CN111175894B - Electro-optical modulator based on low-refractive-index polymer photonic crystal microcavity - Google Patents
Electro-optical modulator based on low-refractive-index polymer photonic crystal microcavity Download PDFInfo
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- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
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Abstract
The invention discloses an electro-optical modulator based on a low-refractive-index polymer photonic crystal microcavity, and belongs to the technical field of optical communication. The waveguide-type silicon dioxide waveguide filter comprises a silicon dioxide substrate, a polymer waveguide, strip-shaped gold electrodes which are symmetrical left and right, and a silicon dioxide coating layer. Etching a series of symmetrical elliptical holes on the polymer waveguide body to form a low-refractive-index polymer one-dimensional photonic crystal nano-beam microcavity; the elliptical hole is divided into a transition hole area and a mirror image hole area; firstly, inputting a wide-spectrum Gaussian light source at the end face of a photonic crystal nano-beam microcavity, applying voltage to a strip-shaped gold electrode on one side, and grounding the voltage of a strip-shaped gold electrode on the other side; then, the intensity and the phase of incident light waves passing through the polymer photonic crystal nano-beam microcavity are changed by utilizing the fast linear electro-optic effect of the polymer photonic crystal nano-beam microcavity; and finally, the spectrograph observes the spectral change to finish the modulation process from the electric signal to the optical signal. The invention has small size, easy waveguide integration, large modulation bandwidth and high efficiency.
Description
Technical Field
The invention belongs to the technical field of optical communication, and particularly relates to an electro-optical modulator based on a low-refractive-index polymer photonic crystal microcavity.
Background
In modern information systems, information generated by human beings and machines exists and propagates in the form of light almost at a certain stage, and an optical interconnection network which takes light waves as carriers and optical fibers as transmission media occupies a core position in all levels of information internetworks, so that integrated photonic waveguide devices increasingly become important technical research directions.
The on-chip electro-optical modulator is a core device in a modern optical communication system, and has attracted wide attention of scientific researchers of various countries. To date, various types of electro-optical modulators have been developed, such as a waveguide type, a mach-zehnder type, a surface plasmon type, and an optical microcavity type.
Because the optical microcavity has an ultra-high quality factor Q to mode volume V ratio (Q/V), the confinement of the optical mode can be greatly enhanced. Researchers have therefore successively proposed electro-optical modulators based on optical microcavities, such as whispering gallery mode microcavities (ring, disk), fabry-perot microcavities, and photonic crystal microcavities (two-dimensional, one-dimensional).
Compared to whispering gallery mode microcavity and fabry-perot microcavity, photonic crystal microcavities have a higher quality factor to mode volume ratio (Q/V). Compared with a two-dimensional flat-plate photonic crystal microcavity, the one-dimensional photonic crystal nano-beam microcavity has the characteristics of easy waveguide integration, compact size, flexible application and the like.
In recent years, electro-optic modulators based on one-dimensional photonic crystal nano-beam cavities are proposed in succession, and mainly silicon-doped electro-optic modulators based on carrier effect are available, such as silicon-organic polymer hybrid integrated electro-optic modulators proposed in documents 1: j. hendrickson, r. soref, j. sweet, w. buchwald, "ultrasonic silicon-crystalline nanobeam electron-optical modulator: design and simulation," opt.express,22(3),3271-3283(2014),. document 2: s. Inoue and A.Otomo, "Electro-optical polymer/silicon hybrid crystal waveguides," applied. Phys. Lett.103,171101(2013), the silicon-based hybrid integrated Electro-optic modulator proposed by T.Pan, C.Qiu, J.Wu, X.Jiang, B.Liu, Y.Yang, H.Zhou, R.Soref, and Y.Su, "Analysis of Electro-optical substrate a graphene-silicon hybrid 1D phosphor waveguide architecture," Opti.Express, 23.18.23357 (TM.) the hybrid integrated Electro-optic modulator proposed by "silicon-based modulators J-Sa-5 J.2015-solar modulator," J.85, J.M.P.J.M.M., "Sa.P.M.M.M.M.M.M.," Sa.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M.M..
However, the electro-optical modulators mentioned in the above documents are all based on one-dimensional photonic crystal nano-beam cavities, in which silicon is doped, and silicon-graphene hybrid integrated electro-optical modulators utilize a carrier dispersion effect mechanism, and the inherent nonlinearity and absorption of the effect can cause nonlinear distortion and increase of power consumption during optical signal transmission, which is more obvious when advanced format signals are modulated.
