| 摘要 |
PURPOSE:To inhibit variation of output and optical feedback caused noise due to change of distance between an output end face of a laser and an optical recording medium and to improve the SN ratio of a detection signal, by arranging resonators periodically in the vertical direction to the optical axis while arranging the sections having a longer effective length of resonator and the sections having a shorter effective length of resonator in parallel with the optical axis. CONSTITUTION:A semiconductor laser comprises a lower clad layer 1, an active layer 2, an upper clad layer 3, a cap layer 25, an insulation layer 24 and electrodes 8 and 9 which are formed on a semiconductor substrate 0. The end face thereof 21 on the side of an optical component (optical recording medium) 10 is rugged, while the output end face 22 thereof is formed specularly by cleavage. The depth DELTAl of recesses in the rugged face is represented as DELTAl1=lambda(1+2N)/4neff and DELTAl2=lambda(1+2N)/4(neff-1), in which lambda is an oscillation wavelength and neff is an effective refractive index. The sum of reflected light from the output end face 21 and reflected light from the optical component 10 is cancelled, since in the semiconductor laser the going and returning optical paths have a difference of lambda/2 between the recessed and protruded sections. Accordingly, output is not varied even if the distance S is changed.
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