108. 7
半導體雷射二極體
(Semiconductor
Laser
Diode)
35
Light emitting diodes vs. Laser diodes
LEDs are based on spontaneous emission, and have
1.A broad output beam that is hard to capture and focus
2.A relatively broad spectral profile
3. Low to moderate overall efficiency
4. Moderate to high speed (≈ 1/t min)
!
Laser Diodes are based on stimulated emission, and have the
opposite characteristics
1. Narrow, highly directed output
2. Sharp, narrow emission spectrum
3. High differential and overall efficiency
4. High to very high speed
Stimulated emission occurs when a passing photon
triggers the recombination of an electron and hole, with
emission of a second photon with the same frequency
(energy), momentum, and phase.
自發的發光
激發的發光