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The article contains sections titled: 1. Introduction 2. Biological Principles 2.1. Organisms 2.2. Biocenosis 2.3. Metabolism 3. Basic Biotechnological Considerations 4. Technology and Operation of a Wastewater-Treatment Plant 5. Examples of Industrial Wastewater-Treatment Plants Based on a Variety of Centralized Processes 5.1. Single-Stage and Multistage Activated-Sludge Plants 5.2. Oxygen-Based Facilities 5.3. Treatment Facilities with Selective Carbon and Nitrogen Elimination 5.4. Trickling-Filter Facilities 5.5. Biofilter Systems 5.6. Indirect-Discharge Facilities

Fabrication of devices composed of Josephson junctions in trilayer technology is usually compromised by the topography of the subjacent layers. If the structures of subsequent layers traverse steps, several adverse effects arise. Lithography may be impaired because of issues with resist thickness uniformity and focus depth, and the superconducting ampacity of the Nb wiring is reduced. Various methods have been tried to planarize perturbing structures. In this contribution, we address a few of the challenges of chemical mechanical polishing. The proposed improvements are based on the well-established IPHT cross-type junction technology.

Tailoring the physicochemical properties of the metallic multijunction nanolayers is a prerequisite for the development of microelectronics. From this perspective, a desired lower reflectance of infrared radiation was achieved by an electrochemical deposition of porous platinum in nonaqueous media on silver mirror supported nickel-chrome and nickel-titanium metallic films with incremental decreasing thicknesses from 80-10 nm. The electro-assembled architectures were examined by means of scanning electron microscopy and Fourier transform infrared spectroscopy and it was observed that the layer and sublayer thicknesses and resistivities have a substantial effect upon the porous platinum morphology and its optical properties. It is here reported that the augmentation of the metallic layer electrical conductivity determines the electroformation of more compact platinum nanolayers. Moreover, the platinum black coating of metallic nanolayers causes a considerable decrease of the reflectance in the region from 1000-8000 cm-1.

In recent years, body scanner technologies based on millimeter-wave and terahertz technologies have been shown to improve security in areas sensitive to terrorist attacks by detecting hazardous objects hidden underneath the clothing of people. Inevitably, useful devices have to provide an adequate compromise between spatial resolution limited due to diffraction and penetration through clothing. Within this context, the spectral absorption of a wide range of fabric, interference caused by the texture, and the effect of moisture within the fabric have to be considered. We have studied these effects by time-domain and Fourier transformation spectroscopy. The experimental findings are verified using a passive THz security camera operating in two frequency bands at 0.85 and 0.35 THz. The latter band was proven to be of superior use for security checks as it provides useful results even in cases of wet clothes.

Extraordinary optical transmission and perfect absorption are two plasmonic-based optical phenomenona that are both accompanied by high local field enhancements that can be exploited for biological and chemical sensing. Here we merge both phenomenona in a slit array metamaterial perfect absorber consisting of a dielectric layer sandwiched between two metallic layers of which the upper layer is perforated with a periodic array of slits. Period and dimensions of the slits and thickness of the dielectric layer are tuned in a way that virtually all light of a certain wavelength incident on the surface passes through the slits and is subsequently absorbed. As a consequence, light–matter interaction is greatly enhanced in the slits. Thus, already small concentrations of analytes down to a monolayer attached to the sidewalls of the slits can be detected by refractive index sensing and identified by their spectral fingerprints with a standard mid-infrared lab spectrometer.

Cryogenic bolometers based on thin silicon nitride membranes show a very high sensitivity, which makes them ideal for ultrasensitive detector applications, particularly in the field of submillimeter-wave imaging. For that, transition-edge sensors (TESs) have been established as a viable approach toward developing multipixel sensor arrays. However, current multiplexer techniques as time- or code-division multiplexing do not scale well to multiplexing levels of several hundred detectors per channel. To achieve such a scalable readout solution, frequency-division multiplexing (FDM) would be an applicable way. For that, the temperature-sensing element of a bolometer has to be resonant or coupled to a resonance circuit, which changes its microwave behavior with the temperature of the absorber.

