CN104568751A - Optical ring-down cavity surface plasmon resonance sensor demodulation device - Google Patents

Abstract

The invention discloses a surface plasmon resonance sensor demodulation device of an optical ringdown cavity, which is characterized in that it comprises a tunable laser pulse generator, a first optical isolator, an erbium-doped fiber amplifier, and an adjustable attenuator sequentially connected by an optical fiber. , a surface plasmon resonance sensor, a coupler and a second optical isolator, the second optical isolator is connected to the first optical isolator, and the coupler is connected to a photodetector. The device improves the sensitivity and measurement speed of the surface plasmon resonance sensor, increases the measurement range, has simple structure, low cost and is easy to realize.

Description

Demodulation device for surface plasmon resonance sensor of optical ring down cavity

technical field

The invention belongs to the technical field of sensors, in particular to a surface plasmon resonance sensor demodulation device of an optical ringdown cavity.

Background technique

At present, the surface plasmon resonance (Surface plasmon resonance, referred to as SPR) sensing technology has developed into a new technology for gas concentration measurement. Researcher Nooke of the German Federal Institute of Materials combined ellipsometry and SPR detection, designed a gold-clad prism BK7 structure, and used a spectrometer to directly scan the spectrum for demodulation. The realized system can be used to measure concentrations of 1.5 -0.3% alkane series gas. In a large number of SPR sensing studies, wavelength-indicating SPR sensors are used. This type of sensor basically adopts the demodulation design of the spectrometer. This solution has a simple optical path and good stability; the sensitivity does not depend on the characteristics of the sample; it is suitable for long-term Large dynamic range experiments. In comparison, the demodulation design of the intensity-indicating SPR sensor is faster and may obtain higher sensitivity, but for the light intensity measurement of a fixed wavelength, the large-scale shift of the sample spectrum will lead to a decrease in sensitivity, so only It is suitable for fields with small dynamic range such as presence detection. SPR technology has the advantages of no labeling of samples, easy implementation, real-time dynamic analysis, high selectivity, high sensitivity, fast analysis speed, etc. It is suitable for gas composition and concentration measurement research, which has attracted extensive attention from many scholars at home and abroad.

"Surface and Interface Analysis" published the article "Surface plasmon sensor for NO2 gas" on page 1623, vol. -Pc) embedded on the PVC substrate, and then stacked on the Ag film, the experimental results show that the film has good sensitivity to NO2 under normal temperature and atmospheric pressure, but it fails to provide an effective processing system for response speed and dynamic range . From the current development point of view, the realization of high measurement sensitivity, fast response speed, and large dynamic range in the demodulation design of gas concentration sensing has become the primary goal of the transformation of SPR sensors to practical ones.

At present, the research on the SPR sensor demodulation system basically focuses on the design of demodulation by directly scanning the spectrum with a spectrometer.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art, and provide a surface plasmon resonance sensor demodulation device for an optical ring-down cavity, which can improve the sensitivity, measurement speed, and increase the measurement range of the surface plasmon resonance sensor, and has a simple structure , low cost and easy to implement.

The technical scheme that realizes the object of the present invention is:

A demodulation device for a surface plasmon resonance sensor in an optical ringdown cavity, comprising a tunable laser pulse generator, a first optical isolator, an erbium-doped fiber amplifier, an adjustable attenuator, a surface plasmon resonance sensor, and a coupler sequentially connected by an optical fiber and the second optical isolator, the second optical isolator is connected with the first optical isolator, and the coupler is connected with the photodetector.

The laser pulse of the tunable laser pulse generator is made of a 10kW fixed-wavelength high-power yttrium-aluminum garnet crystal laser and a tunable diode laser TDL in a PPLN crystal, and is modulated into a tunable laser with a wide range of 1400-1650nm pulse.

The erbium-doped fiber amplifier is pumped back and forth. The input and output ends of the erbium-doped fiber amplifier are respectively connected with a fiber grating, and one of the fiber gratings is a fiber grating with adjustable Bragg wavelength.

The surface plasmon resonance sensor is connected through an optical fiber grating.

The surface plasmon resonance sensor is made by nanosphere etching method.

