Font Size: a A A

Study On The Mechanism Of Mode Competition And Power Equalization In A Dual-Frequency Microchip Laser

Posted on:2017-10-30Degree:MasterType:Thesis
Country:ChinaCandidate:X SunFull Text:PDF
GTID:2348330482986947Subject:Electronics and Communications Engineering
Abstract/Summary:PDF Full Text Request
Laser diode(LD)pumped microchip lasers have many advantages,such as compactness,high efficiency and good beam quality,long lifetime having been found in a wide variety of applications in the fields of photonic generation of millimeter-wave signal research,industrial production,medical treatment,national defense etc.As the radio spectrum resources become increasingly tense,the utilization of millimeter wave spectrum band is being put on the agenda.Dual-frequency microchip lasers,of which the generation of millimeter-wave signals is relatively simple and effective,gain high popularity around the globe in recent years.For further study of photonic generation of millimeter-wave signal in dual-frequency microchip lasers,this thesis focuses on the mode competition and power equalization of dual-frequency microchip laser,theoretically and experimentally.The main contents can be summarized as:(1)An overview of solid lasers,especially microchip lasers.Introduced the research development of continuous pumping and short pulse microchip laser at home and abroad.The application in practice of dual-frequency microchip laser have been introduced briefly at last.(2)Introduced the principle and advantages of dual-frequency laser;sketched the characteristics of several laser crystal in microchip lasers,of which Nd:YVO4 crystal was used in our experiment.We deduced rate equation of three-energy-level and four-energy-level in microchip lasers,theoretically analyzed and investigated LD-pumped dual-frequency microchip lasers' operational characteristics.(3)The mode competition coupling effect between two laser modes in microchip lasers was investigated,and the self-saturation and cross-saturation coefficient in microchip lasers with different reflectivity of output mirror are measured.The dual-frequency microchip lasers rate equation was established in the research,as the two variables: self-saturation coefficient and cross saturation coefficient are undetermined.Thus dual-frequency output power obtained by simulation was well illustrated by changing the parameters of the microchip laser cavity.By comparing the power envelop profiles with the dual-frequency laser power spectrum,the two undetermined coefficients were confirmed.The experimental results showed that with the reflectivity of output mirror at 86 %,81 %,and 61 %,the corresponding self-saturation coefficients are 0.68,0.66 and 0.52 respectively,which means smaller the reflectivity of output mirror makes stronger mode competition while a high reflectivity of the output mirror indicates weak mode competition and a large frequency offset of dual-frequency laser can be obtained in such a case.(4)According to the relationship of stimulated emission cross section spectrum of gain medium and resonant wavelength with the operating temperature of dual-frequency microchip laser,the output power equalization scheme in a dual-frequency Nd:YVO4 microchip laser was investigated.In experiments,by tuning the cavity temperature we examined the relationship between laser temperature and central wavelength shift and power ratio of dual-mode lase can be conducted by adjusting the crystal temperature,and further realized tunable power equalization of dual-frequency laser signal.The experimental results showed that as the temperature increase from 2.5 °C to 30 °C,the central wavelength of dual-mode laser red-shifted gradually,and the spectrum separation between the two modes reflected a gradual decrease and then increase.When the temperature was near by 13 °C,peak power ratio of the two modes was equalized,which was suit for photonic generation of millimeter-wave signal.
Keywords/Search Tags:dual-frequency microchip laser, photonic generation of millimeter-wave signal, rate equation, mode competition, power equalization
PDF Full Text Request
Related items