragg gratings (FBG), fiber delay lines, optical intensity sensors, passive optical networks (PON), self-reference.

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“…In the experiment, strain measurement with a maximum sensitivity of −0.34 V/ has been achieved. Intensity-modulated fiber-optic sensors have attracted significant interest due to their many advantages including simplicity and potential low cost [1,2]. A large number of parameters can be measured by these sensors with the use of inexpensive light sources and simple detection schemes while still benefiting from the intrinsic advantages of photonic sensors.…”

mentioning

confidence: 99%

Intensity-modulated fiber Bragg grating sensor system based on radio-frequency signal measurement

Dong

Shao

et al. 2008

Opt. Lett.

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An intensity-modulated, fiber Bragg grating (FBG) sensor system based on radio-frequency (RF) signal measurement is presented. The RF signal is generated at a photodetector by two modulated optical signals reflected from the sensing FBG and a reference FBG. Wavelength shift of the sensing FBG changes intensity of the RF signal through changing the delay between the two optical signals, with temperature effect being compensated automatically by the reference FBG. It also exhibits important features including potentially high-speed measurement, low cost, and adjustable sensitivity. In the experiment, strain measurement with a maximum sensitivity of −0.34 V/ has been achieved. Intensity-modulated fiber-optic sensors have attracted significant interest due to their many advantages including simplicity and potential low cost [1,2]. A large number of parameters can be measured by these sensors with the use of inexpensive light sources and simple detection schemes while still benefiting from the intrinsic advantages of photonic sensors. However, most fiber-optic sensors based on fiber Bragg gratings (FBGs) are not intensity but wavelength modulated. To monitor the reflection wavelength of FBGs, expensive wavelength measurement instrument, such as FBG interrogators based on wavelength-scanning lasers, tunable filters or CCDs, are normally used. The measurement speed of wavelength measurement instrument is relatively low and typically it is less than 1 kHz. On the other hand, intensity-modulated FBG demultiplexing systems can operate at much higher speeds. To realize intensity-modulated FBG sensors, several different techniques have been reported. By using an edge filter or a matched FBG [3,4], wavelength shift of FBG can be converted into intensity variation. However, this method allows only limited wavelength measurement range and may suffer from the so-called crosssensitivity problem because FBGs are sensitive to both strain and temperature and the two effects are not distinguished by the sensing system. Chirped FBGs may also be used as intensity-modulated sensors by encoding the sensing information into their reflection optical power [5,6]. They are insensitive to temperature but only applicable to a few measurands that change chirp rates of the sensing FBGs.In this Letter, a novel intensity-modulated FBG sensor system that measures parameters through wavelength shift as well as being insensitive to temperature is proposed. The sensor system is shown in Fig. 1. It consists of a broadband light source intensity modulated by a radio frequency (RF) signal, a circulator, a sensing FBG, a reference FBG, and a long length of standard single-mode fiber used as a dispersive medium. Signals reflected from the two FBGs are measured with a photodetector. Since wavelengths of the two FBGs are different and overlap is avoided, there is no optical interference present in the system.Assuming that the intensity of the broadband light source is sinusoidally modulated at frequency f and the modulation index is m ͑0 Ͻ m Յ 1͒, the power...

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Fiber Bragg grating–based self-referencing technique for wavelength-multiplexed intensity sensors

Cited by 40 publications

References 6 publications

Self-referencing techniques in photonics sensors and multiplexing

Self-referencing techniques in photonics sensors and multiplexing

Radio-Frequency Self-Referencing Technique With Enhanced Sensitivity for Coarse WDM Fiber Optic Intensity Sensors

Intensity-modulated fiber Bragg grating sensor system based on radio-frequency signal measurement

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