Microdrilling in steel using ultrashort pulsed laser beams with radial and azimuthal polarization

Institut für Strahlwerkzeuge, University of Stuttgart, Pfaffenwaldring 43, D-70569 Stuttgart, Germany.
Optics Express (Impact Factor: 3.49). 10/2010; 18(21):22305-13. DOI: 10.1364/OE.18.022305
Source: PubMed


A linear to radial and/or azimuthal polarization converter (LRAC) has been inserted into the beam delivery of a micromachining station equipped with a picosecond laser system. Percussion drilling and helical drilling in steel have been performed using radially as well as azimuthally polarized infrared radiation at 1030 nm. The presented machining results are discussed on the basis of numerical simulations of the polarization-dependent beam propagation inside the fabricated capillaries.

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Available from: Rudolf Weber, Oct 16, 2014
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    • "Owing to a wide spectrum of applications, the attention of researchers is directed to cylindrical vector beams (CVBs), in particular, beams with radial and azimuthal polarization. CVBs allow us to receive new effects in such areas as nonlinear optics [1] [2], nearfield optics [3], acceleration of the charged particles [4] [5] [6] [7], quantum information [8] [9], optical capture and manipulation by micro-and nano-objects [10] [11], imaging systems [12] [13], microscopy [14] [15] [16], and processing materials [17] [18] [19] [20] [21]. "
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    ABSTRACT: The generation of cylindrical vector beams in birefringent crystals is studied analytically and experimentally in paraxial and non-paraxial regimes. At sharp focusing (in the non-paraxial case), two foci corresponding ordinary and extraordinary beams are formed along the crystal’s axis. There is the radially polarized distribution in one focus and the azimuthally polarized distribution in the other focus when the incident beam has the vortex phase of the first order and circular polarization of the opposite direction. The results are extended to the generation of higher-order radially and azimuthally polarized laser beams. The physical experiments with an Iceland spar crystal have been conducted.
    Journal of optics 06/2015; 17(6). DOI:10.1088/2040-8978/17/6/065001 · 2.06 Impact Factor
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    • ". (a) Transformation of linear to radial polarization by a subwavelength grating. (b) the grating introduces a -phase shift between TE and TM, leading to a mirroring of the E-field with respect to the local grating line direction A known solution is an assembly of angular segments of crystal quartz with half-wave thickness, employing a different orientation of the in-plane crystal axis per segment [5], which has the advantage of a high damage threshold, but is expensive and not mass fabrication compatible. The same principle can be realized also by using the form birefringence of a subwavelength binary grating of varying direction, etched into a high index substrate. "
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    ABSTRACT: A polarization rotation is realized by subwavelength binary gratings, where the TE and TM round trip phases of the smallest grating modes are fixed to the smallest possible integer numbers of 2pi that allow a straight-through phase difference of pi This results in a subwavelength grating allowing to realize a half-wave element of almost 100% transmission. The principle is applied to a polarization transformation in the 1030-1064 nm wavelength range, using a segmented polarization rotating element converting a linearly polarized incidence to a radial or azimuthal polarization distribution. The elevated costs of such kind of polarization transformers based on assembled birefringent crystals are avoided by using mass-fabrication compatible silicon on insulator technology on a wafer scale. It shows the general potential of microelectronic technology, concerning the batch manufacturing of wavelength-scale diffractive, grating based elements for processing free space waves
    SPIE Photonics Europe, Micro-Optics 2014, Brussels; 04/2014
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    • "The 'polarization test components' consist of a polarizing filter (analyser) and a SPIRICON (CCD) camera, used to verify the state of polarization of the beam. They are removed when the microprocessing tests are carried out. of processing with radial or azimuthal polarization [16] [17] [18] [19] [20]. "
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    ABSTRACT: The use of a liquid-crystal spatial light modulator (SLM) device to convert a linearly polarized femtosecond laser beam into a radially or azimuthally polarized vortex beam is demonstrated. In order to verify the state of polarization at the focal plane, laser induced periodic surface structures (LIPSS) are produced on stainless steel, imprinting the complex vectorial polarization structures and confirming the efficacy of the SLM in producing the desired polarization modes. Stainless steel plates of various thicknesses are micromachined with the radially and azimuthally polarized vortex beams and the resulting cut-outs are analysed. The process efficiency and quality of each mode are compared with those of circular polarization. Radial polarization is confirmed to be the most efficient mode for machining high-aspect-ratio (depth/width > 3) channels thanks to its relatively higher absorptivity. Following our microprocessing tests, liquid-crystal SLMs emerged as a flexible off-the-shelf tool for producing radially and azimuthally polarized beams in existing ultrashort-pulse laser microprocessing systems.
    Journal of optics 07/2012; 14(8):085601. DOI:10.1088/2040-8978/14/8/085601 · 2.06 Impact Factor
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