The need for high data rates in telecommunications requires the constant search for improvements in these systems, especially in minimizing spectrum idleness in optical network. Currently, a solution to this issue is the elastic optical network, leading to numerous studies on the topic. As such, this article presents a study on elastic optical network, which considers physical layer effects (ASE noise and non-linearities) and their influence on the network layer, via the new PRMLSA problem (Power, Routing. Modulation Level and Spectrum Assignment). In the present study, this problem focuses on power, which directly influences the physical layer effects, obtaining promising results compared to current approaches.