| 摘要 |
PURPOSE:To provide a high output power DFB laser of a high efficiency for EDFA pump by providing a variation in a waveguide structure having a phase shifting of one or a plurality of diffraction gratings or its equivalent effect on one side of the center of a resonator consisting of a waveguide, and setting reflectivities of both end faces to a special value or less. CONSTITUTION:A wafer has a composite waveguide structure of an active layer 5 and a waveguide layer 4, and so mesa-etched as to become a stripe. Further, a p-type InP layer 9, an n-type InP layer 10, an n-type InGaAsP layer 11 are formed on the side. Finally, a p-type electrode, and an n-type electrode 13 are formed. Both cleaved end faces are coated with SiNx film 14 to reduce the reflectivities of the end faces to 2% or less. When a forward current is applied to the element, a boundary between the layers 9 and 10 becomes a p-n reverse junction, and hence a current is injected only into the stripe 5. Light goes to and from in a composite waveguide structure (stripe) made of the layers 5, 4 while being fed back by a diffraction grating 2 to cause oscillation. |
