Integrated Front-End Radar Receivers at Ka-Band

This paper describes the Integrated Finline Front-end Radar Receivers at Ka-Band. The Front-receivers developed for Radar applications include combining of finline components on a single MIC substrate with various planar transmission lines. The integrated systems so developed have better noise figure and control over phase and gain imbalances as compared to discrete component systems. Two types of Integrated Front-ends Radar receivers are described here. The developed systems are highly compact and reliable.     

应用于塑料光纤通信接收芯片的集成光电探测器(英文)

基于0.5μm标准Biplor、互补金属氧化物半导体和双扩散金属氧化物工艺设计了两种不同结构不同尺寸的光电探测器,包括传统的P+/N-EPI/BN+结构光电探测器和多叉指P+/N-EPI/BN+结构的光电探测器.通过仿真优化设计了光电探测器的结构参量和性能,测试结果表明:多叉指状P+/NEPI/BN+光电探测器能够改善650nm的响应度以及降低结电容.选择该结构大面积P+/N-EPI/BN+光电探测器用于和跨阻放大器以及后端放大器的单片集成,采用0.5μm标准Biplor、互补金属氧化物半导体和双扩散金属氧化物工艺实现了一个用于650nm塑料光纤通信的单片集成光接收芯片.该光接收芯片的测试结果表明:对650nm的入射光,在160 Mb/s速率的伪随机二进制序列以及小于10-9的误码率条件下,光接收芯片的灵敏度为-15dBm,并能得到清晰的眼图.因此,本文设计的光电探测器可以很好地应用于宽带接入网中的高速塑料光纤通信系统的光接收芯片中.     

集成滤波器结构的可调超导微波谐振腔

在超导微波谐振腔耦合量子比特的杂化器件中,可利用超导材料动态电感随直流电流变化的特性,调节谐振腔的频率,进而匹配量子比特的频率.为抑制引入直流偏置电极导致的微波信号泄漏,在可调腔中加入滤波器是一种有效的方案.本研究以滤波器为切入点,运用计算机模拟,开发了原有“王”字型滤波器新的工作模式,并在实验上制作了可调超导微波谐振腔.测试结果表明,谐振腔的品质因子可达7800,阻抗约1700欧姆,谐振腔的频率可随直流电流发生明显变化,最大变化量可达26 MHz.     

Contemporary Millimeter- and Submillimeter-Wave Astronomy

We discuss the scientific importance of the millimeter- and submillimeter-wave astronomy. The directions of research and the main achievements in cosmology, extragalactic astronomy, and studies of the Galaxy structure, star-formation regions, and Solar-System objects are described. Topical problems are formulated. Existing and planned instruments for the millimeter/submillimeter astronomy are briefly described.     

A 492 GHz Submillimeter-Wave Receiver

A 492 GHz submillimeter receiver was designed for application to the POrtable Submillimeter Telescope (POST). The receiver includes a Schottky diode mixer, a phase-locked Gunn oscillator at 82.3 GHz coupled with multipliers (×2×3), and low-noise amplifiers. In this paper, the system configuration and performance will be introduced.     

Submillimeter-Wave Spectra of the SF Radical

Pure rotational transitions of the SF radical in the ground electronic state, (2)Pi, have been measured in the millimeter- and submillimeter-wave region using a spectrometer equipped with backward wave oscillators as radiation sources. The radical was generated by a dc discharge in a gas mixture of SF(6) and He. Forty-four lines have been measured in the frequency range from 248 to 845 GHz, for J values up to 25.5. The accuracy in line position measurement is typically 20-100 kHz, depending on the Doppler broadening. The present data were analyzed by a least-squares-fit procedure using an effective Hamiltonian for (2)Pi states, together with the transition frequencies in the microwave region available in the literature. The molecular constants have been revised with improved accuracy. Copyright 2001 Academic Press.     

Wideband Windows for Millimeter- and Submillimeter-Wave Vacuum Devices

Radiophysics and Quantum Electronics - We present the results of a theoretical calculation and an experimental study of double-sided antireflective processing of a dielectric plate by creating a...     

