A 300 GHz quasioptical schottky frequency doubler

A monolithically integrated frequency multiplier based on a planar antenna providing impedance matching has been realized and measured at 300 GHz. Each of the two circuits comprises a Schottky varactor, slot antenna, MIM-capacitor and microstrip bias feed. The theoretical design aspects, the technological approach and the RF performance are addressed.     

A frequency doubler for 200 GHz with a planar Schottky varactor

A frequency doubler for 200 GHz utilising a planar surface channel Schottky varactor was designed, constructed and tested. The doubler employes novel split-waveguide mount design with two sliding backshorts at both input and output waveguides. The theoretical maximum efficiency of the doubler is 44.0 % with input power level of 32 mW and the maximum output power is 16.5 mW with input power level of 50 mW. The measured maximum efficiency of the doubler was 7.1 % and the maximum output power was 2.6 mW     

Generation of amplitude squeezed green light from a high efficiency PPKTP frequency doubler

We report on a high-efficiency 532 nm green light conversion from an external cavity-enhanced second harmonic generation of a home-made 1064 nm single-frequency Nd:YVO₄ laser with a periodically poled KTP crystal. A stable green power of 60 mW with a conversion efficiency of 75% was measured. Meantime, we investigate the quadrature amplitude noise of the green light at the same experimental setup and 0.6 dB green light squeezing was experimentally observed (taking into account the total detection efficiency of 58%, the squeezing should be 1.1 dB). The squeezing as a function of input power was also studied and we found qualitative agreement with theoretical prediction.     

Frequency-stabilized semimonolithic frequency doubler with high output power

We present a semimonolithic frequency-doubler from 1080 to 540 nm with 80% doubling efficiency and up to 849-mW output power of green light.     

一种高效的2.45 GHz二极管阵列微波整流电路

 采用4只HSMS 282肖特基二极管阵列,对大功率微波整流电路进行了研究。构造了基于微带线结构的2.45 GHz高效微波整流电路,将微波整流单元电路的输入功率提升到33 dBm。仿真和实验结果表明,在一定微波输入功率的条件下,整流电路在负载较大范围内变化时保持了高整流效率。通过在不同微波输入功率和负载下进行测量,发现当输入微波功率为27.0~31.7 dBm之间变化时,最高整流效率均达到了60%以上,当微波输入功率为30 dBm时,微波整流电路效率达到了63.3%。     

一种高效的2.45 GHz二极管阵列微波整流电路

采用4只HSMS 282肖特基二极管阵列,对大功率微波整流电路进行了研究。构造了基于微带线结构的2.45 GHz高效微波整流电路,将微波整流单元电路的输入功率提升到33 dBm。仿真和实验结果表明,在一定微波输入功率的条件下,整流电路在负载较大范围内变化时保持了高整流效率。通过在不同微波输入功率和负载下进行测量,发现当输入微波功率为27.0~31.7 dBm之间变化时,最高整流效率均达到了60%以上,当微波输入功率为30 dBm时,微波整流电路效率达到了63.3%。     

馈电损耗及高辐射效率微带天线阵研究

 根据串、并馈电微带天线阵列结构,建立了各自等效参数模型,定量分析了微带馈电网络功率损耗对微带天线阵列增益的影响,借助微带线和同轴电缆组成的低损耗混合馈电网络,采用串并馈电方式,完成了C波段4×24元高效率微带天线阵的设计。实测天线阵的各项指标均优于设计要求,其中阵列增益达到25.4 dB,实现了64.5%的辐射效率,较相同阵元数目的微带串馈列实测增益提高1.1 dB,与等效参数理论计算结果很好地吻合。     

馈电损耗及高辐射效率微带天线阵研究

根据串、并馈电微带天线阵列结构,建立了各自等效参数模型,定量分析了微带馈电网络功率损耗对微带天线阵列增益的影响,借助微带线和同轴电缆组成的低损耗混合馈电网络,采用串并馈电方式,完成了C波段4×24元高效率微带天线阵的设计。实测天线阵的各项指标均优于设计要求,其中阵列增益达到25.4 dB,实现了64.5%的辐射效率,较相同阵元数目的微带串馈列实测增益提高1.1 dB,与等效参数理论计算结果很好地吻合。     

A new multi frequency compact microstrip antenna

A single layer, single feed, multi frequency, compact rectangular microstrip antenna is proposed. Resonant frequency has been reduced drastically by cutting unequal rectangular slots at the edge of the patch along with two tiny circular slots created inside the patch to improve return loss. Antenna size has been reduced by 64% with an increased frequency ratio (the ratio of second or higher resonant frequency to the first resonant frequency).     

A right cut method of Brewster angle to reduce the reflection of laser frequency doubler

The ordinary method to cut two light pass surfaces of an optical device in Brewster angle parallelly cannot reduce the harmonic's reflective losses of a laser frequency doubler. Right cut method with two unparallel light pass surfaces of Brewster angle of a laser frequency doubler, and preliminary experiment to demonstrate the usefulness of the technique are given.     

