Acousto-optics bandwidth broadening in a Bragg cell based on arbitrary synthesized signal methods

Abstract

In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%.

Optimal Design of an Ultrasound Transducer for Efficient Acousto-Optic Modulation of Terahertz Radiation

“…The deflection angle between the transmitted and diffracted radiation beams equals the doubled Bragg angle , which depends on the sound frequency F , radiation wavelength , and sound velocity V [ 5 ]: …”

Simultaneous acousto-optic diffractions by two lobes of a shaped phased-array transducer

“…Therefore, reduction of side-lobe intensities and beam steering can be achieved, thus resulting in expanded dynamic range and bandwidth of AO devices [1−5]. Although the best results can be reached when the phase and the amplitude of cells are controlled electronically [5], simply connecting piezoelectric cells in a series with the opposite polarities, which results in the phase shift  , also increases the bandwidth and the dynamic range [2]. To implement this phase shift, a metalized binding layer between a piezoelectric plate and a crystal can be used to connect two parts of a transducer in the opposite direction.…”