CN101639577A - Quantum dot optical modulator based on quantum-confined Stark effect - Google Patents
Quantum dot optical modulator based on quantum-confined Stark effect Download PDFInfo
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- CN101639577A CN101639577A CN200910026876A CN200910026876A CN101639577A CN 101639577 A CN101639577 A CN 101639577A CN 200910026876 A CN200910026876 A CN 200910026876A CN 200910026876 A CN200910026876 A CN 200910026876A CN 101639577 A CN101639577 A CN 101639577A
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Abstract
A quantum dot optical modulator based on quantum-confined Stark effect makes use of quantum confinement effect of quantum dots and consists of four layers of films which are sequentially covered and arrayed from the top to bottom, wherein the first layer is a first ITO film (1), the second layer is a PVK film (2), the third layer is an SiO2 film (4), the fourth layer is a second ITO film (3), anda fifth layer which is a glass substrate (5) is also involved. Therefore, the quantum dot optical modulator can change the light transmittance by changing the voltage applied onto the films. Due to light modulation, switch and filtration functions, the quantum dot optical modulator can be used as a photoswitch, a luminosity modulator and a filter used in the communication field.
Description
Technical field
The present invention proposes a kind of design proposal of photomodulator of membrane structure, be particularly related to the quantum limit Stark effect of utilizing quantum dot and realize modulating action light intensity, photoswitch and controlled color filter can be used as, optical communication field can be applied in, and the signal Processing field.
Background technology
When External Electrical Field during in the semiconductor quantum structured material, it shows a kind of electric absorption character, and promptly the wavelength of absorption edge and width thereof are along with extra electric field changes.This mechanism is called as the quantum limit Stark effect.
When external electric field parallel action during in quantum-well materials, it shows the electric absorption character similar to the body material, and absorption edge moves and widens and shows as the Franz-Keldysh effect.But when external electric field vertically acted on quantum-well materials, situation and parallel field had a great difference.
The quantum limit Stark effect is told us, and extra electric field has certain influence to the excited state of the electronics in the semiconductor, so can use the quantum limit Stark effect of quantum material to make photomodulator and switch.At present, utilizing the optical communication modulator of quantum limit Stark effect, most what utilize is three-five family's semiconductors of quantum well structure.The effect of quantum limit Stark effect in the quantum well structure of germanium obtained good checking.
And quantum dot called be " artificial atom ", the optical characteristics that he exists some atoms to have.Wherein, the structure of quantum dot has significant quantum limit Stark effect, so we can utilize the semiconductor of quantum-dot structure to make the photomodulator of quantum limit Stark effect type.The migration of the Stark of CdSe lowest excited attitude is very big, but because ubiquity photoionization characteristic in the quantum dot, and the randomness of the electronic position that comes out of ionization, so up to the present the Stark effect of colony's colloid quantum dot does not also observe directly.
Summary of the invention
Technical matters: the objective of the invention is to propose a kind of quantum dot optics modulator based on the quantum limit Stark effect, utilized the quantum limit Stark effect of quantum dot, reach modulating action, and then also can reach the effect of controlled filtering and switch light intensity.
Technical scheme: the quantum dot optics based on the quantum limit Stark effect of the present invention is achieved in that this luminosity modulator is rearranged by the covering of four-level membrane order; From top to bottom, ground floor is the film of an ITO, and the second layer is the PVK film, and the 3rd layer is SiO
2Film, the 4th layer is the film of the 2nd ITO, layer 5 is a glass substrate.
The film of the film of a described ITO, the 2nd ITO is the film of transparent conduction, introduces electrode respectively on this double-layer films, as the input end of control signal.The PVK film is the PUK film that comprises CdSe/ZnS type quantum dot of 900nm, wherein contains quantum dot concentration and wants the size of height and quantum dot near identical.This layer is owing to comprising a large amount of quantum dots, so have stronger quantum limit Stark effect.As can be seen, quantum dot luminosity modulator is a kind of electric capacity of nonisulated property, has small stable electric current to pass through.This small stable electric current can effectively suppress the electric field at random that photoionization produced in the colloid quantum dot film, this key point of the present invention just.
