CN103090977B - Terahertz signal detection device - Google Patents
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- CN103090977B CN103090977B CN201310031213.6A CN201310031213A CN103090977B CN 103090977 B CN103090977 B CN 103090977B CN 201310031213 A CN201310031213 A CN 201310031213A CN 103090977 B CN103090977 B CN 103090977B
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Abstract
The invention discloses a terahertz signal detection device which comprises an integrated chip. A low-temperature semiconductor reading circuit and a superconductor detector are simultaneously arranged on the integrated chip, the low-temperature semiconductor reading circuit and the superconductor detector are mutually communicated, and the superconductor detector is used for detecting a terahertz signal. The terahertz signal detection device can not only reduce system noise, and improve sensitivity, working stability and operation speed of a superconductor terahertz direct detector, but also facilitates designing and manufacturing of an imaging system of a terahertz two-dimensional detection array based on a multichannel reading circuit. The terahertz signal detection device can integrate a superconductor component and a semiconductor component on the same chip, and can easily achieve metal thin film wire leading through micromachining technology. Due to the fact that an integration level is improved, a bonding pad is greatly reduced, and therefore, the aims that noise is reduced and systematic operation speed is improved are achieved.
Description
Technical field
The present invention relates to input field, particularly a kind of terahertz signal pick-up unit.
Background technology
Terahertz (THz) (1THz=10
12hz) ripple is commonly referred to as frequency at 0.1THz ~ 10THz(wavelength in 3mm ~ 30 μm) electromagnetic radiation in scope.From frequency, this wave band, between millimeter wave and infrared ray, belongs to far infrared band; From energy, THz wave is between electronics and photon.On electromagnetic spectrum, infrared and the microwave technology of terahertz wave band both sides is very ripe, but Terahertz Technology substantially still one " blank ", studying carefully its cause is because in this frequency range, both not exclusively applicable optical theory processed, also be not exclusively applicable to microwave theory to study, thus also just define in usually said " Terahertz space ".
Before 20th century the mid-80s, owing to lacking effective Terahertz production method and detection means, scientist is very limited for the understanding of this wave band properties of electromagnetic radiation.In recent ten years, developing rapidly of ultrafast laser technique, the generation for terahertz pulse provides stable, reliable excitation source, the generation of terahertz emission and application is obtained flourish.Scientist all over the world tries to be the first and develops this new electromagnetic resource in this field.
Terahertz has the special performances such as transient state, broadband property, coherence, low energy, creates far-reaching influence in fields such as broadband connections, radar, electronic countermeasure, ELECTROMAGNETIC WEAPON, uranology, medical imaging, Non-Destructive Testing, safety inspections.Because the frequency of Terahertz is very high, so its spatial resolution is also very high; Pulse again due to it is very short, so have very high temporal resolution.THz imaging technology and THz wave spectral technology thus constitute two Chief technology of Terahertz application.Meanwhile, because Terahertz energy is very little, destruction can not be produced to material, so have more advantage compared with X ray.In addition, because the vibration of biomacromolecule and the resonant frequency of rotational frequency are all at terahertz wave band, therefore Terahertz has good application prospect in the agriculturals such as grain seed selection and food-processing industry.The application of Terahertz is still in the middle of continuous development research, and its wide science prospect is recognized the world over.
In universe, the energy of half radiation is all at terahertz wave band, and since Big Bang, the photon given off has 98% also in this scope.The characteristic spectral line of a lot of interstellar matter also in this scope, as H
2o, NH
3, O
2, CH
+etc., obtain these information and can study fixed star and nebula evolution, life is formed etc.Astronomer wishes can compare use THz wave with other frequency electromagnetic to the difference showed in some qualities of data, Observational depth, angular resolution and the visual field etc. in cosmic radiation observed result, so they need THz wave detecting instrument to widen the vision, exploitation is at this time just needed to be used for the imaging system of the Terahertz two-dimensional detection array of astronomical sight.In addition, the imaging research of this high sensitivity Terahertz two-dimensional detection array also becomes more and more important in fields such as biology, medical science and safety.
