TW558636B - Antiresonant reflecting optical waveguide (ARROW) surface plasmon resonance (SPR) sensors - Google Patents

Abstract

This surface plasmon resonance (SPR) sensor which is based on an antiresonant reflecting optical waveguide (ARROW) is used to sense the variation of the refractive index of the environment for chemical and biochemical applications. It consists of three sections: input, sensing, and output sections. All the three sections are effectively single-mode ARROW waveguides of the same structure except that the sensing section has an additional metal layer on top of it's core to excite the surface plasmon wave (SPW), which can be coupled with the ARROW waveguide. In order to optimize the sensitivity and tune the operation range into the most sensitive region, a dielectric overlay is coated upon the metal.

Description

558636 V. Description of the invention (1) [Background of the invention] Chemical and biochemical sensors have important and critical applications in the fields of environmental protection, automated processes, medicine and biotechnology. In recent years, sensing systems have tended to be miniaturized. Therefore, various semiconductor sensors using the electrochemical principle and optical fiber sensors using the principle of spectroscopy have become more and more important. Compared with semiconductor sensors, fiber optic sensors are not only easy to achieve miniaturization and can be used for remote sensing, but also have no interference from external electromagnetic waves, can operate in a wide temperature range and harsh environments, etc. Advantages' and wavelength division multiplexing (WDM) technology can be applied to detect multiple substances at the same time. However, traditional fiber optic sensors made with optical fibers are difficult to accurately control due to the complicated process and difficult to accurately control. Manufacturing, reducing costs, and the integrated optical waveguide sensor manufactured using mature integrated circuit technology can not only accurately control the structural parameters of ^ components, increase the stability during mass manufacturing, but also has ^ type, light weight, Coupling with optical fiber to achieve remote sensing detection and other advantages, if necessary, it can be integrated with other sensing or signal processing circuits to form opto-electronic integrated circuits (oEIC,-), which increases the flexibility of its application. 70 Bulk optical waveguides can therefore be selected with the fiber size. At the same time, the application of the integrated single mode on the substrate with transmission loss must often be matched with the optical fiber and Light reflectance consumption rate must be low enough to match the optical waveguide of the silicon waveguide dimensions as input, output coupling waveguide material is the best choice, however, the conventional single-mode fiber fabricated smaller than Xu

558636 V. Description of the invention (2) ^ 'It is not easy to couple with the fiber with high efficiency, and in order to achieve low transmission loss, the isolation layer must be made very thick, so it increases the difficulty in production.' A type is called anti-resonance reflection Optical waveguides (antiresonant reflecting 0pticai waveguides, ARROW) have been proposed [1], and have been verified to have the following advantages: (1) low transmission loss · '(2) single-mode transmission; (3) can be selected elastically The thickness of the optical waveguide layer and the refractive index of the material are matched to the thickness and refractive index of the output and input fibers to achieve the highest output and input coupling efficiency; and (4) can be fabricated on a high refractive index substrate. Using these advantages to design anti-resonance reflective optical waveguide sensing elements, it can overcome many limitations of semiconductors, optical fibers and traditional optical waveguide sensors, and meet the needs of chemical and biochemical sensing. In terms of chemical and biochemical light sensing, because surface plasmon resonance (SPR) has the characteristics of real-time sensing and no labeling [2], it has become widely used in recent years. The attention-grabbing sensing mechanism has developed surface plasmon resonance sensing elements such as 稜鏡 (see Figure 1) and traditional optical waveguides (see Figure 2), and some have been commercialized [2] [3 ]. In view of the fact that the optical waveguide surface plasmon resonance sensing element has many advantages of the aforementioned optical waveguide sensor, the present invention combines the anti-resonance reflective optical waveguide with the surface plasmon resonance sensing mechanism to design an anti-resonance with many advantages. An embodiment of a plasmon resonance sensing element on the surface of the resonant reflection optical waveguide is designed to be suitable for sensing in the underwater environment.

