阅读说明：本技术 一种宽禁带啁啾混合等离激元波导布拉格光栅 (Wide-bandgap chirped hybrid plasmon waveguide Bragg grating ) 是由 许吉 陆昕怡 张思成 周天诺 刘宁 陆云清 于 2020-05-26 设计创作，主要内容包括：本发明揭示了一种宽禁带啁啾混合等离激元波导布拉格光栅,所述宽禁带啁啾混合等离激元波导布拉格光栅的最外两端具有导纳匹配层结构,所述宽禁带啁啾混合等离激元波导布拉格光栅包括匹配层结构、第一组混合等离激元波导布拉格光栅、第二组混合等离激元波导布拉格光栅和第三组混合等离激元波导布拉格光栅。该混合等离激元波导布拉格光栅结构简单,能在预设波段实现对TM模式的宽禁带。根据需求设计结构可以实现特定波段的模式宽带选频,通过改变匹配区的波导长度和光栅周期可以实现对特定波段内的通频带的灵活选择,并且能够对高频通带及高频禁带的位置和透射谱调节和优化。(The invention discloses a wide-bandgap chirped hybrid plasmon waveguide Bragg grating, wherein the outmost two ends of the wide-bandgap chirped hybrid plasmon waveguide Bragg grating are provided with admittance matching layer structures, and the wide-bandgap chirped hybrid plasmon waveguide Bragg grating comprises a matching layer structure, a first group of hybrid plasmon waveguide Bragg gratings, a second group of hybrid plasmon waveguide Bragg gratings and a third group of hybrid plasmon waveguide Bragg gratings. The mixed plasmon waveguide Bragg grating is simple in structure and can realize a wide forbidden band of a TM mode in a preset waveband. The structure can be designed according to requirements to realize mode broadband frequency selection of a specific waveband, flexible selection of a pass band in the specific waveband can be realized by changing the waveguide length and the grating period of the matching region, and the positions and transmission spectrums of a high-frequency pass band and a high-frequency forbidden band can be adjusted and optimized.)

1. The utility model provides a wide forbidden band chirp mixes plasmon waveguide Bragg grating which characterized in that:

the wide-bandgap chirped hybrid plasmon waveguide Bragg grating is composed of a first admittance matching layer hybrid plasmon waveguide structure at an incident end, a second admittance matching layer hybrid plasmon waveguide structure at an emergent end and three groups of hybrid plasmon waveguide Bragg gratings in the middle;

the first group of mixed plasmon waveguide Bragg gratings, the second group of mixed plasmon waveguide Bragg gratings and the third group of mixed plasmon waveguide Bragg gratings are formed by alternately arranging two different mixed plasmon waveguides.

2. The wide-bandgap chirped hybrid plasmon waveguide bragg grating of claim 1, wherein: the first admittance matching layer hybrid plasmon waveguide structure, the second admittance matching layer hybrid plasmon waveguide structure, the first group of hybrid plasmon waveguide Bragg gratings, the second group of hybrid plasmon waveguide Bragg gratings and the third group of hybrid plasmon waveguide Bragg gratings are all arranged on SiO₂A layer of high refractive index material Si is placed centrally over the substrate, on SiO₂A support layer ZnO is respectively arranged on both sides of the substrate to support the metal Ag layer, and a transition layer Si is filled between the support layer and the metal layer₃N₄，

The widths w of the high-refractive-index material Si layers of the first admittance matching layer hybrid plasmon waveguide structure, the second admittance matching layer hybrid plasmon waveguide structure, the first group of hybrid plasmon waveguide Bragg gratings, the second group of hybrid plasmon waveguide Bragg gratings and the third group of hybrid plasmon waveguide Bragg gratings are different.

3. The wide-bandgap chirped hybrid plasmon waveguide bragg grating of claim 1, wherein: the first group of mixed plasmon waveguide bragg gratings are formed by alternately arranging N1 periods of two mixed plasmon waveguides of a mixed plasmon waveguide a with w being 175nm and a mixed plasmon waveguide b with w being 350nm in the sequence of abab … … a, and the period number N1 of the first group of mixed plasmon waveguide bragg gratings is 9.5.