For spectroscopic and imaging applications in the submillimeter wavelength band, superconducting radiation sensors are widely used. Thereby, sensor arrays with a rising number of pixels require multiplexing techniques in order to reduce the number of wires leading to the cryogenic stage. A current steering switch (CSS) provides the basis for one kind of promising code division multiplexers. It is composed of two identical superconducting quantum interference devices (SQUIDs) in parallel current paths. Switching one of them from the superconducting into the normal state, which is controlled by the applied magnetic flux, alters the signal path; thus, they can act as a polarity switch for analog signals. In this paper, we describe a method that uses rapid single-flux quantum (RSFQ) electronics for controlling these switches. Therefore, their SQUIDs are inductively coupled each to the storing loop of an RSFQ delay flip-flop (DFF); hence, the state of the analog switch can be controlled by means of digital RSFQ signals. As a first step, we show the change in the critical current of the SQUIDs by the coupled operating digital circuit. For a wider operating range of the CSS, we developed a DFF, which is able to store a larger quantity of magnetic flux to make it possible to apply more flux to the coupled SQUID. For further improvements, we tested asymmetric SQUIDs to reduce the required magnetic flux. The results of the simulations and measurements are discussed.

An optical metamaterial, operating in between the MID/IR and the visible domain, which uses the effect of extreme coupling between closely spaced nanostructured gold metal plates and a planar gold substrate was realized by means of electron beam lithography and lift-off technique. This regime is only accessible by using an ultrathin oxide layer between metal plates and substrate, where the oxide layerisrealized by atomic layer deposition here. The involved fabrication is discussed in detail. The metamaterial shows the predicted effect of perfect absorption with multiple resonances in the spectral range from 100 THz to 600 THz. The plasmonic based resonance frequencies are very sensitive to the plate size of the grating and the spacer thickness.

We present a newly designed high-detectivity thermoelectric linear array, based on an organic membrane for use in the room temperature range. The sensor array has 64 individual readable channels and was designed and developed for IR spectroscopy. This detector may be used to infer the condition of lubricants and coolants within a mechanical system, so that they can be replaced when needs be, e.g. determining the age of technical oils of wind power plants in real time. Thus valuable resources can be saved and costly damage to equipment avoided. In order to achieve a D* greater than 2 × 109 cmHz1/2/W, the sensor was designed and optimized to be operated under vacuum conditions. To minimize the thermal cross talk between individual pixels, the pixels are separated from each other by a 50 μm slit in the self-supporting organic membrane made of SU-8.

Thermopile detectors are particularly well suited for spectral imaging, space science applications, track recording, presence detection and applications with low energy consumption. The purpose of this work is the fabrication of a surface-micromachined 2-D high detectivity thermopile array using a highly effective BiSb/Sb thermocouple materials combination. The thermoelectric array is built on 8x8 pixels with an active area of [email protected] in square, which are wired directly. Thermopile structure and absorber area are manufactured upon a sacrificial layer based on polyimide, which is removed at the end of the manufacturing process. Thermoelectric layers as well as wiring layers has been patterned almost exclusively by lift-off technique in order to obtain very small structure dimension with high reliability as well as high integration level. The active area of detectors can be equipped with two absorber types for different application, a broadband colloidal silver black layer as well as a quarter wavelength arrangement for the MIR wavelength range from 8 to [email protected] The detectivity of so manufactured FPAs is about 1x10^9 Jones exceeding most of the state-of-the-art thermopile detectors.

We present the concept and experimental set-up of a passive submillimeter-wave stand-off imaging system for security applications. Our ambition is the design of an application-ready and user-friendly camera providing high sensitivity and high spatial resolution at video frame rates. As an intermediate step towards this goal, the current prototype already achieves a frame rate of 10 frames per second and a spatial resolution below 2 cm at 8 m distance. The camera is the result of a continuous development and a unique concept that yielded first high-resolution passive submillimeter-wave images provided by cryogenic sensors in May et al. (2007). It is based on an array of 20 superconducting transition-edge sensors operated at a temperature of 450 mK, a closed-cycle cooling system, a Cassegrain-type optics with a 50 cm main mirror, and an opto-mechanical scanner. Its outstanding features are the scanning solution allowing for high frame rates and the compact and integrated system design.

People have a desire for security, especially when they are about to enter an aircraft. Nobody wants to sit next to a terrorist flying 30,000 ft above ground. So, modern technology is expected to provide a solution to screen anybody willing to enter an aircraft for hidden threats. Obviously the actual solution using metal detectors and manual control is secure only to a certain level; moreover it is inefficient and offending. Security screening and respecting privacy at the same time constitute a conflict which cannot be easily solved. Characteristic for that dilemma is the actual public discussion regarding the so called “strip scanner” [1], where a technology with high security standard obviously violates privacy when in a figurative sense it undresses people and even worse illuminates them with arguable radiation (x-ray or millimetre waves). This article describes a possible solution, which respects people‘s privacy and complies with their basic need for security.

