Telkom UniversityAssignmentFiber Optic Communications SystemDue date: February 21, 2015

1.

Light travelling in air strikes a glass plate at an angle where is measured between the incoming ray and the glass surface. Upon striking the glass, part of the beam is reflected and part is refracted. If the refracted and reflected beams make an angle of with each other, (a) what is the refractive index of the glass? (b) What is the critical angle for this glass?2. A step index multimode fiber with a numerical aparture of 0.20 supports approximately 1000 modes at 850 nm wavelength.(a) What is the diameter of its core?(b) How many modes does the fiber support at 1310 nm?(c) How many modes does the fiber support at 1550 nm?3. (a) Determine the normalized frequency at 820 nm for a step index fiber having a core

radius, (b) How many modes propagate in this fiber at 820 nm?(c) How many modes propagate in this fiber at 1320 nm?(d)How many modes propagate in this fiber at 1550 nm?(e)What prescent of optical power flows in the cladding in each case?

4.

Consider a fiber with a core radius, a core index (a) If what is the value of V and how many modes propagate in the fiber?(b) What percent of the optical power flows in the cladding?(c) If the core cladding difference is reduced to how many modes does the fiber support and what fraction of the optical power flows in the cladding?5. (a) Find the core radius necessary for a single mode operation at 1320 nm of a step index fiber with (b) What are the numerical aparture and maximum acceptance angle of this fiber?

Telkom UniversityAssignment 2Fiber Optic Communications SystemDue date: February 21, 2015

1. A signal travels from point A to point B. (a) If the signal power is 1mW at point A and 0.125mW at point B, what is the attenuation in dB? (b) What is the signal power at point B if the attenuation is 15 dB?2.

A 50 km long optical fiber has a total attenuation of 24 dB. If of optical power get launched into the fiber, what is the output optical power level in dBm and in 3. A transmission line has a bandwidth of 2 MHz. If the signal to noise ratio at the receiving end is 20 dB, what is the maximum data rate that this line can support?4. A step index multimode fiber with a numerical aparture of 0.2 supports approximately 1000 modes at 850nm wavelength.(a) What is the diameter of the core?(b) How many modes does the fiber support at 1320nm?(c) How any modes does the fiber support at 1550nm?5. A manufacturer wishes to make a silica core, step index fiber with V = 75 and a numerical aparture NA = 0.30 to be used at 820nm. If what should the core size and cladding index be?6.

A certain optical fiber has an attenuation of 0.6 dB/km at 1310nm and 0.3 dB/km at 1550nm. Suppose the following two optical signals are launched simultaneously into the fiber: an optical power of 150 at 1310nm and an optical power of 100 at 1550nm. What are the power level in of these two signals at (a) 8 km and (b) 20 km? 7. An optical signal at a specific wavelength has lost 55 percent of its power after traversing 7 km of fiber. What is the attenuation in dB/km of this fiber?8. A continuous 40 km long optical fiber link has a loss of 0.4 dB/km.(a) What is the minimum optical power level that must be launched into the fiber to maintain an optical power level of 2 at the receiving end?(b) What is the required input power power if the fiber has a loss of 0.6 dB/km?9. Given the following parameter values for GaAs at 500 K:

Electron rest mass

Effective electron mass

Effective hole mass

Band gap energy Find the intrinsic carrier concentration.10.