Phase state and related nonlinear coherents states
  We cast the phase state as a $SU(1,1)$ nonlinear coherent state to support the idea that the $SU(1,1)$ representation of the electromagnetic field may be helpful in some instances and to bring forward that it may relate to the phase state problem. We also construct nonlinear coherent states related to the exponential phase operator and provide their corresponding nonlinear annihilation operators. Finally, we discuss the propagation of classical fields through arrays of coupled waveguides that are solved through the use of nonlinear coherent states of $SU(1,1)$ or the exponential phase operator. 
F. Soto-Eguibar, B. M. Rodr\'iguez-Lara and H. M. Moya-Cessa
quant-ph physics.optics