CN104596958A - Analytical method of series-connection LPWG (Long Period Waveguide Grating) biochemical sensor - Google Patents

Abstract

The invention discloses an analytical method of a series-connection LPWG (Long Period Waveguide Grating) biochemical sensor. The coupling property of the LPWG is utilized to enable light in a certain bandwidth range by taking the resonant wavelength as a center in incident light wavelength to enter a tested cladding layer through coupling of the LPWG 1, then the light is coupled by LPWG2 and is enabled to enter a waveguide core layer, and then the light and fundamental modes transmitted in the same direction in the waveguide core layer are interference-output; when a tested substance is changed, resonant wavelength in the output spectrum is offset, and the offset can be detected and the concentration of the tested substance can be calculated; and an absorption spectrum signal of liquid in the output spectrum is analyzed and the tested substance is qualitatively analyzed. According to the analytical method, the problem that the traditional biochemical sensor adopts a specific sensitive film having high cost and single detection index for qualitative analysis is solved; and besides, the problem that the limited bandwidth caused by a water absorption band is required to be avoided in the quantitative determination of water-containing liquid is solved.

Description

Based on the analytical approach of the biochemical sensor of series connection LPWG

Technical field

The invention belongs to integrated optics field, bio-photon field and spectral analysis field, be specifically related to Mode Coupling and the transport property of long-period waveguide grating, and quantification and qualification model and method in biochemical sensitive mechanism.

Background technology

At present, for the biochemical sensor of development both at home and abroad, it is no matter the biochemical sensor detected based on electrochemical principle, microflow control technique or carry out based on optical principle, usually in the biochemical sensitive membrane of the surface of contact deposit of device and measured matter, according to by sensitive membrane to the absorption of predetermined substance or and its generation physicochemical change complete selection and the differentiation of measured matter, and the prism needing volume larger and optical circulator.This design proposal, not only add the design complexity of device, also can increase size and the cost of sensor, and each sensitive membrane only can be carried out qualitative to a kind of respective substance usually, along with the increase of service time and frequency of utilization, sensitive membrane can occur that selectivity is deteriorated, and produce cross-sensitivity, sensitivity and the detection efficiency of sensor can be reduced like this, cause qualitative inaccurate.

Accurate refractive index (RI) sensing is for extremely important scientific research and commercial Application.Because the quantitative detection of substantially all biological and chemical materials can by detecting its refractive index to realize, so, be a condition precedent for the refractive index of accurately resolving measured matter biochemical sensitive.Usual tested substance needs to be admitted to surveyed area as solvent as carrier by water, if selected detection light source wave band comprises the absorption information of water, then can not complete quantitatively or can produce considerable influence to quantitative result.Like this just can only select the detection light source of specific band, which limits sensing range.Particularly at mid and far infrared wave band, the fundamental frequency of basic all substances (comprising biochemical gas, liquid) absorbs information all at mid and far infrared wave band, the absorption coefficient of material is than at large 1 ~ 2 order of magnitude of near-infrared band, greatly can improve detection sensitivity, but at mid and far infrared wave band, the absorption of water is very strong, and the appearance of this challenge brings very big puzzlement to biochemistry detection.Visible, in the research process of biochemical sensor hydrous matter to biochemical sensitive in the adverse effect of quantitative problem carry out further investigation and will be very important.

Summary of the invention

The present invention is the above-mentioned technical matters solved, and proposes a kind of analytical approach of the biochemical sensor based on series connection LPWG.

The technical solution used in the present invention is: based on the analytical approach of the biochemical sensor of series connection LPWG, described sensor comprises sandwich layer and tested covering, and sandwich layer extends LPWG in the side contacted with tested covering to tested covering direction ₁and LPWG ₂, described method specifically comprises the following steps:

S1: incident light enters through sandwich layer first end, part light is through LPWG ₁be coupled into tested covering, part light transmits along sandwich layer;

S2: the part light transmitted along tested covering is through LPWG ₂be coupled into sandwich layer;

S3: in the part light obtained by step S2 and the sandwich layer of step S1, the part interference of light of co-propagate exports, and obtains output spectra, the side-play amount of resonance wavelength and the absorption spectrum information of wherein material in computational analysis output spectra.

Further, in step S1, can through LPWG ₁the part light being coupled into tested covering is the light of the certain bandwidth range centered by resonance wavelength.

