Submillimeter Wave Detection Research Articles

High Performance Heterostructure Low Barrier Diodes for Sub-THz Detection

Heterostructure low barrier diodes (HLBD) based on lattice-matched AlGaInAs triangular barrier have been designed, fabricated, and characterized for zero-bias millimeter-wave and submillimeter-wave detection. Detectors with different barrier height and various active areas have been measured in order to determine the best structure for low-level radiometric detection. Unmatched responsivity of 1500-2000 V/W have been measured around 100 GHz with a video resistance of 400 to 800 Ω. Thanks to these low-impedances high-matched responsivity of 6000 and 5200 V/W have been demonstrated around 90 and 180 GHz, respectively, with a bandwidth of 25 GHz. Avery low noise equivalent power of about 0.6 and 0.7 pW/,/Hz have been deduced at 90 and 180 GHz, respectively. We show also that the dynamic range of these detectors is more than six decades. This performance makes the HLBD an interesting device for low-level sub-THz detection applications.

Modeling and Measuring the Optical Coupling of Lumped Element Kinetic Inductance Detectors at 120–180 GHz

The lumped element kinetic inductance detector (LEKID) is a novel device for high-sensitivity millimeter and submillimeter wave detection. Optimization of this cryogenic device requires the matching of the freespace impedance to the impedance of the absorbing structure defined by an inductance meander. Here we show how this coupling can be modeled and measured using a transmission line model, numerical simulations, and practical quasi-optical room-temperature reflection measurements. Simulations and measurements agree well and allow us to design optimized devices with remarkably high power absorption.

Modeling of Sb‐heterostructure backward diode for millimeter‐ and submillimeter‐wave detection

AbstractWe present modeling of Sb‐heterostructure backward tunneling diode (Sb‐HBD) for high efficient millimeter‐ and submillimeter wave detection. The diode heterostructure is modeled and optimized using TCAD software implementing a non‐local band‐to‐band tunneling model combining with the standard drift‐diffusion model. The physical device model was found to be in good agreement with reported experimental results. InAsSb/AlSb/AlGaSb structures were proposed and simulated considering the material growth. The potential of the Sb‐HBDs for high frequency operation applications is investigated. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Novel Tunable Millimeter-Wave Grating-Gated Plasmonic Detectors

We present the development of tunable, narrow-band plasmonic millimeter wave detectors. The current generation of this class of detector monolithically integrates a 2-D plasmonic absorber and a bolometric sensor in a GaAs/AlGaAs HEMT located at the vertex of a broad-band antenna. Response and transport measurements demonstrate absorption by high-order plasmon modes sensed by the integrated bolometer and with a two order of magnitude improvement in sensitivity and noise equivalent power over prior generations of 2-D plasmonic detectors. We compare these recent results with the state of the art in millimeter and submillimeter wave-detection technology.

Simulation Results on Submillimeter Wave Detection by Josephson Fluxonic Diode and a Method to Address Its Focal Plane Array

Application of radiation to a reverse-biased Josephson fluxonic diode (JFD) creates vortex-antivortex pairs. Pairs are created at each peak of sinusoidal radiation and move under the application of the bias current, exhibiting a voltage which depends on the frequency of incoming radiation. Simulation results for frequencies ranging from 50 to 700 GHz have been obtained. A simple and practical addressing scheme is proposed for a matrix of JFD pixels. Ease of fabrication, inherent gain, simultaneous determination of amplitude and frequency of radiation, large output current, and simple addressability in focal plane arrays are among the advantages of JFD as a direct submillimeter wave detector

SEMICONDUCTOR-SUPERLATTICE FREQUENCY MIXER FOR DETECTION OF SUBMILLIMETER WAVES

We report on a GaAs/AlAs superlattice frequency mixer for detection of submillimeter waves. The mixer is based on the nonlinear miniband transport giving rise to domains excited under the action of a microwave field. We designed the mixer for broadband operation (300–600 GHz). For studying basic properties, we investigated the mixer as a harmonic mixer in 15th order to detect radiation at a radio frequency (RF) near 300 GHz using local oscillator (LO) radiation of a frequency near 20 GHz. We reached a noise equivalent power (NEP) of about 10 fW/Hz. We also show that the use of the superlattice mixer together with a superlattice frequency multiplier allows to realize a superlattice-based free-space transmission line for submillimeter waves.

