A new semiconductor laser diode amplifier structure which consists of
a semiexponential-linear tapered waveguide active layer has been propo
sed to improve the saturation output power. Various characteristic per
formances of this device have been analysed based on the step-transiti
on approach taking into account the effects of the spatial distributio
ns of the carrier density and the optical field. The effects of variou
s tapered structures on the gain saturation, intensity distribution an
d amplified spontaneous emission noise have also been investigated.