A unique system for geomagnetic archaeometry is presented. It uses extremely sensitive superconducting quantum interference devices (SQUIDs) as magnetic field sensors, laid out as intrinsic gradiometers. These sensors are mounted on a non-metallic cart, which guarantees smooth movement even at high speeds. Using a differential global positioning system (GPS) together with an inertial system the measured magnetic field gradient data are located on the mapped area with centimetre resolution and the height profile is also provided using the GPS. All data are stored in a data logger and partially online displayed on a laptop computer. At the time of this report, the system is pushed manually and has been tested on a Neolithic double ring ditch near Weimar, Germany. In a gateway through the rings, remains of palisades and buildings have been well resolved, confirming the high sensitivity of the SQUID-based system. An excavation at the ring ditch showed that material with enhanced susceptibility was the origin of the magnetic field gradient signals. Copyright © 2007 John Wiley & Sons, Ltd.

We report on successful tests of planar LTS SQUID gradiometers on airborne platforms such as helicopter and aircraft. The system works stable and allows profile work without any constraints. In mobile applications the gradient resolution at low frequencies is dominated by motion noise, since the parasitic areas of the SQUID gradiometer lead to strong disturbances if the gradiometer is tilted in the homogenous Earth's magnetic field. The balance can be improved further by software using data of a SQUID magnetometer triple. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

An integrated gradiometer system is presented, consisting of a single-layer high-temperature superconductor dc superconducting quantum interference device (SQUID) and two coils, realized on printed circuit boards. The coils compensate the homogeneous background field, thus allowing the gradiometer to be freely moved in the Earth's magnetic field. The gradiometer signal is not harmed by any additional noise introduced by the homogeneous field compensation. Therefore, a noise-limited magnetic field gradient resolution of 15 pT m−1 Hz−1/2 with a 1/f corner frequency of 2 Hz was achieved. This is preserved even after motion in the Earth's magnetic field. Because of the small dimensions of the compensation coils, the gradiometer system can also be used for non-destructive evaluation. Preliminary measurements were performed by moving the SQUID across a workpiece, without any shielding.

We developed a gradiometer system based on a single-layer high-temperature superconductor dc superconducting quantum interference device (SQUID), which can be freely moved within the Earth's magnetic field during measurement. The problem of circumferential shielding currents in the parallel gradiometer pick-up loop is solved by the use of an appropriately designed magnetometer SQUID integrated on the gradiometer chip. The magnetometer's feedback coil of the flux-locked loop is laid out as a small Helmholtz coil pair, thus keeping the homogeneous magnetic field constant for both the magnetometer and the gradiometer. Therefore, the balance of the directly coupled gradiometer SQUID is enhanced from 100 up to 3800. The noise limited magnetic field gradient resolution of 45 pT m−1 Hz−1/2 is preserved down to frequencies of several Hz even after strong motion in the Earth's magnetic field.

Cryogenic bolometers are adequate sensing devices for sub-millimeter observations. They are used for instrumentation in radio telescopes like the Atacama Pathfinder Experiment (APEX), which is a 12-m radio telescope in Chile's Atacama desert. Through its thin and dry atmosphere, star formation in the red-shifted early universe can be observed. A suitable bolometer has a high sensitivity and consists of several tens to hundreds of pixels that are combined to an array. To meet these requirements, we use transition edge sensors. They detect radiation by measuring a temperature increase in an appropriate absorber. For highest sensitivity, the absorber is only in weak thermal contact to its surroundings. This is achieved by placing it on a SiN membrane that is structured to further decrease the thermal coupling. A superconductor that is biased at its transition temperature serves as thermometer for the transition edge sensor. We present the fabrication of such devices and discuss encountered difficulties. Further, we briefly describe the incorporation of a sensor chip with an array of 39 pixels into an instrument that currently operates at APEX. For the fall of 2010 the installation of a 300 pixel array is scheduled.

Nowadays detection systems based on superconducting nanowire single-photon detectors (SNSPD) are mainly with a single-pixel detector. Multi-pixel systems would extend the field of possible applications. Therefore, new concepts are required for effective readout of multi-pixel SNSPDs. We give an overview of possible concepts, conditions of operation and dedicated effort to optimize the requirements of different applications in the single-photon regime.

The integration of superconductor digital electronics together with superconducting sensors can enable smart multi-channel sensor arrays. Applications of such sensors range from basic astrophysical research to advanced security screening devices. The main advantage of superconducting sensor interfaces is the very low power consumption in combination with a very low noise level; both are required in order to keep the excellent superconducting sensor performance without distortions. The FLUXONICS Foundry technology has been optimized with respect to electronic interfaces circuits for analogue sensor readout and signal multiplexing. In this work, we describe this new interface technology and present a comparison with our standard RSFQ technology.

