Key Points
- Three types of photon/semiconducto interaction
- Spontaneous emission
- Stimulated emission
- Stimulated absorption
- Rate of stimulated process proportional to light
intensity and number of electrons.
- Characterize gain/loss by alpha ~ (n1-n2)
- Population inversion is needed for gain -- Pumping!
- Pumping is moving electrons from lower level to upper
levels.
- Laser -- inversion/stimulated emission/optical
feedback(mirrors)
- Threshold condition -- enough pumping to compensate for
losses.
- Semiconductor laser used n and p recombination and
pumping by FWD bias.
Questions
- What are the three types of
photon/semiconducto interaction?
- What is the rate of stimulated emission related to?
- How do we characterize gain in a optical amplifier?
- What is pumping. How do we achieve it in a solid state
laser?
- What is threshold in a laser?