Generation of a hollow laser beam for atom trapping using an axicon

Manek, I.; Ovchinnikov, Yu. N.; Grimm, Rudolf

doi:10.1016/s0030-4018(97)00645-7

Cited by 150 publications

(80 citation statements)

References 14 publications

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“…The uniform potential is tailored using blue-detuned laser light for the confining walls. The sharp radial trap barrier is provided by a ring beam generated by an axicon [34,35], while two light sheets act as end caps for the axial trapping [36]. Furthermore, the atoms are levitated against gravity by a magnetic saddle potential [3].…”

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confidence: 99%

Homogeneous Atomic Fermi Gases

et al. 2017

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We report on the creation of homogeneous Fermi gases of ultracold atoms in a uniform potential. In the momentum distribution of a spin-polarized gas, we observe the emergence of the Fermi surface and the saturated occupation of one particle per momentum state: the striking consequence of Pauli blocking in momentum space for a degenerate gas. Cooling a spin-balanced Fermi gas at unitarity, we create homogeneous superfluids and observe spatially uniform pair condensates. For thermodynamic measurements, we introduce a hybrid potential that is harmonic in one dimension and uniform in the other two. The spatially resolved compressibility reveals the superfluid transition in a spin-balanced Fermi gas, saturation in a fully polarized Fermi gas, and strong attraction in the polaronic regime of a partially polarized Fermi gas.

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confidence: 99%

Homogeneous Atomic Fermi Gases

et al. 2017

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“…An appropriate example is LiNbO 3 crystals under conditions that a laser beam propagates along the optic axis and the torsion is applied around the same direction [19]. What is the most important, a special singular point of zero birefringence belonging to the torsion axis has been revealed in the geometrical center of XY cross section of a sample, which corresponds to zero shear stress components 5  and 4  . The birefringence has been found to increase linearly with increasing distance from that geometrical center and so the birefringence distribution has a conical shape in the coordinates , ,  X Y n [19].…”

Section: The Principles Of Operation Of a Gradient-index Torsion Axiconmentioning

confidence: 99%

Torque-operated gradient-index axicon

Vasylkiv¹,

Smyk²,

Skab³

et al. 2014

Ukr. J. Phys. Opt.

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“…Inter-cavity techniques for lasing in annular modes [15,16] may have a Gaussian-like profile with minimal and symmetric diffraction, at the expense of low gain and output versatility. Extra-cavity techniques to transform from Gaussian to annular beams can produce thin and dark beams with asymmetric or strong diffraction [1, 2], or efficient Gaussian-like annular beams with limited geometry [17][18][19][20][21][22].Widely used Laguerre Gaussian (LG) beams, LG l p of radial index p = 0 and azimuthal index l, have a Gaussian-like cylindrical profile with a radius to waist ratio of l/2 [23]. The highest efficiency of converting a Gaussian beam into LG 1 0 by typical extra-cavity techniques is ≈ 80% [19], but the overlap between a Gaussian beam and LG l 0 decays significantly with l. For a thin LG beam with radius to waist ratio of ≈ 10 it is practically zero [18].…”

mentioning

confidence: 99%

“…Extra-cavity techniques to transform from Gaussian to annular beams can produce thin and dark beams with asymmetric or strong diffraction [1, 2], or efficient Gaussian-like annular beams with limited geometry [17][18][19][20][21][22].…”

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Producing an efficient, collimated, and thin annular beam with a binary axicon

2018

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We propose and demonstrate a method to produce a thin and highly collimated annular beam that propagates similarly to an ideal thin Gaussian ring beam, maintaining its excellent propagation properties. Our optical configuration is composed of a binary axicon -a circular binary phase grating, and a lens, making it robust and well suited for high-power lasers. It has a near-perfect circular profile with a dark center, and its large radius to waist ratio is achieved with high conversion efficiency. The measured profile and propagation are in excellent agreement with a numerical Fourier simulation we perform. Annular beams, characterized by a hollow ring cross section, are useful for a variety of applications, such as optical dipole traps for ultra-cold atoms [1][2][3][4][5][6], hollow optical tweezers for dielectric particles [7,8], imaging and super-resolution microscopy [9,10], long-ranged atmospheric optical communication [11,12] and material processing [13,14].There are many techniques to produce annular beams. However, it is challenging to produce an ideal Gaussian ring beam that is minimally diffracting. Usually there is a compromise between ring parameters (thinness, darkness at the center), beam propagation (minimal diffraction, collimation, shape invariance), complexity, power handling and efficiency. Inter-cavity techniques for lasing in annular modes [15,16] may have a Gaussian-like profile with minimal and symmetric diffraction, at the expense of low gain and output versatility. Extra-cavity techniques to transform from Gaussian to annular beams can produce thin and dark beams with asymmetric or strong diffraction [1, 2], or efficient Gaussian-like annular beams with limited geometry [17][18][19][20][21][22].Widely used Laguerre Gaussian (LG) beams, LG l p of radial index p = 0 and azimuthal index l, have a Gaussian-like cylindrical profile with a radius to waist ratio of l/2 [23]. The highest efficiency of converting a Gaussian beam into LG 1 0 by typical extra-cavity techniques is ≈ 80% [19], but the overlap between a Gaussian beam and LG l 0 decays significantly with l. For a thin LG beam with radius to waist ratio of ≈ 10 it is practically zero [18].Many techniques to create annular beams, mostly extra-cavity, involve an axicon [17,[20][21][22][24][25][26][27], a refractive conical optical element which inflicts a linear radial phase to the refracted light. An axicon ideally transforms a Gaussian beam into a Bessel beam [28][29][30][31], which opens to a ring with a cylindrical profile of half a 1D Gaussian beam. The main drawback of the axicon is the inherent imperfection of its tip area, which cannot be infinitely polished to a point. The deviation of the output beam from the expected output, which is itself a non-ideal half Gaussian, is stronger for thinner rings requiring a smaller input waist that increases the overlap with the imperfect tip.In this Letter we discuss the propagation of Gaussian ring beams. We propose and demonstrate a novel method to produce a thin and highly collimated annular...

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Generation of a hollow laser beam for atom trapping using an axicon

Cited by 150 publications

References 14 publications

Homogeneous Atomic Fermi Gases

Homogeneous Atomic Fermi Gases

Torque-operated gradient-index axicon

Producing an efficient, collimated, and thin annular beam with a binary axicon

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