3.8 Explain why it is easier to make a single-mode waveguide in a symmetric three-layer
waveguide than it is in an asymmetric three-layer waveguide.
In a symmetric three-layer waveguide there is no cut-off of propagation of the lowest
5.1 What are the factors that determine the thickness of a polystyrene waveguide
formed by spinning a solution of dissolved polystyrene onto a substrate?
density of polymer
concentration of polymer in solution
5.2 An arra
21.5 Name 4 major improvements in integrated optic technology that have occurred over
the past 20 years that have led to modem lightwave telecommunications.
Solution. (Any four of the following)
Low-loss, single-mode optical fibers
17.1 We wish to use a photodiode as a detector for a signal of 9000 wavelength.
Which would be the best choice of material for the photodiode, a semiconductor of
bandgap = 0.5 eV, bandgap = 2 eV, or bandgap = 1 eV? Why? (Assume all three
14.1 Sketch the cross sectional view of a double-heterostructure GaAlAs laser
diode. Choose the thickness and aluminum concentration in each layer required to
produce light emission at 0 = 8500 , along with eld connement to the active
8.1 A dual-channel-coupler type of modulator has been designed so that
+ m ,
m = 0, 1, 2, . . . ,
where is the coupling coefcient and L is the length. Thus, complete transfer of
light will occur from channel 0 to channel 1. If we now apply a voltage
As one goes from lower-order modes to higher-order modes, The ngle, 2,
Since the index or refraction, n2 , is constant, the length of the hypotenuse in Fig. 2.9,kn2 ,
remains constant. Thus the propagation constant, $ ,