CN104180910A - Spectral width measuring device and method used for SLED light source - Google Patents

Abstract

The invention discloses a spectral width measuring device and method used for an SLED light source. The device comprises the SLED light source to be measured, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector, an optical fiber circulator, a 3*3 optical fiber coupler, an online luminous power meter, a first 2*2 optical fiber coupler, a second 2*2 optical fiber coupler, an optical fiber lithium niobate phase modulator, a first Faraday rotary reflector, a delay optical fiber cable, a second Faraday rotary reflector and a data terminal. The number of light paths used for measuring the spectral width of the SLED light source is at least two, and interference exists between the two two-beam light paths. The spectral width measuring device and method used for the SLED light source can quickly and accurately measure the spectral width of the SLED light source, are low in cost and convenient to use and have good application prospects.

Description

A kind of spectrum width measurement mechanism and method for SLED light source

Technical field

The present invention relates to a kind of spectrum width measurement mechanism and method for SLED light source, belong to spectral signature field of measuring technique.

Background technology

Along with the developing rapidly of optical fiber sensing technology, fibre optic gyroscope, fibre optic hydrophone, optical fiber sensing security system be the corresponding application obtaining more extensively and profoundly also in recent years, from before single Military Application develop into present civil area.

Due to the applied concrete know-why difference of these optical fiber sensing systems, the LASER Light Source kind using is also different, only taking optical fiber sensing security system as example, applied just have M-Z, sagnac, many technology paths of OTDR, thereby related LASER Light Source has the polytypes such as DFB-LD type, fiber laser, ASE light source.But, because low relevant wide spectrum light source can suppress interference and the negative effect that in optical fiber, Rayleigh scattering and Kerr effect etc. are brought preferably, thereby fibre optic gyroscope based on wide range LASER Light Source technology, optical fiber sensing security system, fibre optic hydrophone in Fibre Optical Sensor in occupation of more and more important share, the special LASER Light Source that can use hardly other type in the application of fibre optic gyroscope except using wide range LASER Light Source.SLED light source is a kind of most typical wide range LASER Light Source.

But, the spectrum width of LASER Light Source is not more wide better yet, but just can reach within the specific limits optimum efficiency, taking fibre optic gyroscope as example, light source spectrum width is wider in theory, and its effect that suppresses measuring error can be better, but widely can produce harmful effect to the linearity of system scale factor, stability again, therefore, select the SLED light source of suitable spectrum width extremely important, need a kind of device that can accurately measure SLED spectrum width to select SLED light source for this reason.Certainly, use fiber spectrometer can realize this purpose, and can obtain other physical characteristic parameter of LASER Light Source, but problem is, at present, fiber spectrometer price is still very expensive, and other detailed physical features that we do not need to obtain LASER Light Source in this type of application of fibre optic gyroscope is as ripple feature etc., can measure the spectrum width of all laser class light sources does not in fact also pay close attention to fiber spectrometer, thereby, be badly in need of a kind of with low cost, can Quick Measurement the device of SLED type LASER Light Source spectrum width, solve the problems referred to above.

Summary of the invention

The object of the invention is to overcome existing fiber spectrometer expensive, be difficult to penetration and promotion to measure the spectrum width of SLED light source, spectrum width measurement mechanism and method for SLED light source of the present invention, can accurately measure fast the spectrum width of SLED light source, with low cost, easy to use, have a good application prospect.

In order to achieve the above object, the technical solution adopted in the present invention is:

A kind of spectrum width measurement mechanism for SLED light source, it is characterized in that: comprise SLED light source to be measured, the first photodetector, the second photodetector, the 3rd photodetector, optical fiber circulator, 3 × 3 fiber couplers, luminous power on-line measurement meter, the one 2 × 2 fiber coupler, the 22 × 2 fiber coupler, optical fiber lithium niobate phase modulator, the first faraday rotator mirror, postpone optical fiber cable, the second faraday rotator mirror and data terminal

