floquet mode intuition help

[yefj]

Hello, i have created a beam splitter as shown bellow.
so we have m=+1 m=-1 with beta=69.9 degrees.
i need to make m=-1 mode evanecent while m=+1 propagating.
curently they both have the same amplitude and both propagate.
is there an intuition i could follow which could make only the amplitude of m=-1 mode as small as possible or the beta complex(evanecent mode)?
Thanks.

 

[PlanarMetamaterials]

I'm not an expert on this subject -- but don't you need some form of non-reciprocity to independently tune the m = -1 and m = +1 Floquet modes? I would think a magnetic bias might be a starting point.

 

[yefj]

Is there some reading material you could recomend?
Thanks.