Two-photon fluorescence (TPF) of olive oils is discovered and observed experimentally for the first time. Variations of the single-photon fluorescence (SPF) and TPF with the excitation wavelength are investigated for four different olive oils. The results show that fluorescence of the cosmetic olive oils (COO) is very weak and exhibits only one spectral peak around 490 nm. While for the ordinary edible oils (OEO) whether they are during their shelf life or not, their fluorescence spectra may exhibit multiple peak structures. The short-term natural expiration only slightly weakens TPF of OEO. Moreover, the excitation wavelength affects the OEO spectra considerably in terms of the spectral peak number, the spectral peak position, and spectral shapes. When the excitation wavelength decreases from 700 nm, the whole TPF of the OEO also decreases. Relatively, however, the short wave band will decrease and disappear more quickly. While for the SPF, the long wave band will decrease and disappear first. The optimal excitation wavelengths to make the TPF strongest are around 700 nm and 640 nm for OEOs and COO, respectively. And effects of temperature on SPF and TPF of extra virgin olive oil are also explored. This work may be of significance for its potential applications in TPF detection and two-photon laser.

首次发现并通过实验观察到橄榄油的双光子荧光 (TPF)。研究了四种不同橄榄油的单光子荧光 (SPF) 和 TPF 随激发波长的变化。结果表明，化妆品橄榄油 (COO) 的荧光非常微弱，并且在 490 nm 附近仅显示一个光谱峰。而对于普通食用油（OEO）而言，无论是否在保质期内，其荧光光谱都可能呈现出多峰结构。短期自然到期只会略微削弱 OEO 的 TPF。此外，激发波长在光谱峰数、光谱峰位置和光谱形状方面对 OEO 光谱有很大影响。当激发波长从 700 nm 减小时，OEO 的整个 TPF 也减小。然而，相对而言，短波段会更快地减少和消失。而对于 SPF，长波段会先减小并消失。对于 OEO 和 COO，使 TPF 最强的最佳激发波长分别约为 700 nm 和 640 nm。还探讨了温度对特级初榨橄榄油的 SPF 和 TPF 的影响。这项工作可能对其在 TPF 检测和双光子激光中的潜在应用具有重要意义。