@article{KeferPapeBischoffetal.2024, author = {Kefer, Stefan and Pape, Natalie and Bischoff, Kay and Schmauss, Bernhard and Hellmann, Ralf}, title = {Lattice-Like Waveguides With Integrated Bragg Gratings in Planar Cyclic Olefin Copolymers}, series = {Journal of Lightwave Technology}, volume = {42}, journal = {Journal of Lightwave Technology}, number = {18}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, issn = {0733-8724}, doi = {10.1109/JLT.2023.3328323}, pages = {6302 -- 6311}, year = {2024}, abstract = {This contribution demonstrates femtosecond laser direct writing of lattice-like waveguides in planar cyclic olefin copolymer substrates. Based on numerical simulation and experimental near-field analysis, stable single-mode waveguiding around wavelengths of 1550 nm is demonstrated. The waveguiding mechanism is based on a hexagonal array of laser-induced, positive refractive index modification lines. Thus, the lateral extension of the guided mode can be adapted by varying the fabrication parameters and, in consequence, the resulting cross-sectional arrangement of the refractive index perturbations. With an optical attenuationof 2.2 dB·cm-1 around 1550 nm, the fabricated waveguides are well-suited for on-chip integrated photonic devices. Moreover, the waveguides can also be equipped with Bragg gratings to enable the application of the photonic platform as a sensing device. Dependingon their length, the Bragg grating structures exhibit reflectivities ofup to 99\% and spectral widths down to 0.3 nm. The flexibility of the fabrication process and the sensing capabilities of the lattice-like waveguides with integrated Bragg gratings are underlined by an exemplary application study demonstrating a relative pressure sensor. For that, a photonic platform is micromilled to generate a 300 µm thick diaphragm and a reference pressure chamber. The strain introduced to the diaphragm by external pressure changes can then be quantified by the integrated photonic structures.This way, absolute pressure sensitivities of up to 38 pm·kPa-1 can be achieved in a relative pressure range from -60 to 100 kPa. The newly-developed lattice-like waveguides with integrated Bragggratings are therefore well-suited for the realization of novel and adaptable photonic devices and sensors.}, subject = {Wellenleiter}, language = {en} } @inproceedings{KeferSchmaussHellmann2023, author = {Kefer, Stefan and Schmauss, Bernhard and Hellmann, Ralf}, title = {Sapphire-Based Planar Bragg Grating Devices}, series = {28th International Conference on Optical Fiber Sensors}, booktitle = {28th International Conference on Optical Fiber Sensors}, isbn = {978-1-957171-30-2}, doi = {10.1364/OFS.2023.W2.4}, year = {2023}, abstract = {This study reports on the long-term stability and the high-temperature capability of sapphire-based photonic crystal waveguides with integrated Bragg gratings. Furthermore, their Bragg grating reflectivity as well as their temperature sensitivity is quantified.}, subject = {Bragg-Reflektor}, language = {en} } @article{KeferLimbachPapeetal.2024, author = {Kefer, Stefan and Limbach, Tobias and Pape, Natalie and Klamt, Kathrin and Schmauss, Bernhard and Hellmann, Ralf}, title = {Birefringence in Injection-Molded Cyclic Olefin Copolymer Substrates and Its Impact on Integrated Photonic Structures}, series = {Polymers}, volume = {16}, journal = {Polymers}, number = {2}, doi = {10.3390/polym16020168}, pages = {168 -- 168}, year = {2024}, abstract = {This contribution quantifies the birefringence within injection-molded cyclic olefin copolymer plates and discusses its impact on the mechanical properties of the plates. It also focuses on the impact of birefringence on integrated waveguides and Bragg gratings and provides fabrication guidelines for such structures. The anisotropy in all three dimensions of the workpiece is examined by means of polarimetry and a prism coupler. It is found that the