1.5 μm ingaasp fabry‐perot cavity‐type laser amplifiers

To understand the small-signal gain, signal-gain saturation and noise characteristics of 1.5 μm InGaAsP Fabry-Perot cavity-type laser amplifiers, two types of laser amplifiers having different thickness of the active layers were tested. It was found that the larger the gain coefficient (i.e., the larger the injected carrier density), the higher the gain and saturation output of the amplifiers, and the lower the noise level. Stern's gain calculation method was applied to materials for the 1.5-μm region. It was found theoretically that these characteristics are due to the dependence of the carrier lifetime on the injected carrier density and the dependence of the saturation intensity and the population inversion parameter of the gain coefficient, by using the material parameters taking account of the Auger effect and the structure parameters of the device. The feature of the 1.5-μm amplifiers is that the reduction of the carrier lifetime with the increase of the carrier density becomes more significant due to the Auger recombination process. It is important for improving the saturation output by positively utilizing this phenomenon to design the amplifier structure so that the amplifiers can be operated in a high-gain region.