{ "types" : { "Bookmark" : { "pluralLabel" : "Bookmarks" }, "Publication" : { "pluralLabel" : "Publications" }, "GoldStandardPublication" : { "pluralLabel" : "GoldStandardPublications" }, "GoldStandardBookmark" : { "pluralLabel" : "GoldStandardBookmarks" }, "Tag" : { "pluralLabel" : "Tags" }, "User" : { "pluralLabel" : "Users" }, "Group" : { "pluralLabel" : "Groups" }, "Sphere" : { "pluralLabel" : "Spheres" } }, "properties" : { "count" : { "valueType" : "number" }, "date" : { "valueType" : "date" }, "changeDate" : { "valueType" : "date" }, "url" : { "valueType" : "url" }, "id" : { "valueType" : "url" }, "tags" : { "valueType" : "item" }, "user" : { "valueType" : "item" } }, "items" : [ { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2351d23d83d82758f9f2b4a880651d5ac/ifsw", "tags" : [ "myown","chirp","diffraction","peer","interference","diffraction_grating","from:florianbienert" ], "intraHash" : "351d23d83d82758f9f2b4a880651d5ac", "interHash" : "7b7d90ef08e1e7c7c007e0771e7ba3b2", "label" : "Simple spatially resolved period measurement of chirped pulse compression gratings", "user" : "ifsw", "description" : "", "date" : "2023-06-03 15:24:54", "changeDate" : "2023-06-03 15:25:40", "count" : 1, "pub-type": "article", "journal": "Opt. Express","publisher":"Optica Publishing Group", "year": "2023", "url": "https://opg.optica.org/oe/abstract.cfm?URI=oe-31-12-19392", "author": [ "Florian Bienert","Christoph Röcker","Thomas Graf","Marwan Abdou Ahmed" ], "authors": [ {"first" : "Florian", "last" : "Bienert"}, {"first" : "Christoph", "last" : "Röcker"}, {"first" : "Thomas", "last" : "Graf"}, {"first" : "Marwan Abdou", "last" : "Ahmed"} ], "volume": "31","number": "12","pages": "19392--19403","abstract": "We present an easy-to-implement and low-cost setup for the precise measurement of the period chirp of diffraction gratings offering a resolution of 15 pm and reasonable scan speeds of 2 seconds per measurement point. The principle of the measurement is illustrated on the example of two different pulse compression gratings, one fabricated by laser interference lithography (LIL) and the other by scanning beam interference lithography (SBIL). A period chirp of 0.22 pm/mm2 at a nominal period of 610 nm was measured for the grating fabricated with LIL, whereas no chirp was observed for the grating fabricated by SBIL, which had a nominal period of 586.2 nm.", "doi" : "10.1364/OE.489238", "bibtexKey": "Bienert:23" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2a8492260592f80e99852d85b3cde1c6f/ifsw", "tags" : [ "myown","chirp","period","Interference","diffraction","Laser-Interference-Lithography","diffraction_grating","shaping","from:florianbienert","mathematical","Beam","peer","Laser","beams","gratings","interference","model","Gaussian","Holographic","Scanning-Beam-Interference-Lithography" ], "intraHash" : "a8492260592f80e99852d85b3cde1c6f", "interHash" : "9a3e04001920d37b1994c5ed9ba327b8", "label" : "General mathematical model for the period chirp in interference lithography", "user" : "ifsw", "description" : "", "date" : "2023-02-13 10:24:21", "changeDate" : "2023-02-13 09:30:48", "count" : 3, "pub-type": "article", "journal": "Opt. Express","publisher":"Optica Publishing Group", "year": "2023", "url": "https://opg.optica.org/oe/abstract.cfm?URI=oe-31-4-5334", "author": [ "Florian Bienert","Thomas Graf","Marwan Abdou Ahmed" ], "authors": [ {"first" : "Florian", "last" : "Bienert"}, {"first" : "Thomas", "last" : "Graf"}, {"first" : "Marwan Abdou", "last" : "Ahmed"} ], "volume": "31","number": "4","pages": "5334--5346","abstract": "We present a general analytical model for the calculation of the spatial distribution of the grating period, enabling the unification of all configurations of classical laser interference lithography (LIL) and scanning-beam interference lithography (SBIL) into one formalism. This is possible due to the consideration of Gaussian beams instead of point sources which allow for the accurate description of not only the laser&\\#x2019;s far-field but also its near-field. The proposed model enables the calculation of the grating period, the inclination and the slant of the grating lines on arbitrarily shaped substrates, originating from the interference of arbitrarily orientated and positioned Gaussian beams.", "doi" : "10.1364/OE.481887", "bibtexKey": "Bienert:23" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/21105676d6caa214a31e39d6d56969daa/ifsw", "tags" : [ "myown","grating","diffraction","laser","peer","from:a.boubekraoui","Thin-disk" ], "intraHash" : "1105676d6caa214a31e39d6d56969daa", "interHash" : "83e4235580a2d04c84dace8c96f28f1f", "label" : "Intra-cavity wavelength multiplexing of high-brightness thin-disk laser beams", "user" : "ifsw", "description" : "", "date" : "2022-07-12 10:26:37", "changeDate" : "2022-07-12 08:26:37", "count" : 2, "pub-type": "article", "journal": "Applied Physics B", "year": "2022", "url": "https://doi.org/10.1007/s00340-022-07836-5", "author": [ "Ayoub Boubekraoui","Frieder Beirow","Thomas Graf","Marwan Abdou Ahmed" ], "authors": [ {"first" : "Ayoub", "last" : "Boubekraoui"}, {"first" : "Frieder", "last" : "Beirow"}, {"first" : "Thomas", "last" : "Graf"}, {"first" : "Marwan", "last" : "Abdou Ahmed"} ], "volume": "128","number": "7","pages": "120--","abstract": "We report on the first demonstration of an intra-cavity spectral beam combining of two fundamental-mode laser beams generated by a dual Yb:YAG thin-disk resonator. The two thin-disk lasers (TDLs) were operated at the two slightly different wavelengths of 1028 nm and 1032 nm. A resonant diffraction grating waveguide structure was used as common spectral stabilizer and combiner. An average power exceeding 200 W with close to diffraction-limited beam quality ( $$M^2<1.3$$) was obtained with the presented approach.", "issn" : "14320649", "refid" : "Boubekraoui2022", "doi" : "10.1007/s00340-022-07836-5", "bibtexKey": "boubekraoui2022intracavity" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/28369a5b0b9c1d5b9bd78f25cc22c6d13/ifsw", "tags" : [ "myown","chirp","diffraction","diffraction_grating","interference_lithography","LIL","from:florianbienert","grating","peer","interference","therory","algorithm" ], "intraHash" : "8369a5b0b9c1d5b9bd78f25cc22c6d13", "interHash" : "503e2f12069fc6f23a499ccd4bb69f64", "label" : "Theoretical investigation on the elimination of the period chirp by deliberate substrate deformations", "user" : "ifsw", "description" : "", "date" : "2022-06-09 10:04:50", "changeDate" : "2022-06-09 08:04:50", "count" : 3, "pub-type": "article", "journal": "Optics Express","publisher":"Optica Publishing Group", "year": "2022", "url": "https://doi.org/10.1364%2Foe.458636", "author": [ "Florian Bienert","Thomas Graf","Marwan Abdou Ahmed" ], "authors": [ {"first" : "Florian", "last" : "Bienert"}, {"first" : "Thomas", "last" : "Graf"}, {"first" : "Marwan", "last" : "Abdou Ahmed"} ], "volume": "30","number": "13","pages": "22410","abstract": "We present a theoretical investigation on the approach of deliberately bending the substrate during the exposure within laser interference lithography to compensate for the period chirp. It is shown that the yet undiscovered function of the surface geometry, necessary to achieve the zero-chirp case (i.e. having a perfectly constant period over the whole substrate) is determined by a first-order differential equation. As the direct analytical solution of this differential equation is difficult, a numerical approach is developed, based on the optimization of pre-defined functions towards the unknown analytical solution of the differential equation by means of a Nelder-Mead simplex algorithm. By applying this method to a concrete example, we show that an off-center placement of the substrate with respect to the point sources is advantageous both in terms of achievable period and substrate curvature and that a fourth-order polynomial can greatly satisfy the differential equation leading to a root-mean-square deviation of only 1.4 pm with respect to the targeted period of 610\u2005nm.", "doi" : "10.1364/oe.458636", "bibtexKey": "Bienert_2022" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2c92c0beab91cf22a13ce0cb2209438b6/ifsw", "tags" : [ "chirp","period","Interference","diffraction_grating","Laser_beam","ltihography","interference_lithography","from:florianbienert","ifsw","Diffraction","grating" ], "intraHash" : "c92c0beab91cf22a13ce0cb2209438b6", "interHash" : "1ecc9d05102c7ed5274b48e382dbbf69", "label" : "Comprehensive theoretical analysis of the period chirp in laser interference lithography", "user" : "ifsw", "description" : "", "date" : "2022-03-17 14:03:13", "changeDate" : "2022-03-17 13:03:13", "count" : 2, "pub-type": "article", "journal": "Appl. Opt.","publisher":"OSA", "year": "2022", "url": "http://opg.optica.org/ao/abstract.cfm?URI=ao-61-9-2313", "author": [ "Florian Bienert","Thomas Graf","Marwan Abdou Ahmed" ], "authors": [ {"first" : "Florian", "last" : "Bienert"}, {"first" : "Thomas", "last" : "Graf"}, {"first" : "Marwan", "last" : "Abdou Ahmed"} ], "volume": "61","number": "9","pages": "2313--2326","abstract": "We present a theoretical investigation on laser interference lithography used for the exposure of linear gratings. The focus is on the geometry of the arising interference lines on the substrate, in particular on their period and orientation, depending on the illumination geometry as determined by the setup. The common approach with point sources emitting spherical wavefronts is considered for the illumination. Three different cases are discussed, namely the interference between two point sources with either two convex, two concave or mixed, i.e., convex and concave wavefronts. General equations focusing mainly on the calculation of the period and the orientation of the grating lines are derived for each of the three exposure cases considering arbitrarily positioned point sources and arbitrarily shaped substrates. Additionally, the interference of symmetrically positioned point sources illuminating plane substrates is investigated, as these boundary conditions significantly simplify the derived equations.", "doi" : "10.1364/AO.451873", "bibtexKey": "Bienert:22" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2dd7f39693347ef7f245a75e36ca30bf3/ifsw", "tags" : [ "Absorption","Capillary","Diffraction","Interference","Laser","RayTracing","from:peterberger","peer" ], "intraHash" : "dd7f39693347ef7f245a75e36ca30bf3", "interHash" : "5a24b4ea225435ba422eab757dcd2b06", "label" : "Comparison between ray-tracing and physical optics for the computation of light absorption in capillaries -- the influence of diffraction and interference", "user" : "ifsw", "description" : "", "date" : "2020-02-25 17:30:48", "changeDate" : "2020-02-25 16:44:32", "count" : 2, "pub-type": "article", "journal": "Opt. Express","publisher":"OSA", "year": "2012", "url": "http://www.opticsexpress.org/abstract.cfm?URI=oe-20-24-26606", "author": [ "Yuan Qin","Andreas Michalowski","Rudolf Weber","Sen Yang","Thomas Graf","Xiaowu Ni" ], "authors": [ {"first" : "Yuan", "last" : "Qin"}, {"first" : "Andreas", "last" : "Michalowski"}, {"first" : "Rudolf", "last" : "Weber"}, {"first" : "Sen", "last" : "Yang"}, {"first" : "Thomas", "last" : "Graf"}, {"first" : "Xiaowu", "last" : "Ni"} ], "volume": "20","number": "24","pages": "26606--26617","abstract": "Ray-tracing is the commonly used technique to calculate the absorption of light in laser deep-penetration welding or drilling. Since new lasers with high brilliance enable small capillaries with high aspect ratios, diffraction might become important. To examine the applicability of the ray-tracing method, we studied the total absorptance and the absorbed intensity of polarized beams in several capillary geometries. The ray-tracing results are compared with more sophisticated simulations based on physical optics. The comparison shows that the simple ray-tracing is applicable to calculate the total absorptance in triangular grooves and in conical capillaries but not in rectangular grooves. To calculate the distribution of the absorbed intensity ray-tracing fails due to the neglected interference, diffraction, and the effects of beam propagation in the capillaries with sub-wavelength diameter. If diffraction is avoided e.g. with beams smaller than the entrance pupil of the capillary or with very shallow capillaries, the distribution of the absorbed intensity calculated by ray-tracing corresponds to the local average of the interference pattern found by physical optics.", "doi" : "10.1364/OE.20.026606", "bibtexKey": "Qin.2012.Comparison" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/29a1bef5aff0a2fc5f5751d89e09d246b/ifsw", "tags" : [ "Studienarbeit","Diffraction","Laser","OpticalElements","from:florianfetzer","AbdouAhmed,Marwan" ], "intraHash" : "9a1bef5aff0a2fc5f5751d89e09d246b", "interHash" : "4a6e7bb30d7290129b314078327875ec", "label" : "Charakterisierung und Funktionstest eines neuen Strahlteilungskonzptes auf Basis von Beugungsgittern für den Einsatz in der Photovoltaikindustrie", "user" : "ifsw", "description" : "", "date" : "2019-04-09 09:46:57", "changeDate" : "2019-04-09 07:46:57", "count" : 2, "pub-type": "mastersthesis", "year": "2009", "url": "", "author": [ "N. Strachwitz" ], "authors": [ {"first" : "N.", "last" : "Strachwitz"} ], "number": "IFSW09-11", "bibtexKey": "Strachwitz.2009.Charakterisierung" } ] }