birefringence is inhomogenously distributed within the workpieces, whereas the maximum birefringence not only varies locally, but also depends on the observation direction. Overall, a maximum birefringence of 10 × 10-4 is found at the plate's surface near the injection gate. The anisotropy then reduces exponentially towards the center of the workpiece and saturates at 1.8 × 10-4, in a depth of 0.4 mm. Thus, the birefringence strongly affects near-surface photonic structures. It is found that, depending on their orientation and the local birefringence of the substrate, waveguides and Bragg gratings fabricated with comparable parameters behave completely differently in terms of polarization-dependent optical attenuation, cross-sectional intensity distribution and Bragg reflection signal. For example, the support of the TM mode can vary between total loss and an optical attenuation of 0.9 dB × cm-1. In consequence, this study underlines the importance of quantifying the birefringent state of an injection-molded cyclic olefin copolymer workpiece if it is supposed to serve as a substrate for integrated photonic structures. The study furthermore demonstrates that birefringence effects can be omitted by burying the photonic structures deeper into the volume of the thermoplastic.}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{KeferSchmaussHellmann2021, author = {Kefer, Stefan and Schmauss, Bernhard and Hellmann, Ralf}, title = {POLYMER PLANAR BRAGG GRATINGS BASED ON BULK CYCLIC OLEFIN COPOLYMERS: FABRICATION AND FUNCTIONALIZATION}, series = {Proceedings of Student Conference on Sensors, Systems and Measurement 2021}, booktitle = {Proceedings of Student Conference on Sensors, Systems and Measurement 2021}, isbn = {978-80-01-06822-9}, year = {2021}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{KeferPapeGriesetal.2023, author = {Kefer, Stefan and Pape, Natalie and Gries, Nikola and Roth, Gian-Luca and Schmauss, Bernhard and Hellmann, Ralf}, title = {Towards Pressure Sensors Based on Polymer Planar Bragg Gratings}, series = {Organic Photonic Materials and Devices XXV}, booktitle = {Organic Photonic Materials and Devices XXV}, isbn = {9781510659414}, doi = {10.1117/12.2648723}, year = {2023}, abstract = {While Bragg grating-based optical devices have shown promising performances for pressure sensing applications, their sensitivity, especially in the low-pressure regime, is unsatisfying and needs to be optimized by elaborate designs, such as cantilevers or other extrinsic mechanical transducers. This contribution demonstrates and discusses a novel concept for optical pressure sensors based on polymer planar Bragg gratings. Waveguide and Bragg grating are fabricated underneath the surface of a temperature-stable and humidity-insensitive cyclic olefin copolymer substrate by means of a femtosecond laser. Based on the employed direct-writing procedure, in combination with adaptive, in-situ beam shaping with a spatial light modulator, writing depth, i.e., location of the photonic structures within the substrate, as well as Bragg grating periodicity and positioning can be deliberately chosen. Afterwards, the polymer substrate is post-processed with a high-precision micro mill, so a diaphragm comprising the integrated photonic structures is generated. The resulting diaphragm exhibits a thickness of 300 µm and a diameter of 10 mm. Finally, the optical sensor is packaged and sealed to form an air-filled gas pocket underneath the diaphragm. Deformations of the diaphragm by external pressure changes translate to strain variations along the waveguide axis and thus perturb the Bragg grating period. This leads to changes in the grating's wavelength of main reflection, which can be evaluated in order to quantify the relative external pressure. With this straightforward optical sensor concept, pressure sensitivities up to 39 pm kPa-1, within relative pressures ranges from 78 kPa to 372 kPa, are achieved.