Laser beam shaping based on amplitude-phase control of a fiber laser array

Author(s):

Adamov, E. V.; Aksenov, V. P.; Atuchin, V. V.; Dudorov, V. V.; Kolosov, V. V. & Levitsky, M. E.

Abstract:

“A new technique is suggested for the generation of laser beams with an intensity profile specified. The technique is based on the coherent combining of radiation of a fiber laser array with adaptive control of the power and phase of Gaussian subbeams with plane wavefronts. The power and phase of the subbeams are determined for each intensity profile specified in the far field based on the inverse problem solution, for example, by the Gershberg–Saxton method. To form a required phase profile, the stochastic parallel gradient descent (SPGD) method is used along with the inversion of a required phase distribution with a phase corrector. The main advantages of the technique are the adaptive control of the intensity profile and a possibility of generating high-power laser beams. The results of numerical and field experiments are described.”

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Publication: OSA Continuum
Issue/Year: OSA Continuum, Volume 4; Number 1; Pages 182; 2021
DOI: 10.1364/osac.413956

Polymer Optical Waveguide Sensor Based on Fe-Amino-Triazole Complex Molecular Switches

Author(s):

Khan, Muhammad Shaukat; Farooq, Hunain; Wittmund, Christopher; Klimke, Stephen; Lachmayer, Roland; Renz, Franz & Roth, Bernhard

Abstract:

“We report on a polymer-waveguide-based temperature sensing system relying on switchable molecular complexes. The polymer waveguide cladding is fabricated using a maskless lithographic optical system and replicated onto polymer material (i.e., PMMA) using a hot embossing device. An iron-amino-triazole molecular complex material (i.e., [Fe(Htrz)2.85(NH2-trz)0.15](ClO4)2) is used to sense changes in ambient temperature. For this purpose, the core of the waveguide is filled with a mixture of core material (NOA68), and the molecular complex using doctor blading and UV curing is applied for solidification. The absorption spectrum of the molecular complex in the UV/VIS light range features two prominent absorption bands in the low-spin state. As temperature approaches room temperature, a spin-crossover transition occurs, and the molecular complex changes its color (i.e. spectral properties) from violet-pink to white. The measurement of the optical power transmitted through the waveguide as a function of temperature exhibits a memory effect with a hysteresis width of approx. 12 °C and sensitivity of 0.08 mW/°C. This enables optical rather than electronic temperature detection in environments where electromagnetic interference might influence the measurements”

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Publication: Polymers
Issue/Year: Polymers, Volume 13; Number 2; Pages 195; 2021
DOI: 10.3390/polym13020195

Laser photonic-reduction stamping for graphene-based micro-supercapacitors ultrafast fabrication

Author(s):

Yuan, Yongjiu; Jiang, Lan; Li, Xin; Zuo, Pei; Xu, Chenyang; Tian, Mengyao; Zhang, Xueqiang; Wang, Sumei; Lu, Bing; Shao, Changxiang; Zhao, Bingquan; Zhang, Jiatao; Qu, Liangti & Cui, Tianhong

Abstract:

“Micro-supercapacitors are promising miniaturized energy storage devices that have attracted considerable research interest. However, their widespread use is limited by inefficient microfabrication technologies and their low energy density. Here, a flexible, designable micro-supercapacitor can be fabricated by a single pulse laser photonic-reduction stamping. A thousand spatially shaped laser pulses can be generated in one second, and over 30,000 micro-supercapacitors are produced within 10 minutes. The micro-supercapacitor and narrow gaps were dozens of microns and 500 nm, respectively. With the unique three-dimensional structure of laser-induced graphene based electrode, a single micro-supercapacitor exhibits an ultra-high energy density (0.23 Wh cm−3), an ultra-small time constant (0.01 ms), outstanding specific capacitance (128 mF cm−2 and 426.7 F cm−3) and a long-term cyclability. The unique technique is desirable for a broad range of applications, which surmounts current limitations of high-throughput fabrication and low energy density of micro-supercapacitors.”

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Publication: Nature Communications
Issue/Year: Nature Communications, Volume 11; Number 1; 2020
DOI: 10.1038/s41467-020-19985-2

Method for single-shot fabrication of chiral woodpile photonic structures using phase-controlled interference lithography

Author(s):

Swagato Sarkar, Krishnendu Samanta, and Joby Joseph

Abstract:

“In this report, we propose a large-area, scalable and reconfigurable single-shot
optical fabrication method using phase-controlled interference lithography (PCIL) to realize
submicrometer chiral woodpile photonic structures. This proposed technique involves a 3 + 3
double-cone geometry with beams originated from a computed phase mask displayed on a single
spatial light modulator. Simulation studies show the filtering response of such structures for
linearly polarized plane wave illumination, with structural features tunable through a single
parameter of interference angle. Further, these single chiral woodpile structures show dual
chirality on illumination with both right circularly and left circularly polarized light through
simulation. Experimentally fabricated patterns on photoresist show resemblance to the desired
chiral woodpile structures.”

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Publication: Optics Express
Issue/Year: Volume 28, Issue 3, pp. 4347-4361
DOI: 10.1364/OE.384987

Fabrication of oil–water separation copper filter by spatial light modulated femtosecond laser

Author(s):

Xiaoyan Sun, Zhuolin Dong, Kaifan Cheng, Dongkai Chu, Dejian Kong, Youwang Hu and Ji’an Duan

Abstract:

“Surface with oil–water separation performance has attracted more and more attention in the application of oil-containing wastewater purification. Much related work has been done by many researchers. However, there are still many difficulties in rapid manufacturing of filter membranes with special wettability. In this paper, an efficient, flexible method to fabricate microporous arrays by using a femtosecond (fs) laser combined with a spatial light modulator is proposed. The laser treated copper sheet surface shows hydrophobic and superoleophilic properties due to the microstructure. Meanwhile, the array of micro-through-holes on the surface can allow oil to penetrate through holes and prevent water from penetrating. The manufacturing process is not only extremely efficient, with a 10 × 10 focus array used in the ablation, but also it is without chemical method and the filter presents a long-term stable hydrophobic and superoleophilic performance.”