Page 6 558636

[Summary of the Invention] The structure of the plasmon resonance on the surface of the anti-resonant reflective optical waveguide proposed by the present invention is shown in Fig. 3 (a). In order to cover a thin layer of metal B-type Reflective Reflective Optical Waveguide, a dielectric film can be added thereon to adjust the range of sensing operation and sensing characteristics' as shown in Figure 3 (b). ^ The reason for adopting the B-type anti-resonant reflective optical waveguide is that the surface plasmon wave (SPW) is the electromagnetic of the TM mode transmission wheel ^, while the traditional anti-resonant reflective optical waveguide has the TM mode transmission loss Too high 'is not suitable for surface plasmon resonance sensing elements, and the B-type anti-resonance reflective optical waveguide has low transmission loss characteristics for both TE and TM fundamental modes, so it can be applied Design of surface plasmon resonance sensing element. The principle of the anti-resonance reflective optical waveguide of the present invention can be briefly described as follows: light is transmitted, and the transmission loss of the high-order mode is much higher than the energy carried by the high-order mode. Propagate within the measurement area, continuously excite the energy change input to the end of the sensing area and couple to the output optical signal, and measure the propagation constant of the conductance itself due to the surface plasmon resonance (propagat surface plasmon resonance induction area) The optical waveguide coupling fundamental mode 'escapes to the fundamental mode of the high-refractive-index substrate measurement area through the input area, and the surface plasma wave is output. Out of the area, we can borrow to measure the change of the environment. The condition is that the surface electrical mode is on constant) phase The transmission of the combined input of the measuring element is only low-pass along with the light wave. When the light wave passes by the detection input wave and light wave, etc., here

PAGE 7 558636 9! 年 #revised correction / changeover / addition_case number 91102976_year month revision_ 5. Description of the invention (4) Under the condition, the coupling efficiency of the optical waveguide fundamental mode and the surface plasma wave is the highest, A considerable amount of energy can be coupled to the surface plasmon wave propagation. When the refractive index of the environment to be measured changes, the coupling state changes accordingly, resulting in a change in the output optical signal energy. Compared with the traditional optical waveguide surface plasmon resonance sensing element, the unique advantage of the present invention is that the size of the anti-resonance reflective optical waveguide and the choice of the refractive index of the material are quite flexible, which can take into account the excitation of the surface plasmon resonance, and The need for coupling with the input and output of the optical fiber, without the limitation of the size of the traditional optical waveguide being too small. In addition, the anti-resonance reflective optical waveguide surface plasmon resonance sensing element designed by the present invention for underwater operation can detect Excellent surface plasmon resonance sensing element with excellent 10-5 refractive index change. [Detailed description of the invention] The structure of the plasmon resonance sensing element on the surface of the anti-resonance reflective optical waveguide of the present invention is shown in Figure 3 (a), which can be divided into front and rear input and output areas, and the central sensing region. A B-type anti-resonant reflective optical waveguide is included in the input and output regions, and includes a waveguide core layer, a first isolation layer having a refractive index lower than that of the core layer, and a second anti-resonance having a refractive index equal to or higher than that of the core layer. An isolation layer and a high-refractive index substrate; and the sensing area is covered with a thin layer of metal on the aforementioned B-type anti-resonant reflective optical waveguide, and a dielectric film may be added to adjust the sensing depending on the actual application needs The operating range and characteristics of the components are shown in Figure 3 (b). First, select the waveguide with the working wavelength of the light wave used according to the application needs

Page 8 2002. 09. 09. 008 558636 V. Description of the invention (8) [Retrieval information] 1. MA Duguay, Y. Kokubun, T. L. Koch, and L. Preiffer, "Antiresonant reflecting optical waveguides in Si02- Si multi layer structures ,, '

App1. Phys. Lett., Vo1. 49, pp. 13-15, 1986. 2. J. Homola, S. Yee, and G. Gauglitz, “Surface plasmon resonance sensors: review,” Sensors and Actuators B, vo1. 54, pp. 3-15, 1999. 3. RD Harris and JS Wilkinson, “Waveguide surface plasmon resonance sensors,” Sensors and Actuators B, vo1 · 29, pp. 2 6 1 -2 6 7, 1 9 9 5. 4 · T · Baba and Υ · Kokubun, "New polarization-insensitive ant i resonant reflecting optical waveguide (ARROW-B)," IEEE Photon.

Technol Lett., Vo 1. 1, pp. 232-234, 1 9 8 9. 5. Y. -T. Huang, W. -Z · Chang, S · H. Hsu, C. -H.

Chen, and J. -C. Chen, “Antiresonant reflecting optical waveguide surface plasmon resonance sensors,” SPIE ’s International Symposium on

Page 12 558636 V. Description of the invention (9)

Microelectronics and MEMS (MICRO / MEMS 2001), Adelaide, Australia, Dec. 2001. 6. J. Ctyroky, J. Homola, and M. Skalsky, “Tuning of spectral operation range of a waveguide surface plasmon resonance sensor,” Electron. Lett., Vo1. 33, pp. 1 24 6- 1 248, 1 9 9 7.

