CN108955888A - A kind of full optical fiber interferometer Free Spectral Range measuring system and method - Google Patents

Abstract

The invention discloses a system and method for measuring the free spectral range of an all-fiber interferometer. A vector network analyzer is used to measure the microwave signal input by a signal generator and the S21 parameter characteristics of a microwave signal output by a photodetector, and the all-fiber Mach-Zehnder interference The free spectral range of the instrument is converted into the equally spaced comb spectrum of the S21 parameter of the microwave signal, and the free spectral range of the all-fiber Mach-Zehnder interferometer is calculated by observing the _S21 parameter of the vector network analyzer. The invention simplifies the complexity of the free spectral range measurement system of the all-fiber Mach-Zehnder interferometer, reduces the cost of the system, and has simple operation steps.

Description

An all-fiber interferometer free spectral range measurement system and method

technical field

The invention relates to a free spectral range measurement system and method, in particular to an all-fiber interferometer free spectral range measurement system and method.

Background technique

All-fiber Mach-Zehnder interferometers are widely used in fiber optic sensing systems and fiber optic wavelength division multiplexing (WDM) communications because of their small size, light weight, compact structure, anti-electromagnetic interference, and high sensitivity. High-performance optical sensing measurement systems and optical fiber communication systems have strict requirements on the free spectral range of all-fiber Mach-Zehnder interferometers. Therefore, the free spectral range of the all-fiber Mach-Zehnder interferometer is an important parameter to determine its performance. The traditional free free spectral range measurement method is based on the Fabry Perot etalon method or the spectral analyzer method. These two methods are usually simple in principle. However, the free spectral range measurement method based on the Fabry Perot etalon requires an expensive tunable laser, and the operation steps are complicated, which requires high professional skills of the operator. Although the measurement based on the spectrum analyzer is simple, it is limited by the wavelength stability of the light source and the measurement accuracy is low.

Contents of the invention

The technical problem to be solved by the present invention is to provide a free spectral range measurement system and method of an all-fiber interferometer.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

An all-fiber interferometer free spectral range measurement system is characterized in that: it includes a distributed feedback laser, an electro-optical phase modulator, an all-fiber Mach-Zehnder interferometer, a photoelectric detector, a power divider, a signal generator and a vector network analysis The electro-optic phase modulator is optically connected to the distributed feedback laser, the all-fiber Mach-Zehnder interferometer is optically connected to the electro-optic phase modulator, the photodetector is optically connected to the all-fiber Mach-Zehnder interferometer, and the power splitter is connected to the signal generator The device, the electro-optic phase modulator and the vector network analyzer are electrically connected, and the vector network analyzer is electrically connected to the photodetector.

Further, the distributed feedback laser outputs laser light, the signal generator generates a microwave signal, and the microwave signal is modulated onto the optical carrier output of the distributed feedback laser through an electro-optical phase modulator, and then introduced into an all-fiber Mach-Zehnder interferometer, and the whole The output light of the fiber optic Mach-Zehnder interferometer is converted into a microwave signal by a photodetector, and the microwave signal and the microwave signal output by the signal generator are input into a vector network analyzer.

Further, the distributed feedback laser outputs 1550nm laser, and the power of the distributed feedback laser is 10dBm.

Further, the frequency of the microwave signal generated by the signal generator is 10 GHz.

A measurement method of an all-fiber interferometer free spectral range measurement system is characterized in that it comprises the following steps:

Step 1: The distributed feedback laser outputs 1550nm laser, and the power of the distributed feedback laser is 10dBm;

Step 2: The signal generator generates a 10GHz microwave signal;

Step 3: After being modulated by a phase modulator, modulate a 10GHz microwave signal onto a 1550nm optical carrier, and import it into an all-fiber Mach-Zehnder interferometer;

Step 4: The output light of the all-fiber Mach-Zehnder interferometer is input into the photodetector;

Step ₅ : Measure the 10GHz microwave signal produced by the signal generator and the S21 parameter characteristic curve of the microwave signal output by the photodetector with a vector network analyzer analyzer;

Step 6: The single equidistant comb spectrum range of the S ₂₁ parameter is the free spectrum range of the all-fiber Mach-Zehnder interferometer.

Further, in the first step, the frequency and power of the microwave signal output by the signal generator are continuously increased or decreased, and an appropriate microwave frequency and power are selected to facilitate the observation of the _S21 parameters of the vector network analyzer.

