Multiexcitonic two-state lasing in a CdSe nanocrystal laser

We report simultaneous amplified spontaneous emission from two different multiexcitonic transitions − 1 S e - 1 S 3 ∕ 2 and 1 P e - 1 P 3 ∕ 2 − of colloidal CdSe nanocrystals (NCs) stabilized in high volume fraction in titania matrices. Two-state lasing from both multiexcitonic transitions is achieved in a surface-emitting distributed feedback CdSe NC laser. Variable stripe length measurements show that the gain from the 1 P e - 1 P 3 ∕ 2 transition is approximately twice that of the − 1 S e - 1 S 3 ∕ 2 transition for 4.2 nm radius CdSe ∕ ZnS core-shell NCs.