TY - JOUR A1 - Zesch, Christoph A1 - Finkelstein, Daniel A1 - Regehly, Martin A1 - Reif, Jürgen A1 - Schrader, Sigurd T1 - Efficient nanosecond barium nitrate Raman laser for the visible spectral range JF - Optics Express N2 - We report on the design and performance of two solid-state Raman lasers, pumped by a frequency-doubled Nd:YAG laser at 532 nm (8 ns FWHM, 10 Hz, up to 10 mJ), that generate either the first or second Stokes radiation with wavelengths of 563 nm and 598 nm. Barium nitrate crystals with a 1 cm² face area and lengths of 3 cm and 5 cm were used as the Raman-active medium in stable semi-spherical resonators. The Raman lasers produced first Stokes and second Stokes pulses, achieving pulse energies up to 2.3 mJ and conversion efficiencies up to 35% (first Stokes, 5 cm crystal) and 21% (second Stokes, 5 cm crystal). The output beams exhibit nearly Gaussian profiles with beam quality factors of M² = 1.67 and M² = 1.83, respectively. The proposed design and characterization demonstrated a Raman laser with high efficiency and superior beam quality. After subsequent frequency doubling, the output appears well dedicated for future differential absorption LiDAR (DIAL) applications. KW - Gaussian beam KW - laser source KW - Nd:YAG laser KW - Raman laser KW - solid state laser KW - ultraviolet laser Y1 - 2026 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-21320 VL - 34 IS - 4 SP - 6355 EP - 6363 PB - Optica ER - TY - CHAP A1 - Pulwer, Silvio A1 - Fiebelkorn, Richard A1 - Zesch, Christoph A1 - Steglich, Patrick A1 - Villringer, Claus A1 - Villasmunta, Francesco A1 - Gedat, Egbert A1 - Handrich, Jan A1 - Schrader, Sigurd A1 - Vandenhouten, Ralf T1 - Endoscopic orientation by multimodal data fusion T2 - Proc. SPIE 10931, MOEMS and Miniaturized Systems XVIII N2 - To improve the feasibility of endoscopic inspection processes we developed a system that provides online information about position, orientation and viewing direction of endoscopes, to support the analysis of endoscopic images and to ease the operational handling of the equipment. The setup is based on an industrial endoscope consisting of a camera, various MEMS and multimodal data fusion. The software contains algorithms for feature and geometric structure recognition as well as Kalman filters. To track the distal end of the endoscope and to generate 3D point cloud data in real time the optical and photometrical characteristics of the system are registered and the movement of the endoscope is reconstructed by using image processing techniques. KW - endoscope KW - orientation KW - Kalman filter KW - visual odometry KW - mems KW - gyroscope KW - accelerometer Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-11420 SN - 1996-756X ER - TY - CHAP A1 - Zesch, Christoph A1 - Schrader, Sigurd A1 - Prosposito, Paolo A1 - Lux, Oliver A1 - Eichler, Hans J. T1 - Raman lasers for trace gas detection N2 - The emission of commercial solid-state lasers is shifted by Raman lasers to selected wavelengths suitable for trace gas detection. High power Raman lasers based on Ba(NO3)2, diamond and silicon detect CO2, O3 and H2O. Raman lasers base on the physical effect of stimulated Raman scattering. Two new Raman crystals (Spodumene and LuAlO3) are investigated and their SRS-spectra is shown. KW - stimulated Raman scattering KW - Raman laser KW - Barium nitrate KW - Nd:YAG laser KW - trace gas detection Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-15351 SP - 114 EP - 119 PB - SPIE ER - TY - JOUR A1 - Steglich, Patrick A1 - Mai, Christian A1 - Villringer, Claus A1 - Dietzel, Birgit A1 - Bondarenko, Siegfried A1 - Ksianzou, Viachaslau A1 - Villasmunta, Francesco A1 - Zesch, Christoph A1 - Pulwer, Silvio A1 - Burger, Martin A1 - Bauer, Joachim A1 - Heinrich, Friedhelm A1 - Schrader, Sigurd A1 - Vitale, Francesco A1 - De Matteis, Fabio A1 - Prosposito, Paolo A1 - Casalboni, Mauro A1 - Mai, Andreas T1 - Silicon-organic hybrid photonics: an overview of recent advances, electro-optical effects and CMOS integration concepts JF - Journal of Physics: Photonics N2 - In recent decades, much research effort has been invested in the development of photonic integrated circuits, and silicon-on-insulator technology has been established as a reliable platform for highly scalable silicon-based electro-optical modulators. However, the performance of such devices is restricted by the inherent material properties of silicon. An approach to overcoming these deficiencies is to integrate organic materials with exceptionally high optical nonlinearities into a silicon-on-insulator photonic platform. Silicon–organic hybrid photonics has been shown to overcome the drawbacks of silicon-based modulators in terms of operating speed, bandwidth, and energy consumption. This work reviews recent advances in silicon–organic hybrid photonics and covers the latest improvements to single components and device concepts. Special emphasis is given to the in-device performance of novel electro-optical polymers and the use of different electro-optical effects, such as the linear and quadratic electro-optical effect, as well as the electric-field-induced linear electro-optical effect. Finally, the inherent challenges of implementing non-linear optical polymers on a silicon photonic platform are discussed and a perspective for future directions is given. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13882 SN - 2515-7647 VL - 3 IS - 2 ER - TY - JOUR A1 - Bauer, Joachim A1 - Fursenko, Oksana A1 - Marschmeyer, Steffen A1 - Heinrich, Friedhelm A1 - Villasmunta, Francesco A1 - Villringer, Claus A1 - Zesch, Christoph A1 - Schrader, Sigurd T1 - Spectroscopic reflectometry for characterization of Through Silicon Via profile of Bosch etching process JF - Journal of Vacuum Science & Technology B N2 - Through Silicon Via (TSV) technology is a key in 3D integration of circuits by the creation of interconnects using vias, which go through the full silicon wafer. Typically, a highly-selective Bosch Si etch process is used. It is characterized by a high etch rate at a high aspect ratio, whereby scallops on the sidewalls are generated. In this work, square via arrays with dimensions from 3 to 50 μm and up to 300 μm depth were fabricated and analyzed by spectroscopic reflectometry. The reflectometric data are compared to simulations by a novel theoretical approach. In order to simulate the reflectance spectra of TSV arrays, a combination of 2D and 3D rigorous coupled wave analysis was applied. Besides the via depth, the sidewall angle and the corner radius of the bottom profile were considered in the model. The general requirements on spectral resolution in TSV metrology are discussed. Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16093 VL - 37 IS - 6 PB - American Vacuum Society (AVS) ER -