Further, described sandwich layer is rectangular waveguide, and described tested covering is rectangular waveguide.

Further, it is characterized in that, described step S1 is specially: incident light enters from waveguide first end, is L through length ₁lPWG ₁after, the output amplitude of sandwich layer mould and tested cladding mode is respectively A _co(L ₁) and A _cl(L ₁),

$\left[\begin{array}{c}{A}_{\mathrm{co}}\left(L_1\right)\\ A_{\mathrm{cl}}\left(L_1\right)\end{array}\right]{=e}^{j\frac{{\mathrm{\β}}_{\mathrm{co}}+{\mathrm{\β}}_{\mathrm{cl}}}{2}{L}_1}\left[\begin{array}{cc}{e}^{j\frac{{\mathrm{KL}}_1}{2}}& 0\\ 0& e^{-j\frac{{\mathrm{KL}}_1}{2}}\end{array}\right]\·\left[\begin{array}{cc}{t}_1{e}^{j\frac{{\mathrm{\θ}}_1}{2}}& j{r}_1\\ j{r_1}^{*}& t_1{e}^{-j\frac{{\mathrm{\θ}}_1}{2}}\end{array}\right]\left[\begin{array}{c}{A}_{\mathrm{co}}\left(0\right)\\ A_{\mathrm{cl}}\left(0\right)\end{array}\right];$

Wherein, Λ is LPWG ₁cycle, L ₁for LPWG ₁length, for LPWG ₁constant, for LPWG ₁locate the amplitude of tested cladding mode, κ ₁represent LPWG ₁coupling coefficient, for LPWG ₁the amplitude of place's sandwich layer mould, in s ₁for with LPWG ₁relevant constant, for light through length be L ₁lPWG ₁after phase shift, for the effective refractive index of sandwich layer mould, for the effective refractive index of tested cladding mode, $\mathrm{\δ}{\mathrm{\β}}_1={\mathrm{\β}}_{\mathrm{co}}-{\mathrm{\β}}_{\mathrm{cl}}-K_1=\frac{2\mathrm{\π}}{\mathrm{\λ}}(N_{\mathrm{eff}}^{\mathrm{co}}-N_{\mathrm{eff}}^{\mathrm{cl}}-\frac{\mathrm{\λ}}{\mathrm{\Λ}})$ For LPWG ₁the phase mismatch factor, λ represents resonance centre wavelength.

Further, described step S2 also comprises step S20: be the waveguide of d through length, and the output amplitude of sandwich layer mould and tested cladding mode is respectively A _co(L ₁+ d) and A _cl(L ₁+ d);

$\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d)\\ A_{\mathrm{cl}}(L_1+d)\end{array}\right]=\left[\begin{array}{cc}{e}^{j{\mathrm{\β}}_{\mathrm{co}}d}& 0\\ 0& e^{j{\mathrm{\β}}_{\mathrm{cl}}d}\end{array}\right]\·\left[\begin{array}{c}{A}_{\mathrm{co}}\left(L_1\right)\\ A_{\mathrm{cl}}\left(L_1\right)\end{array}\right];$

Wherein, d is LPWG ₁with LPWG ₂the length of connection waveguide.

Further, described step S2 is specially: be L through length ₂lPWG ₂after, the output amplitude of sandwich layer mould and tested cladding mode is respectively A _co(L ₁+ d+L ₂) and A _cl(L ₁+ d+L ₂);

$\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d+L_2)\\ A_{\mathrm{cl}}(L_1+d+L_2)\end{array}\right]{=e}^{j\frac{{\mathrm{\β}}_{\mathrm{co}}+{\mathrm{\β}}_{\mathrm{cl}}}{2}{L}_2}\left[\begin{array}{cc}{e}^{j\frac{{\mathrm{KL}}_2}{2}}& 0\\ 0& e^{-j\frac{{\mathrm{KL}}_2}{2}}\end{array}\right]\·\left[\begin{array}{cc}{t}_2{e}^{j\frac{{\mathrm{\θ}}_2}{2}}& j{r}_2\\ j{r_2}^{*}& t_2{e}^{-j\frac{{\mathrm{\θ}}_2}{2}}\end{array}\right]\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d)\\ A_{\mathrm{cl}}(L_1+d)\end{array}\right];$

