If the grating of Problem 15.1 is fabricated by using the technique of Fig. 7.10, determine two combinations of prism material and angle (α) that could be used with a He-Cd laser (λ0 = 3250 A). ˚  (a)...

If the grating of Problem 15.1 is fabricated by using the technique of Fig. 7.10,

determine two combinations of prism material and angle (α) that could be used

with a He-Cd laser (λ0 = 3250 A). ˚

 (a) If a surface grating is formed on a waveguide, what is the grating spacing

λ required for fourth-order Bragg diffraction, in terms of λ and ng?

(b) Sketch the reflected wave directions, and indicate the angles between

them.

(c) In general, can a scattered wave perpendicular to the direction of the

waveguide be observed for odd orders, such as the first and third order,

of Bragg diffraction?