CN101799334A - Silicon-based optical wave guide temperature sensor based on Mach-Zehnder structure - Google Patents

Abstract

The invention provides a silicon-based optical wave guide temperature sensor based on a Mach-Zehnder structure, realizing temperature sensing by utilizing the sensitivity of a transmission spectrum thereof to temperature. The silicon-based optical wave guide temperature sensor comprises a laser, a Y-shaped wave guide, a first power meter, a Mach-Zehnder wave guide structure and a second power meter, wherein one end of the Y-shaped wave guide is an incident wave guide, a first positive cone is arranged at one end of the incident wave guide and is connected with the laser through optical fibers, the other two ends of the Y-shaped wave guide are respectively a reference arm wave guide and a sensing arm wave guide, a second positive cone is arranged at one end of the reference arm wave guide of the Y-shaped wave guide, and a third positive cone is arranged at one end of the sensing arm wave guide of the Y-shaped wave guide; the first power meter is connected with the second positive cone through optical fibers; the Mach-Zehnder wave guide structure is connected in the middle of the sensing arm wave guide; and the second power meter is connected with the third positive cone of the sensing arm wave guide through optical fibers.

Description

Silica-based optical wave guide temperature sensor based on Mach-Zehnder structure

Technical field

The present invention relates to a kind of silica-based optical wave guide temperature sensor, particularly a kind of silica-based optical waveguide temperature sensing device based on Mach-Zehnder structure.

Background technology

In the temperature sensing field, commercial production and daily life mainly adopt the contact electric transducer to carry out temperature sensing, and as thermopair, thermal resistance etc., but these technology are difficult in the rugged surroundings such as high temperature, high pressure, high humidity, high electromagnetic interference (EMI) and are applied.In hot and humid or high corrosion environment, fax sense itself is understood rapid aged deterioration and can't be measured temperature at all simultaneously.Based on advantages such as the high stability of optical fiber and high temperature resistant, high pressure, high humidity, strong electromagnetic, multiple optical fiber temperature sensing device such as Brillouin scattering temperature sensor, Raman scattering temperature sensor etc. have been developed.Compare with optical fiber, advantage such as intrinsic high temperature resistant, the high pressure of silica-based optical waveguide itself, severe corrosive and antijamming capability are strong can be applied to realize in the rugged surroundings measurement to temperature equally.

Mach-Zehnder structure has been widely used in various modulators and the wave filter as the basic structure of light signal process field.Based on the comb filter that silica-based optical waveguide constituted of Mach-Zehnder structure, because of its transmitted spectrum can be applicable to the temperature sensing field with the drift characteristic of temperature.

In typical Mach-Zehnder structure wave filter as shown in Figure 2, mainly the Y type optical waveguide that is 3dB by splitting ratio constitutes, and two interfere the length of arms to be respectively L ₁, L ₂, its arm length difference Δ L=|L ₁-L ₂|, then the transmitted light intensity P of this wave filter can be expressed as

$P\∝{\sin }^2\frac{\mathrm{n\π}}{\mathrm{\λ}}\mathrm{\ΔL}$

Wherein n is the transmission medium refractive index, and λ is the wavelength of incident light wave.As can be seen from the above equation, the transmitted spectrum of this wave filter is to interfere the relevant pectination spectrum of arm arm length difference Δ L with the refractive index n, two of transmission medium, and as shown in Figure 3, its reuse wavelengths interval delta λ, channelized frequencies interval delta f can be expressed as respectively

$\mathrm{\Δ\λ}=\frac{{\mathrm{\λ}}^2}{\mathrm{n\ΔL}}$

$\mathrm{\Δf}=\frac{c}{\mathrm{n\ΔL}}$

Wherein c is the light velocity in the vacuum.For the incident light wave of fixed wave length, its transmitted light intensity only interferes arm arm length difference Δ L relevant with two of the refractive index n of transmission medium and Mach-Zehnder structure.Responsive to temperature characteristic based on silica-based fiber waveguide refractive index, can make the transmitted spectrum of wave filter drift about, the transmitted light intensity of wave filter also will change thereupon, the present invention has promptly utilized above-mentioned principle design a kind of silica-based optical wave guide temperature sensor based on Mach-Zehnder structure.

Summary of the invention

The objective of the invention is to, a kind of silica-based optical wave guide temperature sensor based on Mach-Zehnder structure is provided, can accurately measure environment temperature to be measured, antijamming capability is strong, is applicable to rugged environment and temperature survey on a large scale.