First Detection of Millimeter/Submillimeter Extragalactic H 2 O Maser Emission

We report the first detection of an extragalactic millimeter wavelength H2O maser at 183 GHz towards NGC 3079 using the Submillimeter Array (SMA), and a tentative submillimeter wave detection of the 439 GHz maser towards the same source using the James Clerk Maxwell Telescope (JCMT). These H2O transitions are known to exhibit maser emission in star-forming regions and evolved stars. NGC 3079 is a well-studied nuclear H2O maser source at 22 GHz with a time-variable peak flux density in the range 3 -- 12 Jy. The 183 GHz H2O maser emission, with peak flux density $\sim$0.5 Jy (7$\sigma$ detection), also originates from the nuclear region of NGC 3079 and is spatially coincident with the dust continuum peak at 193 GHz (53 mJy integrated). Peak emission at both 183 and 439 GHz occurs in the same range of velocity as that covered by the 22 GHz spectrum. We estimate the gas to dust ratio of the nucleus of NGC 3079 to be $\approx$150, comparable to the Galactic value of 160. Discovery of maser emission in an active galactic nucleus beyond the long-known 22 GHz transition opens the possibility of future position-resolved radiative transfer modeling of accretion disks and outflows $<1$ pc from massive black holes.

Nb-based superconducting tunnel junctions as submillimeter-wave direct detectors

Employing an anodization method into our fabrication process, we have successfully fabricated STJs with size of 4 /spl mu/m in diameter, Josephson critical current density of 1000 A/cm/sup 2/, low leakage current of less than 10 pA at 0.3 K and high fabrication yield of more than 90 percent. These STJs were applied to fabricate submillimeter-wave direct detectors using 12 linearly distributed junctions, each circular junction having a current density of 600 A/cm/sup 2/ and size of 4 /spl mu/m in diameter. Direct detection of submillimeter-waves was measured using a Fourier transform spectrometer, which shows a maximum sensitivity at 440 GHz and a fractional bandwidth of 10 percent.

Low noise Nb-based SIS mixer for sub-millimeter wave detection

The Nb-based SIS junction fabrication was started in 1996. The main goals of this project are to establish the capability of high quality SIS junction technology in Taiwan and to fabricate SIS mixer for sub-millimeter wave detection. In the past few years, we have integrated the fabricating facility and processing steps. The self-alignment method was used for junction definition process. The junction size is close to 1 μm in order to minimize its intrinsic capacitance. The critical current density is required to be ≧7.5 kA/cm 2 to get a reasonable ωR n C product of the mixer. The high quality SIS junction was demonstrated from its I–V characteristics. We also fabricated 230 and 350 GHz SIS mixers. The performance test of the mixer shows a low noise temperature level. The details of the mixer fabrication process and performance test will be described in this paper.

SIS receivers for millimeter and submillimeter-wave detection

In this work we report the current status in our development of sensitive heterodyne detectors for efficient down-conversion of submillimeter-wave signals to D-band. These detectors use the strong non-linearity of Nb/Al-AlO/sub x//Nb tunnel junctions and employ preferably quasi-optical techniques to couple local-oscillator and radio-frequency signals to the superconducting junctions via a log-periodic antenna and hyper-hemispherical lens combination. Several devices have been fabricated and tested.

Submillimeter wave detection with high temperature superconducting bolometers

We have fabricated and characterized a planar antenna-coupled microbolometer working at the resistive transition edge of a HT c superconducting film for use as a submillimeter wave detector. A log-periodic antenna was used to couple the incoming radiation to a YBaCuO thin film microbridge. The performance of the antenna and the bolometer response were obtained by using a 119 μm H 2 O laser source. Both the radiation pattern directivity and the detector responsivity were clearly improved by irradiating the antenna from the dielectric substrate side by means of a hyper-hemispherical silicon lens.

