Given the phasor below for a solution in core of fiber.

E$\_($z$\_(1))($ra$)=$AJ$\_($o$)($ur$)$e$^(-$j$\backslash$beta z$),$ real amplitude A$>0$

E$\_($z$\_(1))$ represents the z$-$component of the electric field in the core. J$\_($o$)($ur$)$ is

Bessel function first kind., treat $\text{'}$ u $\text{'}$ as real positive constant $\text{'}$ z $\text{'}$ space

coordinate. Also $\backslash$beta is the waveguide constant.

a$\backslash$omega

E$\_($z$\_(1))($z$,$r$,$t$)=\backslash$beta $,$u z $\text{'}$ dependence E$\_($z$1)$ is a

$($ travelling wave, standing wave$)$ circle one