Since 2007 we are developing passive submillimeter-wave video cameras for persona l security screening. Incontradiction to established portal-based millimeter-wave scanning techniques, t hese are suitable for stand-o or stealth operation. The cameras operate in the 350GHz band and use arrays of superconducting transition-edge sensors (TES), reector optics, and opto-mechanical scanners. Whereas the basic principl e of these devicesremains unchanged, there has been a continuous development of the technical details, as the detect or array, thescanning scheme, and the readout, as well as system integration and performance. The latest prototype of thiscamera development features a linear array of 128 detectors and a linear scanner capable of 25Hz frame rate.Using di erent types of reector optics, a eld of view of 1 2m 2 and a spatial resolution of 1{2cm is providedat object distances of about 5{25m. We present the concept of this camera and give detai ls on system designand performance. Demonstration videos show its capability for hidden threat detectio n and illustrate possibleapplication scenarios.Keywords: submillimeter-wave, THz, terahertz, camera, imaging, video, bolometer, TES

As manmade space debris in the low earth orbit becomes an increasing risk to space missions, which could even result in total mission loss, it has become even more critical to have detailed knowledge of the properties of these particles like the mass, the velocity and the trajectory. In this paper, we present a newly designed, highly sensitive impact detector array with 16 pixels for space debris analysis. The thermopile sensor array, which was developed in the project, consists of 16 miniaturized multi-junction thermopile sensors made by modern thin-film technology on Si wafers. Each thermopile sensor consists of 100 radially arranged junction pairs formed from evaporated antimony and bismuth thin films. The centrally located active (hot) junctions comprise the active area of 1 mm². The output e.m.f. of the sensor is proportional to the temperature difference between the active and the reference junctions. The thermopile requires no cooling and no bias voltage or current for operation. It generates no 1/f noise but only the thermal resistance (Nyquist) noise. The sensor can be used for DC and low frequency AC measurements. The impact energy of micro sized particles is measured by a calorimetric principle. This means that the kinetic energy of the particle is converted into heat by hitting the absorbing foil, which is glued on the surface of the membrane area. This setup in combination with a preceded velocity detector allows the measurement of the most interesting particle quantities mass, velocity and trajectory.

The mapping of the Earth's magnetic field or field gradient is a proven method in surface exploration and archaeometry. Caesium vapour magnetometers show the best magnetic field resolution of commercial devices, but their sampling frequency is limited to 10 Hz. Using SQUIDs it is possible to achieve the same or even better magnetic field resolution with a sampling frequency as high as 100 Hz or more. This allows significantly shorter acquisition times, which is essential for the mapping of large objects. In this paper we check the performance of our developed systems on a neolithic double-ring ditch enclosure near Weimar, Germany. We compare mappings of this area using an electronic caesium gradiometer, an electronic HTS SQUID gradiometer and an integrated planar LTS SQUID gradiometer. With all three systems the magnetic pattern of the ditch is visible; however, the electronic HTS gradiometer shows disturbances of the same order of magnitude as the gradient signal of the ditch, due to an insufficient common mode rejection whilst being moved. The planar LTS SQUID gradiometer shows superior performance. Its mapping shows a much better contrast and features that are not visible in the mapping of the caesium gradiometer.

Submillimeter waves have unique optical properties that allow for applications in the security domain. Especially the high transmission through clothing combined with low transmission through many materials that can be used to build harmful objects enables applications in security screenings. We already showed that it is possible to acquire passive images at 350 GHz with a cooled system based on superconducting detectors working at 500mK. Now we present recent results of our current development of a new prototype of a passive submillimeter video camera for security applications. Compared to its predecessor, it has a larger field of view and can take images at frame rates up to 25 Hz.

Following an established concept of IR spectroscopy, the total absorber was transferred to the THz wavelength. This allows for measurement of effects interesting for life-science applications like DNA hybridization and molecular resonances. The complete process from simulations to measurements will be addressed.

A method has been developped to take into account the presence of a local external magnetic field in Superconducting Quantum Interference Devices (SQUIDs) loops composing Rapid Single-Flux-Quantum (RSFQ) circuits, through modifications of circuit inductances. A good agreement is observed between analytical formulas and simulations performed by time-domain softwares. The agreement with the first experiments is still only qualitative at this stage.