The invention provides a kind of silica-based optical wave guide temperature sensor based on Mach-Zehnder structure, is to utilize its transmitted spectrum that the susceptibility of temperature is realized comprising sensing to temperature:

One laser instrument;

One Y type waveguide, an end of this Y type waveguide is the incident waveguide, and an end of incident waveguide has one first positive cone, and first positive cone of this Y type waveguide is connected with laser instrument by optical fiber;

The two ends in addition of this Y type waveguide are divided into reference arm waveguide and pickup arm waveguide;

One end of the reference arm waveguide of this Y type waveguide has one second positive cone;

One end of the pickup arm waveguide of this Y type waveguide has one the 3rd positive cone;

One first power meter, this first power meter is connected with second positive cone of reference arm waveguide by optical fiber;

One Mach-Zehnder waveguiding structure, this Mach-Zehnder waveguiding structure inserts the centre of pickup arm waveguide;

One second power meter, this second power meter is connected with the 3rd positive cone of pickup arm waveguide by optical fiber.

Wherein the laser instrument that is adopted is the single-mode laser of Distributed Feedback Laser or DBR laser instrument.

Wherein said first positive cone, second positive cone and the 3rd positive cone are positive wimble structure or back taper structure.

Wherein the splitting ratio of Y type waveguide is 3dB.

Wherein two arm length difference of Mach-Zehnder waveguiding structure are a centimetre magnitude.

Wherein first power meter and second power meter adopt light power meter or photo-detector.

The advantage that the present invention has compared with prior art is: utilize the transmitted spectrum of the Mach-Zehnder structure wave filter of silica-based optical waveguide that the susceptibility of temperature is realized sensing to temperature, ripe, highly sensitive, advantage such as selectivity is high, usable range is wide, size is little possesses skills.Reflect the change of the transmitted light intensity that causes because of temperature variation simultaneously by the ratio of pickup arm and reference arm emergent light power, increased the antijamming capability of device.Select the bias point of incident light wave by lambda1-wavelength, can increase the sensitivity of sensor.Because the core sensing arrangement of this sensor is made of silica-based optical waveguide, degree of stability is very high, applicable to rugged environment and temperature survey on a large scale.

Description of drawings

For further specifying concrete technology contents of the present invention, below in conjunction with drawings and Examples to the detailed description of the invention as after, wherein:

Fig. 1 is a structural representation of the present invention.

Fig. 2 is the typical Mach-Zehnder structure filter schematic that adopts 3dB Y type optical waveguide to constitute.

Fig. 3 is the pectination transmitted spectrum of wave filter shown in Fig. 2.

Fig. 4 is that transmitted light wave power is with variation of temperature situation synoptic diagram.

Embodiment

See also shown in Figure 1, the invention provides a kind of silica-based optical wave guide temperature sensor based on Mach-Zehnder structure, it is to utilize its transmitted spectrum that the susceptibility of temperature is realized sensing to temperature, mainly comprise: laser instrument 1, Y type waveguide 2, first power meter 3, Mach-Zehnder waveguiding structure 4, the second power meters 5 etc.

The laser instrument 1 that is adopted can be single-mode lasers such as Distributed Feedback Laser or DBR laser instrument.Splitting ratio is that an end of the Y type waveguide 2 of 3dB is that incident waveguide 21 is in order to import the incident light wave of laser instrument 1, one end of incident waveguide 21 has first positive cone 211, and first positive cone 211 of this Y type waveguide 2 is connected to realize good coupling efficiency with laser instrument 1 by optical fiber.

The two ends in addition of this Y type waveguide 2 are divided into reference arm waveguide 22 and pickup arm waveguide 23 is divided into equicohesive two parts with incident light wave.Distance between this reference arm waveguide 22 and the pickup arm waveguide 23 should be as far as possible little, and then other external disturbance and vibration can act in reference arm waveguide 22 and the pickup arm waveguide 23 simultaneously, cause identical phase differential, can improve the antijamming capability of device greatly.One end of the reference arm waveguide 22 of this Y type waveguide 2 has second positive cone 221, and an end of pickup arm waveguide 23 has the 3rd positive cone 231.Above-mentioned first positive cone 211, second positive cone 221 and the 3rd positive cone 231 also can adopt the back taper structure to increase coupling efficiency between waveguide and optical fiber (first positive cone 211 in the embodiments of the invention, second positive cone 221 and the 3rd positive cone 231 adopt be positive wimble structure).

First power meter 3 is connected with second positive cone 221 of reference arm waveguide 22 by optical fiber, to survey reference The transmitted light intensity of arm waveguide 22 is monitored the variation of the luminous power of laser instrument 1 outgoing

Pickup arm waveguide 23 is coupled into Mach-Zehnder waveguiding structure 4 with incident light wave, and two arm length difference of this Mach-Zehnder waveguiding structure 4 are for centimetre magnitude and remain constant.For the fixing incident light wave of wavelength, its transmitted light intensity general is only determined by the refractive index of silica-based optical waveguide.As shown in Figure 4, the wavelength of incident light wave is λ ₀, when temperature is T ₁The time, the refractive index of silica-based optical waveguide is n ₁, the transmitted spectrum of Mach-Zehnder waveguiding structure 4 is shown in solid line among Fig. 4, and the luminous power of its transmission is P ₁When temperature variation is T ₂The time, based on the temperature sensitivity of silica-based fiber waveguide refractive index, its variations in refractive index is n ₂, the transmitted spectrum of Mach-Zehnder waveguiding structure 4 will drift about, and shown in the dotted line among Fig. 4, the luminous power of transmission this moment is P ₂, therefore can reflect variation of temperature by the transmitted optical power of monitoring Mach-Zehnder wave filter.After 4 pairs of incident light waves of Mach-Zehnder waveguiding structure carry out filtering, by the 3rd positive cone 231 with the light wave coupled into optical fibres.

