Balanced Power Amplification Mechanism For Dual-Frequency Microchip Lasers

The great leap of the communication technology is always accompanied by the explosive demand for higher information exchange efficiency and the communication industry is dedicated to discover a brand new information carrier all the time.The march towards a higher frequency band becomes a dominant trend attached with much attention.Over the years the wide application of 4G wireless communication techniques and other wireless products forces the originally scare resources of Gigahertz band to be much more crowded.With the development of the techniques of “Radio over Fiber” and optical millimeter wave generation,the discussion for the application prospect of millimeter wave band resource becomes a compelling issue.Among the generation techniques,the optical heterodyne photo-mixing method acts as a simple and efficient way of realization.As a perfect laser source with large mode separation and high phase coherence,the dual-frequency microchip laser make itself an key part of the optical heterodyne photo-mixing systems.Since dual frequency laser with balanced power distribution and high output power is highly required on the basis of the characteristics of optical heterodyne photo-mixing method,the thesis was organized as follows:(1)The principles,features and application of millimeter wave techniques and optical millimeter wave generation were introduced;the advantages of optical heterodyne photo-mixing and dual frequency laser were illustrated in detail;an overview of the recent researches and achievements of both dual frequency lasers and MOPA systems from home and abroad were presented.(2)Considering the principles of lasing and basic configuration of microchip lasers,the rate equation of four-level system,gain coefficient curve,dual longitude mode oscillation,etc.were discussed;the tunability of microchip lasers was illustrated based on the thermal and mechanic performance of 4Nd: YVO crystal.(3)The characteristics of two-stage 4Nd: YVO amplifier were investigated,which included small signal gain,saturation operation,amplifier configuration and the match mechanism between the master dual frequency laser and the power amplifier;the theoretical analysis illustrates that the single-pass two-stage configuration performs better when concerning the gain efficiency,thermal management and output beam quality;the beam overlap ratio match and spectrum match between the pump laser and signal laser was discussed and studied.(4)A realization of the MOPA system was presented;a well-designed TEC as well as a Kepler Lens component was introduced in the experimental setup,which facilitated an excellent spectrum and beam overlap match;The amplified dual frequency laser output with balanced power distribution was achieved when the laser oscillator temperature was set at 16?;the corresponding output power was 16.1W with 53.2GHz in mode separation and 0.98 in mode power distribution ratio;the output beam quality was measured as 1.20.