200933137 •九、發明說明： 【發明所屬之技術領域】 ' 本發明涉及一種感測器，尤其涉及一種折射率敏感之 感測器。 【先前技術】 由於具有獨特之光子禁帶（Photonic Band Gap )效應， 光子晶體（Photonic Crystals)為設計微型折射率敏感之感 ❹測器件提供了新之平臺。近幾年，基於光子晶體設計之微 型折射率敏感之感測器相繼問世，由於這種感測器有較高 之微腔讀振品質因素（high-Q microcavity)和很小之傳感 面積（每10 μ m2之傳感面積只要求被測量之樣本為ifL )， 因此該種感測器可用於痕量樣品之測量。 請參閱 J.Topol’ ancik 等人之 “Fluid detection with photonic crystal-based multichannel waveguides” (Applied Physics Letters.82，1143-1145(2003))。J.Topol’ ancik 等人設 w 計之光子晶體波導結構之感測器可探測到之折射率變化為 0.2，此種感測器對折射率之解析度並不高。 E.Chow 等人於 “ultracompact biochemical sensor built with two-dimensional photonic crystal microcavity” (Optic Letters 29,1093-1095(2004)(中提出了 另一種感測器 結構’其採用二維光子晶體微腔結構進行折射率之測量， 折射率之測量範圍可達到1.0到1.5。然而此種感測器中光 線之透過率很低，並且其測量精度不夠高，只能精確到 200933137 0.002;靈敏度也不高，只能達到200nm/RIU，其中RIU指 .單位折射率（Refractive Index Unit )。 4 * 【發明内容】 有鑒於此，有必要提供一種具有更高透光率及測量精 度之折射率感測器。 一種折射率感測器’其包括光源、光子晶體微腔結構 ❹及感測器，該光子晶體微腔結構包括晶體層及大量形成於 該晶體層並規則排列之孔，其中一個孔之直徑與其他孔之 直徑不同從而構成一諧振腔，該諧振腔相對之兩側具有線 缺陷’該線缺陷分別構成第一波導與第二波導，該第一波 導及第二波導與該諳振腔之間分別具有數個孔，該光源設 置於該第一波導之入射端，該感測器設置於該第二波導之 出射端。 該折射率感測器中，第一波導及第二波導之設置使得 ❹光線之透過率可提升到40%到70%，而且傳感器具有較高 之測量精度，可檢測折射率0.001之變化。可檢測折射率之 範圍較大，可從1.0適用到1.6。感測器之靈敏度達到 330nm/RIU。 【實施方式】 參閱圖1及圖2，第一實施例之光子晶體微腔結構1〇〇 包括基底104及晶體層10，晶體層10形成於基底104上。 晶體層10之晶格常數為a，晶體層1〇之厚度為〇.4a〜0.7a， 200933137 本實施例優選為0.6a。晶體層10之材質可選用Si、GaAs . 或GaAlAs。本實施例當中，晶體層10為GaAlAs，其晶格 常數為440奈米。晶體層10 —般通過磊晶生長形成於基體 104上，因此基體104適於磊晶生長晶體層10即可，例如 對於GaAs或GaAlAs材質之晶體層10,可選用GaAs、GaN 作為基底104。對於Si晶體層，可選用Si02作為基底104。 晶體層10内形成有大量孔102。孔102可採用電子束 微影或反應性離子束蝕刻形成。本實施中，孔102呈圓柱 Ο 形，當然孔102還可為其他形狀。孔102排列成m行，依 次記為第1、2、3、…、m行，每行具有η個孔102，依次 記為第1、2、3、…、η個孔。其中m與η為14到18之間 之整數。本實施例中，孔102排列成17行，每行具有17 個孔102。孔102之直徑為0.3a〜0.5a，本實施例當中，孔 102之直徑為0.36a。 每行孔102之中心連線相互平行，同一行内之孔102 ❹為等間距排列，每相鄰之兩行孔102之間交錯排列，從而 所有之孔102構成三角形排列。以第1行第1、2個孔102 與第2行第1個孔102為例，第2行之第1個孔102位於 第1行第1、2個孔102連線之中線上，從而第1行第1、2 個孔102與第2行第1個孔102構成一三角形，優選地， 此三角形為等邊三角形。 第i行第j個孔102之直徑與其他孔102之直徑不同從 而構成一譜振腔12，其中l<i<m，l<j<n。優選地，i為最 靠近m/2之整數，j為最靠近n/2之整數。諧振腔12之直 200933137 徑可為0.05a到〇.6a。本實施例當中’其為〇.55a。 , 第i行之孔102中’諧振腔12兩側各保留有k個孔 ..1〇2 ’ l<k<6，而其餘的孔102被去除，或者說此處並未形 成有孔102,從而於諧振腔12兩側之晶體層1〇内分別形成 兩個線缺陷，兩個線缺陷分別構成第一波導14與第二波導 16。第一波導14及第二波導16均與諧振腔12之間隔有k 個孔102，本實施例中k=3。孔102之直徑以及諧振腔12 ❾之直徑發生改變時，諳振腔12之諧振波長會隨之發生改變。 參閱圖3，本技術方案實施例之折射率感測器2〇〇包括 光源20、光子晶體微腔結構1〇〇及感測器22。光源2〇靠 近第一波導14之入射端142設置，感測器22靠近第二波 導16之出射端162設置。 光源20可為發光二極體或者二極體鐳射器。光源2〇 所發射出之光線之波長處於諧振腔12之諳振波長之間即 可。例如根據上述實施例之光子晶體微腔結構1〇〇,可選用 ❹波長於1800奈米到1830奈米之間之發光二極體或者二極 體鐳射器。 感測器22用於感測從光源20發出並經過第一波導 14、諧振腔12及第二波導16後之光。由於光源2〇之波長 處於紅外波段’因此感測器22須能感測紅外波段之光波 長’例如感測器22可選用氧化鉛-硫化鉛光電陰極攝像管或 者InGaAs紅外探測器。感測器22可與外部之光譜裝置相 連’從而可於外部之光譜裝置上觀察檢測結果。 本實施例之折射率感測器2〇〇中，光源20發出之光線 200933137 經過光子晶體微腔結構100之譜振 邛用後到達感測器22。 .. 狀波長於錢之過程巾會發生之變化 -變化幅度與孔102仲介質之折射率相關。 、彳 102Φ參閱圖Λ’其為採用具有不同折射率之樣品注入到孔 中進行測試之結果示意圖。如，將且 樹脂注射到光子晶體微腔結構100之表面，二士 =率之矽 為200微米_ 500微米之間 =樹月曰之厚度 〇，腔12中。賴脂之折射率從1 446變化到Μ%，變化辦 I為〇.001。每個樣品測量完成後，將感測器200放到丙； ^異丙醇中漂洗並烘乾，然後進行下—次之職^圖4 中^看到，隨被測試樣品折射率之增加，譜振波長之之變 化I也增加。參閱圖5，測量折射率範圍於1〇到i 6之門 之樣品，將測量試樣品之折射率n與諧振波長之漂移量: 又繪於同一直角座標系中，本實施例中測量採用之樣品 為：折射率接近於1之空氣、折射率為1Λ之液體二氧化碳、 〇折射率為033之水、折射率為1>36之丙酮、折射率為I% 之丙酮、折射率為1.46之熔化之酒精、折射率為149之8〇% 之糖溶液、及折射率為L53之氣化鈉溶液。