Research And Implementation Of Integrated Optical Modulation And On-chip Drive Technology

With the rapid development of optical fiber communication technology,LiNbO₃ electro-optic modulators have been widely used due to their low voltage,low insertion loss,high bandwidth and stable operating performance in complex environments.However,due to the drift of the applied electric field,the drastic temperature change in a complex environment and the normal fluctuation of the input RF signal,the LiNbO₃ electro-optic modulator will cause the thermal accumulation effect of the LiNbO₃ medium,causing the modulator operating point to drift,thus it causes distortion of the transmitted radio frequency signal,which seriously affects the communication quality of the transmitted signal.In order to overcome the influence of the above factors on the transmission characteristic curve of the electro-optical modulator and ensure the stability of the performance of the LiNbO₃ electro-optical modulator,this paper uses a method of integrating an external electrical pilot signal and a built-in PD photodetector to complete Automatic tracking and locking of the best working point in a wide temperature range.The specific research contents are as follows:1.Introduce the classification of modulation methods,the working principle of electro-optic modulator and theoretically derive its transmission characteristic curve.At the same time,the working point drift mechanism of the electro-optic modulator and the influence of the working point drift on its modulation performance are analyzed based on the transmission characteristic curve.Then,through the principle analysis,the method that current commonly used electro-optic modulator bias control is introduced,and its feasibility is verified by Matlab software simulation.Finally,based on the comparison of various schemes,a method of integrating an additional 1kHz sinusoidal electric pilot signal and a built-in PD photodetector to achieve automatic control of the bias operating point of the electro-optic modulator is proposed.2.Based on the analysis of the working principle of the electro-optic modulator and the drift of its bias operating point under the continuous temperature change in a complex environment,according to the basic theory of refractive index ellipsoid,the constant temperature change is simulated to the refractive index and phase of the modulator.The influence of the temperature on the output performance of the electro-optic modulator is analyzed,and the simulation is verified by Matlab software.The results prove that automatic control of points is completely feasible by applying a 1kHz sinusoidal electrical pilot signal to achieve the best bias work of the LiNbO₃electro-optic modulator.3.Aiming at the influence of the drift of the DC bias operating point of the LiNbO₃ electro-optic modulator on the communication quality of the modulated signal,a wide temperature range?-55?⁺80??with an integrated 1kHz sinusoidal electric pilot signal and built-in PD photoelectricity is designed.The method of the detector is to complete the automatic tracking and locking of the optimal bias operating point of the LiNbO₃ electro-optic modulator,and to complete the design of the hardware circuit and the realization of the control software.4.The experimental verification of the actual environment of the whole device is completed in the high and low temperature test chamber.In this experiment,all performance index tests are mainly divided into normal temperature test,low temperature test and high temperature test.The temperature change process in the experiment is normal temperature-low temperature-normal temperature-high temperature-normal temperature,and the measured data is analyzed and processed,and finally the test results are obtained.The analysis shows that it meets the design requirements.In this study,the method of integrating an externally applied pilot signal and a built-in PD photodetector was used to fully exploit the performance of the externally modulated optical waveguide,and to conduct integrated design and automatic bias control research,breaking through the LiNbO₃ electro-optic modulator technical difficulties such as automatic control of the optimal offset operating point and adaptability to harsh environments,which can meet the automatic tracking and locking function of the offset operating point of the LiNbO₃ electro-optic modulator over a wide temperature range.The operating temperature range reaches-55?⁺80?,while it satisfys that its insertion loss is less than 4dB,and the fluctuation of optical insertion loss at high temperature or low temperature or normal temperature is less than or equal to 2dB.This method improves the working performance of devices in the field of high-frequency microwave modulation,and fully meets the application needs of special signal transmission fields such as broadband microwave signal modulation,ROF transmission,radar networking,electronic countermeasures,and technical investigation.