In this work, we present all optical reversible implementation of Flip-Flops using semiconductor optical amplifier (SOA) based Mach-Zehnder interferometer (MZI) switches. Improved design of MZI-based functionally reversible RS, D, JK, T and three different implementations of all optical functionally reversible MZI-based Master-Slave Flip-Flop using RS, D and JK Flip-Flop are presented. Detailed analysis and design complexities of all the functionally reversible optical Flip-Flops with improved optical costs have been reported.