A watermarking scheme is proposed based on optical asymmetric cryptography using double random phase encoding in
the gyrator transform domain. It is based on the phase and amplitude truncation during the encryption process. The
scheme is validated through computer simulations showing the scheme's sensitivity to decryption keys and orders of the
gyrator transform. The occlusion and noise attacks have also been analysed. The proposed scheme is significantly
resistant to both these attacks.
An analysis of erbium-doped titanium indiffused LiNbO3 channel waveguides under 1484-nm excitation is presented in terms of a complex refractive index profile under 1484-nm excitation (pump) to obtain modal gain and loss for signal and pump powers, respectively. Closed form analytical expressions for modal fields are used to define the complex index profile. The calculated gain characteristics are compared with available experimental results.