To overcome the limitation of free carrier effect in silicon materials, researchers have proposed hybrid integrated electro-optic modulators incorporating materials with linear electro-optic effects, such as: silicon-polymer and silicon-lithium niobate hybrid integrated electro-optical modulator. Although the hybrid integrated modulator utilizes the fast primary electro-optic effect, the electro-optic overlap of the effective electric field and the effective material region is reduced, resulting in a reduction in modulation efficiency.
Disclosure of Invention
The invention aims at the problems that the traditional electro-optical modulator of the silicon-based photonic crystal microcavity mostly utilizes a carrier dispersion effect mechanism to modulate advanced signals, causes signal distortion, has a non-compact structure, is not beneficial to on-chip integration and the like; the electro-optical modulator based on the low-refractive-index polymer photonic crystal microcavity is simple and compact in structure, easy to integrate on a chip and capable of achieving excellent performances of high efficiency and large bandwidth.
The electro-optic modulator comprises the following components in sequence from bottom to top: the bottom layer of the silicon dioxide substrate base plate, the middle layer of the silicon dioxide substrate base plate comprise a polymer waveguide, strip-shaped gold electrodes which are symmetrical on the left side and the right side, and an upper layer of silicon dioxide coating layer. The middle layer is attached to the bottom layer of the silicon dioxide substrate base plate, and a silicon dioxide coating layer is spin-coated on the top of the middle layer.
The polymer waveguide is of a cuboid structure, a series of elliptical holes symmetrical about a central line are etched on the polymer waveguide body through electron beam lithography, and a low-refractive-index polymer one-dimensional photonic crystal nano-beam microcavity is formed; the elliptical holes are divided into a transition hole area and a mirror image hole area, the long axis and the short axis of each hole are obtained by optimizing the duty ratio calculated by the photon energy band theory, the long axis of each elliptical hole linearly decreases from 1.44 mu m to 1.12 mu m in the transition hole area, and the short axis linearly decreases from 165nm to 125nm in the transition hole area. In the mirror-hole region, the major axis of the elliptical hole was 1.12 μm and the minor axis was 125 nm.
Then, the number of holes in the transition area is 50 on each side, and the number of holes in the mirror image area is 20 on each side; thereby obtaining the Q value of the photonic crystal nano-beam microcavity
Resonant wavelength
Thus obtaining the photon lifetime tau of the cavityphλ Q/2 π c, c is the speed of light), the maximum EO bandwidth f is further estimated3dBCan reach 78 GHz.
The specific dimensions of the two strip-shaped gold electrodes are designed as follows:
first, the effective average electric field over the photonic crystal nanobeam microcavity is calculated by integrating the effective electric field in the y-direction of the polymer waveguide region.
Then, fixing the width of the gold electrode to be 2um, the length of the gold electrode is the same as the length of the polymer waveguide, sequentially increasing the thickness from 400nm to 500nm to 1000nm, and respectively calculating the corresponding average electric field size under each thickness, wherein the calculation result shows that the average electric field size is increased to be gentle and rapid along with the increase of the thickness of the electrode; considering the coating process and the cost, and considering the condition of enough average electric field, the thickness of 800nm is selected in a compromise way.
The spacing between each gold electrode and the photonic crystal nanobeam microcavity is calculated as follows:
firstly, the effective average electric field of the photonic crystal nano beam microcavity is calculated, 7um, 6um, 5um and 4um are sequentially selected according to the distance between two gold electrodes, and along with the reduction of the distance between the two gold electrodes, the average electric field generated by the middle photonic crystal nano beam microcavity is increased, so that the electro-optic efficiency is also increased, but the smaller the electrode distance is, the more the optical mode loss caused by metal absorption is increased, and the electrode distance is selected to be 5 um.
The distance between the two gold electrodes is 5um, the width of the middle photonic crystal nano-beam microcavity is 3um, and the distance between each gold electrode and the photonic crystal nano-beam microcavity is 1.5 um.
