Patent ID: 8179747

Claim:
A thermally assisted magnetic head comprising: a slider that has a magnetic head portion facing a recording medium; a semiconductor laser device that oscillates in a TM mode and that generates light for heating the recording medium; a magnetic recording element that is disposed at the magnetic head portion and that generates a magnetic field for magnetic recording; and a waveguide that is disposed at the magnetic head portion, that has a light-incidence end surface facing a light-emission end surface of the semiconductor laser device, and that guides light from the semiconductor laser device to a surface of the recording medium; wherein the semiconductor laser device comprises: a p-type cladding layer and an n-type cladding layer; a p-side guide layer and an n-side guide layer both of which are placed between the p-type cladding layer and the n-type cladding layer; and an active layer that is placed between the p-side guide layer and the n-side guide layer and that includes at least one quantum well layer; wherein the p-type cladding layer and the n-type cladding layer are each formed of a (Al x1 Ga (1-x1) ) 0.51 In 0.49 P layer (0≦x1≦1); the p-side guide layer and the n-side guide layer are each formed of an Al x2 Ga (1-x2) As layer (0≦x2≦1); the quantum well layer is formed of an Al y Ga (1-y) As (1-x3) P x3 layer (0≦x3≦1, 0≦y≦0.3); and the Al y Ga (1-y) As (1-x3) P x3 layer has a composition in which the ratio x3/(1-x3) of the composition x3 of P to the composition (1-x3) of As satisfies 1/4 or less.