}, subject = {Bragg-Reflektor}, language = {en} } @article{Kefer2022, author = {Kefer, Stefan}, title = {Sapphire Photonic Crystal Waveguides with Integrated Bragg Grating Structure}, series = {Photonics}, volume = {9}, journal = {Photonics}, number = {4}, doi = {https://doi.org/10.3390/photonics9040234}, pages = {234 -- 234}, year = {2022}, abstract = {Abstract: This contribution demonstrates photonic crystal waveguides generated within bulk planar sapphire substrates. A femtosecond laser is used to modify the refractive index in a hexagonal pattern around the pristine waveguide core. Near-field measurements reveal single-mode behavior at a wavelength of 1550 nm and the possibility to adapt the mode-field diameter. Based on farfield examinations, the effective refractive index contrast between the pristine waveguide core and depressed cladding is estimated to 3x10-4. Additionally, Bragg gratings are generated within the waveguide core. Due to the inherent birefringence of Al2O3, the gratings exhibit two distinct wavelengths of main reflection. Each reflection peak exhibits a narrow spectral full width at a half maximum of 130 pm and can be selectively addressed by exciting the birefringent waveguide with appropriately polarized light. Furthermore, a waveguide attenuation of 1 dB cm-1 is determined.}, subject = {Wellenleiter}, language = {en} } @article{KeferPapeRothetal.2021, author = {Kefer, Stefan and Pape, Dominik and Roth, Gian-Luca and Hessler, Steffen and Schmauss, Bernhard and Hellmann, Ralf}, title = {Micromilling-assisted fabrication of monolithic polymer ridge-type waveguides with integrated photonic sensing structures}, series = {Optical Materials Express}, volume = {11}, journal = {Optical Materials Express}, number = {8}, doi = {https://doi.org/10.1364/OME.425778}, pages = {2389 -- 2400}, year = {2021}, abstract = {This study demonstrates and discusses a novel approach for the fabrication and rapid prototyping of monolithic photonic platforms comprising a ridge-type waveguide with integrated sensing structures. First, the bulk injection-molded cyclic olefin copolymer substrates are micromilled in order to define the physical extension of the ridge structure. Cross-sections down to 30 × 30 µm2, exhibiting a mean surface roughness of 300 nm, are achieved with this process. Subsequently, UV radiation is used to modify the ridge structure's refractive index, which leads to the formation of an optical waveguide. By employing a phase mask, it is possible to equip the photonic platform with a Bragg grating suitable for temperature measurements with a sensitivity of -5.1 pm K-1. Furthermore, an integrated Fabry-P{\´e}rot cavity, generated during the micromilling step as well, enables refractive index measurements with sensitivities up to 1154 nm RIU-1.}, subject = {Bragg-Reflektor}, language = {en} } @article{KeferBischoffRothetal.2021, author = {Kefer, Stefan and Bischoff, Kay and Roth, Gian-Luca and Haubner, Julian and Schmauss, Bernhard and Hellmann, Ralf}, title = {Tunable Bulk Polymer Planar Bragg Gratings Electrified via Femtosecond Laser Reductive Sintering of CuO Nanoparticles}, series = {Advanced Optical Materials}, volume = {9}, journal = {Advanced Optical Materials}, number = {13}, doi = {https://doi.org/10.1002/adom.202002203}, pages = {2002203 -- 2002203}, year = {2021}, abstract = {This contribution demonstrates and discusses electrically tunable polymer planar Bragg gratings based on bulk cyclic olefin copolymers. A lithographic single-writing-step method and femtosecond laser reductive sintering of copper(II) oxide nanoparticles are subsequently employed in order to generate buried photonic structures and copper conducting paths on top of the polymer substrate. This way, the necessary number of process steps for fabricating a planar polymer-based electro-optical device is greatly reduced. The response of a fully electrified grating