High-Q Microcavity Based on Whispering Gallery Modes Constructed from Microsphere-Core-Shell Quantum Dot Structure
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the films with an 8 nm layer thickness exhibit a large pyroelectric coefficient between 10°C and 26°C with a maximum value of 4.1 × 10-4 C/m2 K at 16°C. This result demonstrates that the material is a good candidate for uncooled infrared focal plane array applications. CORA LIND
Broadband Frequency-Tunable Micromechanical Oscillator Promises to Extend the Applicability of Microelectromechanical Systems (MEMS) Scientists at the Cornell Center for Materials Research have developed a technique for varying the frequency of oscillations over a 300% range in micronscale cantilever beams. These cantilevers, which are used as micromechanical oscillators, serve as the basic component in numerous microelectromechanical systems (MEMS) devices. When the oscillators are limited to operation at either a fixed resonant frequency or over a narrow frequency range, as, according to the researchers, has previously been the case, the applicability of these devices is restricted. Systems such as electromechanical filters, micromechanical spectrum analyzers, and magnetic resonance force microscopes (MFRM) may benefit from the researchers’ work on broadband tunable microresonators. As reported in the November 13 issue of Applied Physics Letters, M. Zalalutdinov, B. Ilic, D. Czaplewski, and co-workers employed a scanning tunneling microscope (STM) as a vibration actuator and a scanning electron microscope (SEM) as a motion detector in order to excite and detect oscillations in low-stress silicon nitride cantilevers (200 µm × 20 µm × 0.6 µm). By applying a small ac voltage to a z-piezodrive, the tungsten STM tip, while in contact with the cantilever, was driven with
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