Wherein, Λ is LPWG ₂cycle, L ₂for LPWG ₂length, for LPWG ₂constant, for LPWG ₂locate the amplitude of tested cladding mode, κ ₂represent LPWG ₂coupling coefficient, for LPWG ₂the amplitude of place's sandwich layer mould, in s ₂for with LPWG ₂relevant constant, for light through length be L ₂lPWG ₂rear phase shift, $\mathrm{\δ}{\mathrm{\β}}_2={\mathrm{\β}}_{\mathrm{co}}-{\mathrm{\β}}_{\mathrm{cl}}-K_2=\frac{2\mathrm{\π}}{\mathrm{\λ}}(N_{\mathrm{eff}}^{\mathrm{co}}-N_{\mathrm{eff}}^{\mathrm{cl}}-\frac{\mathrm{\λ}}{\mathrm{\Λ}})$ For LPWG ₂the phase mismatch factor, λ represents resonance centre wavelength.

Further, described step S3 is specially: exported by sandwich layer mould to export with tested cladding mode and carry out interference and obtain output spectra, the side-play amount of resonance wavelength and the absorption spectrum information of wherein material in computational analysis output spectra, calculate sandwich layer mould simultaneously and export and be respectively T (L with the output power of tested cladding mode ₁+ d+L ₂) and R (L ₁+ d+L ₂),

$\left[\begin{array}{c}T(L_1+d+L_2)\\ R(L_1+d{+L}_2)\end{array}\right]=\left[\begin{array}{c}{\left|\right|A_{\mathrm{co}}(L_1+d+L_2)\left|\right|}^2\\ {\left|\right|A_{\mathrm{cl}}(L_1+d+L_2)\left|\right|}^2\end{array}\right];$

Wherein, || || ²represent and " determinant " computing is first done to matrix, then carry out the computing of " mould ".

Further, described waveguide parameter is determined by following methods step;

S01: the rectangular waveguide sandwich layer physical dimension of single mode operation and the parameter of sandwich layer within the scope of the incident wavelength determining for resonance wavelength by Marcatili method;

Described rectangular waveguide sandwich layer physical dimension specifically comprises: the width a of sandwich layer mould, the height h of sandwich layer mould, the depth delta h of grating;

The parameter of described sandwich layer mould specifically comprises: transmission β _co, along the transmission K in x, y direction _x, K _y, and calculate in resonance central wavelength lambda _runder sandwich layer Effective index

S02: by the physical dimension of the tested covering of Marcatili method determination rectangular waveguide and the parameter of tested cladding mode;

Described rectangular waveguide tested covering physical dimension specifically comprises: the width b of tested cladding mode, the height h of tested cladding mode;

The parameter of described tested cladding mode specifically comprises: transmission β _cl, along the transmission K in x, y direction _x, K _y, and calculate in resonance central wavelength lambda _runder tested cladding mode effective refractive index

S03: according to the effective refractive index of sandwich layer mould and the effective refractive index of tested cladding mode utilize the phase-matching condition of LPWG determine the periods lambda of LPWG.

Beneficial effect of the present invention: the analytical approach of the biochemical sensor based on series connection LPWG that the present invention proposes, by utilizing the coupled characteristic of LPWG, by the light of the certain bandwidth range in incident light wave centered by resonance wavelength, passes through LPWG ₁be coupled into tested covering, through LPWG ₂again this part optically-coupled is entered waveguide core layer, interfere exporting with the basic mode of symport in waveguide core layer.When liquid changes, the resonance wavelength in output spectra can offset, and can calculate strength of fluid by detecting side-play amount.Analyze the absorption spectrum signal of liquid in output spectra, realize the qualitative of fluid to be measured.Method of the present invention solves conventional biochemical sensor on the one hand and relies on expensive and the certain sensitive film that Testing index is single carrys out problem qualitatively; Solve the bandwidth limitation problems needing the absorption bands avoiding water to bring in liquid, aqueous quantitative detection on the other hand.To realizing the LPWG biochemical sensitive technical research being greater than the high sensitivity of 2000nm/RIU, small size, low cost, wide application background is possessed by military biochemical war agent context of detection, important technical support can be provided in the solution of the civil area problem such as the food concerning national economy, drug safety more and more serious now, there is important scientific meaning and far-reaching realistic meaning.

