CN202394003U - TeraHertz high-speed modulator - Google Patents
TeraHertz high-speed modulator Download PDFInfo
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- CN202394003U CN202394003U CN2011205338463U CN201120533846U CN202394003U CN 202394003 U CN202394003 U CN 202394003U CN 2011205338463 U CN2011205338463 U CN 2011205338463U CN 201120533846 U CN201120533846 U CN 201120533846U CN 202394003 U CN202394003 U CN 202394003U
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Abstract
The utility model discloses a TeraHertz high-speed modulator which comprises a substrate layer; a buffer layer is grown on the substrate layer; a strain quantum well structure is grown on the buffer layer; a metal super material structure consisting of metal resonance units which are lined in an array periodically is prepared on the upper surface of the strain quantum well structure; the buffer layer and the substrate layer are made of the same material; the band gap of a potential well layer is smaller than that of a barrier layer; and the lattice constants of the barrier and the substrate layer are the same or the difference between the lattice constants is within 0.5 percent. According to the TeraHertz high-speed modulator, the strain quantum well structure contains an extremely intensive piezoelectric field which is produced by strain, so that the composite service life and the concentration of a photon-generated carrier can be significantly prolonged, and the requirement on the power of a modulation laser is greatly reduced; and the internal piezoelectric field and the separation degree of a charge space can be flexibly adjusted by changing the In component in the InGaAs/GaAs strain quantum well and the width of the quantum well, so that the modulation rate of the TeraHertz high-speed modulator is adjusted conveniently.
Description
Technical field
The utility model belongs to the THz wave communications field, relates in particular to a kind of terahertz wave modulator.
Background technology
The contradiction of the limited frequency spectrum resource of radio communication and the high speed business demand that increases rapidly forces people to go to develop new spectral band.THz wave is meant that frequency is in electromagnetic wave (1 THz=10 of 0.1 THz to 10 THz scopes
12Hz), wavelength be 0.03 mm to 3 mm, have very big bandwidth, therefore develop the THz wireless communication technology and have important application value.Wherein terahertz wave modulator is one of requisite device in the Terahertz communication system, and the performance of Terahertz modulator mainly is subject to material chosen and preparation at present.The combination of the ultra material of novel semi-conductor base material and electromagnetism (meta-material) is expected to realize some gordian technique of Terahertz, the especially breakthrough of Terahertz modulation technique.
The THz wave modulator of being reported in recent years has the method for utilizing semiconductor piece shape material that the THz ripple is modulated.The Li Jiusheng of the China Measures Institute etc. utilize 808 nm laser radiations to produce photo-generated carrier the THz ripple are modulated based on silicon (Si) wafer of ultra-high resistance rate.Because the recombination lifetime of charge carrier is longer in the ultra-high resistance rate Si sheet, so its modulation rate is merely 0.2k bps.Among the gallium arsenide GaAs life-span of charge carrier shorter, might become the base material of preparation high speed Terahertz modulator.People such as the L. Fekete of Czech take at alternately laminated SiO
2With the way that embeds one deck GaAs defect layer in the MgO periodic structure to constitute 1-D photon crystal; Utilize the change in concentration of the photo-generated carrier that GaAs produces under 810 nm laser radiations to modulate the characteristic that sees through of photonic crystal, thereby realize the purpose of High Speed Modulation THz ripple.But owing to the life-span of charge carrier among the GaAs is shorter; Response time can reach 130 ps magnitudes; Though so can reach the GHz magnitude to the modulation rate of THz ripple in theory; But in order to obtain higher photoproduction carrier concentration and bigger depth of modulation, the luminous flux of 810 nm modulated lasers need reach 0.8 μ J/cm
2High magnitude, its corresponding continuous wave output laser power then need reach 10
5More than the W, this makes it in practical application, receive very big restriction.
The utility model content
Utility model purpose: to the problem and shortage of above-mentioned existing existence; The utility model provides a kind of terahertz wave modulator; Thereby the recombination lifetime that overcomes charge carrier at the existing GaAs based end is too short so that the defective of the modulated laser of the superpower power of needs, has realized under the shooting conditions of low-power modulated laser, also carrying out High Speed Modulation to THz wave.