YBa 2Cu 3O 7− x thin-film Josephson junctions on 2 × 12° bicrystal (110) NdGaO 3 substrates

Grain-boundary YBa 2Cu 3O 7− x Josephson junctions with normal-state resistances from 0.1 to 10 Ω were fabricated on (110) NdGaO 3 bicrystal substrates with a misorientation angle of 2 × 12°. Electrical imaging of the junctions in the temperature range 80 K–300 K was performed by a technique based on laser scanning microscopy. The average values of the electrical transport parameters of the fabricated junctions were shown to be comparable to those of reference junctions made on (100) SrTiO 3 bicrystals. Values of the Josephson linewidth as low as 1 GHz at 77 K have been obtained from the response of the junctions to low-intensity 94 GHz electromagnetic radiation. When high-intensity 94 GHz radiation was applied to the junctions, current steps appeared in the I–V curves at voltages V n = n hf/2 e up to 6.5 mV. These results demonstrate the applicability of YBa 2Cu 3O 7− x grain-boundary junctions made on NdGaO 3 bicrystal substrates for millimeter- and submillimeter-wave detection.

Quantum limited heterodyne detection in superconducting non-linear transmission lines at sub-millimeter wavelengths

A non-linear superconducting transmission line has been successfully employed in heterodyne detection of sub-millimeter waves. In our experiments an Nb/Al/AlOx/Nb tunnel junction, measuring 0.15×40 μm, with a critical current density of about 2500 A/cm2 is used as a distributed mixer element. We have demonstrated that quantum limited sensitivity can be achieved with this type of device. At 460 GHz, a Y-factor of 2.5 has been recorded, corresponding to a double-side-band receiver noise temperature of 80 K. The double-side-band conversion loss is about 1 dB and the mixer noise temperature is estimated to be 18(±10) K.

All-Nb thin film microbridge-type Josephson junction for submillimeter-wave detection

A copolymer of methyl methacrylate (MMA) and 3-triethoxysilylpropyl methacrylate (ESPMA) was proposed as a positive-working electron beam (EB) resist of a new type. It was found that it had 4–10 times the resistance of polymethylmethacrylate (PMMA) against CBrF 3 plasma damage. The mechanism of etching Nb in reactive-ion-etching (RIE) was deciphered. Using the new EB resist and nanometer process technology, an all-Nb thin film microbridge was fabricated. It shows the a.c. Josephson effect, i.e. the Shapiro steps upto the 11th were observed under millimeter-wave (70 GHz) radiation. In addition the coherently working performance of the series array of these thin-film microbridges were observed definitively.

Submillimeter-wave detection with superconducting tunnel diodes

The review presents a theoretical framework for understanding submillimeter detection using an optical photodiode theory. Both gain and noise in the superconductor-insulator-superconductor (SIS) mixer are described in terms of mixing on a photodiode. The role of impedance matching in the proper design of an SIS mixer is described. A variety of methods for achieving good impedance match at submillimeter frequencies are presented. The state of the submillimeter SIS mixer art as practiced in a variety of laboratories is described and summarized.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Millimeter and sub-millimeter wave detection of hydrogen peroxide

The measurement of small concentrations of hydrogen peroxide through the detection of rotational transitions in the millimeter and sub-millimeter wave regions is discussed. Calculated transition frequencies and absorption coefficients of H 2O 2 for frequencies up to 2000 GHz are presented. The reliability of the calculated values is illustrated by measurements of the linewidths and absorption coefficients of transitions in the 140 GHz range. Finally, methods for the detection of trace quantities of the peroxide molecule are briefly described.

Submillimeter wave detector workshop

A brief report on the results of a workshop concerning submillimeter wave detection held September 34, 1985.

Millimeter and submillimeter wave detection and mixing with superconducting weak links

A weak link between two bulk superconductors can exhibit Josephson effects and can be used as a fast sensitive detector or mixer for electromagnetic radiation. Emphasis is placed on the millimeter and submillimeter range where such applications are potentially most important, though such devices should also work well at lower frequencies. The peculiar properties of the weak link make possible a variety of modes of operation including one in which it is both local oscillator and mixer. These modes of operation are analyzed and the pivotal experiments are reviewed. Noise and impedance matching are considered and comparison is made with other types of detectors of millimeter and submillimeter waves.

Millimeter- and submillimeter-wave detection by paramagnetic materials

A scheme for detecting millimeter- and submillimeter-wave radiation by utilizing a paramagnetic material is described. An analysis of the scheme, which indicates the dependence of the noise-equivalent power on various parameters is given. Experimental results obtained at 35 and 50 GHz are presented. The scheme can be extended to higher frequencies by choosing the proper material and coupling structure.