This work presents a 3-Port acoustoelectric switch design for surface acoustic wave signal processing. Using a multistrip coupler, the input acoustic wave at Port 1 is split into two parallel and electrically cross-linked acoustoelectric delay lines where an applied voltage can alter the gain and attenuation in each delay line based on the voltage polarity. The switch is demonstrated using a 270 MHz Leaky SAW mode on an InGaAs on 41° Y-cut lithium niobate heterostructure. Applying a +40 V voltage pulse results in an IL of -12.5 dB and -57.5 dB in the gain and isolation switch paths, respectively. This leads to a 45 dB difference in signal strength at the output ports.
At the molecular level, resonant coupling of infrared radiation with oscillations of the electric dipole moment determines the absorption cross section, $σ$. The parameter σ relates the bond density to the total integrated absorption. In this work, $σ$ was measured for the Si–N asymmetric stretch mode in SiNx thin films of varying composition and thickness. Thin films were deposited by low pressure chemical vapor deposition at 850 °C from mixtures of dichlorosilane and ammonia. σ for each film was determined from Fourier transform infrared spectroscopy and ellipsometric measurements. Increasing the silicon content from 0% to 25% volume fraction amorphous silicon led to increased optical absorption and a corresponding systematic increase in σ from 4.77 × 10–20 to 6.95 × 10–20 cm2, which is consistent with literature values. The authors believe that this trend is related to charge transfer induced structural changes in the basal SiNx tetrahedron as the volume fraction of amorphous silicon increases. Furthermore, experimental $σ$ values were used to calculate the effective dipole oscillating charge, q, for four films of varying composition. The authors find that q increases with increasing amorphous silicon content, indicating that compositional factors contribute to modulation of the Si–N dipole moment. Additionally, in the composition range investigated, the authors found that $σ$ agrees favorably with trends observed in films deposited by plasma enhanced chemical vapor deposition.