Up to now, there have been many researchers realizing having made numerous effort in Terahertz two-dimensional detection array, not only had Traditional photovoltaic conductor and semiconductor bolometer, further comprises highly sensitive superconductor detecting device.Be different from the bolometer being widely used in this field, superconduction Terahertz direct-detection device is based on niobium superconducting tunnel junction (Superconductor Tunnel Junction is called for short STJ) i.e. Nb/Al/AlO
x/ Al/Nb prepares, and in this sandwich structure be made up of superconductor-insulator-superconductor film, the thickness of insulation course is suitable with the coherent length of superconductor, then will there is certain weak coupling between two superconductors.Microcosmic shows as, this structure not only allows single electron to pass through, electronics can the form of Cooper pair (electron pair) be shifted between two pieces of superconductors by tunnel effect, but this transfer probability is very little, thus Weak link is caused between two superconductors, the phase place of their electron wave function is both incomplete same, not independent of one another again, but maintains certain relation.The a series of phenomenon caused by this weak coupling and so-called Josephson effect.Superconduction Terahertz direct-detection device is exactly a kind of THz wave quantum detector based on this Josephson effect, and it assists tunnelling process to realize the detection to terahertz wave signal by photon.Contrast traditional bolometer, it has following advantage: be easy to be prepared into Terahertz two-dimensional detection array, large dynamic range and extremely short response time.
Noise equivalent power (NEP) is the tolerance to a detector sensitivity, and be defined as when output signal-to-noise ratio (SNR) is 1, the signal power that detecting device input end receives, unit is
generally NEP is regarded as the minimum power that detecting device can differentiate.As shown in Equation (1), noise two parts that generally NEP is produced by heat radiation and the detecting device self of background form, and wherein the heat radiation of background is exactly quantum (Phonon1) noise, the Section 1 namely in formula; The noise that detecting device self produces comprises the thermonoise (Johnson) of resistance, detecting device self phonon (Phonon2) noise, primarily of the noise of the sensing circuit generation that prime amplifier (Amplifier) determines, photonic quantum noise, and the noise that some extra factors (Excess) are introduced.
(1)
The NEP of superconduction Terahertz direct-detection device can be expressed as shown in Equation (2), wherein η, S, e and I
0represent the leakage current under quantum efficiency, current-responsive rate, electron charge and the STJ energy gap under voltage bias respectively, this just means under fixing frequency, lower I
0higher η can obtain lower NEP.I under normal circumstances
0determined by STJ leakage current at low temperatures, less knot better can reduce I
0absolute value.Can be divided into two aspects to the contribution of residual leakage electric current, one is the thermal excitation (I of theoretic quasi particle
th), another is the damage of knot, and the hole of such as barrier layer is revealed and edge leakage.I
thwith temperature (T) index decreased, as shown in Equation (3), can effectively be suppressed under 0.3K, k
bit is Boltzmann constant.
Therefore, when using superconduction Terahertz direct-detection device to carry out high-sensitivity detection, we can make it work at as far as possible low temperature, because temperature is lower, the leakage current of STJ is less, and the NEP of Terahertz direct-detection device is also lower, also just means that the sensitivity of detecting device is higher.Therefore after the detecting device determining use when us and probe temperature, from formula (1), determine that the first three items of NEP is also just determined, want to reduce system noise, just must reduce rear two noises being amplifier and other extra factors and introducing, and the size of this two entry value is all subject to the impact of detecting device sensing circuit system to a great extent, therefore the improvement of sensing circuit is just become to the research emphasis reducing system noise.
The circuit that traditional sensing circuit is all made up of the chip of based semiconductor silicon, must at room temperature work, and be connected to work superconduction Terahertz direct-detection device at low temperatures by wire, its noise is very rambunctious.In addition, in the imaging system of the two-dimensional detection array of THz wave, each superconduction Terahertz direct-detection device is just equivalent to a pixel, want to realize being similar to the sensing circuit system of CMOS camera like that to the two-dimensional array image data simultaneously of pixel, just need to use hyperchannel sensing circuit system, and this system wants to realize on traditional sensing circuit to be also very difficult.
