In this paper we’ll discuss technological alternatives related to physical layer security of optical communication systems and networks. In the introduction, an overview of confidentiality and availability issues of the optical networks will be discussed, focusing mainly in the physical layer-related solutions. In the following paragraphs we’ll provide two distinct approaches for the physical layer encryption. The first is based on a One-Time-Pad implementation using synchronized true random sequences. The second uses cryptographic keys generated by Photonic Physical Unclonable Function devices for scrambling the Orthogonal Frequency Division Multiplexing subcarriers.