Semiconductor laser device

A semiconductor laser device comprising:

• a first light emitting portion and a second light emitting portion provided on a substrate and having the same resonator length L,
• wherein each of said first light emitting portion and said second light emitting portion includes a first cladding layer of a first conductivity type, an active layer provided on said first cladding layer and a second cladding layer of a second conductivity type provided on said active layer, and has a stripe structure for injecting carriers,
• said stripe structure of said first light emitting portion has a section having a width changing along a resonator direction and includes a first front end face,
• the following relationships hold:
• Wf1≧W1;
• W1>W2;
• and
• (Wf1−W1)/2L1<(W1−W2)/2L2
• wherein Wf1 is a width of said stripe structure on said first front end face;
• W1 is a width of said stripe structure in a position away from said first front end face by a distance L1;
• and W2 is a width of said stripe structure in a position away from said first front end face by a distance L1+L2 (whereas L1+L2≦L),
• said stripe structure of said second light emitting portion has a section having a width changing along a resonator direction and includes a second front end face, and
• the following relationships hold:
• Wf2≧W3;
• W3>W4;
• and
• (Wf2−W3)/2L3<(W3−W4)/2L4,
• wherein Wf2 is a width of said stripe structure on said second front end face;
• W1 is a width of said stripe structure in a position away from said second front end face by a distance L3 (whereas L1≠L3);
• and W4 is a width of said stripe structure in a position away from said second front end face by a distance L3+L4 (whereas L3+L4≦L)