scholarly journals Nonlinear emission from silver-coated 3D hollow nanopillars

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
L. Ghirardini ◽  
M. Malerba ◽  
M. Bollani ◽  
P. Biagioni ◽  
L. Duò ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Emission Spectra ◽  
Laser Pulses ◽  
Building Blocks ◽  
Metal Nanostructures ◽  
Ultrafast Laser Pulses ◽  
Two Photon ◽  
The Past ◽  
Vibrational Spectroscopies ◽  
The Subject

AbstractHigh aspect ratio metal nanostructures have been the subject of a number of studies in the past, due to their pronounced resonances in the infrared that can be exploited to enhance vibrational spectroscopies. In this work, we investigate the nonlinear optical response of both individual and closely-packed assemblies of vertical hollow Ag nanopillars upon excitation with ultrafast laser pulses. In particular, the analysis of their nonlinear emission spectra evidences an intense two photon photoluminescence (TPPL) emission and a neat signature of second harmonic generation (SHG). Given the relatively low background, this pronounced nonlinear emission could be employed as a local probe for analytes trapped at the surface of the nanopillar or flowing through it. For this reason, these nanostructures may become appealing building blocks in multi-purpose devices for nonlinear photonics and sensing.

scholarly journals Extended depth of focus multiphoton microscopy via incoherent pulse splitting

2020 ◽  
Author(s):  
Bingying Chen ◽  
Tonmoy Chakraborty ◽  
Stephan Daetwyler ◽  
James D. Manton ◽  
Kevin Dean ◽  
...  
Keyword(s):  
Multiphoton Microscopy ◽  
Laser Pulses ◽  
Low Complexity ◽  
Phase Mask ◽  
Light Sources ◽  
Depth Of Focus ◽  
Ultrafast Laser Pulses ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
Extended Depth Of Focus

AbstractWe present a phase mask that can be easily added to any multi-photon raster scanning microscope to extend the depth of focus five-fold at a small loss in lateral resolution. The method is designed for ultrafast laser pulses or other light-sources featuring a low coherence length. In contrast to other methods of focus extension, our approach uniquely combines low complexity, high light-throughput and multicolor capability. We characterize the point-spread function in a two-photon microscope and demonstrate fluorescence imaging of GFP labeled neurons in fixed brain samples as imaged with conventional and extended depth of focus two-photon microscopy.

Interactions of picosecond laser pulses with organic molecules II. Two-photon absorption cross-sections

1972 ◽  
Vol 329 (1576) ◽  
pp. 105-119 ◽  
Keyword(s):  
Cross Sections ◽  
Second Harmonic ◽  
Light Flux ◽  
Laser Pulses ◽  
Photon Absorption ◽  
Exciting Light ◽  
Absorption Cross ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Fluorescence

Absolute values of the two-photon absorption cross-sections of Rhodamine 6G, Rhodamine B, Acridine Red, Disodium Fluorescein and DODCI have been obtained by excitation with a neodymium: glass laser (1060 nm). Measurements over eight orders of magnitude of the exciting light flux were carried out by employing the laser both Q-switched and mode-locked. The two-photon fluorescence flux measurements were calibrated by single-photon fluorescence generated by excitation with second-harmonic laser pulses. The experimental results are compared with values predicted by semi-empirical theoretical models and good agreement is obtained. Two-photon amplification of the mode-locked neodymium laser by organic dyes is shown not to be practicable at present. Other possible two-photon oscillators are discussed.

Probing two-photon excitation dynamics using ultrafast laser pulses

1998 ◽  
Vol 157 (1-6) ◽  
pp. 135-138 ◽  
Author(s):  
J. Swiatkiewicz ◽  
P.N. Prasad ◽  
B.A. Reinhardt
Keyword(s):  
Laser Pulses ◽  
Ultrafast Laser ◽  
Ultrafast Laser Pulses ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation ◽  
Excitation Dynamics

scholarly journals Improving laser standards for three-photon microscopy

2020 ◽  
Author(s):  
Deano M. Farinella ◽  
Arani Roy ◽  
Chao J. Liu ◽  
Prakash Kara
Keyword(s):  
Laser Pulse ◽  
Second Harmonic ◽  
Pulse Amplitude ◽  
Laser Pulses ◽  
Two Photon ◽  
Pulse Intensity ◽  
Third Order Dispersion ◽  
Photon Imaging ◽  
Two Photon Imaging

