Related papers: Two-step excitation of fluorescent proteins with r…
We demonstrate fluorescence generation through a sequential multiphoton process with real intermediary states. Our findings suggest new directions for optical control of previously unexplored molecular excitation pathways.
We demonstrate fluorescence imaging by two-photon excitation without scanning in biological specimens as previously described by Hwang and co-workers, but with an increased field size and with framing rates of up to 100 Hz. During…
In this paper we review the applicability of autofluorescent proteins for single-molecule imaging in biology. The photophysical characteristics of several mutants of the Green Fluorescent Protein (GFP) and those of DsRed are compared and…
The non-classical spectral and temporal features of entangled photons offer new possibilities to investigate the interactions of excitons in photosynthetic complexes, and to target the excitation of specific states. Simulations of…
It has been observed experimentally [H.R. Xia, C.Y. Ye, and S.Y. Zhu, Phys. Rev. Lett. {\bf 77}, 1032 (1996)] that quantum interference between two molecular transitions can lead to a suppression or enhancement of spontaneous emission. This…
Standing-wave excitation of fluorescence is highly desirable in optical microscopy because it improves the axial resolution. We demonstrate here that multiplanar excitation of fluorescence by a standing wave can be produced in a single-spot…
Several matrix approaches were developed to control light propagation through multiple scattering media under illumination of ultrashort pulses of light. These matrices can be recorded either with spectral or temporal resolution. Thanks to…
We demonstrate a direct measurement of the energy levels of impurity-trapped excitons in CaF$_2$:Yb$^{2+}$. The radically different radiative decay rates of the lowest exciton state and higher excited states enable the generation of a…
We report two-photon resonance fluorescence of an individual semiconductor artificial atom. By non-linearly driving a single quantum dot via a two-photon transition, we probe the linewidth of the two-photon processes and show that, similar…
Upon illumination by ultraviolet light, many animal species emit light through fluorescence processes arising from fluorophores embedded within their biological tissues. Fluorescence studies in living organisms are however relatively scarce…
Light-sheet microscopy (LSM) is a powerful imaging technique that uses a planar illumination oriented orthogonally to the detection axis. Two-photon (2P) LSM is a variant of LSM that exploits the 2P absorption effect for sample excitation.…
We demonstrate effective background-free continuous wave nonlinear optical excitation of molecules that are sandwiched between asymmetrically constructed plasmonic gold nanoparticle clusters. We observe that near infrared photons are…
Two-dimensional electronic spectroscopy provides information on coupling and energy transfer between excited states on ultrafast timescales. Only recently, incoherent fluorescence detection has made it possible to combine this method with…
Two-photon processes are crucial in applications like microscopy and microfabrication, but their low cross-section requires intense illumination and limits, e.g., the penetration depth in nonlinear microscopy. Entangled states have been…
Excitation with entangled photon pairs may lead to an increase in the efficiency of two-photon absorption at low photon flux. The corresponding process, entangled two-photon absorption (E2PA), has been investigated in numerous theoretical…
Two-photon microscopy (TPM) enables deep tissue imaging but requires excitation pulses that have a large product of average and peak power, typically supplied by femtosecond solid-state lasers. However, these lasers are bulky and…
Resonant optical excitation of few-level quantum systems enables coherent quantum control, resonance fluorescence, and direct characterization of dephasing mechanisms. Experimental demonstrations have been achieved in a variety of atomic…
We study a system of two interacting, non-indentical quantum emitters driven by a coherent field. We focus on the particular condition of two-photon resonance and obtain analytical expressions for the stationary density matrix of the system…
Entangled two-photon absorption can enable a linear scaling of fluorescence emission with the excitation power. In comparison to classical two-photon absorption with a quadratic scaling, this can allow fluorescence imaging or…
We present a new technique for obtaining simultaneous multimodal quantitative phase and fluorescence microscopy of biological cells, providing both quantitative phase imaging and molecular specificity using a single camera. Our system is…