This study introduces a Bessel-like Beam Generator (BBG) array for optical trapping systems, exploring its application in manipulating dielectric particles in the aqueous medium. The BBG array generates Bessel-like beams through multimode interference. By utilizing heavy water(D2O) with low laser absorption, the photothermal effect induced due to the water convection is reduced, enhancing the trapping performance of D2O. We could trap the polystyrene dietetic particles around the non-diffractive length of BBG. The study analyses the beam profile in D2O and water revealing a significant increase in the non-diffractive length of D2O. These findings have implications for biophysics and medical research, enabling precise manipulation and observation of biological particles in aqueous environments.
We study the Bessel-like beam generator (BBG) exploiting a large-diameter fiber optic platform. The Bessel-like beam is the laser with a specific intensity profile similar to the square of zeroth-order Bessel function, [J0(x)]2 , and has a nondiffractive property. This device is based on the φ=200 microns coreless silica fiber (CSF), which has a larger dimension than generally used optical fiber with 125 microns cladding diameter. As a Gaussian beam from single-mode fiber (SMF) propagates along with this large-diameter CSF, it was successfully converted into a Bessel-like beam serving more lobes than the other all-fiber BBG previously reported. A large number of the lobes can provide a longer nondiffractive length of the Bessel-like beam but, more optical power is required as the beam area gets larger, generating undesirable laser-induced heating in H2O. To solve this problem, we used an 852nm laser which is the wavelength with a small absorption coefficient of water. This enables to reduce of the photothermal effect in the aqueous application of this all-fiber BBG. In this paper, the fabrication of the all-fiber large-diameter BBG and its principle are presented. The photothermal generation in water by the BBG is numerically analyzed for two different wavelengths, 852nm, and 976nm. Furthermore, this photonic device is utilized as an optical tweezer in H2O, discovering its feasibility for an aqueous environment.
We suggest a new way of using Bessel beams to achieve n-dimensional optical control of high-refractive index
microparticles. Although classic optical trapping generally uses bulk optics, this study uses small fiber optics with
maximized efficiency. The Bessel beams follow the propagation axis, and the gradient force generated during this
process creates an axial optical power that enables the confinement of particles. Due to the non-diffractive property of
this beam, the beam diameter is much longer than that of a general Gaussian beam and has a self-healing property that
suppresses the deformation of the beam.
Airy beam has been attracting the attention of current researchers for its unique characteristics such as self-healing
property, non-diffractive nature, and self-accelerating beam trajectory. Normally, this special beam is studied based on a
bulk optic platform using a spatial light modulator or cylindrical lens. Here, we propose the generation of a fiber optic onedimensional
Airy-like beam using a micro-scale cylindrical lens. Experimental measurements demonstrated that the beam
profile had a light distribution similar to the Airy function. Furthermore, its intensity demonstrated a curved trajectory,
which originates from the self-accelerating nature of the Airy-like beam.
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