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Cluster Report Photonics in the Capital Region Berlin-Brandenburg

  • Text
  • Imaging
  • Photonics
  • Berlin
  • Optical
  • Laser
  • Technologies
  • Optics
  • Microsystems
  • Components
  • Brandenburg

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62 Cluster Report Optics and Photonics – Optical Analytics THz laser system for the stratospheric observatory for infrared astronomy © DLR www.fbh-berlin.com/research/iii-v-electronics/terahertz-electronics The IHP – Innovations for High Performance Microelectronics focuses on the research and development of technologies, circuits, and systems for millimetre waves and THz applications. Among other things, it is developing complex SiGe BiCMOS technologies purpose, which operate with special silicon-germanium hetero-junction bipolar transistors (HBTs) and frequencies from 0.5 to 0.7 THz. Together with the electrophotonic technologies developed by IHP, these can be used to realise high-frequency circuits for wireless as well as electrical and electro-optical broadband communication. www.ihp-microelectronics.com The Paul-Drude-Institut für Festkörperelektronik (PDI), a Leibniz Institute in Forschungsverbund Berlin e. V., is developing quantum cascade lasers (QCLs) for the THz range (2 to 5.7 THz) based on the material systems GaAs/(Al,Ga) As and GaAs/AlAs. These QCLs are narrow-band radiation sources and are used for such things as spectroscopic applications and imaging methods developed at the German Aerospace Center in Berlin. At PDI, they are designing and manufacturing the laser structures using molecular beam epitaxy. The QCL structures are then processed in laser strips and the operating parameters determined by Fourier transform spectroscopy. www.pdi-berlin.de THz spectrometers for mobile use The German Aerospace Center (DLR), Institute of Optical Sensor Systems in Berlin is developing THz spectrometers based on QCLs and electronic THz emitters and receivers. These spectrometers can be used in a variety of ways: for high-resolution molecular spectroscopy and the highly sensitive detection of trace gases. An outstanding example is the THz QCL laser system developed by DLR for SOFIA, the Stratospheric Observatory for Infrared Astronomy. It is based on a QCL made by PDI. This unique technology allows a new way to peer into the universe and offers new applications beyond astronomy. For applications in THz imaging, for imaging spectroscopy, and for applications in security and material testing, the DLR imaging process is based on a single-pixel camera and compressed sensing methods. In addition, DLR is researching superconducting THz detectors, with a focus on highly sensitive nanostructured bolometers. The technology is also used to detect ultrashort (ps) THz pulses. www.dlr.de/os/en The research conducted at Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, HHI includes fast optoelectronic THz emitters and detectors. The use of mature technologies and components from indium-phosphide-based telecommunication enables the production of robust and powerful THz systems covering the frequency range from 0.1 to 6 THz. These glass-fibre-based systems have become the worldwide standard for optoelectronic THz systems in recent years, as many beam sources and components are available in high quality. The THz transmitters and receivers developed at Fraunhofer HHI are used both in THz spectros- THz module for mobile use from Fraunhofer HHI © Fraunhofer HHI

Cluster Report Optics and Photonics – Optical Analytics 63 Pyroelectric measuring heads for THz radiation © SLT Sensor- und Lasertechnik GmbH copy and increasingly in the field of non-destructive testing and process control. One example is the non-contact measurement of the wall thickness of plastic pipes during the manufacturing process with an accuracy of less than 10 µm. Based on this technology, HHI launched an integrated fibre-coupled THz transceiver in 2016 that combines a THz transmitter and receiver on a single indium phosphide chip. This configuration enables THz reflection measurements under vertical beam incidence, resulting in very compact, robust, and powerful THz probes. This is one of the most important prerequisites for further applications for THz technology. www.hhi.fraunhofer.de/en THz calibration measuring station with THz camera (1), standard detector (2), and device under test (3) being hit by the THz laser beam (red line). When the gold-plated chopper (5) interrupts the beam, the monitor detector (4) measures the THz output. © PTB from the AMA Association for Sensor and Measurement Technology for this innovation. As a unique selling point, these detectors exhibit a constant spectral sensitivity in the entire THz spectral range and have been successfully sold with individual PTB calibration certificates by SLT worldwide. These detectors are the first that allow the measurement of the THz output of the THz emitters developed at Fraunhofer HHI. www.pyrosensor.de The Federal Institute for Materials Research and Testing Bundesanstalt für Materialforschung und -prüfung (BAM) in Berlin is working on potential applications of commercially available time-resolved THz spectrometers (THz-TDS) for the spectroscopic investigation of dielectrics. Their initial THz activities in the field of spectral material characterisation of liquids, fires, and hazardous substances were supplemented by questions on contactless and non-destructive material testing for the detection of internal defects and structural structures of planar and spherical objects. For the characterisation of multiple layers in planar dielectric composite systems using the Thz TDS, a THz time-of-flight optical layer model was developed to measure the layer build-up in terms of material thickness and identify defects by scanning a dielectric object. The THz-TDS-SAFT tomography was developed for the non-destructive testing of three-dimensional dielectric components. It is used to reconstruct the internal structures of components after scanning with THz radiation. The focus is on the visual detection of material defects, such as pores or cracks in 2D and 3D images. BAM focuses its activities primarily on materials testing. Thz TDS is being prepared for use in industry applications such as the non-destructive testing of polymers, ceramics, and high-performance materials. The hope is that it will offer a viable alternative to existing test systems. www.bam.de/Navigation/EN/About-us/Organisation/Organisation-Chart/President/Department-8/Division-83/division83.html Pyroelectric THz detectors not requiring cooling were developed in a partnership between the Physikalisch-Technische Bundesanstalt (PTB) in Berlin and SLT Sensor- und Lasertechnik GmbH based in Wildau. In 2017, the development team received the special “Young Company” award Calibration and standards The Physikalisch-Technische Bundesanstalt (PTB) in Berlin is the only place in the world where the spectral sensitivity of THz receivers can be traced back to the SI. This calibration service with a THz molecular gas laser not only serves

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