Technical scheme: for realizing above-mentioned utility model purpose; The utility model adopts following technical scheme: a kind of THz wave high-speed modulator; Comprise substrate layer; Growth has a cushion on this substrate layer, in this buffer growth the strained quantum well structure is arranged, at the metal metamaterial structure of being made up of metal resonant element periodic array of the upper surface of this strained quantum well structure preparation; Said strained quantum well structure comprises plural barrier layer and at least one potential well layer, and said potential well layer is in the middle of two barrier layers, and the said strained quantum well structure the superiors and orlop all are barrier layers; Said substrate layer is＜111＞planar orientation, and said cushion is identical with substrate layer material, and the band gap of said potential well layer is less than barrier layer, and the grating constant of said barrier layer and substrate layer is identical or differ and be no more than 0.5%.
When THz wave successively through metal metamaterial structure, strained quantum well structure, cushion, when penetrating from the lower surface of substrate layer at last; Other has a branch of wavelength is that the modulated laser of 810nm incides quantum well; Excite photo-generated carrier; Because thereby the generation of the lattice mismatch of barrier layer and potential well layer is suppressed electric field and can effectively be separated electronics and hole in the photo-generated carrier in the said strained quantum well structure; Thereby significantly increase the concentration and the recombination lifetime of photo-generated carrier, reduce the power of required externally modulated laser greatly.
As preferably, said substrate layer, cushion and barrier layer material are gallium arsenide, and said potential well layer material is an indium gallium arsenic.Perhaps said substrate layer and cushion are gallium arsenide, and said barrier layer material is a gallium aluminium arsenic, and said potential well layer material is a gallium arsenic phosphide.
As preferably, barrier layer and potential well layer all are＜111＞planar orientation in the said strained quantum well structure, and said barrier layer thickness is 10～300nm, and said potential well layer thickness is 1～30nm.
As preferably, said buffer layer thickness is 20～300nm.
As preferably, the thickness of metal resonant element is 0.2～5 micron in the said metal metamaterial structure, and the cycle is 20～80 microns.
Another purpose of the utility model has provided a kind of method for making of above-mentioned THz wave high-speed modulator, specifically may further comprise the steps:
A, through metal organic-matter chemical vapor phase epitaxy technique (MOCVD) or molecular beam epitaxy technique (MBE) one deck cushion of on the substrate layer of＜111＞planar orientation, growing;
B, continue on this cushion barrier layer, potential well layer and the barrier layer of growth＜111＞planar orientation successively then; Thereby constitute the Strained Single Quantum Well layer of＜111＞planar orientation; Wherein the band gap of the material selected for use of potential well layer is less than barrier layer, and the grating constant of said barrier layer and substrate layer is identical or differ in 0.5%;
C, the method through vapor deposition and etching prepare the metal metamaterial structure that the metal resonant element of one deck periodic arrangement is formed at said strained quantum well structure upper surface.
As preferably, said substrate layer, cushion and barrier layer constitute by gallium arsenide, and said potential well layer is made up of indium gallium arsenic.
Beneficial effect: compared with prior art, the utlity model has following advantage: through the strained quantum well structure of growth < 111>orientation on the substrate of < 111>orientation, at the extremely strong piezoelectric field of the inner acquisition of quantum well; This piezoelectric field can separate electronics and the hole in the photo-generated carrier effectively, prolongs the recombination lifetime and increase carrier concentration of photo-generated carrier significantly, thereby can greatly reduce the requirement to externally modulated laser power; Meanwhile; Component and quantum well width through In in the InGaAs/GaAs strained quantum well that changes < 111>orientation; Can regulate the degree that the size of inner piezoelectric field is separated with charge space neatly; And then can regulate the modulation rate of terahertz wave modulator easily as required, modulation rate can reach more than the 10Mbps.
Description of drawings
Fig. 1 is the structural representation of the utility model;
Fig. 2 is the band structure variation diagram of the said strained quantum well structure of the utility model under interior effect of building piezoelectric field;
Fig. 3 is the relation curve of indium (In) component concentration in the intensity of piezoelectric field and the potential well layer in the strained quantum well structure among the said embodiment of the utility model;
Fig. 4 is that the transmitance of THz wave under the said modulators modulate of the utility model is with external excitation intensity variations curve.
Wherein, substrate layer 1, cushion 2, metal metamaterial structure 3, barrier layer 4, potential well layer 5.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment, further illustrate the utility model.Should understand these embodiment only be used to the utility model is described and be not used in the restriction the utility model scope; After having read the utility model, those skilled in the art all fall within the application's accompanying claims institute restricted portion to the modification of the various equivalent form of values of the utility model.
