3.6 Beam Splitting and Beam Steering
73
(a)
(b)
Fig. 3.14 The schematic illustration of two types of beam steering. a By varying the angle A of
the ZIM prism and b by varying the refractive index n =
√
μ of the slab, keeping = μ
the horizontal direction. The far-field polar plot of Fig. 3.15e shows the reduction in
the angle of elevation of the beam from 90
◦ to 45
◦ , as the angle A increases from 0
◦
to 45
◦ . In this way, beam steering is achieved by varying the slope of the emergence
boundary.
In the second technique, the permittivity and the permeability μ are simultaneously varied from 0.001 to 1.0, such that = μ. Therefore, the refractive index
n =
√ μ also gets varied through the same values. In Fig. 3.16a–e, the refractive
index acquires the values—0.001, 0.01, 0.1, 0.5, and 1.0, respectively. In Fig. 3.16a,
when n = 0.001 ≈ 0, the beam is vertical. As the refractive index increases, the
beam starts shifting away from the vertical orientation and begins to approach the
horizontal orientation. In Fig. 3.16a–d, intense beams of light form and are oriented
in particular directions, but in Fig. 3.16e, light is spread in almost all the directions
without the formation of a single well-defined beam. It happens because, in the last
case, the refractive index of the slab is 1.0, i.e., the same as that of air. Hence, light
sees the entire computational region as a single medium, and no refraction takes
place. Whereas in all the other cases, the refractive index of the slab is different
from the surroundings, the refraction does take place. Therefore, in Fig. (a)–(d),
well-defined beams are formed, and in Fig. (e) light spreads in all the directions. The
same can be observed in the polar plot of Fig. 3.16f too. In this way, beam steering
can be achieved by manipulating the refractive index of the slab to values less than
1. Beam splitting and beam steering are important applications from the integrated
photonics point of view.
73
(a)
(b)
Fig. 3.14 The schematic illustration of two types of beam steering. a By varying the angle A of
the ZIM prism and b by varying the refractive index n =
√
μ of the slab, keeping = μ
the horizontal direction. The far-field polar plot of Fig. 3.15e shows the reduction in
the angle of elevation of the beam from 90
◦ to 45
◦ , as the angle A increases from 0
◦
to 45
◦ . In this way, beam steering is achieved by varying the slope of the emergence
boundary.
In the second technique, the permittivity and the permeability μ are simultaneously varied from 0.001 to 1.0, such that = μ. Therefore, the refractive index
n =
√ μ also gets varied through the same values. In Fig. 3.16a–e, the refractive
index acquires the values—0.001, 0.01, 0.1, 0.5, and 1.0, respectively. In Fig. 3.16a,
when n = 0.001 ≈ 0, the beam is vertical. As the refractive index increases, the
beam starts shifting away from the vertical orientation and begins to approach the
horizontal orientation. In Fig. 3.16a–d, intense beams of light form and are oriented
in particular directions, but in Fig. 3.16e, light is spread in almost all the directions
without the formation of a single well-defined beam. It happens because, in the last
case, the refractive index of the slab is 1.0, i.e., the same as that of air. Hence, light
sees the entire computational region as a single medium, and no refraction takes
place. Whereas in all the other cases, the refractive index of the slab is different
from the surroundings, the refraction does take place. Therefore, in Fig. (a)–(d),
well-defined beams are formed, and in Fig. (e) light spreads in all the directions. The
same can be observed in the polar plot of Fig. 3.16f too. In this way, beam steering
can be achieved by manipulating the refractive index of the slab to values less than
1. Beam splitting and beam steering are important applications from the integrated
photonics point of view.