Reserce On Mode Excited Laser On Spatial Light Modulator

As a realization form of space division multiplexing technology,mode division multiplexing technology makes use of the orthogonal characteristics of different high-order transverse modes to regard different transverse modes as independent channels,and multiplexes the information in different channels together.The spatial dimension in the optical wave is regarded as a new multiplexing dimension,which areatly improves the optical communication capacity.The excitation and conversion of high-order transverse mode is the premise of mode division multiplexing technology,and it is the key technology of many applications in mode division multiplexing communication system.In recent years,on-demand mode laser has become a research hotspot.The so-called on-demand mode laser refers to the laser which can produce any high-order mode.At present,the on-demand mode laser with wavelength in 1064nm has been proposed.Althouah this laser can realize the output of any mode,it is difficult to be applied to the mode division multiplexing communication system because its application band is not in the lowest loss window of optical communication.That forces us to research the on-demand laser used in the lowest loss window of optical communication.In this paper,through simulation and experimental verification,the mode excitation and conversion in the laser resonator are deeply studied,and the multi-mode phase plate is applied to the resonator,so as to realize the simultaneous excitation of the fundamental mode and arbitrary Hermite-Gausses mode.Then a laser which can generate arbitrary Hermite-Gausses mode on demand is proposed.The so-called on-demand Hermite-Gausses mode laser refers to the ability to achieve the fundamental mode in the laser ring cavity cycle oscillation,any high-order mode of direct and accurate output.In this paper,an arbitrary Hermite-Gausses mode laser is used to realize the accurate output from Hermite-Gausses HG00 mode to HG55 mode by loading different multi-mode phase plates.The innovation and main work of this paper are as follows:1?A multi-mode phase plate excited by fundamental mode and Hermite-Gausses mode at the same time is proposed.According to the principle of mode excitation and conversion in spatial optical path,a multi-mode phase plate excited by fundamentall mode and Hermite-Gausses mode at the same time is proposed.First of all,the phase of the initial fundamental mode field and the phase of the target Hermite-Gausses mode field are superimposed in a certain way,and then a blazed grating is introduced to make different modes have different propagation directions.In order to make up for the amplitude loss in the process of phase modulation,we introduce the super pixel technology to realize the joint modulation of amplitude and phase,and finally form a multi-mode phase plate of fundamental mode and Hermite-Gausses mode,which is loaded into the spatial light modulator.Then the fundamental mode and Hermite-Gausses mode are excited at the same time.2?One on-demand Hermite-Gausses Mode Laser based on Spatial Light Modulator is proposedIn this paper,one on-demand Hermite-Gausses mode laser based on spatial light modulator is proposed.The multi-mode phase plate is applied to the laser resonator so that the fundamental mode circulates in the laser resonator.The arbitrary high-order Hermite-Gausses mode is directly and accurately output.Firstly,the feasibility of generating arbitrary Hermite-Gausses mode laser scheme is verified by scientific simulation.Then,through the experiment,one on-demand Hermite-Gausses mode laser experimental platform,including laser pump source,gain medium,mode conversion module and ring resonator,is built,and the simulation and experimental results are compared.The accurate output from HG00 mode to HG55 mode is successfully realized.In this experiment,the high gain characteristics of erbium-doped fiber to 980nm pump source are used to provide sufficient gain for the laser.Based on the multi-mode phase plate technology of spatial light modulator,the mode excitation,conversion and control are realized flexibly.By loading the phase plates corresponding to different high-order Hermite-Gausses modes in the spatial optical modulator,the on-demand output from HG00 mode to HG55 mode is realized.