4. The wide-bandgap chirped hybrid plasmon waveguide bragg grating of claim 1, wherein: the second group of mixed plasmon waveguide bragg gratings are formed by alternately arranging N2 periods of two mixed plasmon waveguides of a mixed plasmon waveguide c with w being 200nm and a mixed plasmon waveguide d with w being 450nm in a dcdc … … dc sequence, and the period number N2 of the second group of mixed plasmon waveguide bragg gratings is 10.

5. The wide-bandgap chirped hybrid plasmon waveguide bragg grating of claim 1, wherein: the third group of mixed plasmon waveguide bragg gratings are formed by alternately arranging N3 periods of two mixed plasmon waveguides of w-250 nm mixed plasmon waveguide e and w-525 nm mixed plasmon waveguide f in the order of fefe … … fe, and the period number N3 of the third group of mixed plasmon waveguide bragg gratings is 10.

6. The wide-bandgap chirped hybrid plasmon waveguide bragg grating of claim 1, wherein the period length of the wide-bandgap chirped hybrid plasmon waveguide bragg grating is Λ ═ d_B，1+d_B，2The specific parameter values are determined at the incident wavelength by the following formula:

wherein, Re (n)_eff1) And Re (n)_eff2) The real parts of the effective refractive indices of waveguide a and waveguide b, respectively; d_B，1And d_B，2The lengths of the waveguide a and the waveguide b in one period respectively; q is a Bragg stage number, and 1 is taken; lambda [ alpha ]_bThe center wavelength corresponding to the set of bragg gratings.

7. The wide-bandgap chirped hybrid plasmon waveguide bragg grating of claim 1, wherein: the duty ratios of the first group of mixed plasmon waveguide Bragg gratings, the second group of mixed plasmon waveguide Bragg gratings and the third group of mixed plasmon waveguide Bragg gratings in one period are all 0.5, namely d_B，l＝d_B，2＝Λ/2＝163nm。

8. The wide-bandgap chirped hybrid plasmon waveguide bragg grating of claim 1, wherein: the incident end admittance matching layer structure is a hybrid plasmon waveguide with w equal to 350nm, and the length of the hybrid plasmon waveguide in the propagation direction is 105 nm.

9. The wide-bandgap chirped hybrid plasmon waveguide bragg grating of claim 1, wherein: the exit end admittance matching layer structure is a mixed plasmon waveguide with w being 525nm, and the length of the mixed plasmon waveguide in the propagation direction is 85 nm.

Technical Field

The invention relates to a wide-bandgap chirped hybrid plasmon waveguide Bragg grating which can be applied to the technical fields of optical communication and integrated optics.

Background

In the development of modern communications, strengthening the integration degree of devices has been an important pursuit in photonics research, and various nano-optical waveguide structures typified by photonic crystal waveguides and surface plasmon waveguides have been proposed and developed. Among them, the surface plasmon waveguide breaks the diffraction limit of the conventional optical research, but the waveguide cannot be used for long distance transmission due to ohmic loss, so that a hybrid plasmon waveguide is proposed so that loss and field locality can be balanced. The waveguide structure reduces loss by introducing a low refractive index medium between metal and a high refractive index medium, and ensures excellent field localization capability. Due to the above characteristics, the academia has designed various integrated photonic devices based on hybrid plasmonic waveguides, including surface plasmon nanolens, high efficiency optical modulators and polarizing beamers.

Among them, as a wavelength-dependent photonic device bragg grating, combining the HPWs structure with outstanding filtering characteristics and low loss characteristics has attracted many researchers' research. Xiao Jig et al designed an HPSW-based ultra-compact broadband Bragg grating (Xiao J, Liu J, Zheng Z, et al. design and analysis of a nanostructured graded on a hybrid slab waveguide [ J ]. Journal of optics, 2011, 13 (10): 105001.), which can have 75% transmittance at the center wavelength of 1550nm and an excellent effective mode area, and has a wide application prospect in the direction of high-integration optoelectronics. Importantly, an optical device with the characteristics of high integration and high utilization rate can realize multiple functions by performing fine adjustment on a certain structure, so that the problem of how to solve the problem of the singleness of a forbidden band mode on the basis of an original band-pass filter is very meaningful to research.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a wide-bandgap chirped hybrid plasmon waveguide bragg grating.

