Millimeter wave QWITT diode oscillator

The quantum well injection transit time (QWITT) diode charecteristics, small signal and large signal device models are used. A peak output power density of 35–5 KW/Cm² in the frequency range of 5–8 GHZ hasx been obtained from a planar QWITT Oscillator     

Photodetection properties of semiconductor laser diode detectors

Several commercial GaAlAs and InGaAsP injection lasers have been investigated with respect to their photodetection properties. The responsivity of the laser diode detectors is in the 0.15-0.25 A/W range and the dark current ranges from 5 nA to 500 nA at 3-V reverse bias. The high frequency performance of a laser diode detector strongly depends on the laser structure. The bandwidth is determined by the capacitance of the lasers and ranges from 70 MHz to 1.3 GHz. The structure showing the fastest response was the TJS laser due to its low junction capacitance.     

Millimeter wave detectors using the pyroelectric effect

Experimental work conducted on pyroelectric detectors in the microwave and millimeter wave regions show that the response time of such a device utilizing TGS at room temperature is on the order of 40 ns. An analysis is presented which shows good agreement with the experimental results for both long and short duration pulses. Observing the pyroelectric response also provides a direct measure of the thermal conductivity of the material. Our estimated value for TGS at room temperature is9.1 times 10^{-5}cal/cm.s.°C.     

毫米波肖特基二极管表征和在片测试方法

本文分析了单口和双口毫米波频段肖特基二极管的测试方法并设计了相应的测试版图,计算了截止频率随寄生电阻和零偏本征电容的变化曲线,给出了小信号和大信号等效电路模型。利用两个实际肖特基二极管测试实例对器件的小信号模型参数进行了提取,实验结果表明,在导通和截止的S参数吻合较好。     

Millimeter wave monolithic schottky diode imaging arrays

Planar Schottky diodes are integrated with bow-tie antennas to form a one-dimensional array. The energy is focused onto the antennas through a silicon lens placed on the back of the gallium-arsenide substrate. A polystyrene cap on the silicon lens reduces the reflection loss. A self-aligning process with proton isolation has been developed to make the planar Schottky diodes with a 1.1-THz zero-bias cutoff frequency. The antenna coupling efficiency and imaging properties of the system are studied by video detection measurements at 94 GHz. As a heterodyne receiver, a double-sideband mixer conversion loss of 11.2 dB and noise temperature of 3770°K have been achieved at a local oscillator frequency of 91 GHz. Of this loss, 6.2 dB is attributed to the optical system and the antenna.     

Traveling wave semiconductor laser amplifier detectors

Near-traveling-wave semiconductor laser amplifiers for amplification and detection of optical signals are discussed. Measurements of gain, responsivity, and bandwidth are presented and compared with theory. The system performance of the laser amplifier detector is evaluated by a digital transmission experiment. The importance of using low-reflectivity amplifiers with high-responsivity and weakly wavelength-dependent devices is revealed by computer simulations. The various noise contributions of the laser amplifier detector are analyzed. Expected sensitivity values are given, and it is shown that there exists an optimum amplifier gain with respect to sensitivity     

基于零偏置肖特基二极管的毫米波宽带高灵敏度检波器

Two broadband detectors at W-band and D-band are analyzed and designed with low barrier Schottky diodes. The input circuit of the detectors is realized by low and high impedance microstrip lines, and their output circuit is composed of a radio frequency (RF) bandstop filter and a tuning line for optimum reflection phase of the RF signal. S-parameters of the complete circuit are exported to a circuit simulator for voltage sensitivity analysis. For the W band detectors, the highest measured voltage sensitivity is 11800 mV/mW at 100 GHz, and the sensitivity is higher than 2000 mV/mW in 80-104 GHz. Measured tangential sensitivity (TSS) is higher than-38 dBm, and its linearity is superior than 0.99992 at 95 GHz. For the D band detector, the highest measured voltage sensitivity is 1600 mV/mW, and the typical sensitivity is 600 mV/mW in 110-170 GHz. TSS is higher than-29 dBm, and its linearity is superior than 0.99961 at 150 GHz.     

Effect of finite recovery time on charge-storage diode frequency multipliers

The efficiency of charge-storage diode frequency multipliers is calculated as a function of the order of multiplication and the recovery time for two basic circuits. Results are presented in the form of graphs.     

Optimised frequency multipliers using an ideal step-recovery diode without idlers

A generalised computer analysis on step-racovery-diode frequency multipliers (idlerless) determines optimum efficiencies and conditions under which these occur.     

Millimeter wave propagation in transmission lines with magnetized semiconductor element

Journal of Infrared, Millimeter, and Terahertz Waves - The peculiarities of electromagnetic wave propagation in transmission lines with a gyromagnetic semiconductor element are analysed....     

