An experimental method has been devised to study the flexural vibrations of a bar to accurately determine the Young’s modulus of its material. The vibrations are maintained electrically with the help of tiny magnets glued at the free end of the bar. The distinctive element in the present work is the determination of higher resonant frequencies with notable accuracy along with the fundamental. The actual values of the resonant frequencies in zero magnet-mass condition are obtained from the extrapolated plots of the observed resonant frequencies versus the mass of the magnet. A theoretical model is also developed for the fundamental mode based upon which numerical results are obtained and found to be in conformity with these experimental findings.
This work proposes a scheme of all-optical XNOR/NOT logic gates based on a reflective vertical cavity semiconductor (quantum wells, QWs) saturable absorber (VCSSA). In a semiconductor Fabry-Perot cavity operated with a low-intensity resonance wavelength, both intensity-dependent saturating phase-shift and thermal phase-shift occur, which are considered in the proposed logic operations. The VCSSA-based logics are possible using the saturable behavior of reflectivity under the typical operating conditions. The low-intensity saturable reflectivity is reported for all-optical logic operations where all possible nonlinear phase-shifts are ignored. Here, saturable absorption (SA) and the nonlinear phase-shift-based all-optical XNOR/NOT gates and one-bit memory or LATCH are proposed under new operating conditions. All operations are demonstrated for a VCSSA based on InGaAs/InP QWs. These types of SA-based logic devices can be comfortably used for a signal bit rate of about 10 GHz corresponding to the carrier recovery time of the semiconductor material.
An analytical model for a square split ring resonator (S-SRR) having a
single split-gap is considered here to reliably estimate the
fundamental resonance frequency of the ring. An S-SRR is assumed to be
equivalent to a series-resonant LC loop. The approximate formulas for
equivalent self-inductance and total capacitance of the ring are
derived separately. The total capacitance of the ring is expressed as
a sum of a gap capacitance and a surface capacitance (which is
associated with charges on the SRR walls). Both the capacitances are
influenced by not only the medium in split-gap but also the dielectric
constant of substrate. These are taken care of by including
appropriate weight factors in the expressions for the capacitances.
Again, using the software CST Microwave Studio, the resonance
frequencies are calculated for several values of split-gap and SRR
side length. Then the results of simulation are compared with the
results obtained from our formula. It is found that simulation results
agree quite well with the analytical results. Also, the analytical
result for resonance frequency of SRR shows good agreement with a
previously published experimental result. This model can be used for
studies of the resonant properties of split rings in the microwave and
terahertz regions.
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