The purpose of the invention is realized by the following technical scheme: the wide-bandgap chirped hybrid plasmon waveguide Bragg grating is composed of a first admittance matching layer hybrid plasmon waveguide structure at an incident end, a second admittance matching layer hybrid plasmon waveguide structure at an emergent end and three groups of hybrid plasmon waveguide Bragg gratings in the middle; the first group of mixed plasmon waveguide Bragg gratings, the second group of mixed plasmon waveguide Bragg gratings and the third group of mixed plasmon waveguide Bragg gratings are formed by alternately arranging two different mixed plasmon waveguides.

Preferably, the first admittance matching layer hybrid plasmon waveguide structure, the second admittance matching layer hybrid plasmon waveguide structure, the first group hybrid plasmon waveguide bragg grating, the second group hybrid plasmon waveguide bragg grating and the third group hybrid plasmon waveguide bragg grating are all in SiO₂A layer of high refractive index material Si is placed centrally over the substrate, on SiO₂A support layer ZnO is respectively arranged on both sides of the substrate to support the metal Ag layer, and a transition layer Si is filled between the support layer and the metal layer₃N₄And the widths w of the high-refractive-index material Si layers of the first admittance matching layer hybrid plasmon waveguide structure, the second admittance matching layer hybrid plasmon waveguide structure, the first group of hybrid plasmon waveguide Bragg gratings, the second group of hybrid plasmon waveguide Bragg gratings and the third group of hybrid plasmon waveguide Bragg gratings are different.

Preferably, the first group of mixed plasmon waveguide bragg gratings is formed by alternately arranging N1 periods in the order of abab … … a by two kinds of mixed plasmon waveguides, i.e., a mixed plasmon waveguide a with w equal to 175nm and a mixed plasmon waveguide b with w equal to 350nm, and the period number N1 of the first group of mixed plasmon waveguide bragg gratings is equal to 9.5.

Preferably, the second group of hybrid plasmon waveguide bragg gratings is formed by alternately arranging N2 periods in the order of dccd … … dc by two kinds of hybrid plasmon waveguides, i.e., a hybrid plasmon waveguide c with w being 200nm and a hybrid plasmon waveguide d with w being 450nm, and the period number N2 of the second group of hybrid plasmon waveguide bragg gratings is 10.

Preferably, the third group of hybrid plasmon waveguide bragg gratings is formed by alternately arranging N3 periods of two hybrid plasmon waveguides, i.e., a hybrid plasmon waveguide e with w equal to 250nm and a hybrid plasmon waveguide f with w equal to 525nm, in the order of fefe … … fe, and the period number N3 of the third group of hybrid plasmon waveguide bragg gratings is equal to 10.

Preferably, the period length in the wide-bandgap chirped hybrid plasmon waveguide bragg grating is Λ ═ d_B，1+d_B，2The specific parameter values are determined at the incident wavelength by the following formula:

wherein, Re (n)_eff1) And Re (n)_eff2) The real parts of the effective refractive indices of waveguide a and waveguide b, respectively; d_B，1And d_B，2The lengths of the waveguide a and the waveguide b in one period respectively; q is a Bragg stage number, and 1 is taken; lambda [ alpha ]_bThe center wavelength corresponding to the set of bragg gratings.

Preferably, the duty ratios of the first, second and third groups of mixed plasmon waveguide bragg gratings in one period are all 0.5, that is, d_B，1＝d_B，2＝Λ/2＝163nm。

Preferably, the incident end admittance matching layer structure is a hybrid plasmon waveguide with w ═ 350nm, and the length of the hybrid plasmon waveguide in the propagation direction is 105 nm.