AbstractSignificanceThree-photon excitation microscopy has double-to-triple the penetration depth in biological tissue over two-photon imaging and thus has the potential to revolutionize the visualization of biological processes in vivo. However, unlike the ‘plug-and-play’ operation and performance of lasers used in two-photon imaging, three-photon microscopy presents new technological challenges that require a closer look at the fidelity of laser pulses.AimWe implemented state-of-the-art pulse measurements and developed new techniques for examining the performance of lasers used in three-photon microscopy. We then demonstrated how these techniques can be used to provide precise measurements of pulse shape, pulse energy and pulse-to-pulse intensity variability, all of which ultimately impact imaging.ApproachWe built inexpensive tools, e.g., a second harmonic generation frequency resolved optical gating (SHG-FROG) device, and a deep-memory diode imaging (DMDI) apparatus, to examine laser pulse fidelity.ResultsFirst, SHG-FROG revealed very large third order dispersion (TOD). This extent of phase distortion prevents the efficient temporal compression of laser pulses to their theoretical limit. Furthermore, TOD cannot be quantified when using a conventional method of obtaining the laser pulse duration, e.g., when using an autocorrelator. Finally, DMDI showed the effectiveness of detecting pulse-to-pulse intensity fluctuations on timescales relevant to three-photon imaging, which were otherwise not captured using conventional instruments and statistics.ConclusionsThe distortion of individual laser pulses caused by TOD poses significant challenges to three-photon imaging by preventing effective compression of laser pulses and decreasing the efficiency of nonlinear excitation. Moreover, an acceptably low pulse-to-pulse amplitude variability should not be assumed. Particularly for low repetition rate laser sources used in three-photon microscopy, pulse-to-pulse variability also degrades image quality. If three-photon imaging is to become mainstream, our diagnostics may be used by laser manufacturers to improve system design and by end-users to validate the performance of their current and future imaging systems.

Inorganic-organic Hybrid Materials for Real 3-D Sub-νm Lithography

2003 ◽  
Vol 780 ◽  
Author(s):  
R. Houbertz ◽  
J. Schulz ◽  
L. Fröhlich ◽  
G. Domann ◽  
M. Popall ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Sol Gel ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Hybrid Polymer ◽  
Organic Hybrid ◽  
Two Photon ◽  
Applied Technology ◽  
Scale Structures ◽  
Sol Gel Synthesis

AbstractReal 3-D sub-νm lithography was performed with two-photon polymerization (2PP) using inorganic-organic hybrid polymer (ORMOCER®) resins. The hybrid polymers were synthesized by hydrolysis/polycondensation reactions (modified sol-gel synthesis) which allows one to tailor their material properties towards the respective applications, i.e., dielectrics, optics or passivation. Due to their photosensitive organic functionalities, ORMOCER®s can be patterned by conventional photo-lithography as well as by femtosecond laser pulses at 780 nm. This results in polymerized (solid) structures where the non-polymerized parts can be removed by conventional developers.ORMOCER® structures as small as 200 nm or even below were generated by 2PP of the resins using femtosecond laser pulses. It is demonstrated that ORMOCER®s have the potential to be used in components or devices built up by nm-scale structures such as, e.g., photonic crystals. Aspects of the materials in conjunction to the applied technology are discussed.

Pakistan’s Development: Successes, Failures, and Future Tasks (Presidential Remarks)

1997 ◽  
Vol 36 (4I) ◽  
pp. 321-331
Author(s):  
Sarfraz Khan Qureshi
Keyword(s):  
Indian Subcontinent ◽  
General Meeting ◽  
The Past ◽  
Past Half Century ◽  
The Social ◽  
The Subject ◽  
Golden Jubilee ◽  
Freedom Movement ◽  
Past Half ◽  
Do So

It is an honour for me as President of the Pakistan Society of Development Economists to welcome you to the 13th Annual General Meeting and Conference of the Society. I consider it a great privilege to do so as this Meeting coincides with the Golden Jubilee celebrations of the state of Pakistan, a state which emerged on the map of the postwar world as a result of the Muslim freedom movement in the Indian Subcontinent. Fifty years to the date, we have been jubilant about it, and both as citizens of Pakistan and professionals in the social sciences we have also been thoughtful about it. We are trying to see what development has meant in Pakistan in the past half century. As there are so many dimensions that the subject has now come to have since its rather simplistic beginnings, we thought the Golden Jubilee of Pakistan to be an appropriate occasion for such stock-taking.

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