Further, said step ₅ , repeatedly measuring the S21 parameter characteristic curve of the 10GHz microwave signal produced by the signal generator and the microwave signal output by the photodetector with a vector network analyzer analyzer, and then calculating its average value.

Further, in the step six, a plurality of equally spaced comb spectrums are measured and averaged to improve the measurement accuracy of the free spectral range of the all-fiber Mach-Zehnder interferometer.

Compared with the prior art, the present invention has the following advantages and effects: the present invention does not rely on expensive tunable lasers or spectral analysis with limited resolution, and adopts common distributed feedback lasers and high-precision vector network analyzers ( The frequency resolution can be 1Hz), and the free spectral range of the all-fiber Mach-Zehnder interferometer is converted into the _equidistant comb spectrum of the S21 parameter of the microwave signal through the vector network analyzer, which can accurately measure the all-fiber Mach-Zehnder The free spectral range of the interferometer. The method of the present invention simplifies the complexity of the free spectral range measurement system of the all-fiber Mach-Zehnder interferometer, reduces the cost of the system, and has simple operation steps, and can quickly complete the all-fiber Mach-Zehnder interference by frequency sweeping The free spectral range of the instrument can be measured, and the result measurement is intuitive and has good practical value.

Description of drawings

Fig. 1 is a schematic diagram of an all-fiber interferometer free spectral range measurement system of the present invention.

Fig. ₂ is a schematic diagram of the comb spectrum of the S21 parameter of the all-fiber Mach-Zehnder interferometer converted into a microwave signal by a vector network analyzer according to an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. The following examples are explanations of the present invention and the present invention is not limited to the following examples.

As shown in Figure 1, an all-fiber interferometer free spectral range measurement system of the present invention includes a distributed feedback laser 1, an electro-optic phase modulator 2, an all-fiber Mach-Zehnder interferometer 3, a photodetector 4, a power divider 5, signal generator 6 and vector network analyzer 7, electro-optic phase modulator 2 is optically connected with distributed feedback laser 1, all-fiber Mach-Zehnder interferometer 3 is optically connected with electro-optic phase modulator 2, and photodetector 4 is optically connected with The all-fiber Mach-Zehnder interferometer 3 is optically connected, the power divider 5 is electrically connected to the signal generator 6, the electro-optical phase modulator 2 and the vector network analyzer 7, and the vector network analyzer 7 is electrically connected to the photodetector 4.

The distributed feedback laser 1 outputs laser light, and the signal generator 6 generates microwave signals. The microwave signals are modulated by the electro-optic phase modulator 2 to the optical carrier output of the distributed feedback laser 1, and then imported into the all-fiber Mach-Zehnder interferometer 3. The output light of the fiber optic Mach-Zehnder interferometer 3 is converted into a microwave signal by the photodetector 4 , and the microwave signal and the microwave signal output by the signal generator 6 are input to the vector network analyzer 7 .

The distributed feedback laser 1 outputs 1550nm laser, and the power of the distributed feedback laser is 10dBm. The frequency of the microwave signal generated by the signal generator 6 is 10 GHz.

A measurement method of an all-fiber interferometer free spectral range measurement system, comprising the following steps:

Step 1: The distributed feedback laser outputs 1550nm laser, and the power of the distributed feedback laser is 10dBm; continuously increase or decrease the frequency and power of the microwave signal output by the signal generator, and select the appropriate microwave frequency and power to facilitate observation vector network analysis Instrument S ₂₁ parameters.

Step 2: The signal generator generates a 10GHz microwave signal;

Step 3: After being modulated by a phase modulator, modulate a 10GHz microwave signal onto a 1550nm optical carrier, and import it into an all-fiber Mach-Zehnder interferometer;

Step 4: The output light of the all-fiber Mach-Zehnder interferometer is input into the photodetector;

Step ₅ : Use a vector network analyzer to measure the S21 parameter characteristic curve of the 10GHz microwave signal generated by the signal generator and the microwave signal output by the photodetector; repeatedly use the vector network analyzer to measure the signal generation The _S21 parameter characteristic curve of the 10GHz microwave signal generated by the detector and the microwave signal output by the photodetector is calculated, and then the average value is calculated to improve the measurement accuracy of the free spectral range of the all-fiber Mach-Zehnder interferometer.

Step 6: As shown in Fig. 2, the single equidistant comb spectrum range of the S ₂₁ parameter is the free spectrum range of the all-fiber Mach-Zehnder interferometer. Measure multiple equidistant comb spectra and calculate the average value to improve the measurement accuracy of the free spectral range of the all-fiber Mach-Zehnder interferometer.

