Distribution feedback die semiconductor re - selective manner null

摘要

PURPOSE:To obtain the long-term stability of simple axis mode oscillation by selecting the one whose primary mode is positioned within 10% of the stop band width from the center, with the luminous spectrum, when DC bias of 0.7 to 1.0 times the oscillation threshold currents is applied, as an index. CONSTITUTION:In case that the luminus spectrum under the DC bias of 0.9 times the oscillation threshold currents of lambda/4 shift DFB laser is measured with a spectrum analyzer, the primary mode is positioned in a stop band caught with +1 and -1 modes. And DFB laser, where the relation of ¦deltalambda0¦=0.1(lambda-1+lambda+1) is established between the value of the primary positional deviation deltalambda0 defined as deltalambda0=lambda0-(lambda+1+lambda-1)/2 and the stop band width lambda-1-lambda+1, is selected. As a result, it does not bring about an error floor in the receiving sensitivity properties of the deterioration of a submode suppression ratio at modulation and the code error rate after long fiber transmission, and the long- term stability of simple axis mode oscillation can be obtained.