A semiconductor laser element includes: a stack of layers having resonator
facets; and at least one protection layer formed on at least one of the
resonator facets. Each of the at least one protection layer includes at
least first, second, and third sublayers. The first sublayer is formed
nearest to the stack among the at least first, second, and third
sublayers, and made of a material not containing oxygen (or nitrogen) as
a constituent element. The second sublayer is made of an oxide (or
nitride) produced by oxidizing (or nitriding) a portion of the first
sublayer. The third sublayer is formed farthest from the stack among the
at least first, second, and third sublayers, and made of an oxide (or
nitride). The thickness d2 of the second sublayer and the total thickness
d1 of the first and second sublayers satisfy a relationship,
0.1.ltoreq.d2/d1.ltoreq.0.9.