As shown in Figure 1; A kind of THz wave high-speed modulator comprises semi-insulating GaAs (GaAs) substrate layer 1 of < 111>orientation; At first on substrate, pass through MOCVD metal organic-matter chemical vapor phase epitaxy technique growth one deck GaAs cushion 2; These GaAs buffer layer 2 THICKNESS CONTROL are in 20 to 300 nanometers; Thereby can finally obtain the strained quantum well architecture of high-quality＜111＞planar orientation with overcoming than big-difference what grating constant existed between indium gallium arsenic potential well layer 5 in the follow-up strained quantum well structure and the gallium arsenide substrate layer 1.
The barrier layer 4 of gallium arsenide barrier layer 4, indium gallium arsenic potential well layer 5 and gallium arsenide of growth＜111＞planar orientation successively on this cushion 2 then; Thereby constitute the InGaAs/GaAs strained quantum well structure of＜111＞planar orientation; The thickness of wherein said gallium arsenide barrier layer 4 is 10 to 300 nanometers, and the thickness of said indium gallium arsenic potential well layer 5 is 1 to 30 nanometer; At last prepare the metal metamaterial structure 3 that one deck is made up of metal resonant element periodic array through technologies such as photoetching, vapor deposition and etchings on the GaAs surface of the superiors; The ultra material thickness of this metal is 0.2～5 micron; Cycle is 20～80 microns, and the geometric configuration of resonant element can be the shape of any vibrotron unit.
The electric field energy of suppressing that produces owing to lattice mismatch in the InGaAs/GaAs quantum well of above-mentioned < 111>orientation separates electronics and hole in the photo-generated carrier effectively; Thereby can increase the concentration and the recombination lifetime of photo-generated carrier significantly, greatly reduce the power of required externally modulated laser;
The barrier layer of the InGaAs/GaAs quantum well of above-mentioned < 111>orientation can be by with gallium arsenide substrate layer crystal lattice couplings or differ 0.5% with interior gallium aluminium arsenic (AlGaAs) material, and potential well then can be lower than barrier material and be replaced with the compound semiconductor materials of backing material lattice mismatch by gallium arsenic phosphide (GaAsP) or other band gap (band gap).
The THz wave of being modulated is successively through metal metamaterial structure 3, strained quantum well structure, cushion 2, and the lower surface from GaAs (111) substrate layer 1 penetrates at last, is received and is detected by terahertz time-domain spectroscopy appearance (TDS).Simultaneously, other has a branch of wavelength is that the modulated laser of 810 nanometers shines on the InGaAs/GaAs strained quantum well structure of < 111>orientation, excites photo-generated carrier, and its concentration and recombination lifetime can be regulated and control by the strained quantum well structural parameters.Photoproduction carrier concentration changes with the change of modulating light intensity and is directly proportional with the recombination lifetime of charge carrier, so change the resonance frequency resonant intensity that modulated laser intensity can influence metamaterial structure.Transmitted spectrum reflection through the detected THz wave of TDS be exactly through THz wave ovennodulation, that Strength Changes speed is identical with light modulated.
< 111>introducing of the strained quantum well structure of orientation is the core innovative point of the utility model, also is the gordian technique that realizes with the laser instrument of common power THz wave being carried out High Speed Modulation.Because the grating constant of two kinds of semiconductor materials of the strained quantum well of composition < 111>orientation is different, can in quantum well, produce a piezoelectric field perpendicular to the quantum well direction by piezoelectric effect.As shown in Figure 2, generation suppress electric field (～10
5V/cm) make the band structure run-off the straight of quantum well, thereby cause electronics and hole effective separation spatially in the photo-generated carrier, therefore can significantly increase the concentration and the recombination lifetime of photo-generated carrier.It is estimated that the photo-generated carrier life-span can be by tens psecs in the common GaAs bulk material, extend to tens nanoseconds in the InGaAs/GaAs quantum well structure of the utility model < 111>orientation.The charge carrier recombination lifetime of this order of magnitude can either satisfy 10 Mbps even the more requirement of high modulation speed, can reduce the power of required modulated laser simultaneously again greatly, even can realize with the commercial semiconductor laser of common 100 mW.
Fig. 3 calculates<111>Indium arsenic gallium/gallium arsenide (In of orientation
xGa
1-xAs/GaAs) the piezoelectric field intensity in the quantum well is with the change curve of In component x.Can clearly find out, through changing the In component in the strained quantum well, can quantum well in the intensity of piezoelectric field, thereby the recombination lifetime of control photo-generated carrier.