Accompanying drawing explanation

The three-dimensional structure diagram of the new polymers LPWG biochemical sensor that Fig. 1 provides for the embodiment of the present invention;

Wherein, 1 is LPWG ₁, 2 is the cascade waveguides between two LPWG, and 3 is LPWG ₂, 4 is liquid claddings, and 5 is polymer waveguide sandwich layers, and 6 is SiO ₂covering, 7 is Si substrates, and 8 is liquid turnover micropores.

The Mode Coupling of the sensor mechanism that Fig. 2 provides for the embodiment of the present invention and transport property schematic diagram;

Wherein, (a) is vertical view, and (b) is cross-sectional view.

The calculated results output spectra of the biochemical sensor that Fig. 3 provides for the embodiment of the present invention.

Fig. 4 is the solution of the present invention process flow diagram.

Embodiment

Understand technology contents of the present invention for ease of those skilled in the art, below in conjunction with accompanying drawing, content of the present invention is explained further.

Be illustrated in figure 1 the three-dimensional structure diagram of new polymers LPWG biochemical sensor of the present invention, see the three-dimensional structure diagram of Fig. 1, sensor of the present invention is by two series connection long-period waveguide grating, i.e. LPWG1 and LPWG ₂, and fluid to be measured forms as side covering.Incident light enters LPWG1 through waveguide first end and part optical signals is coupled into tested covering 4, and the light in sandwich layer enters LPWG through one section of straight wave guide 2 ₂.Sandwich layer adopts polymeric material, and other covering except tested covering 4 adopts silicon dioxide.Whole sensor is by sandwich layer 5, SiO ₂covering 6, substrate 7 and micropore 8 form.

Be illustrated in figure 2 Mode Coupling and the transport property schematic diagram of the sensor mechanism of invention, utilize the coupled characteristic of LPWG as shown in the figure, by the light of the certain bandwidth range in incident light centered by resonance wavelength, described certain bandwidth range arranges decision by concrete grating, its method for solving can list of references " the lithium niobate long-period waveguide grating of electro-optical tuning. Chen Kaixin, the intelligent .2012 of Li Jun ", pass through LPWG ₁be coupled into tested covering, through LPWG ₂again this part optically-coupled is entered sandwich layer, export with the sandwich layer Mode interference of symport in sandwich layer.When measured matter changes, the resonance wavelength in output spectra can offset, and such as, when measured matter is liquid, calculates strength of fluid, analyzing the absorption spectrum signal of liquid in output spectra, realizing the qualitative of fluid to be measured by detecting side-play amount.

The analytical approach of the biochemical sensor based on series connection LPWG of the present invention, specifically comprises the following steps:

First carry out key parameter calculating, described key parameter calculating comprises step by step following:

S01: the rectangular waveguide sandwich layer physical dimension of single mode operation and the parameter of sandwich layer mould within the scope of the incident wavelength determining for resonance wavelength by Marcatili method;

Described rectangular waveguide sandwich layer physical dimension specifically comprises: the width a of sandwich layer, the height h of sandwich layer, the tooth depth Δ h of grating;

The parameter of described sandwich layer mould specifically comprises: transmission β, along the transmission K in x, y direction _x, K _y, and calculate the sandwich layer Effective index under resonance central wavelength lambda concrete computing method are the common method of this area, no longer elaborate herein.

S02: by the physical dimension of the tested covering of rectangular waveguide and the parameter of tested cladding mode in Marcatili method determining step 1a;

Described rectangular waveguide tested covering physical dimension specifically comprises: the width b of tested covering, the height h of tested covering;

The parameter of described tested cladding mode specifically comprises: transmission β, along the transmission K in x, y direction _x, K _y, and calculate the tested bag Effective index under resonance central wavelength lambda

S03: according to the effective refractive index of sandwich layer mould and the effective refractive index of tested cladding mode utilize the phase-matching condition of LPWG determine the periods lambda of LPWG thus.

Secondly, according to the key parameter drawn, carry out output spectra calculating, be illustrated in figure 4 the solution of the present invention process flow diagram, specifically comprise step by step following:

S1: if the vertical view (a) of Fig. 2 is with shown in cross-sectional view (b), the cycle of LPWG is Λ, i.e. LPWG ₁and LPWG ₂cycle be Λ, LPWG ₁and LPWG ₂length be respectively L ₁and L ₂, L in the present embodiment ₁=L ₂=L, LPWG ₁and LPWG ₂the length of connection waveguide be d, the width of optical waveguide is a, is highly h, and the degree of depth of grating is Δ h, and the refractive index of sandwich layer is n _co, the refractive index of tested covering is n _cl1, in waveguide, the refractive index of under-clad layer is n _cl2.

