1. UPM, DIAC. Open Course. March 2010 1. INTRODUCTION 1.1 What is it? 1.2 Pros and Cons 1.3 Applications 1.4 Block Diagram

2. 1-2 1.1 WHAT IS IT? (I) Optical (Tele)Communication – Sending information through long distance – Using light as a carrier Can be done by means of – Fiber optic (resembles a transparent human hair) – Free space (air, atmosphere)

3. 1-3 1.1 WHAT IS IT? (II) Optical Communication System – Receives electric information (signal) – Converts it into light (modulation, laser) – Carries it through a fiber – Recovers electric signal (demodulation, photodetector) E O O E Optical Fiber

4. 1-4 1.2 PROS AND CONS (I) Advantages (optical communic. via fiber): – Huge bandwidth Carrier frequency  10 5 GHz Thus: enormous data rate – Low attenuation, α(dB/km)↓, (fewer regenerators) – Electromagnetic isolation (dielectric waveguide) It does not emit It does not suffer from interference – Physical characteristics Small, very light Flexible (same capacity) – Plenty of raw material (25% earth) – It does not need ground. It does not carry electricity – In a nutshell Low cost Better signal quality

5. 1-5 1.2 PROS AND CONS (II) – Huge Bandwidth This single fiber can carry more communications than the giant cooper cable!

6. 1-6 1.2 PROS AND CONS (III) – Evolution of capacity

7. 1-7 1.2 PROS AND CONS (IV) – Low attenuation ─ coaxial / singlemode fiber

8. 1-8 1.2 PROS AND CONS (V) Disadvantages (questionable) – Splices are difficult Nowadays they are made by precise and easy devices – Connectors are expensive and unrealiable Nowadays they are reliable, but still expensive – Fiber does not allow bending Same capacity, it allows smaller bend radius – The whole system is electrical (amplif., add-drop, etc.) Optical elements are taking over – Sharks, termites, squirrels and rats do eat fiber

9. 1-9 1.3 APPLICATIONS (I) Applications: a) Optical Technology – Light signs Safe, cheap (e.g. over neon) Neither flickering, nor buzzing. Fast – Storage: CD, DVD Pretty good capacity Resistance and durability – Making measures: Detection and measure of electromagnetic waves Geology, Agriculture, Meteorology Medicine (Image Diagnosis, etc.)

10. 1-10 1.3 APPLICATIONS (II) Applications: b) Communications – Information: voice, image, data – Free space optical communications Data links between close buildings – Optical fiber communications Data networks (LAN, WAN, SDH) Digital video diffusion TV-wire Plain old telephone service (POST) Undersea cable Military applications DATA COMMUNICATIONS (SDH)

11. 1-11 1.3 APPLICATIONS (III) Last mile. Fiber through the tap?

12. 1-12 1.3 APPLICATIONS (IV) “SAM”

13. 1-13 1.4 BLOCK DIAGRAM Optical communication via fiber