Silicon-based refractive index sensor based on cascaded U-shaped waveguide nested micro-ring

Abstract

The invention provides a silicon-based refractive index sensor based on a cascaded U-shaped waveguide nested micro-ring. The sensor is composed of a silicon substrate layer, a silicon dioxide lower cladding layer, a monocrystalline silicon core layer and a silicon dioxide upper cladding layer which are stacked in sequence from bottom to top, wherein the output end of a first straight waveguide inthe monocrystalline silicon core layer is connected with the input end of a first U-shaped waveguide, the output end of the first U-shaped waveguide is connected with the input end of a second straight waveguide, the output end of the second straight waveguide is connected with the input end of a second U-shaped waveguide, and the output end of the second U-shaped waveguide is connected with the input end of a third straight waveguide; a first micro-ring resonant cavity is located between the first straight waveguide and the second straight waveguide on the inner side of the first U-shaped waveguide, and a second micro-ring resonant cavity is located between the second straight waveguide and the third straight waveguide on the inner side of the second U-shaped waveguide. Compared with a cascade micro-ring sensor in the same size, the sensor has the advantage that the sensing detection range can be doubled on the basis of improving the sensing sensitivity. The sensor has the advantagesof high sensitivity, large sensing range, facilitation of on-chip integration and the like.

Description

technical field [0001] The invention relates to the sensing and detection technology of specific chemical or biological substances such as gas molecules and biomolecules, and belongs to the technical field of light sensing and light integration. Background technique [0002] Optical sensing is mainly divided into two types: marked sensing and mark-free sensing. Labeled sensors need certain treatment to mark the substance to be tested before detecting it, such as adding specific fluorescent substances or radioactive isotopes, etc., and then obtain the corresponding information of the labeled substance to be tested by detecting the label, but this method exists There are disadvantages such as complicated test steps and expensive equipment, and there is also the risk of damage to the object to be tested. The label-free sensor can save cumbersome steps such as marking the object to be tested, and has received more and more attention and demand in various industries. . For exam...

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Problems solved by technology

[0004] The sensing sensitivity of sensors based on a single microring resonator is limited by the structural characteristics of the microring resonator itself, although it is possible to increase the influence of the object to be measured on the evanescent field by periodically digging holes in the ring waveguide, thereby improving Sensing sensitivity of the device, but it will cause the problem of increased optical field loss; currently, two microring resonators are connected in cascade, and the vernier effect generated by them is used to improve the sensitivity, but the cascaded structure of the sensor Range cannot be improved

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