| Millimeter-wave and terahertz wave have many good properties and wide applications.The three basic contents on millimeter-wave and terahertz wave technologies are signal generation,transmission and detection.One effective way is to obtain terahertz source by multiplying the relatively mature microwave and millimeter-wave signal.And for terahertz detection,direction detection is an effective and low-cost method.Schottky barrier diode is very suitable for terahertz frequency multipliers and detectors due to its low parasitic effect and high cut-off frequency.The key technology and difficulty are the accurate modeling technologies of the diode at terahertz frequencies.By now,the mainstream modeling technology is to build the whole 3D electromagnetic model for the parasitic part and use the spice model for the intrinsic part.This is because of its simplicity and convenience.However,its disadvantages are also obvious,which are the inability to deeply and quantitatively study each paretic parameter and the inaccuracy at terahertz frequencies.One way to achieve accurate modeling is by physical models,which faces the lack of universality.So,the physical modeling technology for Schottky barrier diodes has not been widely used.On the other hand,for the transmission of millimeter wave and terahertz wave,the remote application of wireless transmission is limited due to their large attenuations in the atmosphere and large influences from weather.One method that can replace wireless transmission is radio over fiber(ROF)transmission technology,that is,the millimeter wave and terahertz wave are modulated to the optical wave and then transmitted through optical fibers,so as to make full use of the advantages of optical fibers.The key technology is electro-optic modulation.In view of the problems above,this thesis mainly focuses on the key technologies of components of millimeter wave and terahertz wave: frequency multipliers,detectors and electro-optic modulators.The main research contents are as follows.(1)Fast and accurate extraction method for the parasitic parameters of terahertz Schottky barrier diode.Aiming at the problem of how to deeply and quantitatively study parasitic effects,this thesis presents the "one-port three-structure parameter extraction method"(OTPEM).Using three auxiliary structures of diodes as well as their one-port S parameters,the value of each parasitic parameter can be extracted by matrix operations,which is verified in the experiments.This method has been used to quantitatively study the parasitic effect of Schottky barrier diode,and also guide the design of the diode structure.(2)Accurate and general modeling technology for the intrinsic part of terahertz Schottky barrier diode.In view of the inaccuracy of conventional modeling methods and the lack of universality of physical modeling methods,a physical SDD(symbolically defined devices)model is presented in this thesis.Firstly,the physical model of the diode including the special effects is built,and the terahertz nonlinear junction capacitance characteristic is studied.Then,an equation derived that can accurately describe the diode characteristic and meet the requirements of harmonic balance simulation at the same time.This equation is used in the SDD component of ADS(Advanced Design System)and good practicability is realized.Other researchers can easily use the modeling technology presented in this thesis for terahertz Schottky barrier diodes.This model is used in a terahertz monolithic integrated frequency tripler and a terahertz high-efficiency frequency doubler.The consistencies between the simulated and measured results have respectively improved 40% and 60% compared to the conventional method.The modeling technology presented in this thesis has realized both accuracy and practicability.(3)Terahertz monolithic integration technology(TMIC)and high efficiency frequency doubling technology.In view of the relatively backward development of terahertz wave source technology,this thesis studies terahertz frequency multiplying technology based on Schottky barrier diodes.A simpler and accurate optimized diode design method is presented,which can find the optimized parameters and structure of the diode easily and fast based on the requirements of the frequency multipliers.By using the optimized design method and modeling technology for diodes presented in this thesis,a 140 GHz high-efficiency frequency doubler is presented.Its peak efficiency is measured as 34.3%,which has reached the equivalent level of international top frequency multiplier from VDI.On the other hand,in view of the large error of diodes in manual assembly at terahertz frequencies,this thesis studies the terahertz monolithic integration technology,which directly integrate the devices and circuits to avoid this error.A terahertz monolithic integrated frequency tripler is presented,which can cover the frequency band from 330 to 500 GHz.(4)Terahertz low-cost and high-performance detection technology.In view of the relatively backward development of terahertz detection technology,this thesis studies terahertz detectors based on Schottky barrier diodes.Schottky barrier diodes with low barriers are presented by using InGaAs/InP.Compared to conventional diodes with the same structure using GaAs,the barrier height is reduced from 0.78 V to 0.26 V.The detection performance of the diode is also improved by improving the diode structure.A 500-600 GHz zero-biased detector is presented,whose typical voltage responsivities are 900 V/W at 500-560 GHz and 400 V/W at 560-600 GHz.Compared with heterodyne mixers,the terahertz detectors presented in this thesis has the advantages of simple structure and low cost.(5)High-performance electro-optic phase modulation technology.Aiming at the wireless transmission problem of millimeter wave and terahertz wave,this thesis deeply studies the core technology of optical carrier transmission technology,which is the electro-optic phase modulator.A metal electrode fabrication process suitable for lithium niobate thin films on insulators with low loss and high-power handling ability has been developed,which guarantees low half-wave voltages in millimeter-wave region.The measured results of the phase modulator are: optical propagation loss is ~1 dB,half-wave voltage at 30 GHz is 4.4 V with an increment of 28% from 5 to 40 GHz,which is very flat.The presented phase modulator has successfully modulated the millimeter-wave to optical wave in the experiments.According to novelty search report,there are no reports on lithium niobate electro-optic phase modulators with optical propagation loss less than 1 dB and half-wave voltage(30 GHz)less than 4.4 V at home and abroad. |
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