Acousto-optic k-space filtering for multifrequency laser beam shaping

Abstract

One of emerging applications of acousto-optic tunable filters (AOTFs) is spatial filtering of optical beams. A noncollinear AOTF has a tunable ring-shaped transfer function determined by geometry of the refractive index surface in a uniaxial crystal. We rigorously derive the geometrical parameters of the AOTF's elliptic transfer function under noncritical phase matching condition in uniaxial crystals. This basic family of transfer functions can be used for synthesis of axially symmetric transfer functions with the help of multifrequency ultrasonic signals. A two-color tunable optical trap configuration is proposed based on a single AOTF used for laser beam shaping.

Acousto-Optic Transfer Function Control by a Phased-Array Piezoelectric Transducer

“…In those experiments, the AOSF was controlled only by means of frequency tuning. The disadvantage of frequency-only AOSF tuning is the inherent asymmetry of the transfer function [2,3]. The phase control of the transfer function is based on effective acoustic wavefront tilt, which can compensate for this asymmetry of the transfer function.…”

“…The transfer function of a noncollinear AOSF in this diffraction geometry has the O-type topology, and the radius of the phase-matching locus increases with the ultrasound frequency. Accurate analysis shows that the annular transfer function near the NPM diffraction geometry is slightly asymmetric, and the transfer function center shifts with the ultrasound frequency [2,3]. With respect to Equations ( 7) and ( 11), the resulting two-dimensional transfer function will be expressed as T 1 (θ, ϕ; f , Q, ∆φ), where θ and ϕ are the plane-wave direction angles, while f , Q, and ∆φ are the problem parameters corresponding to the ultrasound frequency, normalized amplitude, and the phase delay between the transducer sections.…”

“…LBS is one of the emerging applications of acousto-optic (AO) tunable filters (AOTFs) [2,3]. AOTFs directly filter the angular spectrum of laser beams, as first shown by Balakshy [4].…”

Calibration of Acousto-Optic Interaction Geometry Based on the Analysis of AOTF Angular Performance

“…These theories are all typically under the parallel tangent condition. For the non-parallel tangent condition, Yushkov expressed an exact phase-matching calculation equation at an arbitrary incident angle and recently proposed an alternative method for analyzing the Bragg angle curve in wide-angle AOTFs [ 10 , 20 ]. Zhang discussed the function of the phase mismatching condition and proposed a new tuning method with a non-radio-frequency signal [ 21 ].…”

Investigation of acousto-optic interaction with momentum mismatching considering acoustic anisotropy in birefringent crystal

“…AO techniques are currently widely applied across various domains of scientific and engineering. Non-collinear AOTF, which is commonly used in fields such as spectroscopy, optical imaging, and medical diagnostics, is a typical AO device designed based on the principle of abnormal Bragg diffraction in AO interaction and has the advantages such as compact size, rapid tuning and high diffraction efficiency [1][2][3][4][5][6][7][8] . Typically, the AO interaction is analyzed using the plane wave approximation in which the acoustic wave is considered as a single plane wave propagating perpendicular to the transducer [9] .…”