structure follows temperature changes, induced by the copper conducting path, with sensitivities up to -31 pm K-1. Dilatometric measurements show that the specimen's behavior is correlated to the situationally reduced thermal expansion of the bulk polymer substrate. In consequence, the tuning response of the photonic platform follows a second order polynomial, whereas a direct current of 30 mA, which correlates to a power consumption of 18.3 mW, leads to a local temperature increase and a residual Bragg wavelength shift of 19.6 K and -547 pm, respectively. Moreover, the outstanding flexibility of the proposed fabrication concept is underlined by demonstrating alternative conducting path geometries, whereas one of the additional designs is adapted to control the spectral width of the Bragg grating's reflection peak.}, subject = {Femtosekundenlaser}, language = {en} } @misc{KeferBischoffRothetal.2021, author = {Kefer, Stefan and Bischoff, Kay and Roth, Gian-Luca and Haubner, Julian and Schmauss, Bernhard and Hellmann, Ralf}, title = {Tunable Bulk Polymer Planar Bragg Gratings Electrified via Femtosecond Laser Reductive Sintering of CuO Nanoparticles (Advanced Optical Materials 13/2021)}, doi = {https://doi.org/10.1002/adom.202170048}, year = {2021}, abstract = {This cover image outlines the fabrication method of a polymer planar Bragg grating electrified via femtosecond laser reductive sintering of CuO nanoparticles (see article number 2002203 by Stefan Kefer and co-workers). Based on this sophisticated methodology, bulk cyclic olefin copolymer substrates can be equipped with integrated photonic structures comprising a waveguide as well as a Bragg grating. Its reflective characteristics can be efficiently tuned by means of the subsequently generated Cu conducting path, whereas the applied femtosecond laser process enables an almost limitless degree of freedom towards conducting path geometries.}, subject = {Femtosekundenlaser}, language = {en} } @incollection{KeferRothKaloudisetal.2021, author = {Kefer, Stefan and Roth, Frederick and Kaloudis, Michael and Schmauss, Bernhard and Hellmann, Ralf}, title = {Monitoring of Composite Bicycle Components using Polymer Planar Bragg Gratings}, series = {SMSI 2021 - Sensors and Instrumentation}, booktitle = {SMSI 2021 - Sensors and Instrumentation}, publisher = {AMA Service GmbH}, address = {Wunstorf, Germany}, isbn = {978-3-9819376-4-0}, doi = {10.5162/SMSI2021/B9.2}, pages = {161 -- 162}, year = {2021}, abstract = {This study demonstrates mobile load monitoring of a composite bicycle component using an application- customized polymer planar Bragg grating sensor, evaluated by a mobile interrogation unit. After a referencing procedure, the mechanical load of a seat post is monitored while cycling through a test track.}, subject = {Bragg-Reflektor}, language = {en} } @article{RothHaubnerKeferetal.2020, author = {Roth, Gian-Luca and Haubner, Julian and Kefer, Stefan and Esen, Cemal and Hellmann, Ralf}, title = {Fs-laser based hybrid micromachining for polymer micro-opto electrical systems}, series = {Optics and Lasers in Engineering}, volume = {137}, journal = {Optics and Lasers in Engineering}, number = {10362}, doi = {10.1016/j.optlaseng.2020.106362}, pages = {1 -- 8}, year = {2020}, abstract = {We report on femtosecond laser direct writing of electrically conductive copper structures on transparent cyclic olefin copolymer based planar optical chips. The process is based on a laser-induced reduction of CuO nanoparticles dissolved in a water-soluble resin. Thus generated conductive copper structures are characterized with respect to their chemical composition and electrical resistivity. In addition, the application of ultrashort laser pulses enables a hybrid micromachining approach comprising ablation of polymer substrates and the fabrication of copper patterns in a single laser processing setup. A possible electro-optical application of this approach is demonstrated by employing the copper structures as an electro-thermal microheater in combination with a polymer planar optical Bragg grating sensor. This, in turn, highlights the potential of generating copious micro-opto-electro-mechanical polymer structures for numerous sensing applications ranging from Lab-on-Chip to environmental applications using the presented hybrid micromachining approach.