Strain-mediated ion-ion interaction in rare-earth-doped solids.

It was recently shown that the optical excitation of rare-earth ions produces a local change of the host matrix shape, attributed to a change of the rare-earth ion's electronic orbital geometry. In this work we investigate the consequences of this piezo-orbital backaction and show from a macroscopic model how it yields a disregarded ion-ion interaction mediated by mechanical strain. This interaction scales as1/r3, similarly to the other archetypal ion-ion interactions, namely electric and magnetic dipole-dipole interactions.

ultrasound modulated optical tomography with a persistent spectral hole burning filter.

We present ultrasound modulated optical tomography (UOT) results on mice, using the persistent spectral hole burning (PSHB) effect in a Tm:YAG crystal. Indocyanine green (ICG) solution was injected as an optical absorber and was clearly identified on the PSHB-UOT images, both in the muscle (following an intramuscular injection) and in the liver (following an intravenous injection). This demonstration also validates an experimental setup with an improved level of performance combined with an increased technological maturity compared to previous demonstrations.

Two-pulse photon echo area theorem in an optically dense medium.

We perform a theoretical and experimental study of the two-pulse photon echo area conservation law in an optically dense medium. The experimental properties of the echo signal are studied at 4K on the optical transition  H (1)→H (1) (793 nm) of Tm  in a YAG crystal for a wide range of pulse areas of the two incoming light pulses, up to 4 and ≈7 respectively, with optical depth 1.5.

Piezospectroscopic measurement of high-frequency vibrations in a pulse-tube cryostat.

Vibrations in cryocoolers are a recurrent concern to the end user. They appear in different parts of the acoustic spectrum depending on the refrigerator type, Gifford McMahon or pulse-tube, and with a variable coupling strength to the physical system under interest. Here, we use the piezospectroscopic effect in rare-earth doped crystals at a low temperature as a high resolution, contact-less probe for the vibrations.

Structured ultrasound-modulated optical tomography.

Ultrasound-modulated optical tomography (UOT) is an imaging technique that couples light and ultrasound in order to perform in-depth imaging of highly scattering media. In previous work, we introduced plane wave UOT, an imaging method analogous to x-ray tomography based on the filtered backprojection for image reconstruction. Angle-limited measurements, however, led to drastic loss of lateral spatial resolution.