Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session Y15: Detectors, Sensors, and Transducers |
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Sponsoring Units: GIMS Chair: Sander Otte, National Institute of Standards and Technology Room: B114 |
Friday, March 19, 2010 8:00AM - 8:12AM |
Y15.00001: Table-top Femtosecond Ultra Fast Time Resolvable ARPES Facility at LANL Yinwan Li, Georgi Dakovski, Tomasz Durakiewicz, George Rodriguez, Kevin Graham A table-top ultra fast time resolved ARPES facility with time resolution of tens of femtoseconds is being constructed at Los Alamos National Laboratory. The system enables pump-probe scheme measurement with pump photon beam at low energy laser pulses and high energy probe photon beam obtained by higher harmonic generation (HHG). The pump-probe scheme enables the extension of the ARPES technique to measure the unoccupied states. The tunability of time-difference between probe pulse and pump pulse can be used in the dynamics study of the solids by measuring the decay of the excited states. In this presentation, I will introduce the principle of the technique and the current stage of the system at LANL. [Preview Abstract] |
Friday, March 19, 2010 8:12AM - 8:24AM |
Y15.00002: A Microfocus Beamline for Angle-Resolved Photoemission at the SRC T. Miller, T.-C. Chiang, M. Bissen, M. Fisher, H. Hoechst, S. Janowski, R. Reininger, G. Rogers, M. Severson, J. Bisognano The development and construction of an angle-resolved photoemission (ARPES) system with a small beam focus is underway at the Synchrotron Radiation Center (SRC) in Stoughton, WI. It is expected that this facility will extend the demonstrated utility of ARPES to samples that are inhomogeneous on a micron scale, as may be commonly encountered in modern solid-state research. This facility is being implemented by modifying a branch line of an existing beamline, the Plane-Grating-Monochromator (PGM-B), and one of the SRC Scienta endstations. To achieve a microfocus, a diverting mirror bypasses the existing refocussing mirror, directing the light towards a final Schwarzschild optic. The final optic provides a 50:1 demagnified image at the sample of the PGM-B exit slit and horizontal apertures, producing an adjustable focus of micron or submicron dimensions. The original PGM-B focus can be restored at the same point on the sample as the microfocus by moving the diverting and Schwarzschild mirrors out of the beam path without breaking vacuum. Provision will be made for selecting into the optical path different Schwarzschild optics optimized for different photon energy ranges. In this talk, the system and progress in its development will be described. [Preview Abstract] |
Friday, March 19, 2010 8:24AM - 8:36AM |
Y15.00003: Resolution of 5.4 nm from a Photoemission Electron Microscope Corrected with an Electrostatic Mirror R.C. Word, G.F. Rempfer, L. Almaraz, T. Dixon, R. Konenkamp We report resolution of 5.4 +/- 0.5 nm for a photoemission electron microscope (PEEM) that employs an electrostatic mirror that simultaneously corrects chromatic and spherical aberration. This is a marked improvement over the 8 to 10nm resolution obtained by uncorrected PEEMs, which suffer particularly from chromatic aberration resulting from the acceleration of low energy photoelectrons from the specimen surface. The resolution was obtained in a biological application using sarcoplasmic reticulum from skeletal muscle as a specimen. The sample was deposited on a low photoemission substrate of chromium-coated glass and illuminated with UV light from a 100-mW 244-nm Ar laser. Resolution was determined using the 0.1 to 0.9 contrast change in intensity line profiles as well as by a 2-dimensional Fast Fourier Transform method. The PEEM employs a Y-branched beam separator, three deflection magnets, and twelve electrostatic lenses all heavily filtered to suppress voltage instabilities. Spherical and chromatic aberration coefficients were determined by computer modeling and in-situ experiments to be 1 cm. Once the instrument is perfected, the resolution should be 2 nm. [Preview Abstract] |
Friday, March 19, 2010 8:36AM - 8:48AM |
Y15.00004: NIR spectrometer based on frequency up-conversion technology Lijun Ma, Oliver Slattery, Xiao Tang Due to high noise and low sensitivity of single photon detectors in near the infrared (NIR) range, the performance of NIR spectrometers is limited in comparison to that in visible region. We have implemented a NIR spectrometer based on a frequency up-conversion detector. This detector uses a periodically poled lithium niobate waveguide to convert signal photons at 1310 nm to 710 nm by using a pump laser around 1550 nm. The converted photons at 710 nm are then detected by a silicon-based avalanche photodiode. According to energy conservation condition in the conversion process, tuning the pump wavelength allows us to trace out the spectrum of the signal. We further developed a polarization independent NIR spectrometer with two up-conversion detectors and a polarizing beam splitter. The sensitivity of the spectrometer is better than -120 dBm, which is at least three orders-of-magnitude higher than that of any commercial optical spectrum analyzer in this range. The spectrometer can not only measure polarization-independent spectra, but also provide spectral components for two orthogonal polarization orientations. In this talk, we describe the NIR spectrometer based on frequency up-conversion detectors, and experimentally study its detection efficiency, sensitivity, resolution and its dynamic operation range. [Preview Abstract] |
