Pumping populates a short-lived state |3⟩ that decays rapidly to upper laser level |2⟩; lasing transition |2⟩→|1⟩ is fast, |1⟩→|0⟩ depopulates quickly. Threshold is far lower than three-level systems because |1⟩ is essentially empty in…
Pumping populates a short-lived state |3⟩ that decays rapidly to upper laser level |2⟩; lasing transition |2⟩→|1⟩ is fast, |1⟩→|0⟩ depopulates quickly. Threshold is far lower than three-level systems because |1⟩ is essentially empty in…