Research On Passive Q-switched Laser Based On MXene Saturable Absorber

Passive Q-switched lasers not only have higher peak power and pulse energy,but also have the advantages of low cost,less difficulty in debugging,compact structure and high efficiency.That makes the lasers could be broadly applied in such fields as:biomedicine,laser Display,material processing and lidar.As an emerging two-dimensional material,MXene is highly adjustable and customizable in electronic and optical properties.The subject of this thesis is mainly about the research of a 1064 nm passive Q-switched laser with two-dimensional materials V2CTx and Ti3C2Tx as saturable absorbers.By adjusting the concentration of the saturable absorber,resonant cavity length and other parameters,we explore the application of V2CTx and Ti3C2Tx in Q-switched lasers.The specific research contents are as follows:In theory,taking the Nd:YAG Q-switched laser as an example,the factors which would affect the output characteristics of the Q-switched pulse are analyzed by the rate equations.The working principles of the saturable absorber in passive Q-switched lasers are introduced,which provides a theoretical basis for measuring the saturable absorption characteristics of V2CTx and Ti3C2Tx and for applying them in passive Q-switched lasers.In terms of experiments,the first part is the research of V2CTx passive Q-switched lasers.The V2CTx dispersions with concentrations of 0.05 mg/ml and 0.025 mg/ml are packaged in cuvettes respectively.And they are made into Q-switched devices.The modulation depth and saturated light intensity are measured.The 1064 nm passive Q-switched laser has been realized by semiconductor laser pumping and linear cavity structure.When the dispersion concentration is 0.05 mg/ml,the cavity length is 35 mm,and the pump power is 5.6 W,the narrowest pulse width is 302 ns,the repetition frequency is 155 kHz,and the average output power is 42 mW;When the concentration is 0.025 mg/ml,pump power is 3.2 W,the narrowest pulse width is 624 ns,the repetition frequency is 117 kHz,and the average output power is 48 mW.The results show that V2CTx has the characteristics of saturable absorption.And it is proved that with the same Q-switched device,the shorter the cavity length,the narrower the pulse width,and the higher the repetition frequency.Under the same experimental conditions,the V2CTx dispersion with a concentration of 0.025 mg/ml is deposited on K9 glass slides to make a Q-switched device.Compared with the same concentration dispersion Q-switch device,the modulation depth is improved,and the saturated light intensity is reduced.Pulsed lasers with deposited V2CTx Q-switched devices have higher optical conversion efficiency.In terms of experiment,the second part is the research of Ti3C2Tx passive Q-switched laser.The Ti3C2Tx dispersion with a concentration of about 0.02 mg/ml is encapsulated in a cuvette and is deposited on a K9 glass plate respectively to be made into two different kinds of Q-switching devices.The modulation depth and saturated light intensity are measured.Under the same experimental condition,with the Ti3C2Tx dispersion Q-switched device,the narrowest pulse width is 270 ns,the repetition frequency is 178 kHz,and the average output power is 80 mW when the cavity length is 35 mm and the pump power is 6.1 W.Using the deposited Ti3C2Tx as a Q-switching device,when the pump power is 2.7 W,the narrowest pulse width is 305 ns,the repetition frequency is 210 kHz,and the average output power is 160 mW.The experimental results show that both V2CTx and Ti3C2Tx have good characteristics of saturable absorption,and they have great application prospects in the field of Q-switched lasers.