Study On Lidar Velocimetry And Ranging Based On Monolithic Integrated Dual Frequency DFB Lasers

Compared with traditional radar,Li DAR has the advantages of wide measurement range,high measurement accuracy,strong anti-interference ability and small size,which is widely used in modern society and is widely used in military and civil fields.Low cost,high precision,small size and integration are the main development direction of Li DAR,semiconductor lasers with good working stability,small size,wide wavelength range,long working life,direct modulation and other advantages,has become the ideal light source for Li DAR systems.As a light source for Li DAR speed and distance measurement,dual-frequency semiconductor laser has the advantages of high measurement accuracy,anti-interference,and easy integration,which has broad application prospects.In this paper,the measurement of target speed and distance is achieved using a monolithic integrated dual-frequency Distributed Feedback Laser(DFB)laser based on Reconstruction-Equivalent-Chirp technique.The main contents and findings of this paper are as follows.(1)The design of a monolithic integrated dual-frequency DFB laser based on Reconstruction-Equivalent-Chirp technology was realized,a dual-frequency Li DAR speed measurement system was built,and experimental analysis was completed.The dual-frequency laser can vary the dual-frequency frequency difference(beat frequency)by tuning the bias current,and the beat signal frequency tuning range is 14.4 GHz to 40 GHz.By setting the beat frequency to 15.42 GHz,we studied and analyzed the velocity measurement range of the dual-frequency Li DAR,and the entire velocity measurement range is from 1.56 m/s to 13.62 ?m/s,covering 6 orders of magnitude.By changing the bias current and increasing the beat frequency,the beat frequency can be increased from15.42 GHz to 25 GHz,which can effectively reduce the system error and improve the system speed measurement accuracy.By setting different sampling rates and sampling times,the dual-frequency Li DAR velocimetry system can achieve different measurement resolutions,and the system can achieve velocity resolution accuracy up to19.46 ?m/s.(2)A laser ranging system based on a monolithic integrated dual-frequency DFB laser is proposed,a dual-frequency FMCW Li DAR ranging system is built,and experimental analysis is carried out.For a dual-frequency Li DAR ranging system based on a monolithic integrated dual-frequency DFB laser,the locking range of the dualfrequency laser is 15.2 GHz-15.7 GHz to determine a modulation bandwidth of up to500 MHz,which is achieved by loading a linearly modulated triangle wave signal onto the laser with a center frequency of 15.5 GHz,modulation bandwidth of 320 MHz,and modulation period of 100 ?s.The dual-frequency FMCW laser distance measuring radar enables the measurement of different distances with an experimental range of 50 m to 5km,a maximum relative measurement error of 2.25% at 1 km,and a distance resolution of 0.5 m.The overall relative error rate remains between 0.006% and 0.01% for distance measurements at different modulation bandwidths(10 MHz to 320 MHz).An expansion of the measurement bandwidth from 160 MHz to 320 MHz was achieved using the duplex frequency,and distance measurements were successfully performed.