Use of a diaphragm for transforming a LG10 beam into a Flat-Top

Haddadi, S.; Hasnaoui, Abdelkrim; Fromager, Michaël; Louhibi, D.; Harfouche, A.; Cagniot, Emmanuel; Aı̈t-Ameur, Kamel

doi:10.1016/j.ijleo.2015.11.054

Cited by 5 publications

(6 citation statements)

References 18 publications

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“…the Gaussian LG 00 beam. Nowadays, we are witnessing a new upsurge of investigations on highorder transverse modes in lasers [15][16][17][18][19][20][21][22][23], and specific applications such as particle trapping [24], quantum information [25], optical tweezers [26], and laser beam shaping [27,28]. We can thus legitimately investigate the effects of spherical aberration on the focusing of a high-order transverse mode.…”

Section: Introductionmentioning

confidence: 99%

Structured Laguerre–Gaussian beams for mitigation of spherical aberration in tightly focused regimes

Haddadi¹,

Bouzid²,

Fromager³

et al. 2018

J. Opt.

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Many laser applications utilise a focused laser beam having a single-lobed intensity profile in the focal plane, ideally with the highest possible on-axis intensity. Conventionally, this is achieved with the lowest-order Laguerre–Gaussian mode (LG00), the Gaussian beam, in a tight focusing configuration. However, tight focusing often involves significant spherical aberration due to the high numerical aperture of the systems involved, thus degrading the focal quality. Here, we demonstrate that a high-order radial LGp0 mode can be tailored to meet and in some instances exceed the performance of the Gaussian. We achieve this by phase rectification of the mode using a simple binary diffractive optic. By way of example, we show that the focusing of a rectified LG50 beam is almost insensitive to a spherical aberration coefficient of over three wavelengths, in contrast with the usual Gaussian beam for which the intensity of the focal spot is reduced by a factor of two. This work paves the way towards enhanced focal spots using structured light.

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Section: Introductionmentioning

confidence: 99%

Structured Laguerre–Gaussian beams for mitigation of spherical aberration in tightly focused regimes

Haddadi¹,

Bouzid²,

Fromager³

et al. 2018

J. Opt.

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show abstract

Section: Transformation Of a Radial Laguerre-gaussian Lg P0 Beam Into...mentioning

confidence: 92%

“…The pertinence of parameter η + has been recently demonstrated [15,56]. Indeed, it was found that when η + is close to 0.96, the far-field distribution is made up of a flat-top intensity profile [56]. In contrast, when η + is in the range of 67% to 74%, the far-field is a hollow beam or, more precisely, an optical bottle beam [57].…”

Section: Transformation Of a Radial Laguerre-gaussian Lg P0 Beam Into...mentioning

confidence: 98%

“…Before proceeding, let us consider the value of η + associated with a pure LG p0 beam given in Table 6. Recently, it has been shown [56] that an LG 10 beam can be transformed into an FT profile in the focal plane of a focusing lens by increasing its η + value from 26.4% to 93.4% just by partially truncating the negative ring by using a diaphragm that gives rise to a loss of about 72%. In the next section, it will be shown that a LG 10 beam can be transformed into an FT intensity profile in the far-field region by converting a part of the negative ring into a positive value without loss.…”

Section: Transformation Of a Radial Laguerre-gaussian Lg P0 Beam Into...mentioning

confidence: 99%

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The Advantages and Disadvantages of Using Structured High-Order but Single Laguerre–Gauss LGp0 Laser Beams

Aït-Ameur

2024

Photonics

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Most laser applications are based on the focusing of a Gaussian laser beam (GLB). When the latter is subject to a phase aberration such as the optical Kerr effect (OKE) or spherical aberration (SA), it is recognised that the focusing performance of the GLB is degraded. In this paper, it is demonstrated that high-order radial Laguerre–Gauss LGp0 beams are more resilient than the GLB when subject to the OKE or SA. This opens up opportunities to replace with advantages the usual GLB with a high-order LGp0 beam for some applications.

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“…The LG p mode can be transformed in the focal plane of a lens into a single-lobed beam by using a binary diffractive optical element playing the role of a rectifier [18]. • A simple diaphragm can transform a LG 1 beam into an optical bottle beam [19] or a flat-top intensity profile [20].…”

Section: Introductionmentioning

confidence: 99%

Excitation of high-radial-order Laguerre–Gaussian modes in a solid-state laser using a lower-loss digitally controlled amplitude mask

Bell¹,

Hasnaoui²,

Aı̈t-Ameur³

et al. 2017

J. Opt.

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In this paper we experimentally demonstrate selective excitation of high-radial-order Laguerre–Gaussian (LGp or LG ) modes with radial order p = 1–4 and azimuthal order l = 0 using a diode-pump solid-state laser (DPSSL) that is digitally controlled by a spatial light modulator (SLM). We encoded an amplitude mask containing p-absorbing rings, of various incompleteness (segmented) on grey-scale computer-generated digital holograms, and displayed them on an SLM which acted as an end mirror of the diode-pumped solid-state digital laser. The various incomplete (α) p-absorbing rings were digitally encoded to match the zero-intensity nulls of the desired LGp mode. We show that the creation of LGp, for p = 1 to p = 4, only requires an incomplete circular p-absorbing ring that has a completeness of ≈37.5%, giving the DPSSL resonator a lower pump threshold power while maintaining the same laser characteristics (such as beam propagation properties).

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Use of a diaphragm for transforming a LG10 beam into a Flat-Top

Cited by 5 publications

References 18 publications

Structured Laguerre–Gaussian beams for mitigation of spherical aberration in tightly focused regimes

Structured Laguerre–Gaussian beams for mitigation of spherical aberration in tightly focused regimes

The Advantages and Disadvantages of Using Structured High-Order but Single Laguerre–Gauss LGp0 Laser Beams

Excitation of high-radial-order Laguerre–Gaussian modes in a solid-state laser using a lower-loss digitally controlled amplitude mask

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