1) What are fiber modes? describe mode theory for optical fibers in detail.

2) Draw the structures of Edge emitting LED and Surface emitting LED, describe the operation and derive the internal quantum efficiency of an LED.

3) a) A GaAs LASER operating at 850nm has a 500um length and a refractive index of n=3.7, what are the frequency and wavelength spacing. If at the half power point = 2 nm, what is the spectral width of the gain?

b) Consider a GaAs LASER with an optical cavity of length 250 um and width 100 um. At the normal operating temperature, the gain factor B = 21X10‾³ A/Cm and the effective absorption coefficient = 10 Cm.

i) If the refractive index is 3.6, find the threshold current density and the threshold current Ith. Assume the Laser end faces are uncoated and the current is restricted to the optical cavity.reduced to10 um?

ii)What is the threshold current if the Laser cavity width is

4) describe the significance of link power and rise time budget.

5) (a) describe in detail about the methods of fiber splicing?

(b) describe about the two types of connectors.

6) Discuss the schematic diagram of a typical optical receiver and describe

7) describe the error sources of fundamental receiver operations.