}, subject = {Femtosekundenlaser}, language = {en} } @article{RothHesslerKeferetal.2020, author = {Roth, Gian-Luca and Hessler, Steffen and Kefer, Stefan and Girschikofsky, Maiko and Esen, Cemal and Hellmann, Ralf}, title = {Femtosecond laser inscription of waveguides and Bragg gratings in transparent cyclic olefin copolymers}, series = {Optics Express}, volume = {28}, journal = {Optics Express}, number = {12}, doi = {10.1364/OE.388364}, pages = {18077 -- 18084}, year = {2020}, abstract = {We report on a femtosecond laser based fabrication technique that enables simultaneous single-step generation of optical waveguides and Bragg gratings inside bulk cyclic olefin copolymers. Due to the nonlinear absorption of focused and spatially modulated laser radiation with a wavelength of 514 nm and a pulse duration of 450 fs, a modification concluding a refractive index shift increase inside the substrate can be achieved. A sophisticated characterization of the generated waveguides by means of an elaborate cut-back method reveals a maximum attenuation of 3.2 dB/cm. Additionally, a Mach-Zehnder interferometer is used to examine the waveguide's refractive index profile. The integrated Bragg grating structures exhibit reflectivities up to 95 \% and a spectral full width at half maximum of 288 pm, at a Bragg wavelength of 1582 nm, whereas the grating period can be deliberately chosen by adapting the fabrication parameters. Thus, due to its increased flexibility and the resulting dispensability of cost-intensive phase masks, this method constitutes an especially promising fabrication process for polymer Bragg gratings inside of bulk materials.}, subject = {Femtosekundenlaser}, language = {en} } @misc{KeferDaiYangetal.2020, author = {Kefer, Stefan and Dai, Jixiang and Yang, Minghong and Schmauss, Bernhard and Hellmann, Ralf}, title = {Hypersensitive H2 sensor based on polymer planar Bragg gratings coated with Pt-loaded WO3-SiO2: erratum}, volume = {45}, number = {16}, doi = {https://doi.org/10.1364/OL.401819}, pages = {4498 -- 4498}, year = {2020}, abstract = {We present an erratum to our Letter [Opt. Lett. 45, 3601 (2020)]. Labeling errors in two figures and an incorrect sentence are revised. The corrections have no influence on the conclusions of the original Letter.}, subject = {Gassensor}, language = {en} } @article{KeferDaiYangetal.2020, author = {Kefer, Stefan and Dai, Jixiang and Yang, Minghong and Schmauss, Bernhard and Hellmann, Ralf}, title = {Hypersensitive H2 sensor based on polymer planar Bragg gratings coated with Pt-loaded WO3-SiO2}, series = {Optics Letters}, volume = {45}, journal = {Optics Letters}, number = {13}, doi = {https://doi.org/10.1364/OL.395341}, pages = {3601 -- 3604}, year = {2020}, abstract = {This letter demonstrates a novel hydrogen sensor based on a polymer planar Bragg grating coated with Pt-loaded WO3-SiO2. The reflected Bragg signal shows a distinct peak splitting correlated to substrate anisotropies originating from the injection molding process. Especially at low H2 concentrations, both sensing peaks exhibit an outstanding response to the heat generated by the exothermic reaction between hydrogen molecules and coating. Thereby, a hydrogen volume ratio of 50 ppm leads to a Bragg wavelength shift of -37 pm, which yields an outstandingly low detection limit of only 5 ppm H2 in air. Thus, functionalized polymer planar Bragg gratings are eminently suitable for H2 leak detection applications.