Device for testing linearity of electro-optical modulator

Abstract

The invention discloses a testing device for linearity of an electro-optical modulator. If the electro-optical modulator to be tested is an intensity modulator, an optical wave from an optical sourceis sent to the electro-optical modulator to be tested, a modulation signal generator generates a modulation signal and sends the modulation signal to the electro-optical modulator to be tested, a first demodulator circuit and a second demodulator circuit; a test signal generator generates a test signal and sends the test signal to the electro-optical modulator to be tested and the first demodulator circuit. In the electro-optical modulator to be tested, the modulation signal causes the two optical waves to generate modulation phase difference, the test signal causes the two optical waves to generate test phase difference, the two optical waves are interfered and sent to a detector, and sent to the second demodulation circuit after photoelectric conversion, the first demodulation circuit obtains the size of the test signal, and the second demodulation circuit obtains the test phase difference; if the electro-optical modulator to be tested is a Y-waveguide integrated optical device, theoptical wave of the optical source is sent to the electro-optical modulator to be tested by an electro-optical modulator for modulation, the modulation signal from the modulation signal generator is sent to the electro-optical modulator for modulation, the test signal from the test signal generator is sent to the tested electro-optical modulator, and the other structures are not changed.

Description

technical field [0001] The invention relates to a testing device, in particular to a testing device for an electro-optic modulator. Background technique [0002] Fiber optic gyroscope is a new type of inertial device. It has no moving parts in its structure, and has the advantages of small size, low power consumption, fast start-up, large dynamic range, wide accuracy coverage, long life, high reliability, and low batch cost. There are two schemes of open-loop and closed-loop fiber optic gyroscopes. The closed-loop fiber optic gyroscope is more widely used because of its small nonlinear scale factor and high precision. The typical optical path of the closed-loop fiber optic gyroscope is as follows: figure 1 As shown in the figure, 1 is the light source, 2 is the detector, 3 is the fiber coupler, 4 is the Y waveguide integrated optical device, and 5 is the fiber coil. Y-waveguide integrated optical devices are used as implementation devices for bias modulation and feedback c...

AI Technical Summary

Problems solved by technology

Since the feedback modulation signal applied to the Y waveguide integrated optical device is used to compensate the phase difference caused by the input rate of the fiber optic gyroscope, and the feedback modulation signal is determined according to the slope determined by the half-wave voltage of the Y waveguide integrated optical device, so the Y waveguide is required The response of the integrated optical device is linear, otherwise, when a small signal is input, the phase difference generated by the feedback modulation signal after passing through the Y waveguide integrated optical device may be different from the absolute value of the phase difference generated by the input rate of the fiber optic gyroscope, resulting in an error , this error will cause the nonlinearity of the fiber optic gyroscope at small speeds

[0003] At present, there is no public introduction of a measuring device for measuring the linearity of the Y-waveguide in China. There is only a method of testing the Y-waveguide integrated optical device through the modulation signal of the fiber optic gyroscope. The minimum input signal during the test is limited by the number of digits of the digital-to-analog converter. Usually the precision of the digital-to-analog converter used by the gyro is 16 bits, and there is a sign bit, and the phase measurement accuracy is 10 -4 rad, so it is not possible to compare the usual 10 -5 rad's small signal for testing

[0004] The Y-waveguide integrated optical device is a kind of electro-optic modulator. In high-precision fiber optic gyroscopes, a method to suppress relative intensity noise is to use the intensity modulator. Since the noise signal is relatively small, the small signal nonlinearity of the intensity modulator Noise suppression has a big impact, and there is no public report on measuring the linearity of the intensity modulator.

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