Study Of Frequency Chirped Pulse Laser Beam Diffraction Properties

Ultra short pulsed laser has many promising applications in the fields such as ultra-fast imaging and laser spectroscopy because of its abundant spectrum and wide bandwidth. Linear chirped pulse laser is one of ultra short pulse laser that its frequency is linear changing with time. Chirped pulse laser is important in gain the high-power laser, laser radar, laser ranging and other fields. Use the optical dispersive element such as prisms, gratings can shape a chirped pulse because of the wide spectral characteristics. Therefore, Study of chirped pulse laser diffraction and propagation properties is important to the development of ultra short pulse laser new applications. This paper focuses on calculated and analyzed the chirped-pulse laser diffraction properties. The influence of grating thickness, grating period changing and the parameters of multi-layer gratings to chirped pulse laser diffraction is studied. And designed two devices for chirped pulse laser beam splitting and shaping based on the volume holographic gratings.In the first part of this thesis, the fundamental theory of ultra short pulse laser and chirped pulse laser are discussed. The research situation of ultra short pulse laser and the important application of chirped pulse laser are introduced.In the second part of the thesis, we establish the theoretical model of linear chirped pulse laser incident volume holographic gratings and solved the coupled wave equations. Then the influence of grating thickness, grating period changing to linear chirped pulse laser diffraction is studied. The properties of the spectral intensity and group delay are investigated. The third part the theoretical model of linear chirped pulse laser incident multi-layer volume holographic gratings is established, based on Matrix optics theory, and derivate the coupled wave equations. The influence of intermediate layer thickness and grating thickness changing to chirped pulse laser diffraction is studied. The diffraction properties of multi-layer volume holographic gratings illuminated by linear chirped pulse laser are analyzed.In the fourth part, two chirped pulse laser beam splitting and shaping devices are designed based on multi-layer volume holographic grating. One of the devices is splitting chirped pulse laser beam by multiplexing volume holographic grating, and then shaping the ultra short pulse laser beam. Another device is shaping of chirped pulse laser beam with different parameters by multi-layer volume holographic gratings, then use two-layer volume holographic gratings splitting the beam.