Fig. 4 is that the transmitance of the THz wave modulator that passes through the utility model is with external excitation intensity variations curve.The maximum percentage modulation that visible frequency is 0.66 THz place among the figure can reach 59 %, and modulation rate is 10 Mbps.
Claims (6)
1. THz wave high-speed modulator; It is characterized in that: comprise substrate layer (1); Go up growth at this substrate layer (1) one cushion (2) is arranged; In this cushion (2) growth the strained quantum well structure is arranged, at the metal metamaterial structure of forming by metal resonant element periodic array (3) of the upper surface preparation of this strained quantum well structure; Said strained quantum well structure comprises plural barrier layer (4) and at least one potential well layer (5), and said potential well layer (5) is in the middle of two barrier layers (4), and the said strained quantum well structure the superiors and orlop all are barrier layers; Said substrate layer (1) is＜111＞planar orientation; Said cushion (2) is identical with substrate layer (1) material; The band gap of said potential well layer (5) is less than barrier layer (4), and the grating constant of said barrier layer (4) and substrate layer (1) is identical or differ and be no more than 0.5%.
2. according to the said THz wave high-speed modulator of claim 1, it is characterized in that: said substrate layer (1), cushion (2) and barrier layer (4) material are gallium arsenide, and said potential well layer (5) material is an indium gallium arsenic.
3. according to the said THz wave high-speed modulator of claim 1, it is characterized in that: said substrate layer (1) and cushion (2) are gallium arsenide, and said barrier layer (4) material is a gallium aluminium arsenic, and said potential well layer (5) material is a gallium arsenic phosphide.
4. according to the said THz wave high-speed modulator of claim 2; It is characterized in that: barrier layer (4) and potential well layer (5) all are＜111＞planar orientation in the said strained quantum well structure; Said barrier layer (4) thickness is 10～300nm, and said potential well layer (5) thickness is 1～30nm.
5. according to the said THz wave high-speed modulator of claim 2, it is characterized in that: said cushion (2) thickness is 20～300nm.
6. according to the said THz wave high-speed modulator of claim 1, it is characterized in that: the thickness of metal resonant element is 0.2～5 micron in the said metal metamaterial structure (3), and the cycle is 20～80 microns.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011205338463U CN202394003U (en) | 2011-12-19 | 2011-12-19 | TeraHertz high-speed modulator |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011205338463U CN202394003U (en) | 2011-12-19 | 2011-12-19 | TeraHertz high-speed modulator |
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| CN202394003U true CN202394003U (en) | 2012-08-22 |
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| CN2011205338463U Withdrawn - After Issue CN202394003U (en) | 2011-12-19 | 2011-12-19 | TeraHertz high-speed modulator |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102520532A (en) * | 2011-12-19 | 2012-06-27 | 东南大学 | High-speed terahertz modulator and production method thereof |
| CN108701964A (en) * | 2016-03-15 | 2018-10-23 | 株式会社东芝 | Semiconductor laser apparatus |
| CN110018531A (en) * | 2019-04-04 | 2019-07-16 | 湖南理工学院 | A kind of polarization insensitive Terahertz doped semiconductor Meta Materials lens |
| CN110828604A (en) * | 2019-11-18 | 2020-02-21 | 中国科学院上海技术物理研究所 | Adjustable room-temperature black arsenic-phosphorus terahertz detector and preparation method thereof |
-
2011
- 2011-12-19 CN CN2011205338463U patent/CN202394003U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102520532A (en) * | 2011-12-19 | 2012-06-27 | 东南大学 | High-speed terahertz modulator and production method thereof |
| CN102520532B (en) * | 2011-12-19 | 2014-07-09 | 东南大学 | High-speed terahertz modulator and production method thereof |
| CN108701964A (en) * | 2016-03-15 | 2018-10-23 | 株式会社东芝 | Semiconductor laser apparatus |
| CN110018531A (en) * | 2019-04-04 | 2019-07-16 | 湖南理工学院 | A kind of polarization insensitive Terahertz doped semiconductor Meta Materials lens |
| CN110828604A (en) * | 2019-11-18 | 2020-02-21 | 中国科学院上海技术物理研究所 | Adjustable room-temperature black arsenic-phosphorus terahertz detector and preparation method thereof |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20120822 Effective date of abandoning: 20140709 |
|
| RGAV | Abandon patent right to avoid regrant |