Development of an extremely wide-band planar frequency doubler from Q-band to W-band

A very broadband Q- to W-band MIC frequency doubler with a 28-GHZ band-width, employing a unique planar balanced circuit configuration, has been developed with good performance. Using two beamlead Schottky barrier diodes as varistors, the doubler exhibits an output power of 7±1 dbm and conversion loss of 13±1 db over the 66 to 94 GHZ output frequency range. The development demonstrates a unique concept in realizing wideband planar millimeter wave solid-state sources.     

Microresonator Kerr frequency combs with high conversion efficiency

Microresonator‐based Kerr frequency comb (microcomb) generation can potentially revolutionize a variety of applications ranging from telecommunications to optical frequency synthesis. However, phase‐locked microcombs have generally had low conversion efficiency limited to a few percent. Here we report experimental results that achieve conversion efficiency ( on‐chip comb power excluding the pump) in the fiber telecommunication band with broadband mode‐locked dark‐pulse combs. We present a general analysis on the efficiency which is applicable to any phase‐locked microcomb state. The effective coupling condition for the pump as well as the duty cycle of localized time‐domain structures play a key role in determining the conversion efficiency. Our observation of high efficiency comb states is relevant for applications such as optical communications which require high power per comb line.

     

A solid-state frequency source for radio astronomy in the 100 to 1000 GHz range

A compact Gunn oscillator-multiplier combination can provide the for SIS receivers necessary LO power up to 1000 GHz. Frequency multiplication factors of 2 to 8 are accomplished in a single step using a Schottky mixer diode in the varistor mode.     

A quasiparticle SIN mixer for the 230 GHz frequency range

We report on quasiparticle mixing in the frequency range 220 to 230 GHz using SIN junctions. The lowest double sideband receiver noise temperature measured was about 230 K. This result shows that the SIN junction provides an interesting alternative for high frequency heterodyne receivers where pair tunneling in SIS junctions could give rise to interference from Josephson effects.     

Theory of cascade tripler of optical frequency with high conversion efficiency

The regimes of high conversion efficiency of cascade triplers of optical radiation are theoretically investigated. A conversion efficiency of 100% for plane waves can be reached. Analytical expressions for the wave amplitudes in this case are given. The conversion efficiencies for a laser beam with Gaussian distribution of the amplitude in space and time are numerically computed. The maximum efficiency for such a beam is about 50%. Some experimental situations are discussed.     

高频线阵的研制

本文描述了一种用于侧扫声纳的高频线列阵，该阵由中心频率分别为１００ＫＨｚ和５００ＫＨｚ的两部分构成。由于采用阵元加权排列和充分利用有效工作面积，该阵具有尖锐的主瓣，较高的主、副瓣比和较高的发射、接受灵敏度（１００ＫＨｚ时分别为１７４ｄＢ，５００ＫＨｚ时分另为１７４ｄＢ、－１８３ｄＢ），技术指标达到国外同类高频线阵的水平。满足侧扫声呐的尖波束、低副瓣、大功率、高灵敏度，深水（１００ｍ）使用的要求，本     

Dual-Vivaldi wideband nanoantenna with high radiation efficiency over the infrared frequency band

A dual-Vivaldi nanoantenna is proposed to demonstrate the possibility of wideband operation at IR frequencies. The antenna geometry design is guided by the material properties of metals at IR frequencies. According to our numerical results, this nanoantenna has both high radiation efficiency and good impedance-matching properties over a wide frequency band (more than 122%) in the IR frequency band. The design is based on the well-known Vivaldi antenna placed on quartz substrate but operating as a pair instead of a single element. Such a pair of Vivaldi antennas oriented in opposite directions produces the main lobe in the broadside direction (normal to the axes of the antennas) rather than the usual peak gain along the axis (end fire) of a single Vivaldi antenna. The dual-Vivaldi nanoantenna is easy to fabricate in a conventional electron-beam lithography process, and it provides a large number of degrees of freedom, facilitating design for ultra-wideband operation.     

Experimental access to HSQC spectra decoupled in all frequency dimensions

A new operator called RESET “Reducing nuclEar Spin multiplicitiEs to singuleTs” is presented to acquire broadband proton decoupled proton spectra in one and two dimensions. Basically, the homonuclear decoupling is achieved through the application of bilinear rotation pulses and delays. A [BIRD]^r,x pulse building block is used to selectively invert all proton magnetization remotely attached to ¹³C isotopes, which is equivalent to a scalar J decoupling of the protons directly attached to ¹³C from all other protons in the spin system. In conjunction with an appropriate data processing technique pure shift proton spectra are obtained. For this purpose, the concept of constant time acquisition in the observe dimension is exploited. Both ideas were merged together producing superior HSQC based pseudo 3D pulse sequences. The resulting HSQC spectra show cross peaks with collapsed multiplet structures and singlet responses for the proton chemical shift frequencies. An unambiguous assignment of signals from overcrowded spectra becomes much easier. Finally, the recently introduced SHARC technique is exploited to enhance the capability of the scalar J decoupling method. A significant reduction of the total measurement time is achieved. The time is saved by reducing the number of ¹³C chemical shift evolution increments and working with superimposed narrow spectral bandwidths in the ¹³C indirect domain.