Research On 2-?m Eye-Safe Broadly Tunable Lasers Based On Disordered Tm:CaYAlO₄ Crystal

The 2-?m eye-safe laser is located in the atmospheric transmission window and has strong water absorption.There are unique advantages and applications in the fields of atmospheric monitoring,remote sensing,biomedicine,lidar and pump source for mid-infrared OPOs.Broadly tunable lasers can meet the requirements of various practical applications for different laser wavelengths,greatly expanding the scope and value of lasers,and becoming an important direction in the field of laser research.The disordered Tm:CaYAlO4(CYA)crystal has a wide emission spectrum,which is very suitable for the development of 2-?m eye-safe broadly tunable laser.In the experiment,a semiconductor laser with the center wavelength of 790 nm was used as the pump source,and Tm:CYA crystal was used as the laser gain medium.The 2 ?m broadly tunable characteristics of the continuous-wave laser and the passive Q-switched laser were developed research,the specific research content is divided into the following three parts:(1)A Tm:CYA continuous wave laser experiment was carried out.Using output mirrors with transmittances of 9.1%and 1.7%,continuous wave laser outputs of 1944nm and 1957nm were obtained.The corresponding maximum output power and laser Slope Efficiency is 2.26 W,30.1%and 1.37 W,18.1%.The tunability of CW laser for YAG etalon,quartz birefringent filter,and magnesium fluoride birefringent filter is compared.Using MgF2 birefringent filter as tuning element,Tm:CYA continuous wave broadband wavelength tunable laser is obtained.The tuning range is from 1807 to 2075nm and the tuning width is 268nm.(2)A passively Q-switched broadband wavelength tunable laser experiment based on a MoTe2 two-dimensional saturable absorber was carried out.A pulsed laser of 1929 nm was obtained with a maximum average output power of 0.75 W,a minimum pulse width of 0.69 ?s,and a maximum pulse energy of 10.58 ?J,the maximum peak pulse power is 15.3 W.A tunable Q-switched laser with a wavelength tuning range of 1829 to 1941 nm and a tuning width of 112 nm was realized using YAG etalon as the tuning element.This is the widest range of wavelength tuning currently achieved in Tm:CYA crystals.This is the first time research on a broadband wavelength-tunable passive Q-switched laser based on a two-dimensional material absorber in a Tm:CYA crystal.(3)A passive Q-switched broadband wavelength tunable laser experiment based on a Cr2+:ZnSe crystal saturable absorber was carried out,and a 1935 nm pulsed laser was obtained with a maximum average output power of 0.903 W,a minimum pulse width of 53 ns,and a maximum pulse energy of 67.?J,the maximum peak pulse power is 1.3 kW.A tunable Q-switched laser with a tuning range of 1820 to 1951 nm and a tuning width of 131 nm was achieved using MgF2 birefringent filter as a tuning element.