Absorption loss coefficient of the active layer for 1.48-/spl mu/m bulk and MQW lasers

It is shown that the absorption loss coefficient of the active layer for 1.48-/spl mu/m bulk lasers is 66 cm/sup -1/ which is between 45 and 107 cm/sup -1/ for 1.3-/spl mu/m bulk lasers and for 1.55-/spl mu/m bulk lasers, respectively. It is also described that the absorption loss coefficient of the active layer for 1.48-/spl mu/m multiple-quantum-well (MQW) lasers is 28 cm/sup -1/ which is about two-fifths of that for 1.48-/spl mu/m bulk lasers. Therefore, the high slope efficiency of the 1.48-/spl mu/m MQW lasers is attributed not only to the small optical confinement factor but also to the small absorption loss coefficient of the active layer.