Passive submillimeter wave imaging is a concept that has been in the focus of interest as a promising technology for security applications for a number of years. It utilizes the unique optical properties of submillimeter waves and promises an alternative to millimeter-wave and X-ray backscattering portals for personal security screening in particular. Possible application scenarios demand sensitive, fast, and fleixible high-quality imaging techniques. Considering the low radiometric contrast of indoor scenes in the submillimeter range, this objective calls for an extremely high detector sensitivity that can only be achieved using cooled detectors. Our approach to this task is a series of passives standoff video cameras for the 350 GHz band that represent an evolving concept and a continuous development since 2007. The cameras utilize arrays of superconducting transition-edge sensors (TES), i.e. cryogenic microbolometers, as radiation detectors. The TES are operate at temperatures below 1K, cooled by a closed-cycle cooling system, and coupled to superconducting readout electronics. By this means, background limited photometry (BLIP) mode is achieved providing the maximum possible signal to noise ratio. At video rates, this leads to a pixel NETD well below 1K. The imaging system is completed by reflector optics based on free-form mirrors. For object distances of 3–10m, a field of view up to 2m height and a diffraction-limited spatial resolution in the order of 1–2cm is provided. Opto-mechanical scanning systems are part of the optical setup and capable frame rates up to 25 frames per second. Both spiraliform and linear scanning schemes have been developed.

We present a newly designed thermoelectric detector chip of high detectivity for the space mission BepiColombo to Mercury. The sensor is part of the MERTIS radiometer, which enables radiometric measurements in the spectral range from 7-40 micron to study the thermo-physical properties of the planet's surface material. In collaboration with the DLR Institute of Planetary Research, the Institute of Photonic Technology has developed a sensor array with a specific detectivity D* of 1.3 x 10 9 Jones in vacuum environment and 2 x 15 individual readable channels. In addition, it has an optical slit in the middle, which serves as the entrance slit of a spectrometer downstream. The sensor area is coated with an absorbing layer, in this case silver black having an absorption coefficient of nearly 100 percent in a wavelength range from 0.4 up to 20 micron. To minimize the thermal cross talk between the individual pixels, each pixel is separated by a 50 micron slit in the self-supporting silicon nitride membrane. For good mechanical stability of the pixels, the pixel membrane is tensioned by 10 micron bridges like braces. The sensor is electrically contacted with a star-flex PCB by direct wire bonding and both are mounted on milled aluminum housing. At the Institute of Photonic Technology (IPHT), high detectivity radiation sensors are developed and based on the thermoelectric principle. The thermoelectric materials used are the highly effective combination of n-bismuth(87%)- antimony(13%) / p-antimony. The sensors are designed, in the main, as miniaturized multi-junction thermocouples and made by state of the art thin film technologies allowing for achievable and reproducible detectivities D* in the range of 10 8 up to 2 x 10 9 Jones.

Here we report a laser plasma-driven source of T-rays with the highest pulse energy ever recorded in a laboratory. T-rays are emitted from the rear surface of a solid target in the non-collinear direction at incident laser intensities ~ 1019 W/cm2. Pulse energy measurements reported T-ray pulses with peak energies no less than 700 μJ. Temporal measurements using a single-shot electro-optic method showed the presence of sub-picosecond T-ray pulses with 570 fs duration, thus rendering the peak-power of the source higher even than that of state-of-the-art synchrotrons. A conversion efficiency of higher than 10−3 and an average power of 7 mW makes it the most efficient compact and powerful THz source known today. Spectral analysis revealed the presences of frequencies ranging from 0.1 − 133 THz, while most of the energy is localised in the low frequency region. The dependence of T-ray yield on incident laser energy is linear and shows no signs of saturation. The spatial distribution of the recorded T-rays indicates that most of the T-rays are emitted in the non-collinear direction from the rear-surface of a solid target and the contribution in the forward direction is very small. 2D particle-in-cell simulations show the presence of transient current at the target rear surface.

The performance of an optically pumped Mx magnetometer with miniaturized Cs cell at earth's magnetic field strength (50 μT) is investigated. Operation using detuned high intensity laser light is shown to be superior to the conventional resonant operation in terms of the projected shot-noise-limited ( 50 fT/√Hz) and the actual noise-limited sensitivity using a noise compensation method. The Zeeman light shift effect, emerging due to the off-resonant circularly polarized laser radiation and leading to a strong orientational dependence of the measurement, is suppressed by averaging two identical magnetometer configurations pumped with oppositely circularly polarized light. A residual heading error within the range of 14 nT, limited by the present experimental characterization setup, was achieved.

We have developed a cryogenic measurement system for single-photon counting, which can be used in optical experiments requiring high time resolution in the picosecond range. The system utilizes niobium nitride superconducting nanowire single-photon detectors which are integrated in a time-correlated single-photon counting (TCSPC) setup. In this work, we describe details of the mechanical design, the electrical setup, and the cryogenic optical components. The performance of the complete system in TCSPC mode is tentatively benchmarked using 140 fs long laser pulses at a repetition frequency of 75 MHz. Due to the high temporal stability of these pulses, the measured time resolution of 35 ps (FWHM) is limited by the timing jitter of the measurement system. The result was cross-checked in a Coherent Anti-stokes Raman Scattering (CARS) setup, where scattered pulses from a β-barium borate crystal have been detected with the same time resolution.

