A surface-potential distribution measuring device includes: a laser light source; a Pockels crystal; a mirror; a photodetector that detects light intensity of the laser beam reflected by the mirror; a holding and mounting part that holds and moves the Pockels crystal; a voltage correction database; and a calculation unit that identifies an input voltage corresponding to a testing output voltage as a surface potential of the electric-field-reduction system. The Pockels crystal is formed in such a way that a size of a cross section of the Pockels crystal that is perpendicular to an axial direction changes along the axial direction. The holding and mounting part has a protection unit to protect a structure of the Pockels crystal, a movement unit to that moves the Pockels crystal in order to measure a surface potential of the electric-field-reduction system, and a drive control unit to control the movement unit.

In a surface potential distribution measuring device for an electric field reduction system of a rotating electrical machine, a Pockels crystal is used between a laser and the surface (test location) of the electric field reduction system. Light intensity of a laser beam reflected on a mirror provided between the Pockels crystal and the test location corresponds to an output voltage that is the voltage difference between the first end surface and the second end surface of the Pockels crystal. Even when an inverter voltage is generated, by using a light detector having a frequency band capable of following the high frequency components of the inverter pulse voltage, the light intensity is detected by the light detector. Therefore, from the light intensity (output voltage), the surface potential distribution measuring device can measure the surface potential of the electric field reduction system in which an inverter pulse voltage is generated.

A three-dimensional surface potential distribution measurement apparatus includes: a laser light source; a Pockels crystal; a mirror; a light detector; a support structure which supports the aforementioned elements while maintaining a relative positional relationship therebetween; a movement driver which can move the support structure three-dimensionally; a rotary driver which supports the test object and can rotate the test object about an axis extending in a longitudinal direction of the test object; and a drive controller which controls the movement driver and the rotary driver. The drive controller coordinates a driving operation by the movement driver and by the rotary driver while maintaining a gap between the second end face of the Pockels crystal and a surface of the test object at a predetermined value such that the second end face of the Pockels crystal approaches all the surfaces of the electric field reduction system on the test object.

The following relates generally to optical voltage sensing, and in particular to optical voltage sensing of power grids and of a subject body. For example, some embodiments include an optical resonator comprising: (i) a top electrode layer, (ii) a piezoelectric layer, and (iii) a substrate. A light source may illuminate the optical resonator of the voltage sensor with light comprising an incident optical power at an input wavelength, where the input wavelength is offset from a resonant wavelength of the optical resonator by a baseline voltage. The applied voltage may then be measured by measuring a reflected or transmitted light power.

A voltage measuring device for measuring a voltage by using a Pockels cell includes a Pockels cell changing a refractive index of incident light based on an applied electric field, at least one non-polarized beam splitter splitting an incident beam, a first polarizing plate polarizing a first beam split by the at least one non-polarized beam splitter, a first light detector detecting light polarized based on the first polarizing plate, a wave plate elliptically polarizing and outputting a second beam split by the at least one non-polarized beam splitter, a second polarizing plate polarizing the elliptically polarized second beam, a second light detector detecting light polarized based on the wave plate and the second polarizing plate, and a controller configured to measure a voltage based on a first light intensity determined by the first light detector and a second light intensity determined by the second light detector.

The disclosed technology relates to optical electric field sensor devices with improved thermal stability that leverage the Pockels effect to detect electric fields using rubidium titanyl phosphate (RbTiOPO4) (RTP) crystal(s). An exemplary optical electric field sensor device includes an input collimator configured to collimate an input light beam from a light source. The optical electric field sensor device further includes a crystal material positioned to receive the input light beam via the input collimator, configured to exhibit the Pockels effect when an electric field is applied through the crystal material, and comprising RTP. The optical electric field sensor device further includes an output collimator configured to focus an output light beam received from the crystal material onto at least one detector.

A photonic integrated circuit including a substrate, a plurality of oxide layers on the substrate, and various passive and active integrated optical components in the plurality of oxide layers. The integrated optical components include silicon nitride waveguides, a Pockets effect phase shifter (e.g., BaTiO.sub.3 phase shifter), a superconductive nanowire single photon detector (SNSPD), an optical isolation structure surrounding the SNSPD, a single photon generator, a thermal isolation structure, a heater, a temperature sensor, a photodiode for data communication (e.g., a Ge photodiode), or a combination thereof.

A photonic integrated circuit including a substrate, a plurality of oxide layers on the substrate, and various passive and active integrated optical components in the plurality of oxide layers. The integrated optical components include silicon nitride waveguides, a Pockels effect phase shifter (e.g., BaTiO.sub.3 phase shifter), a superconductive nanowire single photon detector (SNSPD), an optical isolation structure surrounding the SNSPD, a single photon generator, a thermal isolation structure, a heater, a temperature sensor, a photodiode for data communication (e.g., a Ge photodiode), or a combination thereof.