Friday, March 19, 2010 8:48AM - 9:00AM |
Y15.00005: Single Photon Avalanche Diodes with high-speed sub nanosecond periodic gating Alessandro Restelli, Joshua C. Bienfang, Charles W. Clark InGaAs/InP single-photon avalanche diodes (SPADs) are good candidates for single-photon detection in the near infrared range. Compared with their visible-range silicon counterparts however, their performance is limited by strong afterpulsing, which requires a significant recovery time after each detection event, reducing the maximum allowable count rate. Recent experimental work has shown that minimizing the avalanche current by gating the devices with sub-nanosecond bias pulses can allow InGaAs/InP SPADs to operate at higher repetition rates, albeit with lower detection efficiency. Multiple techniques have been used to extract the extremely weak avalanche signals from the large transient signals imposed by the gating pulses themselves. In this work we make a quantitative comparison of a variety of these avalanche-discrimination techniques by implementing them with a single InGaAs/InP SPAD in the sub-nanosecond gating regime and present results for detection efficiency, dark count probability, and afterpulsing probability. [Preview Abstract] |
Friday, March 19, 2010 9:00AM - 9:12AM |
Y15.00006: Photonic Crystal Spectrometer Nadia Pervez, Warren Cheng, Zhang Jia, Marshall Cox, Hassan Edrees, Ioannis Kymissis We have demonstrated a new kind of optical spectrometer employing photonic crystal patterns to selectively outcouple waveguided light from a transparent substrate. This photonic crystal spectrometer functions in a way fundamentally different from other spectrometers in that device size and resolution are decoupled. The system we present would be extremely inexpensive to manufacture, creating the potential for expansion of the spectrometer market. Our device consists of an array of photonic crystal patterns nanofabricated in a polymer on a glass substrate combined with an inexpensive camera. The camera captures an image of the light outcoupled from the patterned substrate; the array of patterns produces a spatially resolved map of intensities for different wavelength bands. The intensity map in the image is converted into a spectrum using the pattern response functions. We present a proof of concept by characterizing a white LED with our photonic crystal spectrometer. [Preview Abstract] |
Friday, March 19, 2010 9:12AM - 9:24AM |
Y15.00007: Single-shot time-resolved THz spectroscopy using non-collinear electro-optic imaging Zhenyou Wang, Fuhai Su, Frank A. Hegmann We demonstrate a technique for rapid substance identification via single-shot, coherent THz imaging using non-collinear electro-optic sampling. A THz probe pulse generated in ZnTe is transmitted through the sample then focused on a (110) ZnTe detection crystal. An 800nm, 100fs optical pulse employed as a sampling beam passes through the ZnTe detection crystal at an angle of 7$^{\circ}$ relative to the THz beam.\footnote{T. Yasuda et al., Opt. Commun. 267, 128 (2006)} The THz field induced birefringence is resolved as a variation of the intensity of the sampling pulse transmitted through a crossed polarizer. The modified sampling beam spot is imaged using a CCD camera. Because of the non-collinear geometry, the spatial overlap between the THz field and the optical pulse depends on the temporal position within the THz waveform. Consequently, we obtain high-resolution 2D images of the THz waveform without scanning the relative path length. The resolution of the absorption spectra extracted from wet paper and lactose using the single-shot imaging approach is comparable to the resolution obtained through conventional scanning lock-in measurements. Possible applications for substance detection are discussed. [Preview Abstract] |
Friday, March 19, 2010 9:24AM - 9:36AM |
Y15.00008: Novel Antenna Coupled 2D Plasmonic Terahertz Detection Greg Dyer, Greg Aizin, Eric Shaner, Mke Wanke, John Reno, S. James Allen Resonant plasmonic detectors are potentially important for terahertz (THz) spectroscopic imaging. We have fabricated and characterized antenna coupled detectors that integrate a broad-band antenna, which improves coupling of THz radiation. The vertex of the antenna contains the tuning gates and the bolometric barrier gate.$^{1-3}$ Incident THz radiation may excite 2D plasmons with wave-vectors defined by either a periodic grating gate or a plasmonic cavity determined by ohmic contacts and gate terminals. The latter approach of exciting plasmons in a cavity defined by a short micron-scale channel appears most promising. With this short-channel geometry, we have observed multiple harmonics of THz plasmons. At 20 K with detector bias optimized we report responsivity on resonance of 2.5 kV/W and an NEP of 5 x 10$^{-10}$ W/Hz$^{1/2}$. This work is supported through NSF NIRT Grant No. ECS0609146, and in collaboration with Sandia, a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. $^{1}$E.A. Shaner, et al., Appl. Phys. Lett. \textbf{90}, 181127 (2007). $^{2}$G. Dyer, et al., J. Phys. Con. Mat., \textbf{21, }195803 (2009). $^{3}$V. Ryzhii, et al., J. Appl. Phys. \textbf{103}, 014504 (2008). [Preview Abstract] |
Friday, March 19, 2010 9:36AM - 9:48AM |