Josephson junctions generate, when subjected to microwave irradiation, voltages with a very high precision and are used in metrology applications. So-called PJVS (programmable Josephson voltage-standards) are capable of generating both AC and DC voltages of up to 10 V. Our work addresses a full fabrication scenario for 10 V PJVS arrays driven at 70 GHz to be used in low microwave-power conditions as in, but not limited to GUNN diodes or cryocooler applications. Nb x Si1−x in its function as a barrier material was characterised with AFM, RBS and reflectometry in order to establish a reliable technological foundation. A 10 V PJVS array driven with microwave power below 50 mW is further presented, which was achieved by optimising the fabrication technology regarding the degree of homogeneity of the Josephson junctions composition and thickness. Control over these parameters is crucial in choosing a stable and well-suited characteristic voltage (I c R n product) and critical current density j c. With this, a low-power operation of a PJVS array is possible without the need for liquid helium cooling, which is currently limiting the availability of PJVS based metrology.

We compare the performance of two methods for the synchronization of the atomic spins in optically pumped magnetometers: intensity modulation of the pump light and the classical M(x) method using B(1) field modulation. Both techniques use the same set-up and measure the resulting features of the light after passing a micro-fabricated Cs cell. The intensity-modulated pumping shows several advantages: better noise-limited magnetic field sensitivity, misalignment between pumping and spin synchronization is excluded, and magnetometer arrays without any cross-talk can be easily set up.

Raman scattering spectroscopy allows the direct and fast study of molecules by analysis of their vibrational normal modes. However, for certain materials the scattered signal is superimposed by fluorescence, which - if present - overwhelms the intrinsically weak Raman signal by orders of magnitude. An approved method to resolve the instantaneous Raman signal of interest from the delayed fluorescence background is time-correlated single-photon counting (TCSPC). For that, a single-photon detector with fast dynamics is required. The, so-called, superconducting nanowire single-photon detector (SNSPD) is a promising candidate for TCSPC. We have developed an optical instrument using such a SNSPD for the TCSPC method. The detector is made from a 5 nm thick NbN film, patterned by electron-beam lithography in a meander line with a width of 100 nm and a filling-factor of 50 %, covering an active area of 4 × 4 μm2. As a proof of concept we have shown that it is possible to resolve low power optical signals (λ between 520 and 630 nm) with a timing jitter of about 35 ps. Based on our experimental results we will discuss perspectives and limits of SNSPD application for spectroscopy.

A newly designed highly detective intra-slit thermoelectric room-temperature linear array is presented. The thermoelectric sensor array ZS-64-2 with 64 individually readable channels was designed and developed for IR spectroscopy. It is suitable for analytical measurement technology, for example, in determining the age of technical oils in real time. For this, the selected absorption bands of the oil are analyzed and evaluated. This allows conclusions be drawn about the condition of lubricants and coolants, so that they can be replaced when it is needed. This method helps to save valuable resources and it helps to avoid costly damages. In order to achieve the high detectivity of D* = 1.8 x 109 Jones the sensor was designed and optimized to be operated under vacuum conditions. For minimizing the thermal cross talk between the individual pixels, they are separated from each other by a 50 micron slit in the self-supporting silicon nitride membrane, which has a thickness of nearly 1 micron.

Against a background of newly emerged security threats the well-established idea of utilizing submillimeter-wave radiation for personal security screening applications has recently evolved into a promising technology. Possible application scenarios demand sensitive, fast, flexible and high-quality imaging techniques. At present, best results are obtained by passive imaging using cryogenic microbolometers as radiation detectors. Building upon the concept of a passive submillimeter-wave stand-off video camera introduced previously, we present the evolution of this concept in a practical application-ready imaging device. This has been achieved using a variety of measures such as optimizing the detector parameters, improving the scanning mechanism, increasing the sampling speed, and enhancing the camera software. The image generation algorithm has been improved and an automatic sensor calibration technique has been implemented taking advantage of redundancy in the sensor data. The concept is based on a Cassegrain-type mirror optics, an opto-mechanical scanner providing spiraliform scanning traces, and an array of 20 superconducting transition-edge sensors (TES) operated at a temperature of 450-650 mK. The TES are cooled by a closed-cycle cooling system and read out by superconducting quantum interference devices (SQUIDs). The frequency band of operation centers around 350 GHz. The camera can operate at an object distance of 7-10 m. At 9m distance it covers a field of view of 110 cm diameter, achieves a spatial resolution of 2 cm and a pixel NETD (noise equivalent temperature difference) of 0.1-0.4 K. The maximum frame rate is 10 frames per second.