All there are some drawbacks in superconduction Terahertz direct-detection device and the traditional connected mode of sensing circuit, first the most frequently used is exactly connecting line mode, superconduction Terahertz direct-detection device and its sensing circuit are isolated in the inside and outside both sides of cooled cryostat (a kind of special cryostat), then on superconductor chip and semi-conductor chip, respectively connector is set, is connected the connection realizing two chip circuits by wire.The shortcoming of this connected mode needs many wires exactly, and these wires can be introduced extra noise and reduce the overall operation speed of circuit; In addition, when we will carry out multichannel collecting data, wire required for circuit connects can double, a large amount of wires is connected to the inside and outside heat transfer showed of cooled cryostat and can not be ignored, and the superconductor chip temperature that this heat transfer can make to be under low temperature raises thus superconduction Terahertz direct-detection device cannot normally be worked.
Another technology welds suturing skill exactly, is fixed on same panel by superconductor chip together with semi-conductor chip, utilizes the pad designed on two chip block circuit to carry out welding and sews up to realize being communicated with.Although this connected mode reduces the quantity employing and connect wire, every chip block all must design a large amount of pads, and each pad has the ~ floating capacitance of pF usually, this electric capacity often can affect the Precision measurement of THz wave.In addition, want to use the semi-conductor chip that can work at low temperatures on this market to build sensing circuit, usually will, by the chip comprising modules required for these, wire or flexible printed wiring board (FPC) must be used to connect.As previously mentioned, this connected mode can not avoid the impact that connection wire brings system equally.
In sum, in the imaging system research of high sensitivity superconduction Terahertz two-dimensional detection array, research in the past concentrates on the circuit design and detecting device preparation technology that use more optimizes, thus improve detection efficiency and the resolution of detecting device, but do not consider the instability that the connection between detecting device to sensing circuit can cause due to heat interchange etc., these all can bring extra noise and instability to detector system, and final gained imaging effect is deteriorated.In addition, existing design is also all not easy to realize multi-channel detection imaging.And for a high sensitivity superconduction Terahertz direct-detection device system, these certainly will consider to solve.
Summary of the invention
Goal of the invention: technical matters to be solved by this invention is for the deficiencies in the prior art, provides a kind of terahertz signal pick-up unit.
In order to solve the problems of the technologies described above, the invention discloses a kind of terahertz signal pick-up unit, comprising integrated chip, described integrated chip is arranged cryogenic semiconductor sensing circuit and superconductor detecting device simultaneously; Cryogenic semiconductor sensing circuit and superconductor detecting device are interconnected, and superconductor detecting device is for detecting terahertz signal.
Cryogenic semiconductor sensing circuit of the present invention comprises biasing resistor R
l, the first field effect transistor JFET1 and the second field effect transistor JFET2, the first field effect transistor JFET1 the first biasing resistor R
s1 and the second second biasing resistor R of field effect transistor JFET2
s2, potentiometer V
r, integrated operational amplifier U3, integrated operational amplifier U4, integrated operational amplifier U5, integrated operational amplifier U6, and integrated operational amplifier U7.
Superconductor detecting device R
sTJtwo ends receive the first field effect transistor JFET1 and the second field effect transistor JFET2 grid separately respectively, and superconductor detecting device R
sTJwherein one end ground connection; The drain electrode of the first field effect transistor JFET1 and the second field effect transistor JFET2 applies the direct current (DC) bias of 9V, and respectively via the first biasing resistor R
s1 and the second biasing resistor R
s2 ground connection; Described biasing resistor R
lwith superconductor detecting device R
sTJbe connected to the positive input terminal of integrated operational amplifier U7 after series connection, the negative input end ground connection of integrated operational amplifier U7, the magnitude of voltage of integrated operational amplifier U7 output terminal is exactly current output value I
oUT.
Described integrated operational amplifier U3 positive input terminal connects the source electrode of the second field effect transistor JFET2, integrated operational amplifier U4 positive input terminal connects the source electrode of the first field effect transistor JFET1, integrated operational amplifier U3 and integrated operational amplifier U4 adopts negative feedback connected mode separately, integrated operational amplifier U3 output terminal connects the negative input end of integrated operational amplifier U5, and integrated operational amplifier U4 output terminal connects the positive input terminal of integrated operational amplifier U5; Described integrated operational amplifier U6 positive input terminal connects potentiometer V
r, integrated operational amplifier U6 adopts negative feedback connected mode to be connected with the positive input terminal of integrated operational amplifier U7 by switch I-bias, and integrated operational amplifier U6 is connected with the output terminal of integrated operational amplifier U5 by switch V-bias simultaneously; Described integrated operational amplifier U5 output terminal connects a resistance and direct earth capacitance respectively.
