Semiconductor laser device having lower threshold current

A semiconductor laser device includes a QW active layer structure including a Ga_xIn_1-;xAs_1-;ySb_y layer wherein 0.31-;x and 0.003y0.008, or a QW active layer structure including a Ga_xIn_1-;xA_s1-;y1-;y2N_y1Sb_y2 layer wherein 0.31-;x, 0