After the photonic crystal nano-beam microcavity and the gold electrodes on the two sides are etched on the silicon dioxide substrate, a silicon dioxide coating layer with the thickness of 2-3 um is spin-coated on the two gold electrodes and the crystal nano-beam microcavity by a spin coating process. Wherein, the silicon dioxide coating layers are filled in the elliptical holes of the photonic crystal nano-beam microcavity and the spacing between the gold electrodes; in order to form Z-direction refractive index symmetry, the thickness of the spin coating is the same as that of the silicon dioxide substrate below.
Furthermore, the refractive index of the photonic crystal nano-beam micro-cavity is 1.699 (n)cavity) (ii) a The refractive index of the silica substrate was 1.45 (n)sub) Refractive index contrast (n)cavity/nsub) As low as 1.17.
The working principle of the electro-optical modulator is as follows:
firstly, inputting a wide-spectrum Gaussian light source on the end face of a photonic crystal nano-beam microcavity by using a three-dimensional finite time domain difference method (3D-FDTD) and a Finite Element Method (FEM), applying voltage to a strip-shaped gold electrode on one side, and grounding the voltage of a strip-shaped gold electrode on the other side to form an external electric field;
then, by utilizing the fast linear electro-optic effect of the polymer photonic crystal nano-beam microcavity, the refractive index of the polymer can be slightly changed, so that the intensity and the phase of incident light waves passing through the photonic crystal nano-beam microcavity are changed;
and finally, observing the spectrum change at the output end of the spectrometer, and finishing a modulation process from the electric signal to the optical signal, namely, regulating and controlling the spectrum movement of the optical signal by the voltage signal.
Through numerical simulation, the magnitude of the applied voltage is adjusted and increased by steps of 2.5V, and the output transmission spectrum of the modulator is obtained, and the modulation efficiency of the output spectrum is as high as 16 pmV. The electro-optical modulator is based on a linear electro-optical effect, the voltage required for shifting the output transmission spectrum by the full width at half maximum is 6.25V, and the size of the resonant cavity is 80um, so that the half-wave voltage product obtained by multiplying the voltage by the length is as low as 0.05V cm.
The invention has the advantages that:
1) compared with the traditional electro-optical modulator, the electro-optical modulator based on the low-refractive-index polymer photonic crystal microcavity has the characteristics of small size, easiness in waveguide integration, large modulation bandwidth and the like.
2) Compared with a similar silicon-based one-dimensional photonic crystal nano beam cavity electro-optical modulator, the electro-optical modulator based on the low-refractive-index polymer photonic crystal microcavity has a compact structure, the length of the whole device is only 80 micrometers, and the half-wave voltage product is as low as 0.05V-cm, so that the on-chip integration is facilitated.
3) The electro-optical modulator based on the low-refractive-index polymer photonic crystal microcavity is simple in preparation process, only needs one-step electron beam etching, and is low in polymer material cost compared with a silicon wafer, so that the whole device is more economical and practical under the condition of realizing the same performance.
Drawings
FIG. 1 is a schematic diagram of the structure of an electro-optic modulator based on a low-index polymer photonic crystal microcavity according to the present invention.
FIG. 2 is a schematic structural diagram of a low-refractive-index polymer one-dimensional photonic crystal nanobeam microcavity according to the present invention.
FIG. 3 is a schematic diagram of the distribution of the electro-optic interaction field when the electro-optic modulator based on the low-refractive-index polymer photonic crystal microcavity of the invention is in operation.
FIG. 4 is a schematic diagram of the electro-optic response output spectrum of the electro-optic modulator of the present invention with different applied voltages.
Detailed Description
The present invention will be described in further detail and with reference to the accompanying drawings so that those skilled in the art can understand and practice the invention.
The invention firstly provides an electro-optic modulator designed based on a Polymer-on-Insulator (Polymer-on-Insulator) one-dimensional photonic crystal nano-beam cavity, the refractive index ratio of a Polymer material to a substrate material is as low as 1.17, the modulation efficiency is as high as 16pm/V, the modulation bandwidth can reach 78GHz, the length of a device is only 80 mu m, and the half-wave voltage product is as low as 0.05V cm; the method can be applied to the fields of optical communication, electric field sensing, tunable photonic devices and the like, and has high application value.
The electro-optic modulator is shown in fig. 1, and sequentially comprises the following components from bottom to top: the bottom layer of the silicon dioxide substrate base plate, the middle layer of the silicon dioxide substrate base plate comprise a polymer waveguide, strip-shaped gold electrodes which are symmetrical on the left side and the right side, and an upper layer of silicon dioxide coating layer. The middle layer is adhered to the silicon dioxide substrate base plate at the bottom layer, and a silicon dioxide coating layer is in spin coating on the top of the middle layer.
