PURPOSE: To obtain a stepped substrate type (TS) semiconductor laser with a long life, which has desired electrical and optical characteristics, by the constitution wherein the position of a diffusing window is located in a range within 1.5μm in the direction so that said position is horizontally separated from the lowest part of the slant surface of the step of the substrate and within 0.5μm in the reverse direction.
CONSTITUTION: Contact point 10 of a slant part curve 14 of the surface of GaAs single crystal substrate and a straight line 13 of a flat part of the surface of the GaAs single crystal substrate is made to be a reference point. From a position 12, which is closer to the step at a window end, a perpendicular line is drawn to the flat part straight line 13. The position of a diffusing window is shown by a distance l between the reference point 10 and the perpendicular line. When the diffusing window position l is changed, the inserted depth of a diffused region 21 into a P type GaxAl1-xAs clad layer 18 is changed. Then the electrical and optical characteristics of a TS type semiconductor laser are conspicuously changed. Of these characteristics, a threshold current value Ith, which is considered to be most sensitive to the threshold current value Ith, is noted. Then it is found that the diffusing window position l, by which the threshold current value Ith can be made 30mA or less, is located within 1.5μm in the separating direction from the step and within 0.5μm in the reverse direction (a range A). When the diffusing window position l is set in the range A, the TS type semiconductor laser with long life is obtained.
KAZUMURA MASARU
SUGINO TAKASHI
OOTA KAZUNARI
WADA MASARU
