  In this paper we study the effect of absorption peak correlation in finite
length carbon nanotubes and graphene nanoribbons. It is shown, in the
orthogonal {\pi}-orbital tight-binding model with the nearest neighbor
approximation, that if the ribbon width is a half of the tube circumference the
effect takes place for all achiral ribbons (zigzag, armchair and bearded), and
corresponding tubes, starting from lengths of about 30 nm. This correlation
should be useful in designing nanoribbon-based optoelectronics devices fully
integrated into a single layer of graphene.
