【摘 要】
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Coherent transitions of charge carriers between the conduction and valence bands of a semiconductor medium are essential for the operation of a semiconductor la
【机 构】
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Department of Physics,The Chinese University of Hong Kong,Shatin,Hong Kong,China
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Coherent transitions of charge carriers between the conduction and valence bands of a semiconductor medium are essential for the operation of a semiconductor laser.In this paper,we study how such interband coherence can be set up by an injection current and a coherent pump-field.In the absence of the pump-field,the injection current is the only source to establish the interband coherence in a semiconductor laser system.A laser threshold is obtained,which shows that a strongly coupled high-Q microcavity has a low threshold value.However,when an exteal pump-field serving as another mechanism to create the interband coherence is applied,the threshold value of the injection current can be lowered and it vanishes for sufficiently strong field.Besides,if the pump-field exceeds a threshold value,it is even possible to achieve a bistability in the inversionless region.Some fundamental macroscopic properties,including polarization,absorption and dispersion for the semicoductor system,are also obtained analytically.
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