Real-space observation of ultraconfined in-plane anisotropic acoustic terahertz plasmon polaritons

Thin layers of in-plane anisotropic materials can support ultraconfined polaritons, whose wavelengths depend on the propagation direction. Such polaritons hold potential for the exploration of fundamental material properties and the development of novel nanophotonic devices. However, the real-space observation of ultraconfined in-plane anisotropic plasmon polaritons (PPs)-which exist in much broader spectral ranges than phonon polaritons-has been elusive. Here we apply terahertz nanoscopy to image in-plane anisotropic low-energy PPs in monoclinic Ag₂Te platelets. The hybridization of the PPs with their mirror image-by placing the platelets above a Au layer-increases the direction-dependent relative polariton propagation length and the directional polariton confinement. This allows for verifying a linear dispersion and elliptical isofrequency contour in momentum space, revealing in-plane anisotropic acoustic terahertz PPs. Our work shows high-symmetry (elliptical) polaritons on low-symmetry (monoclinic) crystals and demonstrates the use of terahertz PPs for local measurements of anisotropic charge carrier masses and damping.

Langmuir and Langmuir-Blodgett films of a maleic anhydride derivative: effect of subphase divalent cations

We report the study of the equilibrium and dynamic properties of Langmuir monolayers of poly(styrene-co-maleic anhydride) partial 2-buthoxyethyl ester cumene terminated polymer and the effect of the Mg(NO(3))(2) addition in the water subphase on the film properties. Results show that the polymer monolayer becomes more expanded when the electrolyte concentration in the subphase increases. Dense polymer films aggregate at the interface. The aggregates are transferred onto silicon wafers using the Langmuir-Blodgett methodology and the morphology is observed by AFM. The structure of aggregates depends on the subphase composition of the Langmuir film transferred onto the silicon wafer.

[Rigid gas permeable contact lenses fitted in a case of congenital glaucoma]

CASE REPORT

A 27-year-old woman with congenital glaucoma with high myopia, low visual acuity and nystagmus in both eyes, was referred for contact lens fitting. We fitted her with aspherical rigid gas permeable (RGP) contact lenses with high transmissibility, which she wore on a daily basis. Her visual acuity improved with the wearing of these lenses, which remained comfortable whilst being worn for 10 hours a day.

DISCUSSION

Contact lenses were fitted according to her corneal topography. Gas permeable contact lenses were chosen as first choice and with proper fitting and vigilant follow-up they may be worn safely on a daily basis.