Submillimeter-Wave Hot-Electron Microbolometer with Andreev Reflection for Radioastronomy

The main tasks of up-to-date submillimeter-wave radioastronomy requires application of superlow-temperature direct detectors (microbolometers) of micron and submicron dimensions built in special planar antennas matching them with input channels of receiving systems and injection of these systems by space vehicles out of the atmosphere to exclude the influence of atmospheric noise and absorption of radiation. Such measures are expected to allow us to obtain a noise equivalent power (NEP) of direct detectors up to 10^-19–10^-18 W/Hz^1/2, which makes it possible to observe the majority of the weakest space radiation sources. The first studies and development of hot-electron microbolometers with Andreev reflection are performed. The NEP of such detectors estimated from dc measurements, corresponds to the above values. The first results of these studies also revealed difficulties of actual realization of the estimated NEP. The difficulties are related to radiation power losses due to imperfect matching in microwave channels and leakage of energy of electrons (acquiring an energy quantum from radiation and transferring it to phonons in the microbolometer absorber. Measures to reduce these losses are planned. A special two-stage cryostat for cooling both optical devices of the telescope built in the cryostat and the two-dimensional receiving array developed on the basis of the above-mentioned microbolometers and required for observing distributed radiation sources is designed within the framework of the Russian project for launching the submillimeter-wave space telescope. An efficient method for multiplexing signals in the receiving array is proposed.     

Temporal Dynamics of Mode Interaction in Submillimeter-Wave Second-Harmonic Gyrotron

Competition of the operating modes at the second cyclotron harmonic with spurious modes at fundamental is studied numerically for the cases of gyrotron and traveling opposite spurious modes in the gyrotron FU II. This competition limits significantly the output power at the second harmonic. The results are in good agreement with experiments.     

A Silicon Shallow-Ridge Waveguide Integrated Superconducting Nanowire Single Photon Detector Towards Quantum Photonic Circuits

A silicon shallow-ridge waveguide integrated superconducting nanowire single photon detector is designed and fabricated.At the bias current of 11.6μA,4% on-chip detection efficiency near 1550 nm wavelength is achieved with the dark count rate of 3 Hz and a timing jitter of 75 ps.This device shows the potential application in the integration of superconducting nanowire single photon detectors with a complex quantum photonic circuit.     

Submillimeter-Wave Spectroscopy of TiCl in the Ground Electronic State

The submillimeter-wave rotational transitions of TiCl in the ground state were observed using a double-modulation technique. TiCl was generated in a DC-discharge of a mixture of TiCl₄ vapor (less than 1 mTorr) and Ar buffer gas (80 mTorr) at a current of 200 mA. The ⁴Φ_3/2, ⁴Φ_5/2, ⁴Φ_7/2, and ⁴Φ_9/2 spin components of Ti³⁵Cl (v=0, 1, 2) and Ti³⁷Cl (v=0) were detected. The data were analyzed using effective rotational constants for each spin component as well as with the usual N² reduced Hamiltonian. Recent Fourier transform and laser data were included in our fits and we confirm that the ground state of TiCl is a ⁴Φ_r electronic state.     

Technology of Production of Integrated Devices for Millimeter Wave Electronics Based on High-Temperature Superconducting Films

In the work, the results on the analysis of phase transitions in amorphous films Y-Ba-Cu-O under their annealing are presented for the purpose to obtain high-temperature superconducting film samples intended for microwave applications. The analysis and choice of material for substrates have been carried out with the purpose to create integrated microwave circuits, using the high-temperature superconducting films. The method of producing the epitaxial Y-Ba-Cu-O films for microwave electronics has been justified. With the purpose of creation of the hybrid integrated circuits with application of high-temperature superconductor films, the data on producing the ohmic contacts with low transitional resistance in a system metal - high temperature superconducting film are presented. The analysis of critical parameters and microwave properties of YBa₂Cu₃O₇ films under their annealing in vacuum has been carried out. The justification of temperature regimes of contact photolithography concerning the YBa₂Cu₃O_7– films is given. The influence of oxygen implantation on structural properties and critical parameters of YBa₂Cu₃O_7– is demonstrated.     