In the present invention, cryogenic semiconductor sensing circuit is communicated with by metallic film lead-in wire with superconductor detecting device.
In the present invention, integrated chip is the circular integrated chip of diameter 12 millimeters.
Beneficial effect: the present invention can not only reduce system noise and improve the sensitivity of superconduction Terahertz direct-detection device, job stability and travelling speed, but also is convenient to the imaging system of designing and making based on the Terahertz two-dimensional detection array of hyperchannel sensing circuit.Superconductor components and parts and semiconductor components and devices are integrated on same chip by the present invention, avoid using connecting wire or sealing wire, but are easy to realize metallic film lead-in wire by micro-processing technology.Because integrated level improves, also drastically reduce the area pad thus achieve the object reducing noise and improve system running speed.Superconduction Terahertz direct-detection device with the consistent size of the silicon hyper-hemispherical lens of coupling terahertz wave signal, and is prepared in integrated chip center by chips of the present invention, thus greatly improves the coupling efficiency of THz wave.
Accompanying drawing explanation
To do the present invention below in conjunction with the drawings and specific embodiments and further illustrate, above-mentioned and/or otherwise advantage of the present invention will become apparent.
Fig. 1 is structural representation of the present invention.
Fig. 2 is physical circuit figure of the present invention.
Embodiment
The invention discloses a kind of terahertz signal pick-up unit, comprise integrated chip, described integrated chip is arranged cryogenic semiconductor sensing circuit and superconductor detecting device simultaneously; Cryogenic semiconductor sensing circuit and superconductor detecting device are interconnected, and superconductor detecting device is for detecting terahertz signal.Described cryogenic semiconductor sensing circuit comprises biasing resistor R
l, the first field effect transistor JFET1 and the second field effect transistor JFET2, the first field effect transistor JFET1 the first biasing resistor R
s1 and the second second biasing resistor R of field effect transistor JFET2
s2, potentiometer V
r, integrated operational amplifier U3, integrated operational amplifier U4, integrated operational amplifier U5, integrated operational amplifier U6, and integrated operational amplifier U7.Superconductor detecting device R
sTJtwo ends receive the first field effect transistor JFET1 and the second field effect transistor JFET2 grid separately respectively, and superconductor detecting device R
sTJwherein one end ground connection; The drain electrode of the first field effect transistor JFET1 and the second field effect transistor JFET2 applies the direct current (DC) bias of 9V, and respectively via the first biasing resistor R
s1 and the second biasing resistor R
s2 ground connection; Described biasing resistor R
lwith superconductor detecting device R
sTJbe connected to the positive input terminal of integrated operational amplifier U7 after series connection, the negative input end ground connection of integrated operational amplifier U7, the magnitude of voltage of integrated operational amplifier U7 output terminal is exactly current output value I
oUT.Described integrated operational amplifier U3 positive input terminal connects the source electrode of the second field effect transistor JFET2, integrated operational amplifier U4 positive input terminal connects the source electrode of the first field effect transistor JFET1, integrated operational amplifier U3 and integrated operational amplifier U4 adopts negative feedback connected mode separately, integrated operational amplifier U3 output terminal connects the negative input end of integrated operational amplifier U5, and integrated operational amplifier U4 output terminal connects the positive input terminal of integrated operational amplifier U5; Described integrated operational amplifier U6 positive input terminal connects potentiometer V
r, integrated operational amplifier U6 adopts negative feedback connected mode to be connected with the positive input terminal of integrated operational amplifier U7 by switch I-bias, and integrated operational amplifier U6 is connected with the output terminal of integrated operational amplifier U5 by switch V-bias simultaneously; Described integrated operational amplifier U5 output terminal connects a resistance and direct earth capacitance respectively.Cryogenic semiconductor sensing circuit is communicated with by metallic film lead-in wire with superconductor detecting device.
