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The surface acoustic wave (SAW) humidity sensor based on the Meso-tetra (4 sulfonatophenyl) porphyrin (TPPS4) nanostrip structure deposited on a bare or metallised surface of the piezoelectric YZ LiNbO3 substrate has been investigated. The SAW attenuation, which greatly increases with humidity in sensors with TPPS4 layers on bare substrates, is almost humidity-independent in devices with TPPS4 layers on metallised substrates. For both types of sensors, the SAW velocity exhibits close-to-linear decrease with growing humidity. The sensor exhibited fast response and recovery times of from 0.8 to 0.5s in both amplitude and phase of the output signal. The real-time monitoring of human breath with the help of the sensor was demonstrated.

The acousto-optic control of light in Zn-diffused LiNbO3 optical waveguides is demonstrated. The guided optical mode diffraction by the surface acoustic waves is consistent with the Klein and Cook model for the intermediate diffraction regime. The SAW induced refractive index change is 1.5*10-4 at acoustic power 130mW. The Zn-diffused lithium niobate waveguides appear to be good candidates for integrated light-control devices based on acousto-optic interaction.

The UV-LED controlled phase shifter of an RF signal based on a GaN-sapphire surface-acoustic-wave (SAW) filter has been implemented. At the optical wavelength 298nm and SAW frequency 307MHz, the UV-induced relative change in SAW velocity per unit optical power density is 2*10-6 (muW/mm2)-1 corresponding to 3.7 deg phase shift. The phase modulation of an RF signal by rectangular UV pulses has been demonstrated. The efficiency of the phase shifter can be considerably improved by proper selection of sheet-resistivity of the GaN layer.

An SAW oscillator based on a GaN-sapphire acoustic delay line is reported. The oscillation frequency is determined by the GaN sound velocity and transducer period and is sensitive to temperature and to ultraviolet radiation. Our results show that GaN-based structures offer the possibility of integrating the acoustic and electronic elements on a single chip capable of operating at relatively high temperatures.

A new solar-blind UV detector based on a GaN surface acoustic wave delay line oscillator is reported. The illumination by an artificial UV source in the presence of sunlight increased the RF spectral line width of the oscillator by almost an order of magnitude, which we attribute to the different noise spectra of these light sources. The output of this detector is a radio signal, which makes it especially attractive for remote sensing applications.

The fabrication of surface acoustic wave (SAW) devices by femtosecond laser micromachining has been demonstrated. The interdigital SAW transducers of 50 μm wavelength were formed on YZ lithium niobate substrate by femtosecond pulse ablation of an aluminium layer. The two-port SAW device has insertion loss of 11 dB at 68 MHz. The S-parameter measurements revealed no degradation in substrate elastic, piezoelectric, and dielectric properties of the substrate due to laser processing.