Tutorial 2: Lasers
4. Semiconductor lasers and light emitted diodes are commonly
found in optical communication systems. Which of these optical sources are preferred for long distance communication systems? Why?
Semiconductor lasers properties:
? High light intensity
? High Coupling efficiency
? Narrow line widths
Less dispersion problem than LEDs
Higher output optical powers, lower losses than LEDs
LEDs properties:
? Wide spectral width
? Low light intensity (High divergence)
? Low Coupling efficiency
High dispersion
Low output optical powers,
High loss
Thus SC lasers are preferred for long distance communication