Super-stability splitting at the inhibition of the zeroth order by an encapsulated grating

A two-port encapsulated grating is proposed, whose zeroth order can be inhibited under normal incidence. The efficiencies of the +/- 1st orders can be more than 47% and 0th order can be less than 4% for both TE and TM polarizations at a bandwidth of 31 nm, from 1532 nm to 1563 nm. In addition, the fabrication tolerance is astonishingly good, where the efficiencies of greater than 47% can be satisfied in the +/- 1st orders within the period of 2914-3015 nm or the duty cycle of 0.290-0.458. The performance has important application value in optical communication, optical storage, etc.