}, subject = {Gassensor}, language = {en} } @article{KeferSauerHessleretal.2020, author = {Kefer, Stefan and Sauer, Theresia and Hessler, Steffen and Kaloudis, Michael and Schmauss, Bernhard and Hellmann, Ralf}, title = {Robust Polymer Planar Bragg Grating Sensors Embedded in Commercial-Grade Composites}, series = {Polymers}, volume = {12}, journal = {Polymers}, number = {3}, doi = {10.3390/polym12030715}, pages = {715 -- 715}, year = {2020}, abstract = {This contribution demonstrates the functionality of polymer planar Bragg grating (PPBG) sensors integrated into commercial-grade carbon fiber reinforced polymer (CFRP) components. Multiple CFRP specimens are generated by curing a stack of pre-impregnated fibers inside of a heated mechanical press, exposing the polymer sensor to a pressure of 7 bar and a temperature of 120 °C for 2 h. After integration, the sensor still exhibits a strong and evaluable signal. Subsequent flexural experiments reveal a linear response of the integrated sensor's Bragg wavelength to the CFRP specimen's maximum deflection. Additional findings demonstrate that the embedded PPBG can be used to detect plastic deformations of a CFRP workpiece, whereas a linear correlation of plastic deformation to the resulting Bragg signal offset is determined. A plausibility check of the obtained results is delivered by a comparison of three-point flexural experiments on bulk CFRP workpieces, without integrated sensors and additional specimens featuring external optical sensors affixed to their surface. It is found that PPBGs based on cyclic olefin copolymers are able to overcome the temperature-related limitations of traditional polymer-based optical sensors and can thus be directly integrated into commercial-grade composites during production.}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{KeferRosenbergerHessleretal.2020, author = {Kefer, Stefan and Rosenberger, Manuel and Hessler, Steffen and Girschikofsky, Maiko and Belle, Stefan and Roth, Gian-Luca and Schmauss, Bernhard and Hellmann, Ralf}, title = {Fabrication and Applications of Polymer Planar Bragg Grating Sensors based on Cyclic Olefin Copolymers}, series = {2019 Photonics \& Electromagnetics Research Symposium - Fall (PIERS - Fall)}, booktitle = {2019 Photonics \& Electromagnetics Research Symposium - Fall (PIERS - Fall)}, publisher = {Institute of Electrical and Electronics Engineers}, isbn = {978-1-7281-5304-9}, doi = {10.1109/PIERS-Fall48861.2019.9021801}, pages = {647 -- 655}, year = {2020}, abstract = {This contribution reviews recent advancements, current research and possible applications of polymer planar Bragg grating (PPBG) sensors with a focus on the utilization of cyclic olefin copolymer (COC) substrates. COC-PPBGs can be handled and fabricated efficiently by employing a single writing step procedure which features simultaneous generation of waveguide and Bragg grating structure within an injection molded substrate. The resulting photonic structures exhibit an attenuation as low as 1.2 dB cm-1 and a reflectivity up to 99 \%. The potential of COC-PPBGs for high-temperature applications is proven by demonstrating temperature measurements up to 160 °C. Moreover, it is possible to employ single PPBGs for multidimensional stress and strain sensing or even three-dimensional shape reconstruction. Due to their excellent properties, it is feasible to integrate COC-PPBGs into commercial-grade carbon fiber reinforced polymer workpieces for structural health monitoring. Furthermore, utilization of appropriate coatings enables functionalization of PPBGs for refractive index sensing and thus biochemical applications. Beside the fabrication and characterization of COC-based PPBGs, this contribution exemplifies and reviews such applications.