The present invention does not rely on expensive tunable lasers or limited-resolution spectral analysis, and uses common distributed feedback lasers and high-precision vector network analyzers (frequency resolution can be 1Hz), through vector network analyzers The free spectral range of the all-fiber Mach-Zehnder interferometer is converted into the _equidistant comb spectrum of the S21 parameter of the microwave signal, and the free spectral range of the all-fiber Mach-Zehnder interferometer can be accurately measured. The method of the present invention simplifies the complexity of the free spectral range measurement system of the all-fiber Mach-Zehnder interferometer, reduces the cost of the system, and has simple operation steps, and can quickly complete the all-fiber Mach-Zehnder interference by frequency sweeping The free spectral range of the instrument can be measured, and the result measurement is intuitive and has good practical value.

The above content described in this specification is only an illustration of the present invention. Those skilled in the technical field to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, as long as they do not deviate from the content of the present invention specification or exceed the scope defined in the claims, all should Belong to the protection scope of the present invention.

Claims (8)

1. An all-fiber interferometer free spectral range measurement system is characterized in that: comprise distributed feedback laser, electro-optic phase modulator, all-fiber Mach-Zehnder interferometer, photodetector, power divider, signal generator and vector The network analyzer, the electro-optic phase modulator and the distributed feedback laser are optically connected, the all-fiber Mach-Zehnder interferometer is optically connected to the electro-optic phase modulator, the photodetector is connected to the all-fiber Mach-Zehnder interferometer, and the power splitter is connected to the The signal generator, the electro-optic phase modulator and the vector network analyzer are electrically connected, and the vector network analyzer is electrically connected with the photoelectric detector. 2. according to a kind of all-fiber interferometer free spectral range measuring system according to claim 1, it is characterized in that: described distributed feedback laser outputs laser light, and signal generator produces microwave signal, and microwave signal is modulated to The output optical carrier of the distributed feedback laser is then introduced into the all-fiber Mach-Zehnder interferometer, the output light of the all-fiber Mach-Zehnder interferometer is converted into a microwave signal by the photodetector, and the microwave signal and the microwave signal output by the signal generator are input Vector network analyzer. 3. A free spectral range measurement system of an all-fiber interferometer according to claim 1, characterized in that: said distributed feedback laser outputs 1550nm laser, and the power of distributed feedback laser is 10dBm. 4. The all-fiber interferometer free spectral range measurement system according to claim 1, wherein the frequency of the microwave signal generated by the signal generator is 10 GHz. 5. A measurement method of an all-fiber interferometer free spectral range measurement system, characterized in that it comprises the following steps: Step 1: The distributed feedback laser outputs 1550nm laser, and the power of the distributed feedback laser is 10dBm; Step 2: The signal generator generates a 10GHz microwave signal; Step 3: After being modulated by a phase modulator, modulate a 10GHz microwave signal onto a 1550nm optical carrier, and import it into an all-fiber Mach-Zehnder interferometer; Step 4: The output light of the all-fiber Mach-Zehnder interferometer is input into the photodetector; Step ₅ : Measure the 10GHz microwave signal produced by the signal generator and the S21 parameter characteristic curve of the microwave signal output by the photodetector with a vector network analyzer analyzer; Step 6: The single equidistant comb spectrum range of the S ₂₁ parameter is the free spectrum range of the all-fiber Mach-Zehnder interferometer. 6. according to the measuring method of all-fiber interferometer free spectrum range measurement system according to claim 5, it is characterized in that: in described step 1, continuously increase or reduce the frequency and the power of signal generator output microwave signal, select Appropriate microwave frequency and power, easy to observe the parameters of vector network analyzer S ₂₁ . 7. according to the measuring method of all-fiber interferometer free spectral range measurement system according to claim 5, it is characterized in that: described step 5, repeatedly measures the 10GHz that signal generator produces with vector network analyzer analyzer _S21 parameter characteristic curves of the microwave signal and the microwave signal output by the photodetector, and then calculate their average value. 8. according to the measuring method of all-fiber interferometer free spectral range measurement system according to claim 5, it is characterized in that: in described step 6, measure a plurality of equidistant comb-shaped spectrums, calculate average value, to improve the measurement of all-fiber Measurement accuracy in the free spectral range of a Mach-Zehnder interferometer.