Enhanced Modulation and Noise Characteristics in 1.55 µm QD Lasers using Additional Optical Pumping

The modulation response, relative intensity noise (RIN) and frequency noise (FN) characteristics of quantum dot (QD) lasers are investigated theoretically in the presence of an external optical beam. Using small signal analysis of the rate equations for carriers and photons, it is demonstrated that by injecting excess carriers into the QDs excited state through optical pumping, the modulation response of QD laser enhances and its bandwidth increases. The external optical pump also helps QD laser to turn on during shorter delay time. Further, it is deduced that the RIN level of QD laser reduces and the damping factor increases due to external beam. Moreover, the frequency noise level of QD laser and correspondingly its linewidth decreases by applying the optical beam.