Adaptive Interferometry Sensor for Detection of Nanoscale Displacements

In this work we present an adaptive holographic interferometry sensing system for measurement of nanoscale displacements of micro- and macro-objects. The system is based on using dynamic hologram continuously recorded in photorefractive CdTe crystal. Theoretical limit for displacement detection which can be provided by the system is 0.1 nm. It is experimentally demonstrated that system is able to detect a displacement from 0.7 nm up to 266 nm in linear regime. We also present theoretical model of adaptive interferometer operation which take into account a displacement speed. Due to its adaptive properties the measurement system can be used for inspection of sub-micro-scale objects with arbitrary shape and surface profile

Exciton Spectroscopy of Spatially Separated Electrons and Holes in the Dielectric Quantum Dots

It is shown that in the potential energy of an exciton of spatially separated electrons and holes (hole moves in the amount of quantum dots (QDs), and the electron is localized on a spherical surface section (QD—dielectric matrix)) taking into account centrifugal energy gives rise band of the quasi-stationary surface exciton states that with the increase of the radius of QD becomes stationary state. The mechanisms of formation of the spectra of interband and intraband absorption (emission) of light in nanosystems containing aluminum oxide QDs, placed in the matrix of vacuum oil, are presented. It is shown that the electron transitions in the area of the surface exciton states cause significant absorption in the visible and near infrared wavelengths, and cause the experimentally observed significant blurring of the absorption edge

Sensing of multimode-fiber strain by a dynamic photorefractive hologram

We present a strain sensor in which a multimode fiber is used as a sensitive element. High sensitivity to dynamic strains is achieved by means of vectorial wave mixing in a photorefractive CdTe:V crystal. It was found that the largest source of noise in our sensor is related to the instability of the polarization state of speckles emerging from the fiber..

Fiber sensors multiplexing using vectorial wave mixing in a photorefractive crystal

We propose a novel multiplexing system for sensing of dynamic strains excited in different multimode optical fibers. Multiplexing of the sensors is implemented by using vectorial wave mixing technique in the reflection geometry of hologram formation in a photorefractive crystal of CdTe:V. We analyzed different mechanisms of the crosstalk between measuring channels and showed that system performance is strongly affected by residual stresses of the photorefractive crystal

Fast adaptative interferometer on dynamic reflection hologram in CdTe:V

We present an adaptive interferometer based on the reflection dynamic hologram recorded in photorefractive CdTe:V crystal with no external electric field..