Light is from waveguide first end, i.e. A end, through LPWG ₁the output amplitude of rear sandwich layer mould and tested cladding mode is respectively A _co(L ₁) and A _cl(L ₁), by coupled mode theory and transfer matrix method.Show that both values are as shown in formula (1),

$\mathrm{\δ}{\mathrm{\β}}_1={\mathrm{\β}}_{\mathrm{co}}-{\mathrm{\β}}_{\mathrm{cl}}-K_1=\frac{2\mathrm{\π}}{\mathrm{\λ}}(N_{\mathrm{eff}}^{\mathrm{co}}-N_{\mathrm{eff}}^{\mathrm{cl}}-\frac{\mathrm{\λ}}{\mathrm{\Λ}})---\left(1\right)$

Wherein, Λ is LPWG ₁cycle, L ₁for LPWG ₁length, for LPWG ₁constant, for LPWG ₁locate the amplitude of tested cladding mode, κ ₁represent LPWG ₁coupling coefficient, for LPWG ₁the amplitude of place's sandwich layer mould, in s ₁for with LPWG ₁relevant constant, for light through length be L ₁lPWG ₁after phase shift, for the effective refractive index of sandwich layer mould, for the effective refractive index of tested cladding mode, $\mathrm{\δ}{\mathrm{\β}}_1={\mathrm{\β}}_{\mathrm{co}}-{\mathrm{\β}}_{\mathrm{cl}}-K_1=\frac{2\mathrm{\π}}{\mathrm{\λ}}(N_{\mathrm{eff}}^{\mathrm{co}}-N_{\mathrm{eff}}^{\mathrm{cl}}-\frac{\mathrm{\λ}}{\mathrm{\Λ}})$ For LPWG ₁the phase mismatch factor, λ represents resonance centre wavelength.

S20: be the waveguide of d through length, the output amplitude of sandwich layer mould and tested cladding mode is respectively A _co(L ₁+ d) and A _cl(L ₁+ d);

$\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d)\\ A_{\mathrm{cl}}(L_1+d)\end{array}\right]=\left[\begin{array}{cc}{e}^{j{\mathrm{\β}}_{\mathrm{co}}d}& 0\\ 0& e^{j{\mathrm{\β}}_{\mathrm{cl}}d}\end{array}\right]\·\left[\begin{array}{c}{A}_{\mathrm{co}}\left(L_1\right)\\ A_{\mathrm{cl}}\left(L_1\right)\end{array}\right];---\left(2\right)$

Wherein, d is LPWG ₁and LPWG ₂the length of connection waveguide.

S2: again through length be L ₂lPWG ₂the amplitude of rear sandwich layer mould and cladding mode is,

$\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d+L_2)\\ A_{\mathrm{cl}}(L_1+d+L_2)\end{array}\right]{=e}^{j\frac{{\mathrm{\β}}_{\mathrm{co}}+{\mathrm{\β}}_{\mathrm{cl}}}{2}{L}_2}\left[\begin{array}{cc}{e}^{j\frac{{\mathrm{KL}}_2}{2}}& 0\\ 0& e^{-j\frac{{\mathrm{KL}}_2}{2}}\end{array}\right]\·\left[\begin{array}{cc}{t}_2{e}^{j\frac{{\mathrm{\θ}}_2}{2}}& j{r}_2\\ j{r_2}^{*}& t_2{e}^{-j\frac{{\mathrm{\θ}}_2}{2}}\end{array}\right]\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d)\\ A_{\mathrm{cl}}(L_1+d)\end{array}\right]---\left(3\right)$

Wherein, Λ is LPWG ₂cycle, L ₂for LPWG ₂length, for LPWG ₂constant, for LPWG ₂locate the amplitude of tested cladding mode, κ ₂represent LPWG ₂coupling coefficient, for LPWG ₂the amplitude of place's sandwich layer mould, in s ₂for with LPWG ₂relevant constant, for light through length be L ₂lPWG ₂rear phase shift, $\mathrm{\δ}{\mathrm{\β}}_2={\mathrm{\β}}_{\mathrm{co}}-{\mathrm{\β}}_{\mathrm{cl}}-K_2=\frac{2\mathrm{\π}}{\mathrm{\λ}}(N_{\mathrm{eff}}^{\mathrm{co}}-N_{\mathrm{eff}}^{\mathrm{cl}}-\frac{\mathrm{\λ}}{\mathrm{\Λ}})$ For LPWG ₂the phase mismatch factor, λ represents resonance centre wavelength.

