Experimental Study Of Spectral Linewidth Narrowing On High Power Diode Laser Stacks

In recent years,with the development of spin-exchange optical pumping,diode pumped alkali vapor laser and high-efficiency all-solid-state laser,the demand for narrow linewidth high-power diode lasers has become more and more urgent.Although narrow linewidth diode lasers of kilowatt-level have been achieved,they are always complex and unscalable.There are still many technical problems to be solved.Based on this,this paper conducts a systematic study on a scalable linewidth narrowing scheme for high power diode stacks,which lays the foundation for the realization of high power multi-stacks linewidth narrowing system in the future.The main work carried out in this paper is as follows:1.Through literature survey,we summarized and analyzed the current research and relative merits of two mainstream diode laser linewidth narrowing schemes based on the plane diffraction grating and volume Bragg grating.In this part,we propose a novel linewidth narrowing scheme on multi-stacks using single plane grating,which has the common advantages of traditional schemes.And its working principle is introduced in detail.2.An external cavity line-narrowing system on a diode stack was built.Firstly,we studied the linewidth narrowing method on a single bar,and obtained a good result(1nm ? 0.3nm,FWHM).On this basis,we expanded it up to multi-bar,and compared the influences of different beam collimating and expanding systems on the spectral characteristics of multi-bar.Based on the optical path compensation scheme,the same multi-bar central wavelength was achieved.In order to meet the application requirement of high pumping power density,the spatial duty ratio enhancement scheme of the output beam of diode stack was explored,and we achieved the high duty ratio output 50%.3.The experiment of linewidth narrowing on double diode stacks using an external cavity was studied.Firstly,the research of dual stacks beam combining technology was carried out.According to this,we constructed the external cavity,and achieved effective linewidth compression and wavelength locking.At last,we propose a scheme of future multi array power expanding linewidth compression system.