}, subject = {Optischer Sensor}, language = {en} } @inproceedings{SauerKeferRuppertetal.2019, author = {Sauer, Theresia and Kefer, Stefan and Ruppert, Wolfgang and Hellmann, Ralf and Kaloudis, Michael}, title = {Integration of Bragg grating sensors in components made of carbon fiber reinforced polymers}, series = {Tagungsband der 20. GMA/ITG-Fachtagung Sensoren und Messsysteme 2019, 25.06.2019 - 26.06.2019, N{\"u}rnberg, Deutschland}, booktitle = {Tagungsband der 20. GMA/ITG-Fachtagung Sensoren und Messsysteme 2019, 25.06.2019 - 26.06.2019, N{\"u}rnberg, Deutschland}, isbn = {978-3-9819376-0-2}, doi = {10.5162/sensoren2019/P3.12}, pages = {806 -- 810}, year = {2019}, abstract = {This contribution discusses the integration of polymer planar Bragg grating sensors (PPBG) into carbon fiber reinforced polymer (CFRP) components. For the first time, it is shown that PPBGs based on cyclic olefin copolymers can be integrated into commercial-grade composites, thereby withstanding the demanding production processes. Pre-impregnated fibers are stacked and partially modified to form a sensor pocket. Afterwards, the CFRP specimen containing the optical sensor is cured in a heated mechanical press for 2 hours at a pressure of 7 bar and a temperature of 120 °C. A subsequent evalutaion of the sensor signal shows a Bragg wavelength shift of 1236 pm and a decline in signal amplitude of -2 dB. Three-point flexural tests of the cured sample reveal a linear behavior of the sensor signal towards external loads. The determined sensitivity in dependence of the CFRP specimen's maximum central deflection is -112 pm/mm, while correlation to the applied force results in a sensitivity of -5 pm/N.}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{RosenbergerBelleHellmann2011, author = {Rosenberger, Markus and Belle, Stefan and Hellmann, Ralf}, title = {Detection of unlabeled DNA hybridization with a planar Bragg Grating Sensor}, series = {XXV International MicroCAD Conference - Sensing Technologies, Miskolc (Hungary)}, booktitle = {XXV International MicroCAD Conference - Sensing Technologies, Miskolc (Hungary)}, number = {Section R}, pages = {67 -- 72}, year = {2011}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{RosenbergerBelleHellmann2011, author = {Rosenberger, Manuel and Belle, Stefan and Hellmann, Ralf}, title = {Optical interrogation of chemical and temperature bragg grating sensors using tunable fiber coupled bandpass filter}, series = {Proceeding XXV microCAD, International scientific conference, 2011, Section H}, booktitle = {Proceeding XXV microCAD, International scientific conference, 2011, Section H}, pages = {25 -- 30}, year = {2011}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{ScheurichBelleHellmannetal.2009, author = {Scheurich, Steffen and Belle, Stefan and Hellmann, Ralf and So, Sik and Sparrow, Ian and Emmerson, Greg}, title = {Application of a silica-on-silicon planar optical waveguide. Bragg grating sensor for organic liquid compound detection}, series = {SPIE Optics an optoelectronics conference, Proceedings of SPIE, Vol. 7356, Prag, CR}, booktitle = {SPIE Optics an optoelectronics conference, Proceedings of SPIE, Vol. 7356, Prag, CR}, number = {7356}, isbn = {978-0819476302}, year = {2009}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{ScheurichBelleHellmannetal.2009, author = {Scheurich, Steffen and Belle, Stefan and Hellmann, Ralf and So, Sik and Sparrow, Ian and Emmerson, Greg}, title = {Planar optical waveguide bragg grating chemical sensor for online process control}, series = {3rd integrated optics - sensors, sensing structures and methodes Korbielow, PL}, booktitle = {3rd integrated optics - sensors, sensing structures and methodes Korbielow, PL}, year = {2009}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{RosenbergerBelleHellmann2009, author = {Rosenberger, Manuel and Belle, Stefan and Hellmann, Ralf}, title = {Optical interrogation of bragg grating sensors using tunable fibre based bandpass filter}, series = {Proceedings of the 20st international science conference, Mittweida}, booktitle = {Proceedings of the 20st international science