S3: exported by sandwich layer mould to export with tested cladding mode and carry out interference and obtain output spectra as shown in Figure 3, provide 3 kinds of different refractivities in figure respectively, namely refractive index is respectively: n _c1-1, n _c1-2, n _c1-3, the output spectra of measured matter, by the absorption spectrum information of the side-play amount of resonance wavelength in computational analysis output spectra and wherein material, realize material quantitatively with qualitative, calculate sandwich layer mould simultaneously and export and be respectively T (L with the output power of tested cladding mode ₁+ d+L ₂) and R (L ₁+ d+L ₂),

$\left[\begin{array}{c}T(L_1+d+L_2)\\ R(L_1+d{+L}_2)\end{array}\right]=\left[\begin{array}{c}{\left|\right|A_{\mathrm{co}}(L_1+d+L_2)\left|\right|}^2\\ {\left|\right|A_{\mathrm{cl}}(L_1+d+L_2)\left|\right|}^2\end{array}\right].---\left(4\right)$

Wherein, || || ²represent and " determinant " computing is first done to matrix, then carry out the computing of " mould ".

Biochemical sensor of the present invention adopts polymeric material as waveguide core layer on silica-based, and makes the LPWG of two series connection at waveguide core sidewall, using measured matter as waveguide covering.Above-mentioned measured matter can be biochemical liquid, biochemical gas or qualified solid matter etc.By two LPWG, the part optically-coupled transmitted in waveguide is entered liquid cladding, after transmission one segment distance, through LPWG, optically-coupled is entered sandwich layer again, finally obtain the spectral signal containing absorbing information because of the side-play amount of the resonance wavelength caused by measured matter refraction index changing and measured matter.

The analytical approach of the biochemical sensor based on series connection LPWG that the present invention proposes, by utilizing the coupled characteristic of LPWG, by the light of the certain bandwidth range in incident light wave centered by resonance wavelength, through LPWG ₁be coupled into tested covering, through LPWG ₂again this part optically-coupled is entered sandwich layer, interfere exporting with the basic mode of symport in sandwich layer.When measured matter changes, the resonance wavelength in output spectra can offset, and can calculate strength of fluid by detecting side-play amount.Analyze the absorption spectrum signal of measured matter in output spectra, realize the qualitative of measured matter.Method of the present invention solves conventional biochemical sensor on the one hand and relies on expensive and the certain sensitive film that Testing index is single carrys out problem qualitatively; Solve the bandwidth limitation problems needing the absorption bands avoiding water to bring in liquid, aqueous quantitative detection on the other hand.To realizing the LPWG biochemical sensitive technical research being greater than the high sensitivity of 2000nm/RIU, small size, low cost, wide application background is possessed by military biochemical war agent context of detection, important technical support can be provided in the solution of the civil area problem such as the food concerning national economy, drug safety more and more serious now, there is important scientific meaning and far-reaching realistic meaning.

Those of ordinary skill in the art will appreciate that, embodiment described here is to help reader understanding's principle of the present invention, should be understood to that protection scope of the present invention is not limited to so special statement and embodiment.For a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within right of the present invention.

Claims (8)

1., based on the analytical approach of the biochemical sensor of series connection LPWG, it is characterized in that, described sensor comprises sandwich layer and tested covering, and sandwich layer extends the first long-period waveguide grating LPWG in the side contacted with tested covering to tested covering direction ₁with the second long-period waveguide grating LPWG ₂, described method specifically comprises the following steps:

S1: incident light enters through sandwich layer first end, part light is through the first long-period waveguide grating LPWG ₁be coupled into tested covering, part light transmits along sandwich layer;

S2: the part light transmitted along tested covering is through the second long-period waveguide grating LPWG ₂be coupled into sandwich layer;

S3: in the part light obtained by step S2 and the sandwich layer of step S1, the part interference of light of co-propagate exports, and obtains output spectra, the side-play amount of resonance wavelength and the absorption spectrum information of wherein material in computational analysis output spectra.

