Pulse Laser Properties Of Diode Pumped Nd-doped Aluminate Disordered Crystals

Narrow pulse,high instantaneous power and high repetition rate ultra-short pulse laser has been applied to many aspects,such as biology,medical treatment and communication,etc.Ultra-fast laser technology is also gradually developing towards ultra-fast and ultra-intensified trends,and promotes the develop of physics,chemistry,materials,micro-processing and other basic disciplines.All-solid-state lasers using semiconductor laser diodes as pump sources are compact,inexpensive,and have very important practical value.The development of lasers is inseparable from gain crystals.Nd³⁺-doped disordered crystals have been proved to be a gain medium with excellent performance.This paper mainly studies the characteristics of continuous laser and mode-locked laser based on two kinds of disordered aluminate crystals Nd:LMA and Nd:ASL.The main content of this paper is divided into four chapters,as follows:The first chapter introduces the characteristics and applications of ultrashort pulse lasers,introduces the mode-locking technique for producing ultrashort pulses,and summarizes the development of ultrafast lasers doped with Nd³⁺disordered crystals in 1?m band in recent years.The second chapter introduces the basic theory of mode locking and dispersion compensation.The principle of mode locking technology is also expounded,and the structure and characteristics of the current commonly used passive mode locking device SESAM are introduced.Introduced several commonly used dispersion compensation techniques.Chapter 3 introduces the continuous and mode-locked laser characteristics of Nd:LMA disordered crystals with a,c axial cutting.High-efficiency continuous laser output of two axially-cut crystals are achieved,among which the c-cut Nd:LMA crystal exhibits better continuous characteristics,and a 6.24 W laser output is obtained at the maximum incident pump power with the center wavelength at 1055.29 nm,corresponding to the high slope efficiency of 53.40%,and the laser output is not saturation.The mode-locked laser characteristics of LD-pumped Nd:LMA disordered crystal are studied for the first time.A pulse laser with a center wavelength of 1055.35nm,FWHM of 0.93 nm,and a maximum power of 1.30 W was obtained by using the c-cut Nd:LMA crystal.The result is excellent in LD-pumped disordered crystal mode-locked lasers both of output power and slope efficiency.The pulse and spectral characteristics of the a-cut Nd:LMA mode-locked laser are similar to the c-cut Nd:LMA laser,and the maximum output power is 0.93 W.The fourth chapter introduces the continuous and mode-locked laser characteristics of Nd:ASL disordered crystals with a,c axial cutting.Both two axially cut Nd:ASL disordered crystals achieve high power and high efficiency continuous laser output.The output spectra of the two crystals are basically the same,but the c-cut Nd:ASL crystal exhibits higher output power and conversion efficiency.A laser output of 9.05 W is obtained without saturation in maximum incident pump power.There are two central wavelengths of 1050.08 nm and 1052.40 nm,corresponding to the high slope efficiency of 60.05%.The mode-locked laser characteristics of LD-pumped Nd:ASL disordered crystal are systematically studied for the first time.The performance of c-cut Nd:ASL crystal is better than that of a-cut Nd:ASL crystal.A pulse laser with a center wavelength of 1052.01 nm,FWHM of 1.09 nm,and a maximum power of 1.08 W is obtained.The pulse width and output spectrum of a-cut Nd:ASL mode-locked laser are very close to the c-cut Nd:ASL crystal,but the maximum output power is lower,which is 0.91 W.The femtosecond mode-locked laser of c-cut Nd:ASL crystal is studied by using two GTI mirrors for dispersion compensation,and an ultrashort pulse with a pulse width of 519 fs,a center wavelength of 1052.15 nm and a FWHM of 2.46 nm is obtained.The time bandwidth product is calculated to be 0.346,which is close to the Fourier transform limit of0.315.The maximum stable mode-locked output power is 0.75 W,which is the highest output power in a LD-pumped disordered crystal femtosecond laser currently.