Second power meter 5 is connected with the 3rd positive cone 231 of pickup arm waveguide 23 by optical fiber, and records the transmitted light intensity through filtered pickup arm waveguide 23.The ratio of the transmitted light intensity that records by first power meter 3 and second power meter 5 reflects the variation of environment temperature, overcome the influence of laser instrument 1 self power jitter simultaneously.The incident wavelength of regulating laser instrument 1 by the bias current of regulating laser instrument 1 in whole device can increase the sensitivity of sensor for temperature to select the suitable wavelengths bias point.Above-mentioned first power meter 3 and second power meter 5 also can adopt photo-detector etc.

For splitting ratio is the Mach-Zehnder waveguiding structure 4 of 3dB, and its transmitted light intensity is

$P\∝{\sin }^2\frac{\mathrm{n\π}}{\mathrm{\λ}}\mathrm{\ΔL}$

Its optical power change is

$\mathrm{\δP}\∝2\sin \frac{\mathrm{n\π}}{\mathrm{\λ}}\mathrm{\Δ}L\cos \frac{\mathrm{n\π}}{\mathrm{\λ}}\mathrm{\ΔLg}\frac{\mathrm{\π\ΔL}}{\mathrm{\λ}}\mathrm{\δn}$

$\frac{\mathrm{\δP}}{P}=2\cot \frac{\mathrm{n\π}}{\mathrm{\λ}}\mathrm{\ΔLg}\frac{\mathrm{\π\ΔL}}{\mathrm{\λ}}\mathrm{\δn}$

For silica-based optical waveguide, the refractive index of infrared band light wave and temperature T satisfy following relation substantially

n＝3.38(1+3.9×10 ^-5T) (77K＜T＜400K，)

$\frac{\mathrm{\δP}}{P}=2.764\×{10}^{-4}\frac{\mathrm{\π\ΔL}}{\mathrm{\λ}}\cot \frac{\mathrm{n\π}}{\mathrm{\λ}}\mathrm{\ΔLg\δT}$

Following formula is the relative variation and the variation of temperature relation of luminous power, and the relative variation that records first power meter 3 and second power meter, 5 light intensity can be realized the measurement to temperature.Because the variation of 4 liang of arm length difference of Mach-Zehnder waveguiding structure that the shrinkage of silica-based optical waveguide heat expansion causes can cause the transmitted spectrum of Mach-Zehnder waveguiding structure 4 to drift about in the same direction, increased the sensitivity of this sensor simultaneously.

Above-described specific embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of being made, be equal to replacement, improvement etc., all should be included within the claim protection domain of the present invention.

Claims (6)

1. silica-based optical wave guide temperature sensor based on Mach-Zehnder structure is to utilize its transmitted spectrum that the susceptibility of temperature is realized comprising sensing to temperature:

One laser instrument;

One Y type waveguide, an end of this Y type waveguide is the incident waveguide, and an end of incident waveguide has one first positive cone, and first positive cone of this Y type waveguide is connected with laser instrument by optical fiber;

The two ends in addition of this Y type waveguide are divided into reference arm waveguide and pickup arm waveguide;

One end of the reference arm waveguide of this Y type waveguide has one second positive cone;

One end of the pickup arm waveguide of this Y type waveguide has one the 3rd positive cone;

One first power meter, this first power meter is connected with second positive cone of reference arm waveguide by optical fiber;

One Mach-Zehnder waveguiding structure, this Mach-Zehnder waveguiding structure inserts the centre of pickup arm waveguide;

One second power meter, this second power meter is connected with the 3rd positive cone of pickup arm waveguide by optical fiber.

2. the silica-based optical wave guide temperature sensor based on Mach-Zehnder structure according to claim 1, wherein the laser instrument that is adopted is the single-mode laser of Distributed Feedback Laser or DBR laser instrument.

3. the silica-based optical wave guide temperature sensor based on Mach-Zehnder structure according to claim 1, wherein said first positive cone, second positive cone and the 3rd positive cone are positive wimble structure or back taper structure.

4. the silica-based optical wave guide temperature sensor based on Mach-Zehnder structure according to claim 1, wherein the splitting ratio of Y type waveguide is 3dB.

5. the silica-based optical wave guide temperature sensor based on Mach-Zehnder structure according to claim 1, wherein two arm length difference of Mach-Zehnder waveguiding structure are a centimetre magnitude.

6. the silica-based optical wave guide temperature sensor based on Mach-Zehnder structure according to claim 1, wherein first power meter and second power meter adopt light power meter or photo-detector.

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