In view of the large scientific and technical interest in the MEMS accelerometer sensor and the limitations of capacitive, resistive piezo, and piezoelectric methods, we focus on the measurement of the seismic mass displacement using a novel design of the all-optical sensor (AOS). The proposed AOS consists of two waveguides and a ring resonator in a two-dimensional rod-based photonic crystal (PhC) microstructure, and a holder which connects the central rod of a nanocavity to a proof mass. The photonic band structure of the AOS is calculated with the plane-wave expansion approach for TE and TM polarization modes, and the light wave propagation inside the sensor is analyzed by solving Maxwell’s equations using the finite-difference time-domain method. The results of our simulations demonstrate that the fundamental PhC has a free spectral range of about 730 nm covering the optical communication wavelength-bands. Simulations also show that the AOS has the resonant peak of 0.8 at 1.644µm, quality factor of 3288, full width at half maximum of 0.5nm, and figure of merit of 0.97. Furthermore, for the maximum 200nm nanocavity displacements in the x- or y-direction, the resonant wavelengths shift to 1.618µm and 1.547µm, respectively. We also calculate all characteristics of the nanocavity displacement in positive and negative directions of the x-axis and y-axis. The small area of 104.35 µm2 and short propagation time of the AOS make it an interesting sensor for various applications, especially in the vehicle navigation systems and aviation safety tools.
Metal nanoparticles (NP) supported on TiO 2 are known to be efficient photocatalysts for solar-to-chemical energy conversion. While TiO 2 decorated with copper NPs has the potential to become an attractive system, the poor oxidative stability of Cu severely limits its applicability. In this work, we demonstrate that, when Cu NPs supported on TiO 2 nanobelts (NBs) are engaged in the photocatalytic generation of H 2 from water under light illumination, Cu is not only oxidized in CuO but also dissolved under the form of Cu + /Cu 2+ ions, leading to a continuous reconstruction of nanoparticles via Ostwald ripening. By nanoencapsulating the CuO x (Cu/CuO/Cu 2 O) NPs by a few layers of carbon supported on TiO 2 (TC@C), Ostwald ripening can be suppressed. Simultaneously, the resulting CuO x @C NPs are photoreduced under light illumination to generate Cu@C NPs. This photoswitching strategy allows the preparation of a Cu plasmonic photocatalyst with enhanced activity for H 2 production. Remarkably, the photocatalyst is even active when illuminated with visible light, indicating a clear plasmonic enhancement of photocatalytic activity from the surface plasmonic resonance (SPR) effect of Cu NPs. Three-dimensional electromagnetic wavefrequency domain (3D-EWFD) simulations were conducted to confirm the SPR enhancement. This advance bodes for the development of scalable multifunctional Cu-based plasmonic photocatalysts for solar energy transfer.
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