The Millimeter- and Submillimeter-Wave Spectrum and the Dipole Moment of Ethylenimine

The 0(0)(0) bands of the ?(2)B(2)-&Xtilde;(2)A(1) and &Btilde;(2)B(1)-&Xtilde;(2)A(1) systems of SrNH(2) were observed at Doppler-limited resolution using a Broida oven source and laser-induced fluorescence detection. A full rotational analysis of both transitions was performed including K(a) levels up to 5 and J levels up to 55. The &Btilde;(2)B(1) state was found to be extensively perturbed and only some of the subbands could be analyzed. The ?(2)B(2) and &Btilde;(2)B(1) states undergo a strong Coriolis-type interaction which results in extremely large spin-rotation splittings in both states, effectively splitting all levels with K(a)(') not equal 0 into two well-separated spin components. Copyright 2000 Academic Press.     

Quick Estimation of Mode Content in a Submillimeter-Wave Gyrotron Output

An inexpensive and quick method for the approximate estimation of the mode content of the output of a submillimeter-wave gyrotron requires a thermographic pattern measurement in one cross section only.     

Submillimeter-Wave Spectroscopy of HNC Produced in an Extended Negative Glow Discharge

Submillimeter-wave transitions of HNC are observed in an extended negative glow discharge. The measurements of the rotational lines in the ground state, as well as in the vibrational fundamentals, are extended to higher J values (up to J=9←8 in the 830-GHz region). The lines in the higher vibrational excited states ν₂+ν₃, 2ν₂, and 2ν₂+ν₃ are also observed and assigned, using the frequency-magnetic field double modulation technique. Dramatic enhancement of the signal intensity strongly suggests that HNC is predominantly produced in the extended negative glow discharge through the dissociative recombination of HCNH⁺ with electrons.     

Superconducting strings

It is known that certain spontaneously broken gauge theories give rise to stable strings or vortex lines. In this paper it is shown that under certain conditions such strings behave like superconducting wires whose passage through astrophysical magnetic fields would generate a variety of striking and perhaps observable effects. The superconducting charge carriers may be either bosons (if a charged Higgs field has an expectation value in the core of the string) or fermions (if charged fermions are trapped in zero modes along the string, as is known to occur in certain circumstances). They might be observable as synchrotron sources or as sources of high-energy cosmic rays. If the charge carriers are ordinary quarks and leptons, the strings have important baryon number violating interactions with magnetic fields; such a string, traversing a galactic magnetic field of 10^?6 G, creates baryons (or antibaryons) at a rate of order 10¹² particles/cm of string per second.     

Superconducting Wigglers

In low- and medium-energy storage rings for synchrotron radiation (SR) production, it is necessary to use high-performance insertion devices (IDs) in order to meet the increasing demand for high X-ray flux to perform life science and material science, since the maximum beam energy and beam current cannot be changed in storage rings without major rebuilds of the accelerator systems.     

Submillimeter-Wave Spectroscopy of CO in the a(3)Pi State

Submillimeter-wave absorption spectrum of CO in electronically excited a(3)Pi state was observed in the 540-830 GHz region by using a phase-locked BWO spectrometer. New rotational transitions up to J = 9-8 in the vibrational excited states up to v = 5 were analyzed accompanied with previous observations in the RF and millimeter-wave regions. A multivibrational states fit among a' (3)Sigma(+) (v = 0-3) and a(3)Pi (v = 0-7) states was performed in order to analyze overall perturbation between the a(3)Pi and a' (3)Sigma(+) states. As a result, the deperturbed rotational parameters were derived precisely to improve the RKR potential. Copyright 2000 Academic Press.     

Noise Stability of SIS Receivers

There is a strong interest in the submillimeter astronomy community to increase the IF bandwidth of SIS receivers in order to better facilitate broad spectral linewidth and continuum observations of extragalactic sources. However, with an increase in receiver IF bandwidth there is a decrease in the mixer stability. This in turn effects the integration efficiency and quality of the measurement. In order to better understand the noise mechanisms responsible for reducing the receiver stability, we employed a technique first described by D.W. Allan and later elaborated upon by Schieder et al. In this paper we address a variety of factors that degrade the noise stability of SIS receivers. The goal of this exercise is to make recommendations aimed at maximizing SIS receiver stability.