可看出諧振波 長之漂移量△ λ與被測試樣品之折射率之間呈良好之線性 關係，即，折射率每增加〇.〇〇1，諧振波長變大〇 33奈米。 本實施例之感測器之靈敏度為33〇nm/Rm。 本實施例之折射率感測器200中，通過光子晶體微腔 結構100中孔102之直徑、諧振腔12之直徑參數之選擇， 及第波導14與第一波導16之設置，使得光線之透過率 11 200933137 y提升到4则70%。而且譜振波長之漂移量與折射 ..率變化Δΐ1之間之數值比達到33〇nm/Rlu，使該折 ΐ2ίΚ)具有較高之測量精度，可測量折射率G.rnn之變1’、’。 =試未知折射率之樣品時’根據檢測到之譜 二到被測試樣品之折射率，且具有较大之折射率測量範 圍，可達到1.0到1.6。 綜上所述，本發明確已符合發明專利之 c申請。惟，以上所述者僅為本發明之較佳實：方 :藝之人士援依本發明之精神所作二=本: 應涵蓋於以下申請專利範圍内。 【圖式簡單說明】 圖1係本技術方案第一實施例之折 晶體微腔結構示意圖。 千W之先子 圖2係圖1沿IMI線之剖面示意圖。 ❹本技術方案實施例提供之折射率感測器示意圖。 圖4係不同折射率之樣品諧振光譜示意圖。 圖5係諧振波長之變化與折射率之間之關係曲線圖。 【主要元件符號說明】 微腔結構 100 基底 104 晶體層 10 孔 102 12 200933137 諧振腔 12 第一波導 14 第二波導 16 感測器 200 入射端 142 出射端 162 光源 20 22 感測器 ❹ ❹ 13200933137 • Nine, invention description: [Technical field to which the invention pertains] The present invention relates to a sensor, and more particularly to a refractive index sensitive sensor. [Prior Art] Due to the unique Photonic Band Gap effect, Photonic Crystals provide a new platform for designing miniature refractive index sensitive sensing devices. In recent years, miniature refractive index sensitive sensors based on photonic crystal design have been successively introduced, because of the high micro-Q microcavity and small sensing area of the sensor. The sensing area per 10 μ m 2 only requires the sample to be measured to be ifL), so this sensor can be used for the measurement of trace samples. See "Fluid detection with photonic crystal-based multichannel waveguides" by J. Topol' ancik et al. (Applied Physics Letters. 82, 1143-1145 (2003)). The sensor of J. Topol' ancik et al. has a photonic crystal waveguide structure that can detect a change in refractive index of 0.2, and the resolution of such a sensor is not high. E. Chow et al., "ultracompact biochemical sensor built with two-dimensional photonic crystal microcavity" (Optic Letters 29, 1093-1095 (2004) (another sensor structure is proposed in which a two-dimensional photonic crystal microcavity structure is employed). For the measurement of refractive index, the refractive index can be measured from 1.0 to 1.5. However, the transmittance of light in such a sensor is very low, and the measurement accuracy is not high enough, only accurate to 200933137 0.002; sensitivity is not high, It can only reach 200 nm/RIU, where RIU refers to the refractive index unit. 4 * [Invention] In view of this, it is necessary to provide a refractive index sensor with higher transmittance and measurement accuracy. A refractive index sensor includes a light source, a photonic crystal microcavity structure, and a sensor. The photonic crystal microcavity structure includes a crystal layer and a plurality of holes formed in the crystal layer and regularly arranged, wherein a diameter of one hole is The other holes have different diameters to form a resonant cavity having line defects on opposite sides thereof. The line defects respectively constitute the first waveguide and the second wave. The first waveguide and the second waveguide and the oscillating cavity respectively have a plurality of holes, the light source