As reported before,1, 2 Safe VISITOR (Safe VISible, Infrared and Terahertz Object recognition) is a German project to build a passive security camera which visualizes sub-mm wavelengths using cooled bolometer arrays. This camera could be used for a variety of application scenarios, such as airport screenings or to protect military camps. In all cases, a practical instrument requires ease of use, in particular a flexible installation and a straightforward usage by the security personnel. Here we present a new generation of Safe VISITOR designed to meet these requirements. The main condition for an effective operation is a high frame rate of the imager. Safe VISITOR is able to record videos up to 10 Hz, using a small array of superconducting bolometers in combination with an opto-mechanical scanner. The required cooling of the detector array is provided by a commercial pulse tube cooler with a second, self-contained cooling stage. The cooling cycle is completely automated; after 10 hours of initial cooling from room temperature the system can operate quasi-continuously. For imaging, a 50 cm diameter optics is used which is able to provide an object resolution of approximately 1.5 cm at 8 m distance. For a flexible installation, the object distance can be tuned manually between 7 and 10 m. Additionally, video streams from two commercial cameras are fused with the sub-mm stream: a CCD for visible light and a microbolometer for far infrared (14 μm). This combines the ability of identification of the person under test with the unprecedented temperature resolution at infrared and the almost perfect transmission at sub-mm. To assist a security official, all image data are displayed in various graphic renditions by a unified system software.

Summary A new generation of High Temperature Superconductive QUantum Interference Detector (HTS SQUID) systems, with an improved ac bias scheme, achieves very low noise even at low frequencies. Based on that technology, robust and reliable systems for measuring TEM under sub-arctic conditions have been developed. Case studies, measured with these systems, will be reported by Woods at 80 th annual SEG meeting 2010.

Due to its high molecular specificity, Raman spectroscopy is a well-established analytical tool. Usually the inelastically scattered Raman light is spectrally dispersed by a spectrometer. Here, we present an alternative method, using an optical fiber as dispersive element. As the group velocity within the fiber is wavelength-dependent, different Raman bands arrive at different times at the detector. In combination with time-correlated single-photon counting, Raman spectra can be measured in the time domain. As detector we implemented a Superconducting Nanowire Single-Photon Detector (SNSPD), which possesses a timing accuracy of about 20 ps. Within this contribution we show first results of Raman spectra measured in the time domain using gradient index fibers of varying length.

We present a novel concept to trim the transmission properties of finite two dimensional photonic crystal slab waveguide structures by UV photobleaching. Systematic fabrication inaccuracies may be compensated due to the shift of the spectral properties during the bleaching process. To prove our concept experimentally, we measured the transmission of UV sensitive photonic crystal structures for different doses. A shift of band edges and defect resonance peaks depending on UV dose is observed due to changes in refractive index and geometry.

We present a novel concept to trim the transmission properties of finite two dimensional photonic crystal slab waveguide structures by UV photobleaching. Systematic fabrication inaccuracies may be compensated due to the shift of the spectral properties during the bleaching process. To prove our concept experimentally, we measured the transmission of UV sensitive photonic crystal structures for different doses. A shift of band edges and defect resonance peaks depending on UV dose is observed due to changes in refractive index and geometry.

We analyzed the dc SQUID with voltage feedback circuit (VFC) and a low-noise roomtemperature preamplifier to evaluate the feasibility of a low-noise SQUID direct-coupled readout scheme (DRS), possibly eliminating the need for a two-stage scheme employing a SQUID preamplifier. The passive VFC, connected in parallel to the SQUID, consists of a resistor Rs in series with an inductor Ls. This inductor is coupled to the SQUID by a mutual inductance Ms .T he purpose of the VFC is to increase the SQUID’s flux-to-voltage transfer coefficient ∂V/∂Φ ,t hus reducing the preamplifier noise contribution δΦpreamp. However, at the same time, VFC introduces the thermal noise of Rs, δΦR, which may not be negligible. Generally, the noise of the readout scheme, δΦreadout, may thus include both δΦpreamp and δΦR ,i .e.,δΦreadout = δΦpreamp + δΦR . To characterize the SQUID operation with VFC we introduced two dimensionless parameters, r=Rs/Rd and Δ=(Ms/Mdyn)�(Rs/Rd), where Rd and Mdyn=1/(∂i/∂Φ) are dynamic properties of the SQUID itself. For assumed intrinsic SQUID parameters, we then numerically analyzed the dependence of δΦreadout noise components on r and Δ to determine their suitable ranges and the minimum of δΦreadout. To verify our analysis, we experimentally characterized, in liquid helium, three niobium SQUIDs with VFC, having suitably chosen r and Δ. The measured SQUID system flux noise was on the order of 1 μΦ0/√Hz, comparable to the intrinsic noise of the SQUID itself. The deduced equivalent voltage noise was comparable to that of a SQUID preamplifier in the twostage readout. Simple single-stage ultra-low-noise SQUID DRS readout was thus demonstrated.

