The Effect Of Applying Electric Field&Materials’Strain Modulation On High Harmonic Generation In Semiconductors

With the development of laser technique,people have already obtained strong femtosecond laser with ultra-short time resolution which is applied broadly in researches as well as our daily life.Especially for the theoretical and experimental researches,by using this attractive tool,people began to study,observe and even control the inner structure of matters and its ultrafast dynamics.And the systems people study gradually expand from atoms and molecules to solids.In this article,we show some researches of the interaction between strong ultrafast laser field and solids,which contains the history of laser and the interaction between laser with matters.And the most important part is our researches about a novel ultrafast dynamical phenomenon called high harmonic generation in solids.In chapter one,we briefly introduce the development of laser technique in few decades,as well as some early researches aiming at its interaction with matters.Then we list some preliminary conceptions and the progress about laser-matter interaction,emphasing the researches and theories about high harmonic generation in solids in these years.In the chapter two,we mainly introduce some theories and calculation methods we used in our researches.The first part in this chapter concludes some elementary knowledge about energy band theory of solids,which establish the footstone of our researches.The second part is about some common calculation methods of studying high harmonic generation in solids.In addition,we add a highlight on semiconductor Bloch equation(SBE)theory as well as VASP software,which is usually used in our simulation.In the chapter three,we show our present researches about high harmonic generation in solid.Here are the three parts of our research:firstly we optimized the harmonic spectra from 2D P3121-SiO2 system by using two-band SBE.It showed us a new possibility about how to improve harmonic efficiency as well as obtain isolated attosecond pulse.Secondly,we analysed the high harmonic generation in few symmetries of bulk SiO2 systems.Since we used multiband SBE this time,we can prove the multiband effects in harmonic spectra.Unfortunately we haven’t gotten the intrinsic relations between crystal symmetry with high harmonic generation until now.Thirdly,we picked monolayer blend AlN as our target system and investigat the strain applied effect on high harmonic spectra,which is still ongoing.But we have already seen the effect of strain applied on harmonic emission.