Optical Networks – Tutorial Lecture #1

Instructor information Name: Thuraya Alrumaih Email: tnalrumaih@pnu.edu.sa Office #: 0,701,39 Office hours: SUN: 9-10 A.M. TUE: 9-10 A.M. THU: 9-10 A.M. Blog : http://net436.wordpress.com/ Networks and Communication Department

Grades Grade Due week Evaluation %5 Every week Assignment Participation attendance (30-March) Week 10 Quiz 15% Total Networks and Communication Department

Overview : •  Light Characteristics •  Light Properties •  Reflection and Refraction

Light Characteristics •  Particle Characteristics –  Light has energy –  Photons are the smallest quantity of monochromatic light –  The energy of a photon is described by: E= hf • (h=6.6260755 x 10 −34 joule.sec) and f is the frequency of light –  The relationship between frequency and speed: v=c/λ • Speed of light changes as it enters denser materials •  Wave Characteristics –  Described by a series of equations

Example #1 A light wave with λ= 1 µm c = 3 ×10^8m/sec. v =? c = 3x10^8 v = c/λ v = 3x10^8 / 1x10^-6 => 3x10^14 m/s

Example #2 Find the energy of a photon travelling with 200 THz frequency. Given that h is Planck’s constant = 6.6256 x10^-34. E= hf E =(6.6256x10^-34)*(200x10^12) => 1.32512x10^-19 Joule

Light Properties •  Light is electromagnetic radiation – Impacted by many parameters: reflection, refraction, loss, polarization, scattering, etc. •  Light of a single frequency is termed monochromatic •  Any electromagnetic wave is governed by a series of equations

Wave Velocity Equation: Phase Velocity •  The wave moves a distance of one wavelength λ in one period T •  From this, we can calculate the phase velocity denoted vp. - (It is how fast the peaks and valleys move.) Vp = λƒ = λ/T Reminder: ƒ= 1/T

Reflection and Refraction •  When light finds a surface separating two media (air and water, for example), a beam gets reflected and another gets refracted (transmitted). -Law of reflection: the angle of incidence θ1 = θ2 the angle of reflection . -Law of refraction: n2 sinθ2 = n1 sinθ1 (Snell’s law.) n is the index of refraction of the medium. In vacuum, n=1. In air, n~1. In all other media, n>1.

Example #4 Water has n=1.33. How much does a beam incident at 45 refracts? n2 sinθ2 = n1 sinθ1 sinθ2 = n1/n2 sinθ1 1/1.33 sin 45 .53165 Θ2=Sin^-1 (.53165) = 32◦