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Publication: Journal of Micromechanics and Microengineering
Issue/Year: Volume 30, Number 6
DOI: 10.1088/1361-6439/ab870d

Microchannels inside bulk PMMA generated by femtosecond laser using adaptive beam shaping

Author(s):

Roth, Gian-Luca; Rung, Stefan; Esen, Cemal & Hellmann, Ralf

Abstract:

“In this contribution, we report on the generation of internal microchannels with basically unlimited channel length inside of PMMA bulk material by femtosecond laser. A precisely controllable and stable circular channel cross section is obtained by using a spatial light modulator to compensate the writing depth depending spherical aberration. Furthermore, the generation of a rotatable elliptical input beam by adaptive optics ensures a fitting of the beam shaping to the writing direction. In this study, we report on both, the effect of the ellipticity of the input beam and the effect of a correction of the spherical aberration on the circularity of the resulting internal microchannels. Moreover, we demonstrate the application of this writing technique by creating microfluidic testing structures inside of a transparent standard polymer.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 28; Number 4; Pages 5801; 2020
DOI: 10.1364/oe.384948

Laser surface structuring of diamond with ultrashort Bessel beams

Author(s):

Sanjeev Kumar, Shane M. Eaton, Monica Bollani, Belén Sotillo, Andrea Chiappini, Maurizio Ferrari, Roberta Ramponi, Paolo Di Trapani, Ottavia Jedrkiewicz

Abstract:

“We investigate the effect of ultrafast laser surface machining on a monocrystalline synthetic diamond sample by means of pulsed Bessel beams. We discuss the differences of the trench-like microstructures generated in various experimental conditions, by varying the beam cone angle, the energy and pulse duration, and we present a brief comparison of the results with those obtained with the same technique on a sapphire sample. In diamond, we obtain V-shaped trenches whose surface width varies with the cone angle, and which are featured by micrometer sized channels having depths in the range of 10–20 μm. By laser writing crossed trenches we are also able to create and tailor on the diamond surface pillar-like or tip-like microstructures potentially interesting for large surface functionalization, cells capturing and biosensing.”

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Publication: Scientific Reports
Issue/Year: Scientific Reports 8, Article number: 14021 (2018)
DOI: 10.1038/s41598-018-32415-0

High efficiency fabrication of complex microtube arrays by scanning focused femtosecond laser Bessel beam for trapping/releasing biological cells

Author(s):

Liang Yang and Shengyun Ji and Kenan Xie and Wenqiang Du and Bingjie Liu and Yanlei Hu and Jiawen Li and Gang Zhao and Dong Wu and Wenhao Huang and Suling Liu and Hongyuan Jiang and Jiaru Chu

Abstract:

“In this paper, we present a focused femtosecond laser Bessel beam scanning technique for the rapid fabrication of large-area 3D complex microtube arrays. The femtosecond laser beam is converted into several Bessel beams by two-dimensional phase modulation using a spatial light modulator. By scanning the focused Bessel beam along a designed route, microtubes with variable size and flexible geometry are rapidly fabricated by two-photon polymerization. The fabrication time is reduced by two orders of magnitude in comparison with conventional point-to-point scanning. Moreover, we construct an effective microoperating system for single cell manipulation using microtube arrays, and demonstrate its use in the capture, transfer, and release of embryonic fibroblast mouse cells as well as human breast cancer cells. The new fabrication strategy provides a novel method for the rapid fabrication of functional devices using a flexibly tailored laser beam.”

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Publication: Optics Express
Issue/Year: Optics Express Vol. 25, Issue 7, pp. 8144-8157 (2017)
DOI: 10.1364/OE.25.008144

Application of cooled spatial light modulator for high power nanosecond laser micromachining

Author(s): Rainer J. Beck, Jonathan P. Parry, William N. MacPherson, Andrew Waddie, Nick J. Weston, Jonathan D. Shephard, and Duncan P. Hand

Abstract:

“The application of a commercially available spatial light modulator (SLM) to control the spatial intensity distribution of a nanosecond pulsed laser for micromachining is described for the first time. Heat sinking is introduced to increase the average power handling capabilities of the SLM beyond recommended limits by the manufacturer. Complex intensity patterns are generated, using the Inverse Fourier Transform Algorithm, and example laser machining is demonstrated. The SLM enables both complex beam shaping and also beam steering.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 16, pp. 17059-17065 (2010)
DOI: 10.1364/OE.18.017059

Parallel photopolymerisation with complex light patterns generated by diffractive optical elements

Author(s): Lóránd Kelemen, Sándor Valkai, and Pál Ormos

Abstract:

“Photopolymerisation by scanning a focused laser beam is a powerful method to build structures of arbitrary complexity with submicrometer resolution. We introduce parallel photopolymerisation to enhance the efficiency. Instead of multidimensional scanning of a single focus, the structure is generated simultaneously with diffractive patterns. We used fixed diffractive optical elements (DOEs), kinoforms, and Spatial Light Modulators (SLMs). The possibilities of photopolymerisation using SLM were investigated: the added flexibility using the programmable device is demonstrated. By using these DOEs, straight and helical cross shaped columns were produced with a single scan at a rate about an order of magnitude faster than by simple scanning. The produced helical structures could be rotated by optical tweezers.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 15, Issue 22, pp. 14488-14497 (2007)
DOI: 10.1364/OE.15.014488