839747.fig.008a
(a)
839747.fig.008b
(b)
839747.fig.008c
(c)
839747.fig.008d
(d)
839747.fig.008e
(e)
Figure 8: Types of lens couplers: (a) dielectric lens, (b) plasmonic lens, (c) negative index lens, (d) photonic crystal lens, (e) hyperlens.