Phase modulation coefficient measurement apparatus for PZT optical fiber phase modulator

Abstract

A phase modulation coefficient measurement apparatus for a PZT optical fiber phase modulator. The apparatus comprises a laser, an M-Z interferometer, a triangular wave driving source used for applying a voltage to an optical fiber phase modulator in the M-Z interferometer so as to cause changes in the length of an optical fiber, a photoelectric detector used for detecting light intensity changes of light outputted by the M-Z interferometer, and an oscilloscope used for displaying a waveform of the light intensity changes. In the apparatus, a triangular wave driving voltage is applied to a PZT optical fiber phase modulator on one arm of an M-Z interferometer, such that the intensity of interference light at an interference point of two arms changes as the voltage linearly increases, and a phase modulation coefficient can be quickly and accurately calculated on the basis of the light intensity in the form of a sine wave that is observed on an oscilloscope.

Description

A phase modulation coefficient measurement device for a PZT optical fiber phase modulator Technical Field

[0001] The utility model relates to the technical field of optical fiber communication, in particular to a phase modulation coefficient measuring device of a PZT optical fiber phase modulator. Background Art

[0002] Fiber optic interferometers have been widely used in sensing and measurement due to their resistance to electromagnetic interference, electrical insulation, high sensitivity, wide range of measurement objects, light weight, and small size. Fiber optic phase sensors, which use phase as the measured quantity, offer advantages such as high precision and a large dynamic range, and are widely used in measuring pressure, temperature, displacement, electromagnetic fields, and acoustic fields. Therefore, phase measurement is crucial in sensors composed of these fiber optic interferometers. Among the commonly used detection technologies, piezoelectric ceramic (PZT) phase modulators are widely used. They can be used in fiber optic interferometers to compensate for external environmental disturbances and improve stability, and in superheterodyne interferometer systems for sensitive and linear detection of optical phase shifts. Therefore, determining the phase shift parameters of piezoelectric ceramics is crucial. Currently, there are two main methods for measuring the phase shift parameters of piezoelectric ceramics. One is based on the theory of elasticity, and the stress-strain relationship of elastic materials is theoretically analyzed to obtain the theoretical relationship between the voltage value of the piezoelectric ceramic and the phase change of the optical signal in the optical fiber. The other is to use the output light intensity of the fiber optic interferometer to judge the phase difference between the two interference arms, thereby determining the phase shift coefficient of the piezoelectric ceramic. However, these two methods are cumbersome to operate, and the measurement stability is insufficient and the measurement accuracy is not high.

[0003] Summary of the Invention

[0004] In view of this, the present invention provides a phase modulation coefficient measurement device for a PZT optical fiber phase modulator, so as to solve the problems existing in the above-mentioned background technology.

[0005] A phase modulation coefficient measuring device for a PZT optical fiber phase modulator comprises a laser, an MZ interferometer, a triangular wave driving source for applying voltage to the optical fiber phase modulator in the MZ interferometer to change the length of the optical fiber, a photodetector for detecting intensity changes of light output by the MZ interferometer, and an oscilloscope for displaying the waveform of the intensity change. The output end of the laser is connected to the input end of the MZ interferometer, the output end of the MZ interferometer is connected to the input end of the photodetector, and the output end of the photodetector is connected to the input end of the oscilloscope.

[0006] Preferably, the MZ interferometer includes a first optical splitter, a second optical splitter and a PZT fiber phase modulator, the input end of the first optical splitter is connected to the output end of the laser, one splitter arm of the first optical splitter is connected to the input end of the second optical splitter, and the other splitter arm is connected to the input end of the PZT fiber phase modulator, the output end of the PZT fiber phase modulator is connected to one splitter arm of the second optical splitter, the light emitted by the laser is divided into two paths through the first optical splitter, one path of light is directly transmitted to the second optical splitter, and the other path of light is transmitted to the second optical splitter through the PZT fiber phase modulator, and the two split light beams generate light interference at the coupling point of the two arms of the second optical splitter.

[0007] Preferably, the first optical splitter and the second optical splitter are both 1×2 optical splitters with equal splitting ratios.

[0008] Preferably, the laser is a narrow linewidth laser.

[0009] Preferably, the light intensity variation waveform displayed on the oscilloscope is a sine wave.

[0010] The beneficial effects of the utility model are:

[0011] The utility model applies a triangular wave driving voltage to a PZT optical fiber phase modulator on one arm of an M-Z interferometer, so that the intensity of the interference light at the interference point of the two arms changes linearly with the increase of voltage. The phase modulation coefficient at the interference point can be calculated quickly and accurately based on the light intensity of the sinusoidal wave seen on the oscilloscope, and the measurement fluctuation error can also be reduced, thereby improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0013] FIG1 is a schematic structural diagram of a phase modulation coefficient measurement device.

