Download ELEG 640/440 Homework 3

ELEG 640/440
Homework # 3
1.
What is a waveguide mode?
2.
A step-index, multimode optical fiber has a core index of refraction = 1.46 and a
cladding index = 1.43. The core diameter is 20 μm. Calculate the number of modes that
this fiber waveguide can support at a wavelength of 1.3 μm.
3.
(a) What is dispersion?
(b) What are the four types of dispersion that can occur in an optical fiber
waveguide?
(c) Explain what causes each of these.
4.
An optical fiber, fused biconic tapered coupler has a coupling coefficient = 4 cm-1.
If all of the optical power is initially coupled into only one of the fibers, how long must
the coupler be to transfer 2/3 of the optical power to the other fiber?
5.
Name six advantages that optical fiber waveguides have as compared to metallic
transmission lines.
6.
A step-index, multimode optical fiber has a core index of refraction of 1.47 and a
cladding index of 1.46. The core diameter is 30 μm. If lightwaves are coupled with their
ray making an angle of 18.7 degrees with the z axis (direction of propagation) of the fiber,
will they be accepted into a guided mode?