CN105572078B - A kind of double-core photonic crystal fiber SRP refractive index sensing models - Google Patents

Abstract

The invention discloses a dual-core photonic crystal fiber SPR refractive index sensing model, which has a circular cross section and includes a base 1, a fiber core and cladding air holes 2, and cladding air holes are around the fiber core. The fiber core is set to the right side fiber core 3 and the left side fiber core 4; the right side fiber core 3 is a solid base material; the left side fiber core 4 includes a silver film 5 and a detection hole 6; its advantages are, Adopt double-core and elliptical detection hole SPR refractive index sensing structure, filter high-order SPP mode within a certain range of refractive index, determine the sensing resonance peak without mode discrimination, can achieve high linearity and high sensitivity sensing, for refractive index dynamics The changing solution can be monitored in real time, greatly improving the sensing efficiency.

Description

A Refractive Index Sensing Model of Dual-Core Photonic Crystal Fiber SRP

technical field

The invention belongs to the field of photonic crystal optical fiber sensing, in particular relates to optical fiber SPR sensing technology, with

The body is a dual-core photonic crystal fiber SPR refractive index sensing model.

Background technique

Surface plasmon resonance (SPR) behavior is a physical optical phenomenon, which describes the resonance phenomenon of surface plasmon (SPP) in metals or doped semiconductors. It is very sensitive to the refractive index change of the dielectric attached to the metal surface. Real-time and rapid detection, no labeling, less sample consumption, etc., so it has very broad application prospects in the fields of chemistry, biology, environment and medicine, and has become a new field of research in optical detection and sensing technology in recent years.

With the emergence of photonic crystal fiber (PCF) in the field of optical fiber SPR sensing, its excellent characteristics such as unlimited single-mode characteristics, high birefringence, controllable dispersion, high nonlinearity, flexible and controllable structure design, etc., have been favored by researchers. Widely concerned, it has shown great potential application value in the field of SPR sensing.

In July 2012, the National Patent Office published an invention patent application for "a photonic crystal fiber SPR sensing model that is easy to achieve phase matching" with the publication number CN 102590148 A. The invention patent application adopts the core cladding structure, the material is quartz glass, the core air hole is set in the center of the fiber core, and the cladding is provided with six cladding air holes arranged in a regular hexagon, two of which are symmetrical to the center The inner surface of the air hole in the cladding is coated with a gold film, which better solves the phase matching problem between the core and the SPP mode in the traditional optical fiber. However, in practical applications, the coupling between the basic core mode of the photonic crystal fiber and the high-order SPP mode will cause multiple resonance peaks. Due to the interference of the high-order SPP mode, it is necessary to conduct mode discrimination in actual measurement to find the The refractive index is obtained by measuring the resonance peak. For the sensing of the change of the refractive index of the medium, this not only makes the sensing process more complicated but also reduces the sensing efficiency.

Contents of the invention

The technical problem to be solved by the present invention is to provide a dual-core photonic crystal fiber SPR refraction index sensing model for the above-mentioned deficiencies or defects in the prior art. The model adopts a double-core and elliptical detection hole structure, which effectively solves the influence of high-order SPP modes on the measurement resonance peak, and has the characteristics of high linear sensing and high sensitivity.

Technical solution of the present invention is:

A dual-core photonic crystal fiber SPR refractive index sensing model, which has a circular cross section, includes a base, a core, and cladding air holes, and cladding air holes around the core. It is characterized in that the core It is set as a right fiber core and a left fiber core; the right fiber core is a solid base material; the left fiber core includes a silver film and a detection hole.

The material of the base and the right core is silica with a refractive index of 1.45.

The cladding air holes are periodically arranged in a regular hexagon, the distance between adjacent cladding air holes is 2um, and the diameter of the cladding air holes is 1um.

The detection hole is elliptical, the long axis of the detection hole is 1.6um, and the short axis is 1.18um. The detection hole is used to place the solution to be tested.

The thickness of the silver film is 40nm.

After adopting the above structure, compared with the prior art, the advantages of the present invention are: adopt the SPR refractive index sensing structure with double cores and elliptical detection holes, filter high-order SPP modes within a certain range of refractive index, and determine whether the sensing resonance peak is Mode discrimination is required, high linearity and high sensitivity sensing can be achieved, real-time monitoring is possible for solutions with dynamic changes in refractive index, and the sensing efficiency is greatly improved.