is disposed at an incident end of the first waveguide, and the sensor is disposed at an exit end of the second waveguide. In the rate sensor, the first waveguide and the second waveguide are arranged such that the transmittance of the xenon light can be increased to 40% to 70%, and the sensor has a high measurement accuracy and can detect a change in the refractive index of 0.001. The range of the ratio is large, and can be applied from 1.0 to 1.6. The sensitivity of the sensor reaches 330 nm/RIU. [Embodiment] Referring to FIG. 1 and FIG. 2, the photonic crystal microcavity structure 1 of the first embodiment includes a substrate 104. And the crystal layer 10, the crystal layer 10 is formed on the substrate 104. The crystal layer 10 has a lattice constant a, and the thickness of the crystal layer 1〇 is 〇.4a~0.7a, 200933137. This embodiment is preferably 0.6a. The material may be selected from Si, GaAs or GaAlAs. In this embodiment, the crystal layer 10 is GaAlAs, and its lattice constant is 440 nm. The crystal layer 10 is generally formed on the substrate 104 by epitaxial growth, so the substrate 104 is suitable. The crystal layer 10 can be grown by epitaxial crystal, for example For the crystal layer 10 of GaAs or GaAlAs, GaAs or GaN can be used as the substrate 104. For the Si crystal layer, SiO 2 can be used as the substrate 104. A large number of holes 102 are formed in the crystal layer 10. The holes 102 can be electron beam lithography or Reactive ion beam etching is formed. In the present embodiment, the holes 102 have a cylindrical shape, and of course the holes 102 may have other shapes. The holes 102 are arranged in m rows, which are sequentially referred to as first, second, third, ..., m rows, and each row has n holes 102, which are sequentially referred to as first, second, third, ..., n holes. Wherein m and η are integers between 14 and 18. In this embodiment, the holes 102 are arranged in 17 rows with 17 holes 102 per row. The diameter of the hole 102 is 0.3a to 0.5a. In the present embodiment, the diameter of the hole 102 is 0.36a. The center lines of each row of holes 102 are parallel to each other, and the holes 102 in the same row are arranged at equal intervals, and the adjacent two rows of holes 102 are staggered so that all the holes 102 form a triangular arrangement. Taking the first row and the second hole 102 in the first row and the first hole 102 in the second row as an example, the first hole 102 in the second row is located on the line connecting the first row and the second hole 102 of the first row, thereby The first row and the second hole 102 of the first row form a triangle with the second row and the first hole 102. Preferably, the triangle is an equilateral triangle. The diameter of the jth hole 102 of the i-th row is different from the diameter of the other holes 102 to constitute a spectral cavity 12, where l < i < m, l < j < n. Preferably, i is an integer closest to m/2 and j is an integer closest to n/2. The diameter of the cavity 12 can be from 0.05a to 〇6a. In the present embodiment, it is 〇.55a. In the hole 102 of the i-th row, there are k holes . . . 