Phase-tuned acousto-optic spatial filter.

An acousto-optic (AO) tunable filter with a phase-controlled dual-section piezoelectric transducer is designed and created for laser beam shaping (LBS). Owing to the acoustic beam steering effect, we experimentally observe splitting of the two-dimensional transfer function. As a result, we demonstrate generation of tunable bottle laser beams and dual-ring intensity distributions for the diffracted beam.

Independent multicolored bottle-beam generation using acousto-optic spatial shaping of a femtosecond laser beam.

We report on the development of a tunable spectral and spatial frequency shaping system for ultrashort laser pulses using acousto-optic filters. The system enables the creation of arbitrary axially symmetric multi-wavelength field configurations in the Ti:sapphire laser emission range near 800 nm and controlling them at a multi-kilohertz rate. We experimentally demonstrate independent generation of two-colored annular intensity distributions from a single femtosecond laser beam and a bottle beam having the hollow cylindrical volume with the aspect ratio of 9:1.

Analysis of Acousto-Optic Figure of Merit in KGW and KYW Crystals.

Monoclinic potassium rare-earth crystals are known as efficient materials for solid-state lasers and acousto-optic modulators. A number of specific configurations for acousto-optic devices based on those crystals have recently been proposed, but the acousto-optic effect of those crystals has only been analyzed fragmentarily for some interaction directions. In this work, we numerically searched for the global maxima of an acousto-optic figure of merit for isotropic diffraction in KGd(WO) and KY(WO) crystals.

Characterization and alignment of acousto-optic devices using digital tailored RF waveforms.

Acousto-optic (AO) devices are used in a variety of light control and processing applications in different environments, including laboratory conditions and the field environment, as well as on air- and space-borne platforms. Accurate alignment and calibration of AO deflectors and tunable filters is crucial for correct operation and to achieve specified performances of those devices. We describe a simple routine to test and align AO devices with a programmable RF waveform generator.

Ring-shaped optical trap based on an acousto-optic tunable spatial filter.

We report on a novel, to the best of our knowledge, optical scheme of an annular optical trap based on an acousto-optic tunable spatial filter. Design of the optical trap is proposed and validated. Experimental demonstration with polystyrene microspheres includes controllable arrangement of freely floating particles into a circular pattern, aggregation, and disaggregation of the particles.

AOTF-based hyperspectral imaging phase microscopy.

Phase imaging microscopy with incoherent object illumination is convenient and affordable for biomedical research and clinics since it provides easy integration with a variety of bright-field optical microscopes. We report the design of a new hyperspectral imaging system based on a combination of a spatial light modulator (SLM) and an acousto-optic tunable filter (AOTF) for phase imaging microscopy. Contrast of phase-only objects originates from matched spectral and spatial filtering performed by the SLM and the AOTF located in Fourier-conjugate optical planes in the back-end of the optical system.

Optimization of noncollinear AOTF design for laser beam shaping.

Optimization of a wide-angle paratellurite acousto-optic tunable filter (AOTF) is performed for applications in laser beam shaping systems. The AOTF configuration with annular transfer function is analyzed. It is demonstrated that the optimal AOTF design for single-frequency operation as a narrow-band spatial frequency filter is obtained at acoustic propagation angle of 5.

Novel protocol of hyperspectral data acquisition by means of an acousto-optical tunable filter with synthesized transmission function.

A new protocol of hyperspectral data acquisition with an acousto-optical tunable filter is proposed and tested experimentally. Correction for the illumination source spectrum and regular spectral sensitivity factors is embedded in the data acquisition routine. The protocol is based on the adaptive electronic setting of the filter transmission passband inversely proportional to the power spectrum of the light source.

Compact acousto-optic imaging spectro-polarimeter for mineralogical investigations in the near infrared.

Spectral imaging in the near infrared is a promising method for mineralogy analysis, in particular well-suited for airless celestial objects or those with faint atmospheres. Additional information about structure and composition of minerals can be obtained using spectral polarimetry with high spatial resolution. We report design and performance of laboratory prototype for a compact near infrared acousto-optic imaging spectro-polarimeter, which may be implemented for remote or close-up analysis of planetary surfaces.

Hyperspectral imaging acousto-optic system with spatial filtering for optical phase visualization.

We report a method for phase visualization in the images of transparent specimens using analog image processing in incoherent light. The experimental technique is based on adaptive bandpass spatial filtering with an amplitude mask matched with an acousto-optic tunable filter in a telecentric optical system. We demonstrate the processing of microscopic images of unstained and stained histological sections of human thyroid tumor with improved contrast.

70 GHz arbitrary modulation of chirped laser pulses by means of acousto-optics.

We report the arbitrary modulation of chirped ultrashort laser pulses with a 70 GHz bandwidth. In the proof-of-principle experiment, modulation of Ti:sapphire laser emission was performed by the acousto-optic dispersive delay line, and the temporal pulse shape was measured with a picosecond streak camera.

Anisotropic diffraction of bulk acoustic wave beams in lithium niobate.

The formalism of planar diffraction tensor was applied to the analysis of anisotropy of bulk acoustic wave diffraction and to build a full map of anisotropic diffractional coefficients for three bulk acoustic wave modes propagating in lithium niobate. For arbitrary propagation direction the diffractional coefficients derived allow estimation of ultrasonic beam divergence in far-field. Analysis of obtained data revealed that the maxima of acousto-optic figure of merit for anisotropic diffraction in the YZ plane correspond to moderate diffractional spreading of the beams exceeding isotropic diffraction 2-3 times.

Influence of acoustic energy walk-off on acousto-optic diffraction characteristics.

Influence of acoustic beam energy walk-off on characteristics of Bragg diffraction of light is studied theoretically and experimentally by the example of a paratellurite single crystal. Two cases of isotropic and anisotropic light scattering are examined. Angular and frequency characteristics of acousto-optic interaction are calculated in wide ranges of Bragg angles and ultrasound frequencies by means of modified Raman-Nath equations.

Advanced spectral processing of broadband light using acousto-optic devices with arbitrary transmission functions.

In the paper, we developed a dispersive method for transmission function synthesis of collinear and quasi-collinear acousto-optic tunable filters. General theoretical consideration was performed, and modelling was made for broadband and narrowband signals. Experimental results on spectral shaping of femtosecond laser emission were obtained.

MTF formalism for measurement of spectral resolution of acousto-optical devices with synthesized transmission function.

We demonstrate use of the modulation transfer function method in the spectral domain for dynamic measurement of the spectral resolution and modulation contrast of acousto-optic light dispersive delay lines and programmable filters with synthesized transmission. The method is useful for performance characterization of acousto-optic devices for ultrafast pulse shaping and adaptive spectroscopy.

Adaptive acousto-optic technique for femtosecond laser pulse shaping.

We discuss the theoretical and experimental investigation of acousto-optic dispersive tunable filters, based on quasi-collinear geometry of light-sound interaction in a tellurium dioxide single crystal. The geometry uses the effect of strong acoustic anisotropy in the paratellurite as well as peculiarities of acoustic wave reflections at the free boundary of the crystal. A mathematical concept for determination of optical, electrical, and constructional parameters of the filters is developed.