Research On Characteristics Of A Novel Saturable Absorber 2 ?m All-solid-state Pulsed Laser Based On Layered Double Hydroxide

The 2 ?m band laser is located at eye-safe band and has a wide range of application prospects in industrial processing,clinical medicine,national defense and military,and environmental monitoring.Compared with continuous wave(CW)lasers,pulsed lasers have the advantages of high peak power and narrow pulse width,and Q-switched modulation and mode-locking technologies are the main technical paths to obtain highperformance pulsed lasers.Among them,passive Q-switched modulation and passive mode-locking technology have the features of low process cost and simple operation,and the saturable absorber is one of the core devices in passive Q-switched modulation and passive mode-locking.In recent years,due to the advantages of easy preparation and broadband absorption of two-dimensional(2D)materials,the preparation of saturable absorbers with them has become a new research hotspot in solid-state laser technology.In this work,a new type of 2D material saturable absorber was prepared by using layered double hydroxide(LDH),and its morphology and optical absorption characteristics in the wavelength region of 2 ?m were systematically characterized and tested.By optimizing the design of the resonant cavity,2 ?m Tm:YAG ceramic passively Q-switched laser and passively mode-locked laser were developed respectively,and the2 ?m pulsed laser operation was realized.The optical modulation performance of the novel 2D LDH saturable absorber in 2 ?m band is verified experimentally.The main research contents of the paper are as follows:1.The NiV-LDH and NiCo-LDH solutions were prepared by the hydrothermal method and liquid phase exfoliation method,and the saturable absorber element was prepared by the drop coating method.The morphology and optical properties were studied to explore the feasibility of LDHs as saturable absorbers in the 2 ?m band.2.A flat-cavity Tm:YAG ceramic passively Q-switched laser was built,and the prepared NiV-LDH and NiCo-LDH saturable absorbers were inserted into the resonator,respectively,for releasing the passively Q-switched laser.The characteristics of Tm:YAG ceramic 2 ?m CW laser and passively Q-switched laser under output mirrors with different transmittance were studied.The 2 ?m passively Q-switched laser with the narrowest pulse width of 322.6 ns was obtained,the corresponding pulse repetition frequency and single pulse energy were 111.9 k H and2.10 ?J,respectively.3.An X-cavity Tm:YAG ceramic passively mode-locked laser was built,and NiV-LDH and NiCo-LDH saturable absorber mirrors were used as one of the end mirrors in the resonator.In further,The optical modulation performance of the 2 ?m ultrafast pulse laser was researched.Combined with the theoretical analysis and simulation of related literature,the pulse width of the narrowest Q-locked mode-locked laser is calculated to be 221 ps,and the corresponding repetition frequency is 143 MHz.Finally,not only the main work of this paper is summarized,but also the shortcomings of it are pointed out.In addition,an improvement plan is made to prospected future research work.