Li, Qianliang, Perrie, Walter, Li, Zhaoqing, Edwardson, Stuart P 
ORCID: 0000-0001-5239-4409 and Dearden, Geoff ORCID: 0000-0003-0648-7473
(2022)
Two-photon absorption and stimulated emission in poly-crystalline Zinc Selenide with femtosecond laser excitation.
OPTO-ELECTRONIC ADVANCES, 5 (1).
p. 210036.
Abstract
The optical nonlinearity in polycrystalline zinc selenide (ZnSe), excited with 775 nm, 1 kHz femtosecond laser pulses was investigated via the nonlinear transmission with material thickness and the Z scan technique. The measured two photon absorption coefficient β was intensity dependent, inferring that reverse saturated absorption (RSA) is also relevant during high intensity excitation in ZnSe. At low peak intensity I < 5 GW cm–2, we find β = 3.5 cm GW–1 at 775 nm. The spec-tral properties of the broad blueish two-photon induced fluorescence (460 nm-500 nm) was studied, displaying self-ab-sorption near the band edge while the upper state lifetime was measured to be τe ~ 3.3 ns. Stimulated emission was ob-served when pumping a 0.5 mm thick polycrystalline ZnSe sample within an optical cavity, confirmed by significant line narrowing from Δλ = 11 nm (cavity blocked) to Δλ = 2.8 nm at peak wavelength λp = 475 nm while the upper state lifetime also decreased. These results suggest that with more optimum pumping conditions and crystal cooling, polycrystal-line ZnSe might reach lasing threshold via two-photon pumping at λ = 775 nm.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ZnSe, femtosecond laser, nonlinear absorption, stimulated emission, fluorescence |
| Divisions: | Faculty of Science and Engineering > School of Engineering |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 09 Feb 2022 11:09 |
| Last Modified: | 18 Jan 2023 21:12 |
| DOI: | 10.29026/oea.2022.210036 |
| Open Access URL: | https://www.oejournal.org/article/doi/10.29026/oea... |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3148594 |
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