In Europe, the FLUXONICS Foundry develops fabrication processes and design kits for superconductor digital and mixed-signal circuits. We describe the implementation of the “European Roadmap for Superconductor Electronics” into the recent foundry process for superconductor digital electronics. Following the hierarchical cell-based design strategy, we developed a design kit with basic cells. We present experimental results of the process quality, the verified operation margins of the library cells, and the results of low- and high-speed investigations of test circuits. The process is suitable for the integration of complex digital and mixed-signal circuits for smart multichannel superconductor sensor applications with a digital interface.

We present a concept for a time-tagged multiplexed readout of several superconducting nanowire single-photon detector elements for small arrays in ultra-short pulsed laser applications. The detector elements were coupled in an array by a superconducting delay line giving each detector element a temporal signature. The complete detector chain is biased by one bias supply. The patterning concept and the first experimental proof of principle are demonstrated on two-detector element arrays with delay times of 86 and 156 ps each made from a 5-nm NbN film on sapphire. We discuss the propagation delay of a delay line taking the geometric and kinetic inductance into account. We show that mainly the normal conducting propagation velocity defines the characteristic time of the delay line and that the inductance dependent response pulse width currently limits the maximum number of detector elements.

We report on fast terahertz detectors based on antenna-coupled BiSb/Sb thermoelements operating at room temperature. A response time of the thermocouples as low as 22 μs and a noise equivalent power of 170 pW/Hz at 1 kHz modulation frequency is measured in air at room temperature. The integration capability of these mass producible devices enables large-scale detector arrays for real-time terahertz imaging applications. Due to the fast response time, multiplexing of the detectors can be used to reduce the required readout circuits.

A planar superconducting quantum interference device (SQUID) magnetometer consisting of a parallel gradiometer SQUID with integrated input coils connected to an on-chip pickup loop was designed and fabricated in conventional niobium technology. SQUID bootstrap circuitry (SBC) incorporating suitable current and voltage feedbacks was also integrated into the design. For a SQUID inductance of Ls = 350 pH and a chip size of 5 × 5 mm2, the field resolution of the voltage-biased SQUID magnetometer reached

Against a background of newly emerged security threats, the well-established idea of utilizing submillimeter-wave radiation for personal security screening applications has recently evolved into a promising technology. Possible application scenarios demand sensitive, fast, flexible and high-quality imaging techniques. At present, best results are obtained by passive imaging using cryogenic microbolometers as radiation detectors. Building upon the concept of a passive submillimeter-wave stand-off video camera introduced previously, we present the evolution of this concept into a practical application-ready imaging device. This has been achieved using a variety of measures such as optimizing the detector parameters, improving the scanning mechanism, increasing the sampling speed, and enhancing the image generation software. The camera concept is based on a Cassegrain-type mirror optics, an optomechanical scanner, an array of 20 superconducting transition-edge sensors operated at a temperature of 450 to 650 mK, and a closed-cycle cryogen-free cooling system. The main figures of the system include: a frequency band of 350±40 GHz, an object distance of 7 to 10 m, a circular field of view of 1.05 m diameter, and a spatial resolution in the image center of 2 cm at 8.5 m distance, a noise equivalent temperature difference of 0.1 to 0.4 K, and a maximum frame rate of 10 Hz.

International audience; Thermal radiation sensors are based on two signal transduction stages: radiation to thermal and thermal to electrical. The most common of these sensors are the radiation thermocouple using the Seebeck effect and the bolometer applying the thermoresistive effect. While the bolometer requires a bias current for signal generation the thermocouple is generally operated unbiased. The paper theoretically investigates a biased thermocouple instead, which can be thought of as a combination of both thermal radiation sensor types. Its responsivity and detectivity is calculated based on previous theories of the performance of bolometers and radiation thermocouples, respectively, thereby including the Peltier effect. The electrical resistance and thermal conductance of the thermocouple as input parameters for these calculations are modeled using a simple strip geometry to facilitate one-dimensional analytical electrothermal modeling.