A Method For Evaluating Beam Quality Of Laser Diode

The configuration and principle of laser diode and its mode field distributions,several methods for evaluating beam quality are discussed.Furthermore,a new methodfor evaluating beam quality of laser diode is proposed.The main work of this dissertation is summarized as follows:1 . Several methods such as focused spot size,far-field divergence angle,timesdiffraction limited factorβ,Strehl rate,energy circl rate and M2 factor are summarized.The application range,strongpoint and shortcoming of them especially used inevaluating beam quality of laser diode is also analysed.2.The main factors to influence collimating the beam of laser diode with lenses areanalysed. A new quality parameter(Where L is the size of the emitter in the direction parallel to the junction plane,θ⊥is theangle of the beam in the perpendicular direction,θ//is the angle of the beam in theparallel direction,As is the astigmatism parameter of a semiconductor laser ) forevaluating beam quality of laser diode is given.The difficulty of collimation is wellexpressed by use of f(L,θ⊥,θ//,As). The smaller the value of f(L,θ⊥,θ//,As) is, the moreeasily the beam is collimated.Furthermore we give a reference value of the f(L,θ⊥,θ//,As),when the f(L,θ⊥,θ//,As) value of the beam is smaller than this value,this beam can becollimated without much difficulty.