Embodiment
Superconductor components and parts and semiconductor components and devices are integrated into the technique on same chip by the present invention, this block integrated chip contains the function of high sensitivity superconduction Terahertz direct-detection and low noise multi-channel low-temperature semiconductor readout circuit, a large amount of connecting lines and pad can be reduced, operation can be more prone to, reach the highest travelling speed etc.Gallium arsenide (GaAs) has superior Electronic Transport Properties and special optical character, and the high impedance detector that the superconduction Terahertz direct-detection device of the very applicable low operating temperatures of GaAs technotron (JFET) is such, the low temperature sensing circuit integrated chip therefore adopting GaAsJFET semiconductor technology to prepare more is conducive to realizing the direct-coupled system of superconductor and semiconductor.
Based on niobium superconducting tunnel junction (STJ) i.e. Nb/Al/AlO
x/ Al/Nb and a kind of THz wave quantum superconductor detecting device prepared, it assists tunnelling process to realize the detection to terahertz wave signal by photon.GaAs has superior Electronic Transport Properties and special optical character, and the high impedance detector that the superconduction Terahertz direct-detection device of the very applicable low operating temperatures of GaAsFET is such, the low temperature sensing circuit integrated chip therefore adopting GaAs JFET semiconductor technology to prepare more is conducive to realizing the direct-coupled system of superconductor and semiconductor.
Integrated chip design becomes diameter to be the circular chip of 12 millimeters by the present invention, with the consistent size of silicon hyper-hemispherical lens, and superconduction Terahertz direct-detection device is prepared in integrated chip center.So, as long as this circular chip is placed on lens plane and the edge that aligns, just easily also make superconduction Terahertz direct-detection device be positioned at lens plane center very accurately, completely eliminate the problem of lateral deviation, thus greatly improve the coupling efficiency of THz wave.
In order to reduce the interference of thermonoise, the sensitive detectors detecting feeble signal all needs to be operated in below low temperature 4.2K (sometimes even will to below 0.3K) and reaches higher sensitivity behaviour as far as possible.In many cases, these detecting devices all have higher impedance, and therefore transimpedance research is just very necessary.If can use in the working temperature of detecting device as the semiconductor field effect transistor (FET) of sensing circuit, so this will have very large benefit to reduction system noise.
The field effect transistor that can use at low temperatures has much can candidate, such as mos field effect transistor (MOSFET), junction field effect transistor (JFET) and metal-semiconductor field effect transistor (MESFET) etc.And MESFET is because there is larger leakage current (about 10
-13a) sensing circuit of high impedance detector is not suitable as.MOSFET is then widely used in the cryotronics equipment of satellite-borne.But at low temperatures, observed too much extraordinary noise in N-shaped MOSFET, this phenomenon is referred to as war ping effect, and in order to prepare sensing circuit, thisly non-linearly must to suppress.One method carefully repairs dopant profiles to optimize MOSFET, and another kind of method uses p-type MOSFET exactly.
Gaas compound semiconductor (GaAs) has superior Electronic Transport Properties and special optical property, is widely used in the key areas such as laser diode and high speed integrated circuit.Electron effective mass minimum in GaAs makes GaAs JFET also be applicable to very much profound hypothermia application.It has high grid impedance and low-leakage current, and compares MOSFET, and the gate capacitance of GaAs JFET is also very little, will produce great signal to noise ratio (S/N ratio) like this in charge integrated amplifiers.These characteristics are all advantages powerful when being applied in low temperature sensing circuit.But in fact, the gate electrode of FET is typically connected to photon detector, feedback capacity and reset FET, and all these has high impedance.GaAs JFET, when Low ESR configures, can realize under low temperature
low noise voltage.
Also following result is had: use heat curing techniques about the low-frequency noise of GaAs JFET when configuring with high impedance under low temperature and gate leak current characteristic, when low in energy consumption to 1 below μ W, gate leak current only has 3 electronics/second, we can obtain a low-down noise grade ~
these results mean that GaAs JFET is applicable to the low temperature sensing circuit of high impedance detection system very much.In addition, the gate capacitance of GaAs JFET is little of below 0.1pF, and therefore it can be applied to photon number resolv-ing detector by structure charge integrated amplifiers.