1 〇 2 ' l < k < 6 on both sides of the resonant cavity 12, and the remaining holes 102 are removed, or holes 102 are not formed here. Therefore, two line defects are respectively formed in the crystal layer 1 两侧 on both sides of the resonant cavity 12, and the two line defects respectively constitute the first waveguide 14 and the second waveguide 16. The first waveguide 14 and the second waveguide 16 are spaced apart from the resonant cavity 12 by k holes 102, which is k=3 in this embodiment. When the diameter of the hole 102 and the diameter of the cavity 12 are changed, the resonant wavelength of the oscillating chamber 12 changes. Referring to FIG. 3, the refractive index sensor 2 of the embodiment of the present invention includes a light source 20, a photonic crystal microcavity structure 1 and a sensor 22. The light source 2 is disposed adjacent to the incident end 142 of the first waveguide 14, and the sensor 22 is disposed adjacent to the exit end 162 of the second waveguide 16. Light source 20 can be a light emitting diode or a diode laser. The wavelength of the light emitted by the light source 2 处于 is between the resonance wavelengths of the resonant cavity 12. For example, according to the photonic crystal microcavity structure 1 of the above embodiment, a light-emitting diode or a diode laser having a germanium wavelength of between 1800 nm and 1830 nm can be used. The sensor 22 is for sensing light emitted from the light source 20 and passing through the first waveguide 14, the resonant cavity 12, and the second waveguide 16. Since the wavelength of the light source 2 is in the infrared band 'the sensor 22 must be able to sense the wavelength of the light in the infrared band', for example, the sensor 22 can be a lead oxide-sulfurized lead photocathophoto camera or an InGaAs infrared detector. The sensor 22 can be coupled to an external spectral device so that the detection results can be viewed on an external spectral device. In the refractive index sensor 2 of the embodiment, the light emitted by the light source 20 is passed through the photonic crystal microcavity structure 100 and reaches the sensor 22. .. The wavelength of the process towel will change - the magnitude of the change is related to the refractive index of the medium 102.彳 102Φ Refer to the figure ’, which is a schematic diagram of the results of testing with a sample having a different refractive index injected into the hole. For example, the resin is injected onto the surface of the photonic crystal microcavity structure 100, and the 二 = rate 矽 is between 200 μm and 500 μm = the thickness of the tree 曰 〇, the cavity 12 . The refractive index of lyophilic acid changed from 1 446 to Μ%, and the change I was 〇.001. After each sample is measured, the sensor 200 is placed in C; rinsed and dried in isopropyl alcohol, and then subjected to the next-time job ^ Figure 4, seeing, with the increase of the refractive