Patent ID: 8111728

Claim:
A semiconductor laser comprising: a semiconductor substrate; a lower cladding layer disposed above said semiconductor substrate; an active layer disposed above said lower cladding layer; a first upper cladding layer disposed above said active layer; a second upper cladding layer disposed above said first upper cladding layer and having a mesa structure; a high-order mode filter layer formed on both side faces of said second upper cladding layer, continuously extending from said both side faces onto at least a part of a side region on both side regions of said second upper cladding layer and having a band gap not exceeding a band gap of said active layer; and a block layer formed on said high-order mode filter layer and on the regions of both side regions of said second upper cladding layer, said block layer including a layer having a band gap greater than the band gap of said active layer, wherein said high-order mode filter layer includes a GaInP layer.