Study On Power Equalization Mechanism Of Neodymium-doped Combined Crystal Dual-wavelength Laser

For the past few years,with the rapid growth of mobile Internet,all kinds of new wireless communication services are emerging,network data volume presents exponential growth,limited spectrum resources become more and more scarce,and previously unused millimeter waves and submillimeter waves are also on the agenda.In order to obtain the above signals,we need a suitable dual-frequency/dual-wavelength laser,and in common crystal lasers,the neodymium-doped laser has become one of the main research objects of the dual-frequency/dual-wavelength laser with its larger gain bandwidth.Based on this,a more special Nd:YVO4/Nd:GdVO4 combined crystal laser is proposed,and its temperature-controlled output characteristics are studied experimentally.Finally,the realization mechanism of power balance is theoretically analyzed.The general contents of the fbll text are as follows:(1)The practical significance and application prospect of submillimeter wave is summarized,and its common optical generation methods are introduced.Finally,the research status of dual-frequency/dual-wavelength laser at home and abroad is introduced briefly.(2)Firstly,the composition of the erbium-doped combined crystal dual-wavelength laser is introduced.Then the working principle of the laser,the theory of the rate equation and output characteristics of the four-level system is analyzed from the perspective of quantum theory.Finally,the power balance adjustment method of this kind of laser is presented.(3)The output characteristics of the dual-wavelength laser based on the Nd:YVO4/Nd:GdVO4 combined ciystal has been investigated experimentally.During the experiment,setting the pump current at 14.5 A,rising the heat sink temperature of the combined crystal from 5? to 40? with 5? intervals,a laser signal with super-large frequency separation up to 310 GHz is achieved.The experimental results show that the laser signal power has a negative correlation with the heat sink temperature.The fitting rates of the left and right peaks power vs.heat sink temperature are-0.0190/? and-0.0082/?,respectively.When setting the heat sink temperature at 32.36?,the laser reaches power balance.In addition,the experiment also shows that the wavelengths of the laser signal red-shifting linearly with the heat sink temperature increasing.The measured red-shift rate of the left peak and right peak are 9.70 pm/? and 6.12 pm/?,respectively.(4)Based on the crystal thermal effect,the simulation of temperature field distribution of combined crystal and the dynamic test results of corresponding fluorescence spectra,it is indicated that power tunability is caused by the difference in temperature variation characteristics of the two crystal fluorescence spectra in the combined crystal.Among them,the simulation results show that there is a temperature difference between the inside and outside of the combined crystal.The temperature of the front-end Nd:YVO4 crystal and the heat sink temperature are about 25?,and the temperature of the back-end Nd:GdVO4 crystal and the heat sink temperature is about 50?.The results of fluorescence spectrum detection show that the change of the left and right peaks of the fluorescence spectrum of Nd:YVO4/Nd:GdVO4 combined crystal is basically the same as that of the left and right peaks of the actual output signal,and the rate matching is also high,and there is also power balance point.