N-shaped GaAs JFET has good performance under temperature 4.2K, and has same outstanding performance when its characteristic and 4.2K when temperature is low to moderate 0.3K, does not occur the non-linear phenomena of any similar war ping effect.The input current noise of GaAs JFET is extremely low, dissipative type and enhancement mode field effect transistor, has multiple door size, good conducting resistance (being less than 1M Ω), very high off resistance (being greater than 1T Ω) and very little gate capacitance (being less than 100fF), low noise voltage
minimum ground gate leak current (is less than 10
-18a), even also there will not be unnecessary noise when connection high impedance detector, the amplifier be therefore made up of it is well suited for the high impedance detector as STJ superconduction Terahertz direct-detection device.
As shown in Figure 1, what connect superconductor components and parts and semiconductor components and devices is no longer above-described connection wire or sealing wire to the present embodiment, but is easy to realize metallic film lead-in wire by micro-processing technology.Because integrated level improves, naturally this lead-in wire will shorten, and also drastically reduce the area pad thus achieves the object reducing noise and improve travelling speed.Meanwhile, the carrier mobility of GaAs is more than 5 times of Si, and this just determines the performance that the low temperature sensing circuit designed based on GaAs JFET has super low-power consumption.After tested, the summation for multiple amplifier power consumption of 32 passage sensing circuits is about 3 μ W, does not therefore worry the thermal effect because circuit working produces.
The high sensitivity superconduction Terahertz direct-detection device system being integrated with low noise cryogenic semiconductor sensing circuit is preparation like this, first the amplifier required for sensing circuit is prepared based on GaAs JFET semiconductor technology, the various semiconductor devices such as multiplexer, then superconductor Terahertz direct-detection device is prepared at reserved on this same chip space place, and in preparation process, make semiconductor circuit be communicated with superconductor direct-detection device simultaneously, finally be formed in high sensitivity Terahertz direct-detection device system same chip being integrated with low noise cryogenic semiconductor sensing circuit.
Design about superconduction Terahertz direct-detection device is such, and first according to superconduction BCS theory, as shown in Equation (4), Δ, h and kB represent the energy gap of Nb STJ, Planck's constant and Boltzmann constant respectively, by the superconduction critical temperature T of Nb
cin=9.2K substitution formula, the energy gap frequency V that Nb is corresponding can be drawn
g=720GHz.Namely, under temperature is absolute zero, the ideal frequency that Nb STJ can detect is 720GHz.And the actual work temperature of detecting device is certainly higher than absolute zero, so the detection frequency that we design superconduction Terahertz direct-detection device is 650GHz(wavelength 450 μm).
hv
g＝2Δ＝3.52k
BT
c(4)
Secondly, because the electric capacity (C) of STJ knot is comparatively large, high frequency THz signal can be shorted, and an available superconductive micro-strip line (inductance L) connecting STJ knot forms LC resonant circuit, its bandwidth determines the frequency response of STJ direct-detection device, the critical current density (J of it and STJ
c) be directly proportional, but J
clarger, the leakage current of device relatively will be larger, and noise also becomes large thereupon.We adopt distribution junction array, namely place several STJ on the microstrip line and tie, reach with less J
cobtain the object of larger bandwidth.Wide band logarithmic periodic planes antenna is used with the efficient coupling of incident terahertz signal; STJ junction area is 4 μm
2, normal state resistivity R
n=55 Ω, J
c=10
3a/cm
2(4.2K); Adopt 12 STJ, form 2 group of 6 junction array in the both sides of antenna, can realize in 650GHz bandwidth more than 10%, noise equivalent power (NEP) reaches
high sensitivity superconduction Terahertz direct-detection device.
Final high sensitivity superconduction Terahertz direct-detection device system is one piece of chip being integrated with superconduction Terahertz direct-detection device and low noise multi-channel low-temperature semiconductor readout circuit, achieves the connection of superconductor and semiconductor simultaneously.Below for the sensing circuit of high sensitivity Terahertz direct-detection device, its concrete design and course of work is described.