The polymer waveguide is a rectangular parallelepiped structure, as shown in fig. 2, and breaks the original periodicity in the structure by artificially introducing defects into the photonic crystal, allowing the previously forbidden light to propagate therein. The target mode of light at the 1550nm communication band is localized in the defect region based on the photon energy band calculations. Optimization determined that the polymer waveguide was 80um long, 3um wide and 550nm thick. Etching a series of elliptical holes which are symmetrical about a central line on a polymer waveguide body through electron beam lithography to form a low-refractive-index polymer one-dimensional photonic crystal nano-beam microcavity; since the elliptical aperture forms a larger photon forbidden band and better limits light than a conventional circular aperture. The elliptical holes are divided into a transition hole area and a mirror image hole area. In the transition hole region, the major axis of the elliptical hole linearly decreases from 1.44 μm to 1.12 μm, and the minor axis linearly decreases from 165nm to 125 nm. In the mirror hole area, the major axis of the elliptical hole is 1.12 mu m, and the minor axis is 125nm and remains unchanged; all adjacent holes are equally spaced, 510 nm.
In this embodiment, when the low refractive index polymer one-dimensional photonic crystal nanobeam microcavity is used as the electro-optical modulator, the Q value of the microcavity needs to be limited to 104Left and right because of its photon lifetime (τ) with the cavityph) Proportional, cavity photon lifetime in vacuum from τphCalculating as lambda Q/2 pi c; λ is the resonance wavelength and c is the speed of light. This results in a cut-off frequency f3dB＝1/τphThe upper limit of (3). If EO bandwidth of the order of 100GHz is desired, the Q should not exceed 104. In the adopted structure that the hole number of the transition zone is 50 per side and the hole number of the mirror zone is 20 per side, the structure
Thus, the cavity photon lifetime τphCalculated as 12.8ps and estimated maximum EO Bandwidth f3dBAnd can reach 78 GHz.
The long axis and the short axis of the elliptical hole are obtained by optimizing a duty ratio f calculated by a photon energy band theory, and the duty ratio calculation formula is as follows:
rxis the minor axis of the elliptical hole, ryIs a major axis of the elliptical hole; a is the center-to-center distance between the two elliptical holes; omeganbThe width of the polymer waveguide.
The two strip-shaped gold electrodes are symmetrical about the middle photonic crystal nano-beam microcavity structure, and the specific size design of the gold electrodes is as follows:
firstly, the effective average electric field E on the photonic crystal nano-beam microcavity is calculated by integrating the effective electric field in the y direction of the polymer waveguide regionavgThe calculation formula is as follows:
dx, dy, and dz are the triple integrals for the polymer waveguide xyz in the three directions;
is the square of the optical field in the photonic crystal nano beam microcavity, namely the optical field power. EyIs the effective electric field component in the y-direction of the applied electric field.
Then, the width of the gold electrode is equal to the effective average electric field E of the photonic crystal nano-beam microcavityavgThe influence is not large, so the width of the gold electrode is fixed to be 2um, the length is the same as the length of the polymer waveguide, the thickness is sequentially increased from 400nm to 1000nm, the corresponding average electric field size under each thickness is respectively calculated, and the calculation result shows that the average electric field size is increased to be gentle as the thickness of the electrode is increased. Considering the coating process and the cost, and considering the condition of enough average electric field, the thickness of 800nm is selected in a compromise way.
The spacing between each gold electrode and the photonic crystal nanobeam microcavity is calculated as follows:
firstly, calculate the effective average electric field of photonic crystal nanometer bundle microcavity, 7um, 6um, 5um and 4um are selected in proper order to the interval between two gold electrodes, and along with the reduction of interval between two gold electrodes, the average electric field that middle photonic crystal nanometer bundle microcavity produced increases, leads to the lightning efficiency also to increase, but, the electrode spacing is less, because the optical mode loss that the metal absorption arouses can increase, is unfavorable for the insertion loss of device like this, considers that the selection electrode spacing is 5 um.
The distance between the two gold electrodes is 5um, the width of the middle photonic crystal nano-beam microcavity is 3um, and the distance between each gold electrode and the photonic crystal nano-beam microcavity is 1.5 um.
