The effect of power, length and external reflectivity and its impact on key laser parameters such as linewidth broadening and power spectra are investigated utilizing hybrid silicon lasers coupled to ultra-low-loss waveguides (ULLW's) in a completely integrated system. Numerical simulations are done utilizing non-linear rate equations. Process flow is examined in mitigating the inadvertent effects that arise in fabrication of this system and address the best methods for controlling key parameters pertinent to linewidth narrowing. Time-domain and power spectra are captured to determine linewidth broadening as a function of feedback. Limiting terms such as feedback lengths, laser power, and interface reflectivities are analyzed and the best parameters for operation in the area of narrowest linewidth are determined. It is determined that increasing the length and reducing intensity noise will result in the narrowest linewidth laser.