Page 13

Claims (1)

558636 Feiguang π: ρ: …… Cheng_Case No. 91102976_Year Month Amendment_ VI. Patent Application Scope 1. An anti-resonance reflective optical waveguide surface plasmon resonance sensing element, including an input area, a sense The measurement area and an output area, each of which includes an anti-resonant reflective optical waveguide, and the anti-resonant reflective optical waveguide in the sensing area is covered with a metal layer. 2. The plasmon resonance sensing element on the surface of the anti-resonance reflective optical waveguide as described in item 1 of the scope of the patent application, is a combination of a metal layer and the anti-resonance reflective optical waveguide, so that the light waves propagating in the anti-resonance reflective optical waveguide can be transmitted. It can be appropriately coupled to the surface polycondensation wave (surface ρ 1 asm ο nwa ν e), to achieve the purpose of sensing by changing the coupling state of the refractive index of the environment to be measured. 3. The anti-resonance reflective optical waveguide surface plasmon resonance sensing element according to item 1 of the scope of the patent application, wherein the anti-resonant reflective optical waveguide includes a waveguide core layer and two or more layers of anti-spectral vibration ( antiresonance) cladding, so that the light waves propagating in the core area of the waveguide have a high reflectivity at the interface. 4 · The plasmonic resonance sensing element on the surface of the anti-resonance reflective optical waveguide as described in item 3 of the scope of patent application, wherein the material and size of the waveguide core layer of the anti-resonance reflective optical waveguide can be elastically selected and designed to match the input and output fibers Match. 5. The anti-resonance reflective optical waveguide surface plasma resonance sensing element according to item 1 of the scope of the patent application, wherein the anti-resonant reflective optical waveguide is a B-type anti-resonant Object 636 positive / correction f charge month 范围 The scope of patent application, a low refractive index first barrier, and the thickness meets the anti-resonance first isolation layer. Vibration-reflecting optical waveguide, including an optical waveguide core layer separated from the layer and a 6-ray index of refraction equal to that of the core layer or antiresonance condition Π Li: ί Enclosing anti-spectral vibration reflected light according to item 1 or 5 The electro-hydraulic resonance sensor on the surface of the waveguide. The transverse (TM) mode transmission wheel of the anti-resonance reflective optical waveguide is a single-mode state. Only the low-loss transmission transverse magnetic field (τμ) fundamental mode ( Code & Transmission & Consumption is less than 1 dB / cm), the other modes are not able to transmit with low loss (typically higher than 10 dB / cm) w " Γ · Resistance as described in item 5 of the scope of patent application If the refractive index of the second isolation layer is the same as that of the core layer, the thickness of the second isolation layer is half of the thickness of the core layer to meet the anti-resonance condition. 8 · The plasmon resonance sensing element on the surface of the anti-resonance reflective optical waveguide as described in item 1 of the patent application, wherein the metal layer material covering the core layer of the waveguide of the anti-resonant reflective optical waveguide in the sensing area is A coupling surface plasmon wave can be formed as a criterion. 9. The anti-resonance reflective optical waveguide surface electropolymer resonance sensing element according to item 1 of the scope of the patent application, wherein the waveguide core layer is silicon dioxide (si 〇2) and the metal layer material is gold (Au), Its thickness is between 30 and 40 nm. Page 17 558636 Revised / Corrected / Additional_Case No. 91102976_ Revised / Revised_ 6 、 Applicable patent scope 1 0. The plasmon resonance on the surface of the anti-resonant reflective optical waveguide as described in item 1 of the patent scope The sensing element may further be covered with a dielectric layer on the surface of the metal layer on the waveguide core layer of the anti-resonant reflective optical waveguide in the sensing area. By changing the refractive index and thickness of the material of the additional dielectric layer, the resistance can be adjusted. Operating range and sensing characteristics of the plasmon resonance sensing element on the surface of the resonant reflection optical waveguide. 11. The anti-resonance reflective optical waveguide surface plasmon resonance sensing element according to item 10 of the patent application scope, wherein the waveguide core layer is silicon dioxide (Si02) and the metal layer is 30 to 40 nm thick. Gold (Au) is used for sensing in the water environment (refractive index 1.32). The material of the dielectric layer covering the metal layer is aluminum oxide (Al203), and the thickness is between 12 and 18 nm. Page 18 558636 Case No. 91102976 Correction Scheme 1 4 匚 «1 4-^ Refractive index Sensing area Output area Input area 34 33 32 36 37 35 I 4 «c di 匚 ηι 4%-> Refractive index diagram three (b) Page 558636 Case No. 91102976 minutes jT month (.7 correction chart) ο ο ο ο 5 0 5 I 1 1 I fine η c 9 1.30 1.32 1.34 1.36 1.38 1.40 1.42 Refractive index of the test environment Figure 4