When adding the voltage of V on two electrodes, Stark migration meeting changes with the variation of impressed voltage, and the secondary linear equation is
The wherein variation of the energy of Δ E material two energy levels, V is an impressed voltage, and d is the thickness of thin layer, and α is the polarizability of material.When the energy level of material changes, will produce certain variation to the absorptivity of light.By the change of electrode both end voltage, we can obtain the variation of light wave absorptivity in quanta point material of certain wavelength as can be seen.(4) layer is the SiO of 3.5nm
2Film because SiO
2Be fine non-polarized material, thus the fine puncture that prevents electric current, and can reach stable electric current effect.
But the realization of the modulation function of this invention: when light signal advanced quantum dot luminosity modulator, film and the 4th layer of two ends that is the film top electrode of the 2nd ITO at an ITO add modulation voltage, in film, can produce the electric field of certain intensity, because the quantum limit Stark effect of quantum dot makes the absorptivity to light wave of membraneous material produce certain variation, and then reaches the effect to the light intensity modulation.
The key technical index of quantum dot luminosity modulator of the present invention---the amplitude of variation of absorption efficiency, modulating speed, the half-wave overall with is as follows respectively: for the amplitude of variation of absorptivity, from figure (2), we are the amplitude of variation at specific absorption rate peak and fluorescence intensity peak as can be seen, and this amplitude of variation directly has influence on the extinction ratio of device.Its response speed is in the ns level, and the response speed of modulation also can reach the ns level.
Beneficial effect: the present invention has following advantage compared with prior art:
The objective of the invention is to propose a kind of quantum dot optics modulator, can be used as photoswitch and controlled filtering based on the quantum limit Stark effect.The present invention utilizes the effect of quantum limit Stark effect in quantum dot, adopted the small stable electric current in the membrane type structure to control the electric field at random that photoionization produces, then can change the absorptivity of light in rete by changing outer field voltage, to the light intensity modulation effect, and then reach the effect and the controlled filter effect of switch.
1. quantum dot luminosity modulator proposed by the invention has used the QCSE electricity of quantum dot to cause absorption, and its amplitude of variation for the absorption efficiency of the light wave maximum of 625nm has reached 830cm
-1And this device that the material of traditionally QW type is done, 10
5First absorption peak can only widen 15% during the electric field of V/cm, and absorptivity can only reduce by 26%.
2. the modulating speed of quantum dot luminosity modulator proposed by the invention is the another big advantage of quanta point material at this on the one hand, and interband transition speed surpasses the ns level, and intersubband transitions can arrive the ps level.The extinction ratio of QD-QCSE luminosity modulator proposed by the invention is bigger, generally greater than 18DB.And the polarization irrelevant of the light patterns of this modulator and input.
3. quantum dot luminosity modulator proposed by the invention, as it harass of semiconductor material, reliability, temperature tolerance, aspects such as capacity usage ratio are all very desirable.
Description of drawings
Fig. 1 is the structural representation of modulator of the present invention.
Fig. 2 adds 0V, 4V, the absorption coefficient of this device behind the voltage of 8V.
Fig. 3 is the relation of electric current and voltage in the film.
Fig. 4 adds 0V, 4V, the fluorescence intensity of this device behind the voltage of 8V.
Embodiment
This luminosity modulator is covered by the four-level membrane order and rearranges; From top to bottom, ground floor is the film 1 of an ITO, and the second layer is that the PVK film is SiO for 2, the three layers
2Film is the film 3 of the 2nd ITO for 4, the four layers, and layer 5 is a glass substrate 5.
The film 1 of a described ITO, the film 3 of the 2nd ITO are the film of transparent conduction, introduce electrode respectively on this double-layer films, as the input end of control signal.
Below in conjunction with accompanying drawing technical scheme of the present invention is further described.
Quantum dot optics modulator based on the quantum limit Stark effect proposed by the invention, utilized the quantum limit Stark effect of quantum dot, realized the absorptivity regulation and control of light wave in quanta point material, and then used this action effect to realize modulation effect light intensity.Fig. 1. be structural representation, for the introducing of modulating action, we use the ito glass of film 3 of film 1, the 2nd ITO of an ITO to introduce electrode.Contain quantum dot in 4 layers of the films, so under the electric field action that voltage produces the quantum limit Stark effect can take place, light is absorptivity generation red shift phenomenon in material.That is to say that we can use voltage that the transmitance of light is regulated and control.So by changing the voltage on the electrode, we can modulate seeing through light intensity.Figure (2) transmitance of light wave as can be seen changes.Change according to this, we can obtain the modulation voltage that we need.