Description of drawings

Fig. 1 is a schematic diagram of the internal structure of a dual-core photonic crystal fiber SPR refractive index sensing model of the present invention;

Fig. 2 is a sensing characteristic curve of a dual-core photonic crystal fiber SPR refractive index sensing model of the present invention;

Figure 3 is the dispersion curve of each SPP mode and the right core mode appearing in the 900nm-1800nm band when the refractive index of the solution to be tested is 1.45;

Figure 4 is the dispersion curve of each SPP mode and the right core mode appearing in the 900nm-1800nm band when the refractive index of the solution to be measured is 1.50;

In the figure: 1. Substrate, 2. Cladding air hole, 3. Right fiber core, 4. Left fiber core, 5. Silver film, 6. Detection hole.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

A dual-core photonic crystal fiber SPR refractive index sensing model, the cross-section of which is circular, includes a substrate 1, a core and cladding air holes 2, and cladding air holes 2 around the core, characterized in that the The fiber cores are set as the right fiber core 3 and the left fiber core 4; the right fiber core 3 is a solid base material; the left fiber core 4 includes a silver film 5 and a detection hole 6.

The material of the base 1 and the right core 3 is silicon dioxide with a refractive index of 1.45.

The cladding air holes 2 are periodically arranged in regular hexagons, the distance between adjacent ones is 2um, and the diameter of the cladding air holes 2 is 1um.

The detection hole 6 is elliptical, the long axis of the detection hole 6 is 1.6um, and the short axis is 1.18um. The detection hole 6 is used to place the solution to be tested.

The thickness of the silver film 5 is 40nm.

The SPR refractive index sensing model of the photonic crystal fiber with dual cores and elliptical side cores used in the present invention uses the base film of the right core 3 to couple with the SPP mode in the left core 4 to achieve resonance coupling under phase matching conditions , the light localized in the right core 3 is largely absorbed by the silver film 5 in the left core 4, and the transmission loss reaches a peak value. The detection of the refractive index of the medium is realized by utilizing the characteristic that the resonance wavelength is very sensitive to the change of the refractive index of the metal surface medium. The sensing characteristic curve is shown in FIG. 2 . The refractive index of the solution in the hole 6 to be tested is within the range of 1.45-1.50, and has ultra-high linearity, and the sensitivity reaches 10412nm/RIU.

The detection hole 6 is elliptical and can effectively filter the high-order SPP mode, as shown in Figure 3 and Figure 4, which respectively represent all the left side of the solution in the hole 6 to be tested when the refractive index of 1.45 and 1.5 in the 900nm-1800nm band SPP mode in core 4 and the basement film dispersion curve of core 3 on the right. When the SPP mode and basement film dispersion are the same, it is the phase matching point. Combining Figure 3 and Figure 4, it can be obtained that in the 1112.37nm-1376.35nm band and 1387.4 Only the SPP1 mode that needs to be measured exists in the nm-1633.75nm band. The corresponding ranges of the refractive index are 1.45-1.472 and 1.474-1.5, and no mode resolution is required for SPR sensing in the range of the refractive index, which can effectively simplify the sensing steps.

A dual-core photonic crystal fiber SPR refractive index sensing model of the present invention uses metallic silver as the excited surface plasmon metal, the sensitivity can reach 10412nm/RIU, and it has ultra-high linearity in the range of 1.45-1.50 refractive index. The detection hole For the elliptical shape within a certain range of refractive index, the resonant peak can be directly measured without mode discrimination to obtain the refractive index, which greatly simplifies the sensing steps and increases the sensing efficiency. The obtained characteristic has good application value in the field of photonic crystal fiber sensing in the future.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, those who make several equivalent substitutions or obvious modifications without departing from the concept of the present invention, and have the same performance or use, shall be deemed to belong to the claims submitted by the present invention defined scope of protection.

Claims (2)

1. a kind of double-core photonic crystal fiber SPR refractive index sensing models, its cross section is circle, including substrate (1), fibre core and Covering airport (2), fiber core are covering airport (2), it is characterised in that described fibre core is arranged to right side fibre core (3) With left side fibre core (4)；Described right side fibre core (3) is solid base material；Described left side fibre core (4) includes silverskin (5), inspection The material of gaging hole (6), described substrate (1) and right side fibre core (3) is silica, and its refractive index is 1.45, described covering Airport (2) is with regular hexagon periodic arrangement, and covering airport (2) adjacent spacing is 2 μm, a diameter of 1 μ of covering airport (2) M, described detection hole (6) are ellipse, and detection hole (6) major axis is 1.6 μm, and minor axis dimension is 1.18 μm, and detection hole (6) is used for Place solution to be measured.

2. a kind of double-core photonic crystal fiber SPR refractive index sensing models as claimed in claim 1, it is characterised in that described Silverskin (5) thickness is 40nm.