Generation And Manipulation Of Multi-dimensional Spatiotemporal Structured Light Field

Structured light has unique phase,polarization and amplitude distribution.Among the structured light,the polarization distribution of cylindrical vector beams（CVBs）on the beam profile with cylindrical symmetric distribution.CVBs have a lot of potential application in materials processing,optics communication and microscopy technology,etc.CVBs can be generated by a lot of methods,however,the research of how to manipulate the temporal and frequency domain is relativity rare.Due to the application demands of multi-dimensional manipulation of the structured light,the generation and manipulation of multi-dimensional structured light would have important significance.CVBs can be generated by using various modulation elements outside the laser cavity or directly generated from the laser cavity.Compared to the generation outside the laser cavity,CVBs generation from laser cavity have some advantages,such as compactness,high efficiency and higher mode purity.In general,the CVBs generation from laser can be achieved by using pumping light shaping,thermally induced birefringence effect of gain medium or few-mode fiber grating,etc.However,these methods have some common disadvantages like complicated system and large optical loss.Recently,the appearance of Pancharatnam–Berry phase element–q-plate could achieve the manipulation of polarization state of light and it is helpful to obtain high efficiency laser.We used the q-plate as the mode convertor in laser cavity to demonstrate the switchable radially and azimuthally polarized beams fiber or solid-stated laser.At the same time,we have manipulated the temporary and frequency domain of structured light laser.This thesis addresses the application requirements of multi-dimensional structured light,focusing on the generation and multi-dimensional manipulation of structured light,the main content are as follows:（1）We demonstrated the high efficiency radially and azimuthally polarized beams freom Yb-doped fiber laser,and the radially and azimuthally polarized beams could be easily switched and the slope efficiency is highest in 1μm.Firstly,we used the polarization-maintaining Yb-doped fiber as the gain medium.Secondly,a polarizer was inserted in laser cavity to induced the linear polarization Gaussian beam oscillation.Lastly,we used q-plate as the mode converter which could demonstrated the switchable radially and azimuthally polarized beams output,and the slope efficiency and mode purity could reach up to 70.6%and⁹7%.For the first time,to our knowledge,a controlled switchable four degenerate LP₁₁ mode generated from Yb-doped fiber laser have been demonstrated and the modes properties and manipulation law have been obtained.By combining a q-plate and two quarter wave-plates,the high-order mode TM₀₁、TE₀₁、HE₂₁^even、HE₂₁^oddcould be easily switched and generated.At the same time,the system slope efficiency 39.4%can be obtained.（2）We demonstrated the wavelength-locked structured light laser and the influence of volume Bragg grating（VBG）for laser wavelength and spectrum width have been researched.Q-plate as the mode converter in laser cavity and the VBG as the reflection mirror and wavelength selection element.The output laser wavelength was locked at 1053.4 nm and spectrum width of 0.06 nm.The laser slope efficiency of36%and the purity of radially and azimuthally polarized beams larger than 95%can be achieved.（3）For the first time,we used the graphene as the saturable absorber,demonstrating the radially and azimuthally polarized beams passively Q-switched fiber laser.Firstly,we fabricated the 6-8 layers graphene saturable absorber mirror and the modulation depth of graphene saturable absorber was 13.2%could be obtained by using the Z-scan technology.Secondly,we used the graphene saturable absorber mirror in Yb-doped fiber laser,a passively Q-switched switchable radially and azimuthally polarized beams laser could be achieved with output power of 253 mW,single pulse energy of 7.73μJ.At the same time,based on the organic/inorganic hybrid perovskite as the pulse modulator,we demonstrated the pulsed radially and azimuthally polarized beams fiber laser and the temporary regulation law of fiber laser could be obtained.Firstly,we fabricated the organic/inorganic hybrid perovskite with the modulation depth of 22.7%as the saturable absorber.Secondly,we used the organic/inorganic hybrid perovskite in Yb-doped fiber laser,the passively Q-switched switchable radially and azimuthally polarized beams Yb-doped fiber laser can be obtained.The minimum output pulse duration of 919 ns and repetition rate could be tunable from 15.2 kHz to36.4 kHz.（4）We demonstrated the temporary and frequency domain manipulation at the same time for the solid-state laser and pulsed CVBs laser operation.Using the accusto-optic Q-switcher and the birefringence filter in laser cavity,an actively Q-switched and switchable single-wavelength and dual-wavelength radially and azimuthally polarized beams Nd:YVO₄ solid-state laser could be achieved.The output shortest pulse width and pulse peak power are 28 ns,0.83 kW,respectively.