Monolithically integrated membrane-in-the-middle cavity optomechanical systems.

We describe curved-mirror Fabry-Perot cavities with embedded silicon nitride membranes, fabricated using a monolithic surface-micromachining process. The presence of the suspended membranes was confirmed by confocal microscopy, and their properties were verified through optical studies and thermomechanical calibration of mechanical/vibrational noise spectra measured at room temperature and atmospheric pressure. The cavities exhibit reflectance-limited finesse (F ∼ 103) and wavelength-scale mode volumes (VM ∼ 10·λ3). The short cavity length (L ∼ 2·λ) results in large optomechanical coupling, which is desirable for numerous applications in sensing and quantum information.

Liquid infiltration of monolithic open-access Fabry-Perot microcavities.

We describe a monolithic approach to fabricating large-scale arrays of high-finesse and low-mode-volume Fabry-Perot microcavities with open access to the air core. A stress-driven buckling self-assembly technique was used to form half-symmetric curved-mirror cavities, and a dry etching process was subsequently used to create micropores through the upper mirror. We show that the cavities retain excellent optical properties, with reflectance-limited finesse ∼2500 and highly predictable Laguerre-Gaussian modes. We furthermore demonstrate the ability to introduce liquids into the cavity region by microinjection through the pores. Applications in sensing, optofluidics, and cavity quantum electrodynamics are envisioned.

Cadmium-induced oxidative stress in two potato cultivars.

A hydroponic experiment was carried out to characterize the oxidative stress responses of two potato cultivars (Solanum tuberosum L. cvs. Asterix and Macaca) to cadmium (Cd). Plantlets were exposed to four Cd levels (0, 50, 100, 150 and 200 microM) for 7 days. Cd concentration was increased in both roots and shoot. Number of sprouts and roots was not decreased, whereas Cd treatment affected the number of nodal segments. Chlorophyll content and ALA-D activity were decreased in both cultivars, whereas carotenoids content was decreased only in Macaca. Cd caused lipid peroxidation in roots and shoot of both cultivars. Protein oxidation was only verified at the highest Cd level. H(2)O(2) content was increased in roots and shoot of Asterix, and apparently, a compensatory response between roots and shoot of Macaca was observed. SOD activity was inhibited in roots of Asterix at all Cd treatments, whereas in Macaca it was only increased at two highest Cd levels. Shoot SOD activity increased in Asterix and decreased in Macaca. Root CAT activity in Asterix decreased at 100 and 150 microM, whereas in Macaca it decreased only at 50 microM. Shoot CAT activity was decreased in Macaca. Root AsA content in Macaca was not affected, whereas in shoot it was reduced at 100 microM and increased at 200 microM. Cd caused increase in NPSH content in roots and shoot. Our results suggest that Cd induces oxidative stress in both potato cultivars and that of the two cultivars, Asterix showed greater sensitivity to Cd levels.