Described SLED light source to be measured, the second photodetector is connected with 3 × 3 fiber couplers by optical fiber circulator respectively, described the first photodetector, the 3rd photodetector is connected with 3 × 3 fiber couplers respectively, described 3 × 3 fiber couplers respectively with the one 2 × 2 fiber coupler, the 22 × 2 fiber coupler is connected, described the one 2 × 2 fiber coupler is connected with the first faraday rotator mirror by optical fiber lithium niobate phase modulator, described the 22 × 2 fiber coupler is connected with the second faraday rotator mirror by postponing optical fiber cable, described the one 2 × 2 fiber coupler, the 22 × 2 fiber coupler is connected by optical fiber, described 3 × 3 fiber couplers are also connected with luminous power on-line measurement meter, described the first photodetector, the second photodetector, the 3rd photodetector is connected with data terminal respectively by cable.

Aforesaid a kind of spectrum width measurement mechanism for SLED light source, is characterized in that: be at least two for measuring the light path approach of SLED light source spectrum width, and exist two two-beam roads to interfere.

The measuring method of a kind of spectrum width measurement mechanism for SLED light source based on above-mentioned, is characterized in that: comprises the following steps,

Step (1), exports three road interference lights by data terminal control the first photodetector, the second photodetector, the 3rd photodetector, makes adjacent two-way interference light have the phase differential of 120 ° by 3 × 3 fiber couplers;

Step (2), modulates by optical fiber lithium niobate phase modulator the phase differential that three road interference lights cause in external disturbance

Step (3), according to formula (1), calculates interference light intensity

Wherein, i (k) is spectral concentration function; K is the wave number of interference light, k=2 π/λ, and λ is for interfering light wavelength;

Step (4), according to formula (2), (3), calculates the spectral concentration function i (k) of SLED light source,

Δk/k＝Δλ/λ (2)

$i\left(k\right)=\frac{1}{\sqrt{\mathrm{\π\Δk}}}{e}^{-{\left(\frac{k-k_0}{\mathrm{\Δk}}\right)}^2}---\left(3\right)$

Wherein, Δ λ is the spectrum width of SLED light source, and Δ k is the increment of wave number k,

${\∫}_{-\∞}^{\∞}i\left(k\right)\mathrm{dk}=I_0$

Wherein, I ₀for the light intensity of SLED light source;

Step (5), according to improper integral formula (4),

${\∫}_{-\∞}^{\∞}\cos \mathrm{ax}\·e^{(-{\mathrm{bx}}^2)}\mathrm{dx}=\sqrt{\frac{\mathrm{\π}}{b}}{e}^{(-\frac{a^2}{4b})}---\left(4\right)$

Wherein, formula (4) is improper integral formula, and a, b are constant;

Step (6), brings formula (1) into according to formula (2), formula (3), formula (4), obtains formula (5),

Step (7), according to formula (5), obtains the spectrum width Δ λ of SLED light source,

The invention has the beneficial effects as follows: spectrum width measurement mechanism and method for SLED light source of the present invention, can accurately measure fast the spectrum width of SLED light source, with low cost, easy to use, have a good application prospect.

Brief description of the drawings

Fig. 1 is the system chart of the spectrum width measurement mechanism for SLED light source of the present invention.

Fig. 2 is the process flow diagram of the spectrum width measuring method for SLED light source of the present invention.

Fig. 3 is the spectrogram of SLED light source of the present invention.

Embodiment

Below in conjunction with Figure of description, the invention will be further described.Following examples are only for technical scheme of the present invention is more clearly described, and can not limit the scope of the invention with this.