While giving full play to the advantages of SPR technology, this device no longer sticks to the fact that the SPR sensor is only used as a single advantageous functional device to achieve gas concentration measurement. It uses optical fiber connection to form an optical cavity ring-down system, and the SPR sensor in the ring-down time of the optical fiber ring cavity The difference in attenuation before and after the change in absorption or response obtains the concentration of the measured gas. The device improves the sensitivity and measurement speed of the surface plasmon resonance sensor, increases the measurement range, has simple structure, low cost and is easy to realize.

Description of drawings

Fig. 1 is the structural representation of embodiment.

In the figure, 1. Tunable laser pulse generator 2. First optical isolator 3. Erbium-doped fiber amplifier 4. Adjustable attenuator 5. Surface plasmon resonance sensor 6. Coupler 7. PC 8. Second optical isolation 9. Light detector.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited thereto.

Example:

Referring to Fig. 1 , a demodulation device for a surface plasmon resonance sensor of an optical ringdown cavity comprises a tunable laser pulse generator 1, a first optical isolator 2, an erbium-doped fiber amplifier 3, and an adjustable attenuator 4 sequentially connected by optical fibers , a surface plasmon resonance sensor 5 , a coupler 6 and a second optical isolator 8 , the second optical isolator 8 is connected to the first optical isolator 2 , and the coupler 6 is connected to the photodetector 9 .

The laser pulse of the tunable laser pulse generator 1 is made of a 10kW high-power yttrium aluminum garnet crystal laser with a fixed wavelength and a tunable diode laser TDL in a PPLN crystal, and modulated into a wide range of 1400-1650nm tunable laser pulse.

Described erbium-doped fiber amplifier 3 is pumping type back and forth, respectively connects a fiber grating at the input of erbium-doped fiber amplifier 3, output end, and wherein a fiber grating is the fiber grating of adjustable Bragg wavelength.

The surface plasmon resonance sensor 5 is connected through an optical fiber grating.

The surface plasmon resonance sensor 5 is fabricated by nanosphere etching.

Specifically, as shown in Figure 1, the PC 7 is respectively connected with the tunable laser pulse generator 1, the erbium-doped fiber amplifier 3, the adjustable attenuator 4, and the photodetector 9, and the tunable laser pulse generator 1 sends a pulse The laser pulse with a width of 5ns and 1400-1650nm enters the first optical isolator 2, the optical pulse is amplified by the erbium-doped fiber amplifier 3 and adjusted by the adjustable attenuator 4, and passes through the surface plasmon resonance sensor 5, and the light is absorbed in the coupler 6 Divided into two paths, one path of light continues to circulate in the optical fiber loop through the second optical isolator 8, and the other path is received by the optical detector 9 and sent to the PC 7 for processing. The photodetector 9 records the values of each cycle of light pulses that gradually attenuate. When the amplitude is the initial value 1/e, the time is defined as the ring-down time. According to the ring-down time, it can be obtained that the specified wavelength laser passes through the surface plasmon resonance sensor 5. Attenuation, using the ring-down time change caused by the unresponsive system, can be further calculated to obtain the corresponding sensing quantity.

Claims (5)

1. A light ring down cavity surface plasmon resonance sensor demodulation device is characterized in that it comprises a tunable laser pulse generator, the first optical isolator, an erbium-doped fiber amplifier, an adjustable attenuator, and a surface A plasmon resonance sensor, a coupler and a second optical isolator, the second optical isolator is connected with the first optical isolator, and the coupler is connected with an optical detector. 2. The optical ring down cavity surface plasmon resonance sensor demodulation device according to claim 1, wherein the laser pulse of the tunable laser pulse generator is a high-power yttrium aluminum garnet with a fixed wavelength of 10kW The crystal laser and the tunable diode laser TDL are differentially modulated into 1400-1650nm wide range tunable laser pulses in the PPLN crystal. 3. optical ring-down cavity surface plasmon resonance sensor demodulation device according to claim 1, is characterized in that, described erbium-doped fiber amplifier is pumping type front and rear, respectively connects at the input and output ends of erbium-doped fiber amplifier A fiber grating, wherein one of the fiber gratings is a fiber grating with tunable Bragg wavelength. 4. The device for demodulating a surface plasmon resonance sensor in an optical ring-down cavity according to claim 1, wherein the surface plasmon resonance sensor is connected through a fiber Bragg grating. 5. The device for demodulating a surface plasmon resonance sensor of an optical ring-down cavity according to claim 1, wherein the surface plasmon resonance sensor is made by nanosphere etching.