In Fig. 1, sensing circuit is a negative-feedback circuit, has constant voltage and constant current two kinds of mode of operations, dotted line frame place R in figure
sTJrepresent high sensitivity superconduction Terahertz direct-detection device, R
lfor biasing resistor, R
sfor the biasing resistor of field effect transistor, V
rthe voltage that divides by potentiometer, which determine the size being added to detecting device upper offset.
The magnitude of voltage at detecting device two ends obtains like this: R
sTJtwo ends receive field effect transistor 2 input ends, and 2 JFET field effect transistor form common drain follower, and enlargement factor is A=g
mr
s/ (1+g
mr
s), because g
mr
s>>1, so A ≈ 1.U3, U4 be two integrated transporting dischargings as follower, then amplify 10 times by integrated transporting discharging U5, obtain detecting device two ends voltage export V
oUT.
The current value flowing through detecting device obtains like this: resistance R
land R
sTJon voltage amplify 1 times, due to R through integrated transporting discharging U7
sTJ< R
l, this voltage is approximately R
lthe voltage at two ends, namely this magnitude of voltage equals current output value I
oUT.
When switch is positioned at I-bias, be constant current source pattern, due to negative feedback, U6+,-both end voltage is identical, is now added in R
land R
sTJon voltage equal on potentiometer voltage, due to R
sTJ<<R
l, electric current is approximately V
r/ V
l, now bias source is current source.
When switch is positioned at V-bias, for constant pressure source pattern, due to negative feedback, integrated transporting discharging U6+,-both end voltage is identical, so the voltage that U5 exports equals the voltage on potentiometer, namely the voltage (i.e. U5 input terminal voltage) at the device two ends voltage (U5 output voltage) that is potentiometer is divided by the enlargement factor of U5, and now bias source is voltage source.
When measuring Terahertz response signal, generally use constant pressure source pattern.Namely the voltage at device two ends is fixed on a constant value, then measure have Terahertz wave amplitude according to and there is no to flow through during THz wave irradiation the curent change of device.Because be added in the electric current I=V on device
r/ (R
l+ R
sTJ), R
ltoo large then electric current adds not quite, when device creepage is larger, and desirable R
l=100K Ω; And for the minimum leakage current 100pA of superconduction Terahertz direct-detection device, desirable R
l=100M Ω.In order to improve signal to noise ratio (S/N ratio), using chopper to adjust incident terahertz signal, using lock-in amplifier to carry out relevant detection.
After superconductor Terahertz direct-detection device and cryogenic semiconductor sensing circuit complete Integrated design, consider the coupling efficiency η between THz wave and direct-detection device as described in formula (2), the present embodiment has done again further design to this integrated chip.When detecting, collimator optical system is used to be coupled to THz wave, detector chip is fixed on by low temperature glue the High Resistivity Si hyper-hemispherical lens planar central position that diameter is 12 millimeters, and energy centralization is coupled on detecting device by THz wave scioptics and flat plane antenna.When hyper-hemispherical lens is used for the coupling between THz wave and direct-detection device, if light beam misalignment sample will reduce coupling efficiency, during coupling, usually there will be lateral deviation and tilting tolerance.Lateral deviation refers to that light beam impinges upon the range deviation of position to detecting device of lens plane, and tilting tolerance refers to the angular deviation in beam direction and vertical lens plane normal direction.The deviation of this both direction is less, then THz wave is higher to the coupling efficiency of direct-detection device by silicon hyper-hemispherical lens.
In practical operation uses, be difficult to detecting device to be placed on lens plane center, often occur that detecting device off-beams center causes coupling efficiency difference even to can't detect the problem of THz wave.So this integrated chip design becomes diameter to be the circular chip of 12 millimeters by we, with the consistent size of High Resistivity Si hyper-hemispherical lens plane, and superconduction Terahertz direct-detection device is prepared in integrated chip center.So, as long as this circular chip is placed on lens plane and the edge that aligns, just easily superconduction Terahertz direct-detection device is also made to be positioned at lens plane center very accurately, so just completely eliminate the problem of above-mentioned lateral deviation, therefore substantially increase the coupling efficiency of THz wave.