[0014] FIG2 is a schematic diagram of a sine wave waveform displayed by an oscilloscope. DETAILED DESCRIPTION

[0015] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments illustrated in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. Furthermore, descriptions of known structures and technologies are omitted in the following description to avoid unnecessary confusion regarding the concepts of the present invention.

[0016] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0017] It should be understood that although the terms "first," "second," and so on may be used in this disclosure to describe various types of information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are merely used to distinguish information of the same type from one another. For example, first information could also be referred to as second information, and similarly, second information could also be referred to as first information without departing from the scope of this disclosure.

[0018] In order to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings.

[0019] The utility model provides a phase modulation coefficient measuring device for a PZT optical fiber phase modulator, comprising a laser, an MZ interferometer, a triangular wave driving source for applying voltage to the optical fiber phase modulator in the MZ interferometer to change the length of the optical fiber, a photodetector for detecting changes in the light intensity of light output by the MZ interferometer, and an oscilloscope for displaying the waveform of the light intensity change. The output end of the laser is connected to the input end of the MZ interferometer, the output end of the MZ interferometer is connected to the input end of the photodetector, and the output end of the photodetector is connected to the input end of the oscilloscope.

[0020] Preferably, the MZ interferometer includes a first optical splitter, a second optical splitter, and a PZT fiber phase modulator. The input end of the first optical splitter is connected to the output end of the laser, one splitter arm of the first optical splitter is connected to the input end of the second optical splitter, and the other splitter arm is connected to the input end of the PZT fiber phase modulator. The output end of the PZT fiber phase modulator is connected to one splitter arm of the second optical splitter. The light emitted by the laser is split into two paths by the first optical splitter, one of which is directly transmitted to the second optical splitter, and the other is transmitted to the second optical splitter via the PZT fiber phase modulator. The two split light beams generate optical interference at the coupling point between the two arms of the second optical splitter.

[0021] When the optical path difference between the two arms of an MZ interferometer changes, the intensity of the light interference also changes. A photodetector connected to the splitter arm of the second optical splitter measures the change in light intensity. When a triangular wave drive source is applied to the PZT fiber phase modulator, the light intensity detected by the photodetector changes linearly with the voltage. Therefore, the light intensity observed on an oscilloscope appears as a sinusoidal wave. The difference between the two peaks (or valleys) of the sine wave indicates that the phase amplitude of the PZT fiber phase modulator is 2π. The driving voltage difference at these two points is U, and the phase modulation coefficient is 2π / U radians. By measuring multiple peaks (or valleys), the fluctuation error in the measurement can be reduced. As shown in Figure 2, one channel is a triangular wave, and the other is a sinusoidal wave of phase information detected by the interferometer. The voltage difference corresponding to 2π × 3 is 297.5 mV, so the phase modulation coefficient can be calculated.

[0022] In this embodiment, the laser is a narrow linewidth laser, the first optical splitter and the second optical splitter are both 1×2 optical splitters with equal splitting ratios, and the oscilloscope is a multi-channel oscilloscope.

[0023] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A device for measuring the phase modulation coefficient of a PZT fiber phase modulator, characterized in that It includes a laser, an M-Z interferometer, a triangular wave driving source for applying a voltage to the fiber optic phase modulator in the M-Z interferometer to cause a change in the fiber length, a photodetector for detecting the change in the light intensity of the light output from the M-Z interferometer, and an oscilloscope for displaying the waveform of the light intensity change. The output end of the laser is connected to the input end of the M-Z interferometer, the output end of the M-Z interferometer is connected to the input end of the photodetector, and the output end of the photodetector is connected to the input end of the oscilloscope.

2. The phase modulation coefficient measuring device for the PZT fiber optic phase modulator according to claim 1, characterized in that, The M-Z interferometer includes a first optical splitter, a second optical splitter, and a PZT fiber optic phase modulator. The input end of the first optical splitter is connected to the output end of the laser. One splitting arm of the first optical splitter is connected to the input end of the second optical splitter, and the other splitting arm is connected to the input end of the PZT fiber optic phase modulator. The output end of the PZT fiber optic phase modulator is connected to one splitting arm of the second optical splitter. The light emitted by the laser is split into two paths by the first optical splitter. One path of light is directly transmitted to the second optical splitter, and the other path of light is transmitted to the second optical splitter through the PZT fiber optic phase modulator. The two split light beams interfere with each other at the coupling point of the two arms of the second optical splitter.

3. The phase modulation coefficient measuring device of the PZT fiber optic phase modulator according to claim 2, characterized in that, Both the first optical splitter and the second optical splitter are 1×2 optical splitters with an equal splitting ratio.

4. The phase modulation coefficient measuring device for the PZT fiber optic phase modulator according to claim 1, characterized in that The laser is a narrow linewidth laser.

5. The phase modulation coefficient measuring device of the PZT fiber optic phase modulator according to claim 1, characterized in that, The waveform of the light intensity change displayed on the oscilloscope is a sine wave.

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