As shown in Figure 1, solid line is optical fiber; Dotted line is cable, spectrum width measurement mechanism for SLED light source of the present invention, comprise SLED light source 1 to be measured, the first photodetector 2, the second photodetector 3, the 3rd photodetector 4, optical fiber circulator 5,3 × 3 fiber couplers 6, luminous power on-line measurement meter the 7, the one 2 × 2 fiber coupler the 8, the 22 × 2 fiber coupler 9, optical fiber lithium niobate phase modulator 10, the first faraday rotator mirror 11, postpone optical fiber cable 12, the second faraday rotator mirror 13 and data terminal 14

Described SLED light source 1 to be measured, the second photodetector 3 is connected with 3 × 3 fiber couplers 6 by optical fiber circulator 5 respectively, the first photodetector 2, the 3rd photodetector 4 is connected with 3 × 3 fiber couplers 6 respectively, 3 × 3 fiber couplers 6 respectively with the one 2 × 2 fiber coupler 8, the 22 × 2 fiber coupler 9 is connected, the one 2 × 2 fiber coupler 8 is connected with the first faraday rotator mirror 11 by optical fiber lithium niobate phase modulator 10, the 22 × 2 fiber coupler 9 is connected with the second faraday rotator mirror 13 by postponing optical fiber cable 12, the one 2 × 2 fiber coupler 8, the 22 × 2 fiber coupler 9 is connected by optical fiber, 3 × 3 fiber couplers 6 are also connected with luminous power on-line measurement meter 7, the first photodetector 2, the second photodetector 3, the 3rd photodetector 4 is connected with data terminal 14 respectively by cable.

Wherein 3 × 3 fiber couplers 6 have the phase bias characteristic of 120 degree, thus between the light splitting of 3 road interference lights of input, there is the phase differential of 120 degree, can be by the phase differential of interference light by 3 road interference light signals demodulation out, then continues to calculate the spectrum width of SLED light source 1.

Be at least two for the light path approach of measuring SLED light source 1 spectrum width, and exist two two-beam roads to interfere, as shown in Figure 1, can form light path approach has 6,

1)1-5-6-8-10-11-10-8-9-12-13-12-9-6；

2)1-5-6-9-12-13-12-9-8-10-11-10-8-6；

3)1-5-6-8-10-11-10-8-6；

4)1-5-6-9-12-13-12-9-6；

5)1-5-6-8-10-11-10-8-9-12-13-12-9-8-10-11-10-8-6；

6)1-5-6-9-12-13-12-9-8-10-11-10-8-9-12-13-12-9-6；

6 above-mentioned light path approach, as long as there are two two-beam roads of existence to interfere.

As shown in Figure 2, the measuring method of the spectrum width measurement mechanism for SLED light source based on above-mentioned, comprises the following steps,

Step (1), control the first photodetector (2), the second photodetector (3), the 3rd photodetector (4) output three road interference lights by data terminal (14), make adjacent two-way interference light have the phase differential of 120 ° by 3 × 3 fiber couplers (6);

Step (2), modulates by optical fiber lithium niobate phase modulator (10) phase differential that three road interference lights cause in external disturbance

Step (3), according to formula (1), calculates interference light intensity

Wherein, i (k) is spectral concentration function; K is the wave number of interference light, k=2 π/λ, and λ is for interfering light wavelength;

Step (4), according to the spectral concentration function i (k) of formula (2), (3) calculating SLED light source, the spectrogram of SLED light source, as shown in Figure 3,

Δk/k＝Δλ/λ (2)

$i\left(k\right)=\frac{1}{\sqrt{\mathrm{\π\Δk}}}{e}^{-{\left(\frac{k-k_0}{\mathrm{\Δk}}\right)}^2}---\left(3\right)$

Wherein, Δ λ is the spectrum width of SLED light source, and Δ k is the increment of wave number k,

${\∫}_{-\∞}^{\∞}i\left(k\right)\mathrm{dk}=I_0$

Wherein, I ₀for the light intensity of SLED light source;

Step (5), according to improper integral formula (4),

${\∫}_{-\∞}^{\∞}\cos \mathrm{ax}\·e^{(-{\mathrm{bx}}^2)}\mathrm{dx}=\sqrt{\frac{\mathrm{\π}}{b}}{e}^{(-\frac{a^2}{4b})}---\left(4\right)$

Wherein, formula (4) is improper integral formula, and a, b are constant;

Step (6), brings formula (1) into according to formula (2), formula (3), formula (4), obtains formula (5),

Step (7), according to formula (5), obtains the spectrum width Δ λ of SLED light source,

In sum, spectrum width measurement mechanism and method for SLED light source of the present invention, can accurately measure the spectrum width of SLED light source fast, with low cost, easy to use, has a good application prospect.

