Optimization of Pump Current for Pulse Distortionless Amplification in Quantum Well Amplifiers

In this paper, we have developed a novel method to optimize pump currents for pulse distortionless amplification in a quantum well semiconductor optical amplifier (QW-SOA). The relationship between the pump current and the maximum distance along the amplifier cavity where the input Gaussian pulse can be amplified without any distortion is proposed. For a given cavity length, we have obtained an optimum pump current where the input pulse obtains high gain distortionless amplification (e.g., for a 750 μm long QW-SOA, the maximum gain of distortionless amplification is 18.7 dB when a Gaussian pulse with 1 mW peak power and 2 ps pulse width is applied). Also, an expression which indicates the optimum pump current as a function of the input signal peak power is presented. The dependence of the optimized pump current obtained by the proposed method on the input pulse width is analyzed and it was found that as the input pulse width increases, the optimized pump current decreases. The suitability of optimized pump current for pulse trains is discussed and it was confirmed that the pump current optimization method is suitable for the distortionless amplification of pulse trains.