title: Ultrafast wavelength-dependent lasing-time dynamics in single ZnO nanotetrapod and nanowire lasers.
abstract: The ultrafast lasing dynamics of single zinc oxide nanotetrapods and nanowires are investigated by two-color femtosecond excitation/optical injection spectroscopy. The transient spectral gain induced by time-delayed optical injection pulses (400 nm) is used to investigate the spectrally and temporally resolved lasing properties in a single tetrapod or nanowire laser excited by 267-nm pulses. The lasing output pulse exhibits a faster lasing decay time than the carrier decays due to the superlinear dependence of the lasing on the carrier density. Lasing at the low-energy side of the gain bandwidth (392 nm) has a full width at half maximum (fwhm) for stimulated emission of 1.7 ps. Lasing at 390 nm, the high-energy side of the gain bandwidth, has a fwhm of 2.1 ps for a single example nanowire. The change in lasing dynamics as a function of wavelength is affected by band gap renormalization, since lasing in the electron-hole plasma regime depends not only on the carrier density but also on the band gap shift with carrier density.
authors.affiliation: Department of Chemistry, and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA.
authors.forename: Jae Kyu
authors.initials: JK
authors.lastname: Song
authors.forename: Jodi M
authors.initials: JM
authors.lastname: Szarko
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Leone
authors.forename: Shihong
authors.initials: S
authors.lastname: Li
authors.forename: Yiping
authors.initials: Y
authors.lastname: Zhao