Preferably, the exit-end admittance matching layer structure is a hybrid plasmon waveguide with w ═ 525nm, and the length of the hybrid plasmon waveguide in the propagation direction is 85 nm.

Compared with the prior art, the invention adopting the technical scheme has the following technical effects: the mixed plasmon waveguide Bragg grating is simple in structure, can cut off a TM mode at a specified wide waveband, can flexibly design and realize mode frequency selection of the specified wide waveband according to requirements, can realize dynamic selection of a pass band in the specified waveband by changing the waveguide length and the grating period of a matching region, and can optimize the adjustment of the positions of a high-frequency pass band and a high-frequency forbidden band and a transmission spectrum.

Drawings

Fig. 1 is a schematic structural view of the xy cross section of the structure of the hybrid plasmon waveguide of the present invention.

Fig. 2 is a schematic cross-sectional view of the structure xz of the hybrid plasmon waveguide bragg grating of the present invention.

Fig. 3 is a graph showing the change of the real part of the TM mode effective refractive index with wavelength when the high refractive index material of the present invention has a Si width w of 175nm, 350nm, 200nm, 450nm, 250nm, and 525 nm.

Fig. 4 is a graph showing the change of the imaginary part of the TM mode effective refractive index with wavelength when the high refractive index material of the present invention has a Si width w of 175nm, 350nm, 200nm, 450nm, 250nm, and 525 nm.

FIG. 5 shows the present invention when the structural parameters are set as: TM mode transmission spectra of the hybrid plasmon waveguide bragg grating were incident perpendicularly from air with incident light at w 1-4000 nm, w 2-200 nm, h 1-100 nm, h 2-15 nm, h 3-450 nm, h 4-400 nm, w1 a-175 nm, w1 b-350 nm, w2 a-200 nm, w2 b-450 nm, w3 a-250 nm, and w3 b-525 nm.

Detailed Description

Objects, advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments. The embodiments are merely exemplary for applying the technical solutions of the present invention, and any technical solution formed by replacing or converting the equivalent thereof falls within the scope of the present invention claimed.

The invention discloses a wide-bandgap chirped hybrid plasmon waveguide Bragg grating which is composed of a first admittance matching layer hybrid plasmon waveguide structure at an incident end, a second admittance matching layer hybrid plasmon waveguide structure at an emergent end and three groups of hybrid plasmon waveguide Bragg gratings in the middle. The first group of mixed plasmon waveguide Bragg gratings, the second group of mixed plasmon waveguide Bragg gratings and the third group of mixed plasmon waveguide Bragg gratings are formed by alternately arranging two different mixed plasmon waveguides.

The first admittance matching layer hybrid plasmon waveguide structure, the second admittance matching layer hybrid plasmon waveguide structure, the first group of hybrid plasmon waveguide Bragg gratings, the second group of hybrid plasmon waveguide Bragg gratings and the third group of hybrid plasmon waveguide Bragg gratings are all arranged on SiO₂A layer of high refractive index material Si is placed centrally over the substrate, on SiO₂Two sides of the substrate are respectively provided with a support layer ZnO for supporting the infinite-width metal Ag layer, and a transition layer Si is filled between the support layer and the metal layer₃N₄。

The widths w of the high-refractive-index material Si layers of the first admittance matching layer hybrid plasmon waveguide structure, the second admittance matching layer hybrid plasmon waveguide structure, the first group of hybrid plasmon waveguide Bragg gratings, the second group of hybrid plasmon waveguide Bragg gratings and the third group of hybrid plasmon waveguide Bragg gratings are different.

The mixed plasmon waveguide is formed by placing a high-refractive-index material Si layer in the middle above a SiO2 substrate, respectively placing a supporting layer ZnO on each of two sides of a SiO2 substrate, supporting an infinite-width metal Ag layer, and filling a transition layer Si3N4 between the supporting layer and the metal layer. The widths w of the respective high refractive index material Si layers of the different hybrid plasmon waveguides are different.

The first group of mixed plasmon waveguide bragg gratings are formed by alternately arranging N1 periods of two mixed plasmon waveguides of a mixed plasmon waveguide a with w being 175nm and a mixed plasmon waveguide b with w being 350nm in the sequence of abab … … a, and the period number N1 of the first group of mixed plasmon waveguide bragg gratings is 9.5.