More than show and described ultimate principle of the present invention, principal character and advantage.The technician of the industry should understand; the present invention is not restricted to the described embodiments; that in above-described embodiment and instructions, describes just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.

Claims (3)

1. the spectrum width measurement mechanism for SLED light source, it is characterized in that: comprise SLED light source to be measured (1), the first photodetector (2), the second photodetector (3), the 3rd photodetector (4), optical fiber circulator (5), 3 × 3 fiber couplers (6), luminous power on-line measurement meter (7), the one 2 × 2 fiber coupler (8), the 22 × 2 fiber coupler (9), optical fiber lithium niobate phase modulator (10), the first faraday rotator mirror (11), postpone optical fiber cable (12), the second faraday rotator mirror (13) and data terminal (14),

Described SLED light source to be measured (1), the second photodetector (3) is connected with 3 × 3 fiber couplers (6) by optical fiber circulator (5) respectively, described the first photodetector (2), the 3rd photodetector (4) is connected with 3 × 3 fiber couplers (6) respectively, described 3 × 3 fiber couplers (6) respectively with the one 2 × 2 fiber coupler (8), the 22 × 2 fiber coupler (9) is connected, described the one 2 × 2 fiber coupler (8) is connected with the first faraday rotator mirror (11) by optical fiber lithium niobate phase modulator (10), described the 22 × 2 fiber coupler (9) is connected with the second faraday rotator mirror (13) by postponing optical fiber cable (12), described the one 2 × 2 fiber coupler (8), the 22 × 2 fiber coupler (9) is connected by optical fiber, described 3 × 3 fiber couplers (6) are also connected with luminous power on-line measurement meter (7), described the first photodetector (2), the second photodetector (3), the 3rd photodetector (4) is connected with data terminal (14) respectively by cable.

2. a kind of spectrum width measurement mechanism for SLED light source according to claim 1, is characterized in that: be at least two for measuring the light path approach of SLED light source spectrum width, and exist two two-beam roads to interfere.

3. the measuring method based on a kind of spectrum width measurement mechanism for SLED light source claimed in claim 1, is characterized in that: comprises the following steps,

Step (1), control the first photodetector (2), the second photodetector (3), the 3rd photodetector (4) output three road interference lights by data terminal (14), make adjacent two-way interference light have the phase differential of 120 ° by 3 × 3 fiber couplers (6);

Step (2), modulates by optical fiber lithium niobate phase modulator (10) phase differential that three road interference lights cause in external disturbance

Step (3), according to formula (1), calculates interference light intensity

Wherein, i (k) is spectral concentration function; K is the wave number of interference light, k=2 π/λ, and λ is for interfering light wavelength;

Step (4), according to formula (2), (3), calculates the spectral concentration function i (k) of SLED light source,

Δk/k＝Δλ/λ (2)

$i\left(k\right)=\frac{1}{\sqrt{\mathrm{\π\Δk}}}{e}^{-{\left(\frac{k-k_0}{\mathrm{\Δk}}\right)}^2}---\left(3\right)$

Wherein, Δ λ is the spectrum width of SLED light source, and Δ k is the increment of wave number k,

${\∫}_{-\∞}^{\∞}i\left(k\right)\mathrm{dk}=I_0$

Wherein, I ₀for the light intensity of SLED light source;

Step (5), according to improper integral formula (4),

${\∫}_{-\∞}^{\∞}\cos \mathrm{ax}\·e^{(-{\mathrm{bx}}^2)}\mathrm{dx}=\sqrt{\frac{\mathrm{\π}}{b}}{e}^{(-\frac{a^2}{4b})}---\left(4\right)$

Wherein, formula (4) is improper integral formula, and a, b are constant;

Step (6), brings formula (1) into according to formula (2), formula (3), formula (4), obtains formula (5),

Step (7), according to formula (5), obtains the spectrum width Δ λ of SLED light source,