conference, Mittweida}, year = {2009}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{RosenbergerBelleHellmann2011, author = {Rosenberger, Manuel and Belle, Stefan and Hellmann, Ralf}, title = {Detection of biochemical reaction and DNA hybridization using a planar bragg grating sensor}, series = {Proceeding SPIE, Vol. 8073, article id: 80730C}, booktitle = {Proceeding SPIE, Vol. 8073, article id: 80730C}, number = {8073}, doi = {10.1117/12.886785}, year = {2011}, subject = {Bragg-Reflektor}, language = {en} } @article{GirschikofskyRosenbergerBelleetal.2011, author = {Girschikofsky, Maiko and Rosenberger, Manuel and Belle, Stefan and Brutschy, Malte and Waldvogel, Siegfried and Hellmann, Ralf}, title = {Highly sensitive detection of naphthalene in solvent vapor using a functionalized PBG refractive index sensor}, series = {Sensors}, volume = {12}, journal = {Sensors}, number = {2}, doi = {10.3390/s120202018}, pages = {2018 -- 2025}, year = {2011}, subject = {Bragg-Reflektor}, language = {en} } @article{GirschikofskyRosenbergerBelleetal.2011, author = {Girschikofsky, Maiko and Rosenberger, Manuel and Belle, Stefan and Brutschy, Malte and Waldvogel, Siegfried and Hellmann, Ralf}, title = {Optical planar bragg grating sensor for real-time detection of benzene, toluene und xylene in solvent vapour}, series = {Sensors \& Actuators, B - Chemical}, volume = {171/172}, journal = {Sensors \& Actuators, B - Chemical}, number = {8/9}, pages = {338 -- 342}, year = {2011}, subject = {Bragg-Reflektor}, language = {en} } @article{BelleRosenbergerHellmann2011, author = {Belle, Stefan and Rosenberger, Manuel and Hellmann, Ralf}, title = {Evanescent wave planar bragg grating sensor for real-time detection of unlabelled biomolecules}, series = {Optics Express}, journal = {Optics Express}, year = {2011}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{BelleScheurichHellmann2009, author = {Belle, Stefan and Scheurich, Steffen and Hellmann, Ralf}, title = {Interrogation water content in organic solvents by planar bragg grating sensors}, series = {Proceedings SENSOR}, booktitle = {Proceedings SENSOR}, number = {Vol. II, P3.2}, isbn = {978-3-9810993-6-2}, pages = {324 -- 329}, year = {2009}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{GirschikofskyRosenbergerBelleetal.2012, author = {Girschikofsky, Maiko and Rosenberger, Manuel and Belle, Stefan and Hellmann, Ralf}, title = {Surface modifications of planar bragg grating refractive index sensors for gas detection}, series = {Proceedings of the XXVI International MicroCAD Conference - Sensing Technologies, Miskolc (Hungary)}, booktitle = {Proceedings of the XXVI International MicroCAD Conference - Sensing Technologies, Miskolc (Hungary)}, year = {2012}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{GirschikofskyRosenbergerBelleetal.2012, author = {Girschikofsky, Maiko and Rosenberger, Manuel and Belle, Stefan and Brutschy, Malte and Waldvogel, Siegfried and Hellmann, Ralf}, title = {α-Cyclodextrin functionalized planar Bragg grating sensor for the detection of small arene traces in solvamt vapour}, series = {14th international meeting on chemical sensors (IMCS 2012)}, booktitle = {14th international meeting on chemical sensors (IMCS 2012)}, isbn = {978-3-9813484-2-2}, doi = {10.5162/IMCS2012/7.5.1}, pages = {646 -- 648}, year = {2012}, subject = {Bragg-Reflektor}, language = {en} } @inproceedings{GirschikofskyRosenbergerBelleetal.2012, author = {Girschikofsky, Maiko and Rosenberger, Manuel and Belle, Stefan and Brutschy, Malte and Waldvogel, Siegfried and Waldvogel, Ralf}, title = {Functionalized planar Bragg grating sensor for the detection of BTX in solvent vapour}, series = {Proceedings of SPIE 8439, Optical Sensing and Detection II, 843916}, booktitle = {Proceedings of SPIE 8439, Optical Sensing and Detection II, 843916}, number = {8439}, doi = {10.1117/12.921078}, year = {2012}, subject = {Bragg-Reflektor}, language = {en} }