index of the sample to be tested, The change I of the spectral wavelength also increases. Referring to Figure 5, a sample having a refractive index ranging from 1 〇 to i 6 is measured, and the refractive index n of the test sample and the drift of the resonant wavelength are measured: also plotted in the same rectangular coordinate system, which is used in the measurement in this embodiment. The sample was: air having a refractive index close to 1, air carbon dioxide having a refractive index of 1 、, water having a refractive index of 033, acetone having a refractive index of 1 > 36, acetone having a refractive index of 1%, and melting having a refractive index of 1.46. Alcohol, a sugar solution having a refractive index of 149 to 8〇%, and a vaporized sodium solution having a refractive index of L53. It can be seen that there is a good linear relationship between the drift amount Δ λ of the resonance wavelength and the refractive index of the sample to be tested, that is, for each increase of the refractive index 〇.〇〇1, the resonance wavelength becomes larger than 33 nm. The sensitivity of the sensor of this embodiment is 33 〇 nm / Rm. In the refractive index sensor 200 of the present embodiment, the diameter of the hole 102 in the photonic crystal microcavity structure 100, the selection of the diameter parameter of the resonant cavity 12, and the arrangement of the waveguide 14 and the first waveguide 16 enable the transmission of light. Rate 11 200933137 y increased to 4 and 70%. Moreover, the ratio of the drift of the spectral wavelength to the refractive index. The ratio of the change Δΐ1 reaches 33〇nm/Rlu, so that the fold has a high measurement accuracy, and the change of the refractive index G.rnn can be measured 1', '. = When trying a sample with unknown refractive index, the refractive index of the sample to be tested, according to the detected spectrum, and the larger refractive index measurement range, can reach 1.0 to 1.6. In summary, the present invention has indeed met the c application of the invention patent. However, the above is only the preferred embodiment of the present invention: The person skilled in the art is entitled to the spirit of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the structure of a folded crystal microcavity according to a first embodiment of the present technical solution. The first of thousands of W Figure 2 is a schematic cross-sectional view of Figure 1 along the IMI line. A schematic diagram of a refractive index sensor provided by an embodiment of the present technical solution. Figure 4 is a schematic diagram of the resonance spectrum of a sample with different refractive indices. Figure 5 is a graph showing the relationship between the change in resonant wavelength and the refractive index. [Main component symbol description] Microcavity structure 100 Substrate 104 Crystal layer 10 Hole 102 12 200933137 Resonant cavity 12 First waveguide 14 Second waveguide 16 Sensor 200 Incident end 142 Exit end 162 Light source 20 22 Sensor ❹ ❹ 13