Research On Laser Beam Shaping Technology In Temporal And Spatial Domains

It has new requirements for laser source in modern optical communication, so the temporal and spatial shaping technology of the laser beam also has new requirements. Because of the requirements of optical communication, the modulation laser signal must have some features, for example the frequency must continuous change in very high frequency range, the output waveform is sine wave, and the modulation depth should achieve 33%.In the previous study of the temporal shaping, the research is still blank in this area, so it is necessary conduct relevant research in this area. In the spatial shaping, it mainly changes the spot's intensity, it is hope that the energy distribution of the laser beam is uniform before modulated, when using the array detectors to detect the laser beam, we hope that the laser beam's energy distribution is uniform before arrive the detectors, especially TEM00 mode laser output, the energy distribution of the laser beam is Gaussian distribution, so it should be changed the Gaussian distribution of the laser beam into uniform distribution. In order to conduct the modulation of the laser, so it needs a effective method to analyze and evaluate the shaping effect.The contents researched in this paper are divided into three aspects, In the first aspect analyzing the direct modulation of the Semiconductor lasers, in this section it introduces the direct modulation's principles and characteristics, on this bias by analyze the difficulty of the direct modulation and the factors which affect the modulation depth, making the signal generator, finally completed the direct modulation of the Semiconductor lasers. In the second aspect for electro-optical modulation system, analyzing the crystal material and the working principle of electro-optic modulator and so on. According to the laboratory conditions demonstrated the external modulation in principle, in the third aspect build the evaluation methods for the experiment of spatial shaping, written the procedures for measuring the spot's energy distribution. Through the direct modulation of Semiconductor lasers, the output modulation signal's frequency continuous changed from 50MHz to200MHz, and the output waveform is sine wave. Under the premise of make sure that the output optical signal is not distortion, decrease the output power and increase the amplitude of the electric signal will increase the output optical signal's modulation depth. The modulation depth can reach 33% at last. It meets the technical requirement finally. Through the procedures for measuring the spot energy distribution, it can get the energy distribution of the laser spot successfully, it provides a method for measuring the spot energy distribution.