The invention provides a kind of terahertz signal pick-up unit; the method and access of this technical scheme of specific implementation is a lot; the above is only the preferred embodiment of the present invention; should be understood that; for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.The all available prior art of each ingredient not clear and definite in the present embodiment is realized.
Claims (1)
1. a terahertz signal pick-up unit, is characterized in that, comprises integrated chip, described integrated chip is arranged simultaneously cryogenic semiconductor sensing circuit and superconductor detecting device; Cryogenic semiconductor sensing circuit and superconductor detecting device are interconnected, and superconductor detecting device is for detecting terahertz signal;
Described cryogenic semiconductor sensing circuit comprises biasing resistor R
l, the first field effect transistor JFET1 and the second field effect transistor JFET2, the first field effect transistor JFET1 the first biasing resistor R
s1 and the second second biasing resistor R of field effect transistor JFET2
s2, potentiometer V
r, integrated operational amplifier U3, integrated operational amplifier U4, integrated operational amplifier U5, integrated operational amplifier U6, and integrated operational amplifier U7;
Superconductor detecting device R
sTJtwo ends receive the first field effect transistor JFET1 and the second field effect transistor JFET2 grid separately respectively, and superconductor detecting device R
sTJwherein one end ground connection; The drain electrode of the first field effect transistor JFET1 and the second field effect transistor JFET2 applies the direct current (DC) bias of 9V, and respectively via the first biasing resistor R
s1 and the second biasing resistor R
s2 ground connection; Described biasing resistor R
lwith superconductor detecting device R
sTJbe connected to the positive input terminal of integrated operational amplifier U7 after series connection, the negative input end ground connection of integrated operational amplifier U7, the magnitude of voltage of integrated operational amplifier U7 output terminal is exactly current output value I
oUT;
Described integrated operational amplifier U3 positive input terminal connects the source electrode of the second field effect transistor JFET2, integrated operational amplifier U4 positive input terminal connects the source electrode of the first field effect transistor JFET1, integrated operational amplifier U3 and integrated operational amplifier U4 adopts negative feedback connected mode separately, integrated operational amplifier U3 output terminal connects the negative input end of integrated operational amplifier U5, and integrated operational amplifier U4 output terminal connects the positive input terminal of integrated operational amplifier U5;
Described integrated operational amplifier U6 positive input terminal connects potentiometer V
r, integrated operational amplifier U6 adopts negative feedback connected mode to be connected with the positive input terminal of integrated operational amplifier U7 by switch I-bias, and integrated operational amplifier U6 is connected with the output terminal of integrated operational amplifier U5 by switch V-bias simultaneously;
Described integrated operational amplifier U5 output terminal is linked in sequence ground connection after a resistance and direct earth capacitance;
Cryogenic semiconductor sensing circuit is communicated with by metallic film lead-in wire with superconductor detecting device;
Integrated chip is the circular integrated chip of diameter 12 millimeters.
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| CN103515711A (en) * | 2013-10-23 | 2014-01-15 | 哈尔滨工业大学 | Infrared radiation transmitting microstrip antenna based on random metallic mesh |
| CN104091851B (en) * | 2014-06-11 | 2015-07-22 | 南京大学 | Terahertz sensor based on ring gate MOSFET structure |
| CN104634540A (en) * | 2015-01-21 | 2015-05-20 | 北京理工大学 | Testing system and testing method for front end of heterodyne terahertz quasi-optical receiver |
| CN105140248B (en) * | 2015-07-23 | 2018-02-06 | 南京大学 | A kind of high responsive operation method based on CMOS Terahertz sensors |
| CN111614402B (en) * | 2020-04-23 | 2022-06-14 | 复旦大学 | Terahertz PAM-4 signal generation system and method based on binary driving single modulator |
| CN112540056B (en) * | 2020-12-07 | 2021-11-16 | 南京大学 | Array terahertz receiving device and reading device thereof |
| CN112881469B (en) * | 2021-01-13 | 2024-01-26 | 上海科技大学 | Silicon-based terahertz metal waveguide process reliability testing device and testing method thereof |
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