In order to realize the function of photoswitch, we can be according to the transmitance of ripple under different voltages of certain wavelength, add certain modulation voltage after, the transmitance of light is reduced, be the opening state of photoswitch.And when not adding modulation voltage, be the closed condition of photoswitch.
For the function of controllable filter, the different as can be seen transmitance difference of light wave in film among the figure (2) is so for the light wave of some wavelength, can reach the effect of filtering.By the effect of modulation voltage, we can make the transmitance of film change, and will reach the effect of controlled filtering.
Preparation method of the present invention is as follows:
Preparation method of the present invention is as follows: adopt electron beam evaporation method to plate ito thin film 100nm on the quartz substrate of twin polishing, square resistance is about 20 ohm, and then the plating 5nm SiO that uses the same method
2Adopt whirl coating at SiO
2The PVK:CdSe/ZnS polymeric media film of preparation thickness 900nm on the substrate.The method evaporation 100nm film of using d.c. sputtering at last is as electrode.
Claims (3)
1. quantum dot optics modulator based on the quantum limit Stark effect is characterized in that: this luminosity modulator is covered by the four-level membrane order and rearranges; From top to bottom, ground floor is the film (1) of an ITO, and the second layer is PVK film (2), and the 3rd layer is SiO
2Film (4), the 4th layer is the film (3) of the 2nd ITO, layer 5 is glass substrate (5).
2. the quantum dot optics modulator based on the quantum limit Stark effect according to claim 1, the film (3) that it is characterized in that film (1), the 2nd ITO of a described ITO is the film of transparent conduction, on this double-layer films, introduce electrode respectively, as the input end of control signal.
3. the quantum dot optics modulator based on the quantum limit Stark effect according to claim 1, it is characterized in that PVK film (2) is the PUK film that comprises CdSe/ZnS type quantum dot of 900nm, wherein contain quantum dot concentration and want the size of height and quantum dot near identical.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105487264A (en) * | 2015-12-29 | 2016-04-13 | 东南大学 | Electro-optical modulating device preparing method based on quantum restriction Stark effect |
| CN108364706A (en) * | 2018-01-29 | 2018-08-03 | 太原理工大学 | A kind of multipurpose electric field generating apparatus for super cold polar molecule manipulation |
| CN108873393A (en) * | 2018-05-29 | 2018-11-23 | 河海大学 | A method of preparing the optical modulator based on CdSe nanometer stick array |
| CN108983446A (en) * | 2017-06-01 | 2018-12-11 | Tcl集团股份有限公司 | A kind of light intensity modulator |
-
2009
- 2009-05-27 CN CN200910026876A patent/CN101639577A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105487264A (en) * | 2015-12-29 | 2016-04-13 | 东南大学 | Electro-optical modulating device preparing method based on quantum restriction Stark effect |
| CN105487264B (en) * | 2015-12-29 | 2018-11-09 | 东南大学 | A kind of electro-optical modulation device preparation method based on quantum confined stark effect |
| CN108983446A (en) * | 2017-06-01 | 2018-12-11 | Tcl集团股份有限公司 | A kind of light intensity modulator |
| CN108983446B (en) * | 2017-06-01 | 2021-04-06 | Tcl科技集团股份有限公司 | Light intensity modulator |
| CN108364706A (en) * | 2018-01-29 | 2018-08-03 | 太原理工大学 | A kind of multipurpose electric field generating apparatus for super cold polar molecule manipulation |
| CN108364706B (en) * | 2018-01-29 | 2019-10-11 | 太原理工大学 | A kind of multipurpose electric field generating apparatus for super cold polar molecule manipulation |
| CN108873393A (en) * | 2018-05-29 | 2018-11-23 | 河海大学 | A method of preparing the optical modulator based on CdSe nanometer stick array |
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