The second group of mixed plasmon waveguide bragg gratings are formed by alternately arranging N2 periods of two mixed plasmon waveguides of a mixed plasmon waveguide c with w being 200nm and a mixed plasmon waveguide d with w being 450nm in a dcdc … … dc sequence, and the period number N2 of the second group of mixed plasmon waveguide bragg gratings is 10.

The third group of mixed plasmon waveguide bragg gratings are formed by alternately arranging N3 periods of two mixed plasmon waveguides of w-250 nm mixed plasmon waveguide e and w-525 nm mixed plasmon waveguide f in the order of fefe … … fe, and the period number N3 of the third group of mixed plasmon waveguide bragg gratings is 10.

The grating period lengths of the first group of mixed plasmon waveguide Bragg gratings, the second group of mixed plasmon waveguide Bragg gratings and the third group of mixed plasmon waveguide Bragg gratings are Λ, the duty ratios in one period are 0.5, namely d_B，1＝d_B，2＝Λ/2＝163nm。

The incident end admittance matching layer structure is a mixed plasmon waveguide with w being 350nm, and the length d of the mixed plasmon waveguide in the propagation direction_M，1Is 105 nm.

The structure of the outgoing end admittance matching layer is a mixed plasmon waveguide with w being 525nm, and the length d of the mixed plasmon waveguide in the propagation direction_M，2Is 85 nm.

Fig. 1 is a schematic diagram of a cross-sectional structure of a hybrid plasmonic waveguide, the material distribution of the structure being as follows: the dimensions of the structure are set as follows: w 1-4000 nm, w 2-200 nm, h 1-100 nm, h 2-15 nm, h 3-450 nm, and h 4-400 nm; wherein w1 is the width of the metal Ag layer, h1 is the thickness of Ag, h2 is the thickness of the transition layer Si3N4, w2 is the width of the support layer ZnO, h3 is the thickness of the support layer, w is the width of the high refractive index layer Si, and h4 is the thickness of the high refractive index layer Si.

Fig. 2 is a schematic longitudinal sectional structure diagram of a waveguide device in which bragg gratings having refractive indexes alternately arranged are introduced on the basis of the hybrid plasmon waveguide of fig. 1.

d_B，1＝d_B，2＝Λ/2＝163nm，w1a＝175nm，w1b＝350nm，w2a＝200nm，w2b＝450nm，w3a＝250nm，w3b＝525nm，d_M，1＝105nm，d_M，285 nm. Other materials and parameters of construction are consistent with those of FIG. 1.

The structure of figure 1 is subjected to mode analysis by using a finite element algorithm of COMSOL Multiphysics software, parametric scanning is started, the wavelength range is from 1200nm to 1900nm, the step length is 10nm, the effective refractive index of the structure under different wavelengths is calculated, and the calculation result comprises a real part and an imaginary part of the effective refractive index when the width w of the high-refractive-index material Si is 175nm, 350nm, 200nm, 450nm, 250nm and 525 nm. Fig. 3 is a curve of the real part of the TM mode effective refractive index with the wavelength when the width w of the high refractive index material Si is 175nm, 350nm, 200nm, 450nm, 250nm, and 525nm, where the abscissa in fig. 3 is the wavelength and the ordinate is the real part of the refractive index; fig. 4 is a graph showing a change curve of an imaginary part of the TM mode effective refractive index with a wavelength when the width w of the high refractive index material Si is 175nm, 350nm, 200nm, 450nm, 250nm, and 525nm, where the abscissa in fig. 4 is the wavelength and the ordinate is the imaginary part of the refractive index.