After the photonic crystal nano-beam microcavity and the gold electrodes on the two sides are etched on the silicon dioxide substrate, a silicon dioxide coating layer with the thickness of 2-3 um is spin-coated on the two gold electrodes and the crystal nano-beam microcavity by a spin coating process. Wherein, the silicon dioxide coating layers are filled in the elliptical holes of the photonic crystal nano-beam microcavity and the spacing between the gold electrodes; in order to form Z-direction refractive index symmetry, the thickness of the spin coating is the same as that of the silicon dioxide substrate below.
Furthermore, the refractive index of the photonic crystal nano-beam micro-cavity is 1.699 (n)cavity) (ii) a The refractive index of the silica substrate was 1.45 (n)sub) Refractive index contrast (n)cavity/nsub) As low as 1.17.
The working principle of the electro-optical modulator is as follows:
firstly, inputting a wide-spectrum Gaussian light source on the end face of a photonic crystal nano-beam microcavity by using a three-dimensional finite time domain difference method (3D-FDTD) and a Finite Element Method (FEM), applying voltage to a strip-shaped gold electrode on one side, and grounding the voltage of a strip-shaped gold electrode on the other side to form an external electric field;
then, by utilizing the fast linear electro-optic effect of the polymer photonic crystal nano-beam microcavity, the refractive index of the polymer can be slightly changed, so that the intensity and the phase of incident light waves passing through the photonic crystal nano-beam microcavity are changed;
the electro-optic effect calculation formula is as follows:
Δnavgis the average refractive index change of the polymer; n is the refractive index of the polymer without an electric field, namely 1.699; r is33The maximum electro-optic coefficient of the electro-optic polymer is 110 pm/V.
And finally, observing the spectrum change at the output end of the spectrometer, and finishing a modulation process from the electric signal to the optical signal, namely, regulating and controlling the spectrum movement of the optical signal by the voltage signal.
When the electro-optical modulator works, the electro-optical interaction in the polymer one-dimensional photonic crystal nano beam cavity is obtained through numerical simulation, as shown in fig. 3, the applied voltage is adjusted to increase by a step diameter of 2.5V, the output transmission spectrum of the modulator is obtained, and the modulation efficiency of the output spectrum is as high as 16pm/V, as shown in fig. 4. The shift in the position of the output transmission peak spectrum when the unit voltage of 1V was applied was the slope in the graph, and the voltage required to output the shift in the full width at half maximum of the transmission spectrum (equal to the resonance frequency divided by the cavity Q value) was 6.25V. Here the resonance peak positions are: 1556.85 nm; the cavity Q value is 15500, and the calculated full width at half maximum is 100 pm; it can be seen that the applied voltage of 1V can be shifted by 16pm, then 100pm is needed, and since the electro-optic modulator is based on the linear electro-optic effect, 100pm/16pm is 6.25V, the size of the resonant cavity is 80um, and thus the product of the half-wave voltage is as low as 0.05V cm by multiplying the voltage by the length.
The observation of the output spectrum shows that the output modulation spectrum has good linear modulation when voltage is applied, and the spectral line width is almost unchanged, which indicates that the electro-optical modulator is not absorptive, namely the device has low power consumption.
For proposed micro-scale resonator modulators, whose modulation bandwidth is mainly limited by cavity photon lifetime, the modulator modulation bandwidth can be as high as 78 GHz.