2. method according to claim 1, is characterized in that, in step S1, and can through the first long-period waveguide grating LPWG ₁the part light being coupled into tested covering is the light of the certain bandwidth range centered by resonance wavelength.

3. method according to claim 2, is characterized in that, described sandwich layer is rectangular waveguide, and described tested covering is rectangular waveguide.

4. method according to claim 3, is characterized in that, described step S1 is specially: incident light enters from waveguide first end, is L through length ₁the first long-period waveguide grating LPWG ₁after, the output amplitude of sandwich layer mould and tested cladding mode is respectively A _co(L ₁) and A _cl(L ₁),

$\left[\begin{array}{c}{A}_{\mathrm{co}}\left(L_1\right)\\ A_{\mathrm{cl}}\left(L_1\right)\end{array}\right]=e^{j\frac{{\mathrm{\β}}_{\mathrm{co}}+{\mathrm{\β}}_{\mathrm{cl}}}{2}{L}_1}\left[\begin{array}{cc}{e}^{j\frac{{\mathrm{KL}}_1}{2}}& 0\\ 0& e^{-j\frac{{\mathrm{KL}}_1}{2}}\end{array}\right]\·\left[\begin{array}{cc}{t}_1{e}^{j\frac{{\mathrm{\θ}}_1}{2}}& j{r}_1\\ j{r_1}^{*}& t_1{e}^{-j\frac{{\mathrm{\θ}}_1}{2}}\end{array}\right]\·\left[\begin{array}{c}{A}_{\mathrm{co}}\left(0\right)\\ A_{\mathrm{cl}}\left(0\right)\end{array}\right];$

Wherein, Λ is the first long-period waveguide grating LPWG ₁cycle, L ₁be the first long-period waveguide grating LPWG ₁length, be the first long-period waveguide grating LPWG ₁constant, be the first long-period waveguide grating LPWG ₁locate the amplitude of tested cladding mode, κ ₁represent the first long-period waveguide grating LPWG ₁coupling coefficient, be the first long-period waveguide grating LPWG ₁the amplitude of place's sandwich layer mould, in s ₁for with the first long-period waveguide grating LPWG ₁relevant constant, () ^*represent transposition, δ is the first long-period waveguide grating LPWG ₁from coupling coefficient, for light through length be L ₁the first long-period waveguide grating LPWG ₁after phase shift, for the effective refractive index of sandwich layer mould, for the effective refractive index of tested cladding mode, $\mathrm{\δ}{\mathrm{\β}}_1={\mathrm{\β}}_{\mathrm{co}}-{\mathrm{\β}}_{\mathrm{cl}}-K_1=\frac{2\mathrm{\π}}{\mathrm{\λ}}(N_{\mathrm{eff}}^{\mathrm{co}}-N_{\mathrm{eff}}^{\mathrm{cl}}-\frac{\mathrm{\λ}}{\mathrm{\Λ}})$ Be the first long-period waveguide grating LPWG ₁the phase mismatch factor, λ represents resonance centre wavelength, A _co(0) amplitude of sandwich layer mould initial position is represented, A _cl(0) amplitude of tested cladding mode initial position is represented.

5. method according to claim 3, is characterized in that, described step S2 also comprises step S20: be the waveguide of d through length, and the output amplitude of sandwich layer mould and tested cladding mode is respectively A _co(L ₁+ d) and A _cl(L ₁+ d);

$\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d)\\ A_{\mathrm{cl}}(L_1+d)\end{array}\right]=\left[\begin{array}{cc}{e}^{j{\mathrm{\β}}_{\mathrm{co}}d}& 0\\ 0& e^{j{\mathrm{\β}}_{\mathrm{cl}}d}\end{array}\right]\·\left[\begin{array}{c}{A}_{\mathrm{co}}\left(L_1\right)\\ A_{\mathrm{cl}}\left(L_1\right)\end{array}\right];$

Wherein, d is the first long-period waveguide grating LPWG ₁with the second long-period waveguide grating LPWG ₂the length of connection waveguide.

