Modeling and experimental electro-optic response of dielectric lithium niobate waveguides used as electric field sensors

Gutiérrez‐Martínez, C.; Santos-Aguilar, Joel; Ochoa-Valiente, R; Santiago-Bernal, Misael; Morales‐Díaz, Adolfo

doi:10.1088/0957-0233/22/3/035207

Cited by 14 publications

(6 citation statements)

References 19 publications

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“…Several approaches to fiber optic sensors for electric fields have been demonstrated which could be used for EFEG [16]–[18]. These sensors appear to have sensitivity ∼1 mV per meter sufficient to measure the brain's electric fields, but a to improvement in sensitivity would lead to more reliable observations of brain signals.…”

Section: Discussionmentioning

confidence: 99%

Electric Field Encephalography as a Tool for Functional Brain Research: A Modeling Study

Petrov

Sridhar

2013

PLoS ONE

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We introduce the notion of Electric Field Encephalography (EFEG) based on measuring electric fields of the brain and demonstrate, using computer modeling, that given the appropriate electric field sensors this technique may have significant advantages over the current EEG technique. Unlike EEG, EFEG can be used to measure brain activity in a contactless and reference-free manner at significant distances from the head surface. Principal component analysis using simulated cortical sources demonstrated that electric field sensors positioned 3 cm away from the scalp and characterized by the same signal-to-noise ratio as EEG sensors provided the same number of uncorrelated signals as scalp EEG. When positioned on the scalp, EFEG sensors provided 2–3 times more uncorrelated signals. This significant increase in the number of uncorrelated signals can be used for more accurate assessment of brain states for non-invasive brain-computer interfaces and neurofeedback applications. It also may lead to major improvements in source localization precision. Source localization simulations for the spherical and Boundary Element Method (BEM) head models demonstrated that the localization errors are reduced two-fold when using electric fields instead of electric potentials. We have identified several techniques that could be adapted for the measurement of the electric field vector required for EFEG and anticipate that this study will stimulate new experimental approaches to utilize this new tool for functional brain research.

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Section: Discussionmentioning

confidence: 99%

Electric Field Encephalography as a Tool for Functional Brain Research: A Modeling Study

Petrov

Sridhar

2013

PLoS ONE

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“…The measurand 50 Hz ac E-field was produced by use of two plane copper electrodes, such as the approach used in [20], as shown in Fig. 3.…”

Section: Methodsmentioning

confidence: 99%

“…The transmission ratio of the transformer is 1∶22.7. Tunable output range of the ac voltage regulator is 0-260 V. Thus the range of ac voltage applied to the two electrodes is U ac 0-5902 V. According to similar formula in [20] for calculating the electric field in the sensing crystal, and some known parameters including distance among electrodes, sensor, and organic glass holder and relative permittivities of the BBO crystal and holder, ε r1 6.7 and ε r2 3.4, we can approximately evaluate the relationship between the measurand electric field in air E ac and the applied voltage U ac , i.e.,…”

Section: Methodsmentioning

confidence: 99%

Optical electric-field sensor based on angular optical bias using single β-BaB₂O₄ crystal

Shen

Zeng

2013

Appl. Opt.

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A novel optical electric-field sensor is proposed and demonstrated in experiment by use of a single beta barium borate (β-BaB2O4, BBO) crystal. The optical sensing unit is only composed of one BBO crystal and two polarizers. An optical phase bias of 0.5π is provided by using natural birefringence in the BBO crystal itself. A small angle (e.g., 0.6°) between the sensing light beam and principal axis of the crystal is required in order to produce the above optical bias. Thus the BBO crystal is used as the electric-field-sensing element and quarter waveplate. The ac electric field in the range of (1.4-703.2) kV/m has been measured with measurement sensitivity of 1.39 mV/(kV/m) and nonlinear error of 0.6%. Compared with lithium niobate crystal used as an electric-field sensor, main advantages of the BBO crystal include higher measurement sensitivity, compact configuration, and no ferroelectric ringing effect.

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“…The interface discontinuity is determined by the relative permittivity of both dielectrics (air, ε r1 = 1; LiNbO 3 crystal, ε r2 = 35). When the optically sensed electric field Ez is perpendicular to the crystal surface, the relationship between the field components E and Ez, is given as [23] …”

Section: Electric Fields Relationship On An Air-dielectric Linbomentioning

confidence: 99%

On the Design of Video-Bandwidth Electric Field Sensing Systems Using Dielectric ${\rm LiNbO}_{3}$ Electro-Optic Sensors and Optical Delays as Signal Carriers

2013

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As the measurement of wide-band (multimegahertz) electric fields is often of practical interest in industrial and commercial environments, in this paper, a methodology of design and implementation of a wide-band electric field sensing scheme, using optical delays as information carriers is described. The scheme is based on a lithium niobate (LiNbO 3 ) birefringent optical waveguide that performs simultaneously as an optical retarder and as a dielectric (electrode-less) sensor. In this scheme, the LiNbO 3 sensor introduces an optical delay and simultaneously senses an on-air electric field and imprints it around an optical delay. At the receiver, the sensed electric field is detected when the sensor and demodulator are optically matched, i.e., when both introduce identical optical delays. An important aspect, when sensing electric fields using LiNbO 3 dielectric sensors, is that the optically sensed field is weaker than the external field by a factor given by the ratio of the permittivity of the surrounding dielectric media over the LiNbO 3 permittivity (boundary condition for normal electric fields). When the surrounding media is air, the optically sensed electric field is 35 times weaker than the external field, as described in this paper. Another practical issue is that a birefringent optical waveguide is highly sensitive to optical polarization variations. Such a sensitivity implies that the output dc component of the received light changes with time (dc-drift). The dc-drift performance of the proposed electric field sensing scheme is measured and reported in this paper. The dc-drift can be minimized using polarization-insensitive LiNbO 3 unbalanced Mach-Zehnder interferometers.Index Terms-Lithium niobate LiNbO 3 , dielectric electro-optic sensors, wide-band electric field sensing, optical retarders.

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Modeling and experimental electro-optic response of dielectric lithium niobate waveguides used as electric field sensors

Cited by 14 publications

References 19 publications

Electric Field Encephalography as a Tool for Functional Brain Research: A Modeling Study

Electric Field Encephalography as a Tool for Functional Brain Research: A Modeling Study

Optical electric-field sensor based on angular optical bias using single β-BaB₂O₄ crystal

On the Design of Video-Bandwidth Electric Field Sensing Systems Using Dielectric ${\rm LiNbO}_{3}$ Electro-Optic Sensors and Optical Delays as Signal Carriers

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Modeling and experimental electro-optic response of dielectric lithium niobate waveguides used as electric field sensors

Cited by 14 publications

References 19 publications

Electric Field Encephalography as a Tool for Functional Brain Research: A Modeling Study

Electric Field Encephalography as a Tool for Functional Brain Research: A Modeling Study

Optical electric-field sensor based on angular optical bias using single β-BaB2O4 crystal

On the Design of Video-Bandwidth Electric Field Sensing Systems Using Dielectric ${\rm LiNbO}_{3}$ Electro-Optic Sensors and Optical Delays as Signal Carriers

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Optical electric-field sensor based on angular optical bias using single β-BaB₂O₄ crystal