Claims (3)
1. The electro-optical modulator based on the low-refractive-index polymer photonic crystal microcavity is characterized by sequentially comprising the following components from bottom to top: the middle layer of the silicon dioxide substrate base plate comprises a polymer waveguide, strip-shaped gold electrodes which are symmetrical on the left side and the right side, and a silicon dioxide coating layer on the upper layer; the middle layer is attached to the silicon dioxide substrate base plate at the bottom layer, and a silicon dioxide coating layer is spin-coated on the top of the middle layer;
the polymer waveguide is of a cuboid structure, a series of elliptical holes symmetrical about a central line are etched on the polymer waveguide body through electron beam lithography, and a low-refractive-index polymer one-dimensional photonic crystal nano-beam microcavity is formed; the elliptical holes are divided into a transition hole area and a mirror image hole area, the long axis and the short axis of each hole are obtained by optimizing the duty ratio calculated by the photon energy band theory, in the transition hole area, the long axis of the elliptical hole is linearly decreased from 1.44 mu m to 1.12 mu m, and the short axis is linearly decreased from 165nm to 125 nm; in the mirror hole area, the major axis of the elliptical hole is 1.12 mu m, and the minor axis is 125nm and remains unchanged;
then, the number of holes in the transition area is 50 on each side, and the number of holes in the mirror image area is 20 on each side; thereby obtaining photonic crystal nanobeam microcavity
Resonant wavelength
Thus obtaining the photon lifetime tau of the cavityphWhere c is the speed of light, further estimate the maximum EO bandwidth f3dBCan reach 78 GHz;
the specific dimensions of the two strip-shaped gold electrodes are designed as follows:
firstly, calculating an effective average electric field on a photonic crystal nano-beam microcavity by integrating an effective electric field in the y direction of a polymer waveguide region;
then, fixing the width of the gold electrode to be 2um, the length of the gold electrode is the same as the length of the polymer waveguide, sequentially increasing the thickness from 400nm to 500nm to 1000nm, and respectively calculating the corresponding average electric field size under each thickness, wherein the calculation result shows that the average electric field size is increased to be gentle and rapid along with the increase of the thickness of the electrode; considering the coating process and the cost, and considering the condition of enough average electric field, the thickness of 800nm is selected in compromise;
the spacing between each gold electrode and the photonic crystal nanobeam microcavity is calculated as follows:
firstly, calculating an effective average electric field of a photonic crystal nano-beam microcavity, sequentially selecting 7um, 6um, 5um and 4um as the distance between two gold electrodes, and increasing the average electric field generated by the middle photonic crystal nano-beam microcavity with the decrease of the distance between the two gold electrodes to increase the electro-optic efficiency, but the smaller the electrode distance is, the more the optical mode loss caused by metal absorption is increased, and the electrode distance is selected to be 5 um;
the distance between the two gold electrodes is 5um, the width of the middle photonic crystal nano-beam microcavity is 3um, and the distance between each gold electrode and the photonic crystal nano-beam microcavity is 1 um;
after a photonic crystal nano-beam microcavity and gold electrodes on two sides are etched on a silicon dioxide substrate, a silicon dioxide coating layer with the thickness of 2-3 um is spin-coated on the two gold electrodes and the crystal nano-beam microcavity by a spin coating process; wherein, the silicon dioxide coating layers are filled in the elliptical holes of the photonic crystal nano-beam microcavity and the spacing between the gold electrodes; in order to form Z-direction refractive index symmetry, the thickness of the spin coating is the same as that of the silicon dioxide substrate below.
2. The electro-optic modulator of claim 1 wherein the photonic crystal microbeam microcavity has a refractive index n, and wherein the photonic crystal microbeam microcavity has a refractive index ncavityIs 1.699; refractive index n of silica substratesubIs 1.45, and has a refractive index contrast difference ncavity/nsubAs low as 1.17.
3. The electro-optic modulator based on the low refractive index polymer photonic crystal microcavity of claim 1, wherein the electro-optic modulator operates according to the following principle:
firstly, inputting a wide-spectrum Gaussian light source on the end face of a photonic crystal nano-beam microcavity by using a three-dimensional finite time domain difference method (3D-FDTD) and a Finite Element Method (FEM), applying voltage to a strip-shaped gold electrode on one side, and grounding the voltage of a strip-shaped gold electrode on the other side to form an external electric field;
then, by utilizing the fast linear electro-optic effect of the polymer photonic crystal nano-beam microcavity, the refractive index of the polymer can be slightly changed, so that the intensity and the phase of incident light waves passing through the photonic crystal nano-beam microcavity are changed;
finally, observing the spectrum change at the output end of the spectrometer, and completing a modulation process from the electric signal to the optical signal, namely, adjusting and controlling the spectrum movement of the optical signal by the voltage signal;
adjusting the magnitude of the applied voltage through numerical simulation, increasing by steps of 2.5V to obtain the output transmission spectrum of the modulator, wherein the modulation efficiency of the output spectrum is as high as 16 pmV; the electro-optical modulator is based on a linear electro-optical effect, the voltage required for shifting the output transmission spectrum by the full width at half maximum is 6.25V, and the size of the resonant cavity is 80um, so that the half-wave voltage product obtained by multiplying the voltage by the length is as low as 0.05V cm.
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