Two-photon microscope using a fiber-based approach for supercontinuum generation and light delivery to a small-footprint optical head

Abstract We study supercontinuum generation (SC) in graphene-covered nanowires based on a generic model that correctly accounts for the evolution of the photon number under Kerr and two-photon absorption processes, and the influence of graphene is treated within the framework of saturable photoexcited-carrier refraction. We discuss the role of the various effects on the generation of supercontinuum by a thorough analysis of short-pulse propagation in two different kinds of graphene-covered nanowires, one made of silicon nitride and the other made of silicon. Finally, we discuss the effect of stacking graphene layers as a means to enhance SC generation with pulse powers compatible with those in integrated optical devices.

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Broadband supercontinuum generation in As_2Se_3 chalcogenide wires by avoiding the two-photon absorption effects

Optics Letters ◽

10.1364/ol.38.001185 ◽

2013 ◽

Vol 38 (7) ◽

pp. 1185 ◽

Cited By ~ 29

Author(s):

Alaa Al-kadry ◽

Chams Baker ◽

Mohammed El Amraoui ◽

Younès Messaddeq ◽

Martin Rochette

Keyword(s):

Supercontinuum Generation ◽

Photon Absorption ◽

Two Photon Absorption ◽

Two Photon

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Spectral-temporal modulation of supercontinuum generation for two-photon optogenetics (Conference Presentation)

Optogenetics and Optical Manipulation ◽

10.1117/12.2251501 ◽

2017 ◽

Author(s):

Yuan-Zhi Liu ◽

Haohua Tu ◽

Javier I. Suárez ◽

Parijat Sengupta ◽

Stephen A. Boppart

Keyword(s):

Supercontinuum Generation ◽

Temporal Modulation ◽

Two Photon

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Sub-millisecond optogenetic control of neuronal firing with two-photon holographic photoactivation of Chronos

10.1101/062182 ◽

2016 ◽

Cited By ~ 5

Author(s):

E. Ronzitti ◽

R. Conti ◽

E. Papagiakoumou ◽

D. Tanese ◽

V. Zampini ◽

...

Keyword(s):

Action Potentials ◽

Neuronal Firing ◽

Laser Illumination ◽

Temporal Precision ◽

Temporal Complexity ◽

Two Photon ◽

Light Delivery ◽

Network Manipulation

ABSTRACTOptogenetic neuronal network manipulation promises to at last unravel a long-standing mystery in neuroscience: how does microcircuit activity causally relate to behavioral and pathological states? The challenge to evoke spikes with high spatial and temporal complexity necessitates further joint development of light-delivery approaches and custom opsins. Two-photon scanning and parallel illumination strategies applied to ChR2- and C1V1-expressing neurons demonstrated reliable, in-depth generation of action potentials both in-vitro and in-vivo, but thus far lack the temporal precision necessary to induce precisely timed spiking events. Here, we show that efficient current integration enabled by two-photon holographic amplified laser illumination of Chronos, a highly light-sensitive and fast opsin, can evoke spikes with submillisecond precision and repeated firing up to 100 Hz. These results pave the way for optogenetic manipulation with the spatial and temporal sophistication necessary to mimic natural microcircuit activity.

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Two-photon excitation microscopy in cellular biophysics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100136684 ◽

1995 ◽

Vol 53 ◽

pp. 62-63

Author(s):

David W. Piston ◽

Brian D. Bennett ◽

Robert G. Summers

Keyword(s):

Confocal Microscopy ◽

Laser Beam ◽

Duty Cycle ◽

Excited Electronic State ◽

Input Power ◽

Two Photon ◽

Simultaneous Absorption ◽

Photon Excitation ◽

Very High ◽

Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10-5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

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Two-photon excitation fluorescence microscopy in living systems

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146618 ◽

1993 ◽

Vol 51 ◽

pp. 154-155 ◽

Cited By ~ 1

Author(s):

David W. Piston

Keyword(s):

Confocal Microscopy ◽

Fluorescence Microscopy ◽

Singlet State ◽

Excited Electronic State ◽

Input Power ◽

Two Photon ◽

Simultaneous Absorption ◽

Photon Excitation ◽

Very High ◽

Two Photon Excitation

Two-photon excitation fluorescence microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. Two-photon excitation arises from the simultaneous absorption of two photons in a single quantitized event whose probability is proportional to the square of the instantaneous intensity. For example, two red photons can cause the transition to an excited electronic state normally reached by absorption in the ultraviolet. In our fluorescence experiments, the final excited state is the same singlet state that is populated during a conventional fluorescence experiment. Thus, the fluorophore exhibits the same emission properties (e.g. wavelength shifts, environmental sensitivity) used in typical biological microscopy studies. In practice, two-photon excitation is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 maintains the average input power on the order of 10 mW, only slightly greater than the power normally used in confocal microscopy.

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