6. method according to claim 3, is characterized in that, described step S2 is specially: be L through length ₂the second long-period waveguide grating LPWG ₂after, the output amplitude of sandwich layer mould and tested cladding mode is respectively A _co(L ₁+ d+L ₂) and A _cl(L ₁+ d+L ₂);

$\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d+L_2)\\ A_{\mathrm{cl}}(L_1+d+L_2)\end{array}\right]=e^{j\frac{{\mathrm{\β}}_{\mathrm{co}}+{\mathrm{\β}}_{\mathrm{cl}}}{2}{L}_2}\left[\begin{array}{cc}{e}^{j\frac{{\mathrm{KL}}_2}{2}}& 0\\ 0& e^{-j\frac{{\mathrm{KL}}_2}{2}}\end{array}\right]\·\left[\begin{array}{cc}{t}_2{e}^{j\frac{{\mathrm{\θ}}_2}{2}}& j{r}_2\\ j{r_2}^{*}& t_2{e}^{-j\frac{{\mathrm{\θ}}_2}{2}}\end{array}\right]\·\left[\begin{array}{c}{A}_{\mathrm{co}}(L_1+d)\\ A_{\mathrm{cl}}(L_1+d)\end{array}\right];$

Wherein, Λ is the second long-period waveguide grating LPWG ₂cycle, L ₂be the second long-period waveguide grating LPWG ₂length, be the second long-period waveguide grating LPWG ₂constant, be the second long-period waveguide grating LPWG ₂locate the amplitude of tested cladding mode, κ ₂represent the second long-period waveguide grating LPWG ₂coupling coefficient, be the second long-period waveguide grating LPWG ₂the amplitude of place's sandwich layer mould, in s ₂for with LPWG ₂relevant constant, for light through length be L ₂the second long-period waveguide grating LPWG ₂rear phase shift, $\mathrm{\δ}{\mathrm{\β}}_2={\mathrm{\β}}_{\mathrm{co}}-{\mathrm{\β}}_{\mathrm{cl}}-K_2=\frac{2\mathrm{\π}}{\mathrm{\λ}}(N_{\mathrm{eff}}^{\mathrm{co}}-N_{\mathrm{eff}}^{\mathrm{cl}}-\frac{\mathrm{\λ}}{\mathrm{\Λ}})$ Be the second long-period waveguide grating LPWG ₂the phase mismatch factor, λ represents resonance centre wavelength.

7. method according to claim 3, it is characterized in that, described step S3 is specially: exported by sandwich layer mould to export with tested cladding mode and carry out interference and obtain output spectra, the side-play amount of resonance wavelength and the absorption spectrum information of wherein material in computational analysis output spectra, calculate sandwich layer mould simultaneously and export and be respectively T (L with the output power of tested cladding mode ₁+ d+L ₂) and R (L ₁+ d+L ₂),

$\left[\begin{array}{c}T(L_1+d+L_2)\\ R(L_1+d+L_2)\end{array}\right]=\left[\begin{array}{c}{\left|\right|A_{\mathrm{co}}(L_1+d+L_2)\left|\right|}^2\\ {\left|\right|A_{\mathrm{cl}}(L_1+d+L_2)\left|\right|}^2\end{array}\right];$

Wherein, || || ²represent and " determinant " computing is first done to matrix, then carry out the computing of " mould ".

8. the method according to claim 4 to 7 any one, is characterized in that, described sensor parameters is determined by following methods step:

S01: the rectangular waveguide sandwich layer physical dimension of single mode operation and the parameter of sandwich layer within the scope of the incident wavelength determining for resonance wavelength by Marcatili method;

Described rectangular waveguide sandwich layer physical dimension specifically comprises: the width a of sandwich layer, the height h of sandwich layer, the depth delta h of grating;

The parameter of described sandwich layer mould specifically comprises: transmission β _co, along the transmission K in x, y direction _x, K _y, and calculate the sandwich layer Effective index under resonance central wavelength lambda

S02: by the physical dimension of the tested covering of Marcatili method determination rectangular waveguide and the parameter of tested cladding mode;

Described rectangular waveguide tested covering physical dimension specifically comprises: the width b of tested covering, the height h of tested covering;

The parameter of described tested cladding mode specifically comprises: transmission β _cl, along the transmission K in x, y direction _x, K _y, and calculate the tested cladding mode effective refractive index under resonance central wavelength lambda

S03: according to the effective refractive index of sandwich layer mould and the effective refractive index of tested cladding mode utilize the phase-matching condition of LPWG determine the periods lambda of LPWG.