Discussion On The Combining Effect Of Laser Beam In Spatial And Time-Domain

Based on the interference theory of light, Gaussian beam as a beam model, the coherent combining effect of continuous wave lasers array and Q-switched pulse lasers array is studied usingβand PIB to evaluate the combining effect.For the continuous wave lasers array, influences of duty ratio, propagation distance, and phase errors on the combining effect are researched. The influences of duty ratio onβand PIB are different. Duty ratio has little influence onβas it reduces in a certain range, with the increase of propagation distance, the influence of duty ratio onβwill become even small, finally close to its ideal value. The PIB decreases linearly with the decrease of duty ratio, PIB stays unchanged with the increase of propagation distance.βdecreses rapidly with the increase of the phase errors, and PIB decreses to some extent. When the phase errors increase to a certain value, the coherent combining may become meaningless.For the pulse lasers, besides spatial combining, the problem of time-domain combining also exists. The combining is studied from the point of view of time-domain in this paper. The research way is to caculate the waveform of the output pulse of Q-swiched solid-state lasers starting from the rate equations of the four levels laser system and then caculate the combined waveform. Mainly studied are the relationship between the combined pulse and a single pulse, including their peak and width, the influences of time delay on peak and width of the combined pulse, the influences of time delay onβand PIB. The results show that the peak of the combined pulse increases linearly with the increase of the peak of the single pulse, the combined pulse has the same width with the single pulse; time delay has serious influence on the waveform the combined pulse, it can cause the decrease of the peak and the increase of the width of the combined pulse. When the time delay increases to half the width of the single pulse, the peak of the combined pulse decreases approximately to one third the peak of the combined pulse without time delay, and the width of the combined pulse increases to three times the width of the combined pulse without time delay.βdecreases seriously with the increase of the time delay, while PIB almost stays unchanged.