Millimeter wave narrowband optical fiber links using externalcavity semiconductor lasers

We present the theoretical analysis and the experimental implementation of a narrowband millimeter wave optical fiber communication system using an external cavity semiconductor laser. We derive analytic expressions and present experimental data for the modulation response, relative intensity noise, carrier-to-noise ratio, and harmonic distortion for a semiconductor laser in an external cavity operating as a transmitter in the millimeter wave frequency range. We present a system implementation of this capable of transmitting 40-Mbt/s digital data at a 35-GHz subcarrier frequency with bit-error rates below 10^-9 over a 6.3-km-long optical fiber link     

Design guidelines for terahertz mixers and detectors

Twin-slot antennas and coplanar waveguides are a popular choice for coupling signals to state-of-the-art mixers and detectors at terahertz frequencies. Although these sensors show promising performance in terms of noise temperature, they usually also show a considerable downward shift in the center frequency of their spectral response, especially when compared with calculations obtained with commonly used simplified models. In this paper, we describe an accurate and complete electromagnetic model of these detectors, which represents a significant improvement over other published approaches. We present the procedure used to obtain a very good agreement between measurements and calculations at terahertz frequencies both in terms of center frequency and bandwidth. The wide variety of measured and calculated data presented in this paper also demonstrates the effectiveness and reliability of the electromagnetic model in all the investigated frequency bands.     

The frequency chirp of current modulated semiconductor diode lasers

Wavelength modulation or frequency chirp accompanies the power modulation of current modulated semiconductor diode lasers. Standard diode laser theory predicts that the laser gain and wavelength are clamped for modulation frequencies well below the relaxation oscillation frequency (except at frequencies so low that temperature modulation in the laser induces wavelength modulation). The wavelength clamping is not observed in experiments. We show that straightforward analysis of the wave equation for the laser waveguide can re-solve this discrepancy.     

基于频率选择表面的毫米波压缩感知成像

基于频率选择表面,提出了一种毫米波压缩感知成像方法。通过在频率选择表面单元中加载开关二极管,并随机控制它们处于开/关状态,设计了一种可随机切换的新型毫米波成像掩膜板。通过将这种随机掩膜板放置于毫米波天线上,能够构造出相应的随机测量矩阵并获取足够多的有效测量次数。利用恢复重构算法进行了成像仿真验证,结果证实了所提方法的可行性。     

Superconducting detectors and mixers for millimeter and submillimeter astrophysics

Superconducting detectors will play an increasingly significant role in astrophysics, especially at millimeter through far-IR wavelengths, where the scientific opportunities include key problems in astronomy and cosmology. Superconducting detectors offer many benefits: outstanding sensitivity, lithographic fabrication, and large array sizes, especially through the recent development of multiplexing techniques. This paper describes the scientific opportunities, the basic physics of these devices, the techniques for radiation coupling, and reviews the recent progress in direct detectors, such as transition-edge bolometers, and the work on tunnel junction (superconductor-insulator-superconductor) and hot-electron mixers.     

Equalisation of semiconductor diode laser frequency modulation with a passive network

An equalisation network has been developed that improves the direct frequency modulation performance of GaAlAs semiconductor diode lasers. At modulation frequencies below 10 MHz, thermal modulation of the diode laser active region causes an enhanced frequency modulation response. A passive network has been developed which shapes the injection current modulation waveform to suppress the low-frequency enhancement.     

Experimental study of frequency multipliers based on a GaAs/AlAs semiconductor superlattices in the terahertz frequency range

Frequency multipliers based on a GaAs/AlAs semiconductor quantum superlattice have been experimentally studied. The power spectrum of the harmonics in the output signal from a multiplier with an input-signal frequency of 140–160 GHz has been measured. Planar diodes with a small active region (an area of 1–2 μm²) have been used in this study. For fabrication of the diodes, structures of heavily doped superlattices with the miniband width 24 meV have been used, these structures were grown by the molecular-beam epitaxy method. Measurements have been conducted using a BOMEM DA3.36 Fourier spectrometer equipped with a detector based on a bolometer cooled to the temperature of liquid helium. The results of the measurements have been used to plot the dependences of the power of the harmonics on the frequency in the range from 0.4 to 8.1 THz. It has been found that the character of the microwave-power distribution over the number of harmonics is close to the spectrum of a sequence of sign-alternating pulses which appear in the diode circuit when the applied voltage of the input signal exceeds the threshold of the diode. The minimal time of establishment of the pulse front and pulse duration are equal to 123 and 667 fs, respectively.