Y15.00009: Photo-assisted Shot Noise as universal photon detectors Christian Glattli, Yodchay Jompol, Ivana Petkovic, Fabien Portier, Patrice Roche Photon assisted shot noise (PASN) is a universal phenomenon occurring in all mesoscopic conductors. It has been observed in diffusive metallic thin films [1] and in Quantum Point Contacts (QPCs) realized in 2D electron gas [2] at temperature $<$ 1 K for frequencies up to 20GHz. We propose to exploit PASN to realize radiation detectors working at temperature $>$ 4K and frequencies up to tens of THz. PASN originates from the creation of electron-hole pairs of energy $h\nu $ when an ac voltage $V_{ac} $ at frequency $\nu $is applied on a contact of a mesoscopic conductor. The electron-hole pairs are then dissociated by random scattering in the conductor. This generates a low frequency current shot noise $S_I =4h\nu \,J_1 (eV_{ac} /h\nu )^2\,G\,F$, with $F$ the ordinary shot noise Fano factor, $G$ the conductance and $J_1 $ a Bessel function. This relation being independent of material or geometrical details and free from unknown parameters, PASN radiation detectors are expected robust and universal for radiation metrology. Possible conductors are tunnel junctions, Graphene, doped semi-conductors, QPCs, etc., for a wide range of temperatures $<$1K to $\sim $100K and frequencies GHz to 10 THz. [1] Kozhevnikov et al. PRL \textbf{84},3398(2000). [2] Reydellet et al. PRL \textbf{90},176803(2003). [Preview Abstract] |
Friday, March 19, 2010 9:48AM - 10:00AM |
Y15.00010: ABSTRACT WITHDRAWN |
Friday, March 19, 2010 10:00AM - 10:12AM |
Y15.00011: A resistance thermometer for the low millikelvin temperatures Nodar Samkharadze, Ashwani Kumar, Gabor Csathy Resistance thermometers, while being easy to use, are known be unreliable below a few tens of mK. It is thought that unintentionally applied power coming from a ground loop or radio frequency signals reaching the thermometer will heat up the sensing element or cause temporal fluctuations in the temperature and hence the resistance. We built a thermometer based on a carbon composition resistor that has an unusually good thermal contact with its environment, which makes it immune to heating by spurious power. Therefore we think that it will be useful for routine resistive thermometry below 10mK. In addition our thermometer has a few other desirable properties: it can be used to measure from a few millikelvin all the way to room temperature and the carbon resistor sensor is commercially available. [Preview Abstract] |
Friday, March 19, 2010 10:12AM - 10:24AM |
Y15.00012: Advantages of synchronized lock-in amplifiers in experiments Andreas Rydh The lock-in amplifier is a versatile instrument in many disciplines of physics, due to its ability to resolve small AC signals of given frequency and phase with high resolution. A modern, digital lock-in amplifier digitizes the signal before demodulation and further processing and is thus little more than a data acquisition unit (ADC) and a computer. With the availability of powerful signal processors such as DSPs and field-programmable gate arrays (FPGAs), the potential of the lock-in technique has broadened. Several frequency components of a signal could for instance be studied simultaneously. Combining several ADCs in one instrument rather than having separate lock-in amplifiers is especially advantageous. We have developed such a lock-in amplifier with eight simultaneous-sampling inputs connected to an FPGA. With synchronized channels, the time resolution is increased, making it possible to study time-dependent signals and their correlation. This makes the signal source stability less critical and further improves the signal to noise ratio. Examples of experimental use include transport measurements, low-temperature thermometry and frequency characterization. [Preview Abstract] |
Friday, March 19, 2010 10:24AM - 10:36AM |
Y15.00013: ABSTRACT WITHDRAWN |
Friday, March 19, 2010 10:36AM - 10:48AM |
Y15.00014: Precision Non-Contact Dynamic Measurement of Casimir Force between a Metallic Sphere and Semiconducor Plate Chia-Cheng Chang, Umar Mohideen A dynamic measurement of the Casimir force between a gold coated sphere and Si plate performed by using a high vacuum based short coherence light source interferometer will be presented. The comparison of results with Lifshitz theory will be discussed. The results will find application in the design of MEMS (Micro Electro-Mechanical Systems). [Preview Abstract] |
Friday, March 19, 2010 10:48AM - 11:00AM |
Y15.00015: Millimeter-Wave Transmittance and Reflectance Measurement on Pure and Diluted Carbonyl Iron Konstantin Korolev, Shu Chen, Zijing Li, Mohammed Afsar Transmittance and reflectance measurements on highly absorbing carbonyl iron materials over a broad millimeter-wave frequency range have been performed. Frequency dependence of the complex dielectric permittivity of carbonyl iron diluted composite and pure powdered materials have been determined in the millimeter waves for the first time. The measurements have been employed using a free-space quasi-optical millimeter-wave spectrometer equipped with a set of high power backward wave oscillators as sources of coherent radiation, tunable in the range from 30 -- 120 GHz. Significant transmission zone of the millimeter-wave radiation at frequency around 60 GHz has been observed in transmittance spectra for the carbonyl iron materials. [Preview Abstract] |
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