Enhanced broadband ultrafast detection of ultraviolet emission using optical Kerr gating

Abstract

We demonstrate a high-sensitivity ultrafast emission spectrometer based on the optical Kerr effect that time resolves emission simultaneously in the ultraviolet and visible ranges. We show that using benzene as the Kerr medium leads to the optimal balance between time-resolution and sensitivity of the optical shutter with low losses due to ultraviolet absorption. Using this medium together with high contrast broadband polarizers and charge-coupled device detection, we achieve efficient detection of emission transients (bandwidth >1.5 eV) in a time bin of ~500 fs. To highlight the distinctive insights that can be gained by resolving complex subpicosecond dynamics in a single experiment, we present UV-visible transient emission spectra of technologically relevant wide bandgap zinc oxide. With an enhanced broadband detection, subpicosecond effects such as thermalization, bandgap renormalization, and carrier trapping can be easily assessed, with ramifications for optoelectronics and energy-related technologies.

Femtosecond broadband fluorescence upconversion spectroscopy: Spectral coverage versus efficiency

“…Here we test that principle for broadband fluorescence upconversion spectroscopy (FLUPS). [4][5][6][7] Fluorescence gating has been performed with a Kerr shutter, [8][9][10][11][12][13][14][15] by non-collinear optical parametric amplification [16][17][18][19][20] or by diffraction from a transient grating, 21 in addition to broadband upconversion schemes. [4][5][6][7][22][23][24][25] Here we consider only reports where spontaneous emission from molecular or similar sources is gated, dispersed, and registered simultaneously at all relevant wavelengths with a view to obtain true molecular spectra.…”

Room-Temperature Exciton Lasing In Ultrathin Film of Coupled Nanocrystals

“…Lines are two-exponential fits to the data. carrier dynamics of the various samples [3,4]. As readily seen from figure 1(c), a drastic decrease in emission lifetime occurs in the crystalline coupled-nanospheres film (< 5 ps) while both the annealed sample (blue) and that of the dispersed ZnO nanospheres (black) have much longer lifetimes (> 30 ps).…”

Excitonic Lasing in Solution-Processed Subwavelength Nanosphere Assemblies

“…This is apparent in the slight differences that we observe in the lasing spectra as a function of both sample position and in time (Figure S4). Furthermore, using a high sensitivity transient emission technique based on optical Kerr gating (Figure S3), described previously, we are able to resolve the temporal dynamics of individual modes with ∼200 fs time resolution . By examining spectral slices at discrete times after pumping in a 140 nm thick ZnO–NSs film (Figure S5), we observe that lasing modes are transiently populated as the system evolves.…”