Semiconductor laser element having end-facet protection layer which includes unoxidized or unnitrided first sublayer formed on end facet and second sublayer produced by oxidizing or nitriding the surface of the first sublayer

A semiconductor laser element comprising:

• a stack of a plurality of layers having cleaved faces which are perpendicular to a light propagation direction and function as resonator faces;
• and
• at least one protection layer formed on at least one of said cleaved faces;
• wherein each of said at least one protection layer includes at least first, second, and third sublayers,
• said first sublayer is formed nearest to said stack among said at least first, second, and third sublayers, and made of a material which does not contain oxygen as a constituent element,
• said second sublayer which is made of a material comprising an oxide produced by oxidizing a portion of said first sublayer, and has a thickness d2,
• said third sublayer is formed farthest from said stack among said at least first, second, and third sublayers, and made of a material comprising an oxide,
• said first and second sublayers have a total thickness d1, and
• said total thickness d1 and said thickness d2 of said second sublayer satisfy a relationship, 0.1≦d2/d1≦0.9.