When the structural parameters are set as: w 1-4000 nm, w 2-200 nm, h 1-100 nm, h 2-15 nm, h 3-450 nm, h 4-400 nm, w1 a-175 nm, w1 b-350 nm, w2 a-200 nm, w2 b-450 nm, w3 a-250 nm, w3 b-525 nm, d_B，1＝d_B，2＝A/2＝163nm，d_M，1＝105nm，d_M，2When the wavelength is 85nm, a TM mode transmission spectrum of the hybrid plasmon waveguide bragg grating in which incident light is vertically incident from the air as in fig. 5 is obtained, and the abscissa in fig. 5 is the wavelength and the ordinate is the transmission efficiency.

The three mixed plasmon waveguide Bragg gratings are all internally provided with two mixed plasmon waveguides with different widths w in a periodic and alternate arrangement mode, the incident end of each grating is a mixed plasmon waveguide with w equal to 350nm, and the emergent end of each grating is a mixed plasmon waveguide with w equal to 525 nm. The hybrid plasmon waveguide Bragg gratings with the same three sections of period lengths are spliced in series, and the overall structure is optimized by utilizing the admittance matching principle, so that the hybrid plasmon waveguide Bragg grating with the double forbidden bands is obtained.

The period length of the wide-bandgap chirped hybrid plasmon waveguide Bragg grating is Λ -d_B，1+d_B，2The specific parameter values are obtained by the following formula:

wherein, Re (n)_eff1) And Re (n)_eff2) The real parts of the effective refractive indices of waveguide a and waveguide b, respectively; d_B，1And d_B，2The lengths of the waveguide a and the waveguide b in one period respectively; q is a Bragg stage number, and 1 is taken; lambda [ alpha ]_bThe center wavelength corresponding to the set of bragg gratings.

The grating period lengths of the three groups of mixed plasmon waveguide Bragg gratings are all 163 nm.

The admittance matching layer mixed plasmon waveguide structure of the incident end and the emergent end can modulate the waveguide length of the admittance matching area through the admittance matching principle so as to realize the transmission spectrum optimization of a low-frequency pass band, a high-frequency pass band and a forbidden band frequency band.

The transmission spectrum of the mixed plasmon waveguide Bragg grating can obviously vibrate at two sides of a forbidden band, in order to reduce the vibration peak of the transmission spectrum of the passband at the two sides of the forbidden band and improve the transmittance of the passband, the length of a waveguide matching region can be modulated by utilizing the admittance matching principle, so that the admittance value of the mixed plasmon waveguide Bragg grating reaches a specific optimal value Y_op＝X_op+iZ_op. This optimum is achieved by calculating the admittance of the outermost layer of the bragg structure region, i.e. as follows:

wherein, η_RAnd η_IIs the real and imaginary part of the outermost admittance, which is N through its effective refractive index of width dB_A＝n_A-iκ_ACalculated from the material of (A), i.e. η_A＝η_R-iη_I＝n_A-iκ_A. Effective phase thickness at normal incidence is defined as_A＝α-iβ＝(2π/λ)(n_A-iκ_A)d_A。

The admittance of the matching layer is calculated by:

wherein the phase thickness of the matching layer is_M＝(2π/λ)n_Md_MRefractive index n of simple substrate for easy calculation_subIs set to 1. By adjusting d_MSo that Y is_MIs close to Y_opNamely admittance matching, and then transmission spectrum optimization of a TM mode low-frequency pass band, a TM mode high-frequency pass band and a TM mode forbidden band is realized.

The incident end admittance matching layer structure is a mixed plasmon waveguide with w being 350nm, and the length d of the mixed plasmon waveguide in the propagation direction_M，1Is 105 nm;

the structure of the outgoing end admittance matching layer is a mixed plasmon waveguide with w being 525nm, and the length d of the mixed plasmon waveguide in the propagation direction_M，2Is 85 nm.

The mixed plasmon waveguide Bragg grating can realize the cut-off of a TM mode in a wide waveband range near 1450nm-1650nm, can realize the dynamic selection of a pass band in a specified waveband by changing the waveguide length and the grating period of a matching region, and can realize the adjustment and optimization of the positions and transmission spectrums of a high-frequency pass band and a high-frequency forbidden band.

The invention has various embodiments, and all technical solutions formed by adopting equivalent transformation or equivalent transformation are within the protection scope of the invention.