  Lattice modes are intrinsic to the periodic structures and their occurrence
can be easily tuned and controlled by changing the lattice constant of the
structural array. Previous studies have revealed excitation of sharp absorption
resonances due to lattice mode coupling with the plasmonic resonances. Here, we
report the first experimental observation of a lattice induced transparency
(LIT) by coupling the first order lattice mode (FOLM) to the structural
resonance of a metamaterial resonator at terahertz frequencies. The observed
sharp transparency is a result of the destructive interference between the
bright mode and the FOLM mediated dark mode. As the FOLM is swept across the
metamaterial resonance, the transparency band undergoes large change in its
bandwidth and resonance position. Besides controlling the transparency
behaviour, LIT also shows a huge enhancement in the Q-factor and record high
group delay of 28 ps, which could be pivotal in ultrasensitive sensing and slow
light device applications.
