Mid-infrared n-Ge on Si Plasmonic Based Microbolometer Sensors

The detection and amplification of molecular absorption lines from a chemical weapons simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. A free-standing Si0.25Ge0.75 microbolometer detector with n-Ge plasmonic antenna is demonstrated as an integrated mid-infrared plasmonic sensor

Design of the Front End Electronics for the Infrared Camera of JEM-EUSO, and manufacturing and verification of the prototype model

The Japanese Experiment Module (JEM) Extreme Universe Space Observatory (EUSO) will be launched and attached to the Japanese module of the International Space Station (ISS). Its aim is to observe UV photon tracks produced by ultra-high energy cosmic rays developing in the atmosphere and producing extensive air showers. The key element of the instrument is a very wide-field, very fast, large-lense telescope that can detect extreme energy particles with energy above $10^{19}$ eV. The Atmospheric Monitoring System (AMS), comprising, among others, the Infrared Camera (IRCAM), which is the Spanish contribution, plays a fundamental role in the understanding of the atmospheric conditions in the Field of View (FoV) of the telescope. It is used to detect the temperature of clouds and to obtain the cloud coverage and cloud top altitude during the observation period of the JEM-EUSO main instrument. SENER is responsible for the preliminary design of the Front End Electronics (FEE) of the Infrared Camera, based on an uncooled microbolometer, and the manufacturing and verification of the prototype model. This paper describes the flight design drivers and key factors to achieve the target features, namely, detector biasing with electrical noise better than $100 \mu$V from $1$ Hz to $10$ MHz, temperature control of the microbolometer, from $10^{\circ}$C to $40^{\circ}$C with stability better than $10$ mK over $4.8$ hours, low noise high bandwidth amplifier adaptation of the microbolometer output to differential input before analog to digital conversion, housekeeping generation, microbolometer control, and image accumulation for noise reduction

Calculation of thermal parameters of SiGe microbolometers

The thermal parameters of a SiGe microbolometer were calculated using numerical modeling. The calculated thermal conduction and thermal response time are in good agreement with the values found experimentally and range between 2x10$^-7$ and 7x10$^-8$ W/K and 1.5 and 4.5 ms, respectively. High sensitivity of microbolometer is achieved due to optimization of the thermal response time and thermal conduction by fitting the geometry of supporting heat-removing legs or by selection of a suitable material providing boundary thermal resistance higher than 8x10$^-3$ cm$^2$K/W at the SiGe interface.Comment: 11 pages, 6 figure

Metal silicide/poly-Si Schottky diodes for uncooled microbolometers

Nickel silicide Schottky diodes formed on polycrystalline Si films are proposed as temperature sensors of monolithic uncooled microbolometer IR focal plane arrays. Structure and composition of nickel silicide/polycrystalline silicon films synthesized in a low-temperature process are examined by means of transmission electron microscopy. The Ni silicide is identified as multi-phase compound composed by 20 to 40% of Ni3Si, 30 to 60% of Ni2Si and 10 to 30% of NiSi with probable minor content of NiSi2 at the silicide/poly-Si interface. Rectification ratios of the Schottky diodes vary from ~100 to ~20 for the temperature increasing from 22 to 70C; they exceed 1000 at 80K. A barrier of ~0.95 eV is found to control the photovoltage spectra at room temperature. A set of barriers is observed in photo-emf spectra at 80K and attributed to the Ni-silicide/poly-Si interface. Absolute values of temperature coefficients of voltage and current are found to vary from 0.3 to 0.6%/K for forward biasing and around 2.5%/K for reverse biasing of the diodes.Comment: 18 pages, 7 figure

Spectral Spatial Fluctuations of CMBR: Strategy and Concept of the Experiment

Spectral Spatial Fluctuations (SSF) of the Cosmic Microwave Background Radiation (CMBR) temperature are considered as a result of an interaction of primordial atoms and molecules with CMBR in proto-objects moving with peculiar velocities relative to the CMBR. Expected optimistic values of $\Delta T/T$ are 2x10^{-5}--2x10^{-6}$for SSF caused by HeH$^+$at z =20-30 which are possible redshifts of early reionization scenario. The bandwidth of the lines is 0.1-2depending on the scale of proto-objects and redshifts. For the SSF search CMBR maps in different spectral channels are to be observed and then processed by the Difference method. Simulation of the experiment is made for MSRT (Tuorla Observatory, Finland) equipped with a 7x4 beam cryo-microbolometer array with a chopping flat and frequency multiplexer providing up to 7 spectral channels in each beam (88-100 GHz). Expected$\Delta $T/T limit in the experiment is 2x10$^{-5}$ with 6'-7' angular and 2% frequency resolution. Simulation shows that SSF may be recognized in the angular power spectrum when S/N in single frequency CMBR maps is as small as 1.17 or even something less for white noise. Such an experiment gives us a possibility to set upper limit of SSF in MM band and prepare future SSF observations.Comment: 26 pages, 6 figure

Association of mid-infrared solar plages with Calcium K line emissions and magnetic structures

Solar mid-IR observations in the 8-15 micrometer band continuum with moderate angular resolution (18 arcseconds) reveal the presence of bright structures surrounding sunspots. These plage-like features present good association with calcium CaII K1v plages and active region magnetograms. We describe a new optical setup with reflecting mirrors to produce solar images on the focal plane array of uncooled bolometers of a commercial camera preceded by germanium optics. First observations of a sunspot on September 11, 2006 show a mid-IR continuum plage exhibiting spatial distribution closely associated with CaII K1v line plage and magnetogram structures. The mid-IR continuum bright plage is about 140 K hotter than the neighboring photospheric regions, consistent with hot plasma confined by the magnetic spatial structures in and above the active regionComment: 5 pages, 4 figures. Accepted by PAS

CMOS Terahertz Metamaterial Based 64 × 64 Bolometric Detector Arrays

We present two terahertz detectors composed of microbolometer sensors (vanadium oxide and silicon pn diode) and metamaterial absorbers monolithically integrated into a complementary metal oxide semiconductor (CMOS) process. The metamaterial absorbers were created using the metal-dielectric-metal layers of a commercial CMOS technology resulting in low-cost terahertz detectors. The scalability of this technology was used to form a 64 × 64 pixel terahertz focal plane array

Air-bridge microbolometer for far-infrared detection

A new microbolometer for far-infrared detection has been fabricated that allows an increase in sensitivity of a factor of 4 over the best previously reported bolometer. By suspending the detector in the air above its substrate a reduction in the thermal conductance out of the device by a factor of 5 has been achieved. At a modulation frequency of 100 kHz this microbolometer has an electrical noise equivalent power of 2.8×10^−11 W(Hz)^−1/2. A thermal model is also presented that accurately fits the response of the detector

Single-cycle THz pulses with amplitudes exceeding 1 MV/cm generated by optical rectification in LiNbO3

Using the tilted-pulse-intensity-front scheme, we generate single-cycle terahertz (THz) pulses by optical rectification of femtosecond laser pulses in LiNbO3. In the THz generation setup, the condition that the image of the grating coincides with the tilted-optical-pulse front is fulfilled to obtain optimal THz beam characteristics and pump-to-THz conversion efficiency. The designed focusing geometry enables tight focus of the collimated THz beam with a spot size close to the diffraction limit, and the maximum THz electric field of 1.2 MV/cm is obtained