scholarly journals Interaction of Tungsten tips with Laguerre-Gaussian beams

2021 ◽  
Vol 255 ◽  
pp. 11003
Author(s):  
Abhisek Sinha ◽  
Debobrata Rajak ◽  
Shilpa Rani ◽  
Ram Gopal ◽  
Vandana Sharma
Keyword(s):  
Femtosecond Laser ◽  
Near Field ◽  
Energy Levels ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Gaussian Beams ◽  
Good Source ◽  
Laser Modes ◽  
The Difference ◽  
Electron Pulses

Interaction of femtosecond laser pulses with metallic tips have been studied extensively and they have proved to be a very good source of ultrashort electron pulses. We present our study of interaction of Laguerre-Gaussian (LG) laser modes with Tungsten tips. We report a change in the order of the interaction for LG beams and the difference in the order of interaction is attributed to ponderomotive shifts in the energy levels corresponding to the enhanced near field intensity supported by numerical simulations.

Far-field and near-field material processing with. femtosecond laser pulses

1999 ◽  
Vol 69 (7) ◽  
pp. S7-S11 ◽  
Author(s):  
F. Korte ◽  
S. Nolte ◽  
B.N. Chichkov ◽  
T. Bauer ◽  
G. Kamlage ◽  
...  
Keyword(s):  
Material Processing ◽  
Femtosecond Laser ◽  
Near Field ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Far Field

Nonlinear spectroscopy in the near-field: time resolved spectroscopy and subwavelength resolution non-invasive imaging

Nanophotonics ◽  
2014 ◽  
Vol 3 (1-2) ◽  
pp. 61-73 ◽  
Author(s):  
Mahesh Namboodiri ◽  
Tahirzeb Khan ◽  
Khadga Karki ◽  
Mehdi Mohammad Kazemi ◽  
Sidhant Bom ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Near Field ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Nonlinear Spectroscopy ◽  
Spectroscopic Techniques ◽  
Time Resolved ◽  
Spatially Resolved ◽  
First Results ◽  
Wavelength Resolution

AbstractThe combination of near-field microscopy along with nonlinear optical spectroscopic techniques is presented here. The scanning near-field imaging technique can be integrated with nonlinear spectroscopic techniques to improve spatial and axial resolution of the images. Additionally, ultrafast dynamics can be probed down to nano-scale dimension. The review shows some examples for this combination, which resulted in an exciton map and vibrational contrast images with sub-wavelength resolution. Results of two-color femtosecond time-resolved pump-probe experiments using scanning near-field optical microscopy (SNOM) on thin films of the organic semiconductor 3,4,9,10 Perylenetetracarboxylic dianhydride (PTCDA) are presented. While nonlinear Raman techniques have been used to obtain highly resolved images in combination with near-field microscopy, the use of femtosecond laser pulses in electronic resonance still constitutes a big challenge. Here, we present our first results on coherent anti-Stokes Raman scattering (fs-CARS) with femtosecond laser pulses detected in the near-field using SNOM. We demonstrate that highly spatially resolved images can be obtained from poly(3-hexylthiophene) (P3HT) nano-structures where the fs-CARS process was in resonance with the P3HT absorption and with characteristic P3HT vibrational modes without destruction of the samples. Sub-diffraction limited lateral resolution is achieved. Especially the height resolution clearly surpasses that obtained with standard microCARS. These results will be the basis for future investigations of mode-selective dynamics in the near-field.

Recording of optical near-field in laser photoelectron microscope by means of two-photon ionization by femtosecond laser pulses

2004 ◽  
Author(s):  
Sergey V. Chekalin ◽  
V. O. Kompanets ◽  
Vladilen S. Letokhov ◽  
Yu A. Matveets ◽  
B. N. Mironov ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Near Field ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Two Photon ◽  
Photon Ionization

scholarly journals Analysis of the modulation depth of some femtosecond laser pulses in holographic interferometry

2021 ◽  
Author(s):  
Halima Benzehoua ◽  
Latifa Dalil-Essakali ◽  
Abdelmajid Belafhal
Keyword(s):  
Femtosecond Laser ◽  
Holographic Interferometry ◽  
Modulation Depth ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Gaussian Beams ◽  
Frequency Detuning ◽  
Fringe Contrast ◽  
Temporal Profiles

Abstract On the basis of the modulation depth in the interference and holographic processes, we discuss in this paper the quality of holograms generated by some femtosecond laser pulses of two different colors. The modulation depth in terms of the fringe contrast (MDFC ratio) of Higher-order sh- and ch-Gaussian temporal profiles (shnGTP and chnGTP) are investigated in detail. It’s shown that, when we use two lasers having a very large frequency detuning, the shnGTP exhibit more precise results than the Gaussian beams for holography. shnGTP give new areas of frequency detuning to realize the very significant value of the MDFC ratio for obtaining better holograms, which is impossible with Gaussian beams. It also permits flexibility in the variable frequency difference and pulse duration for good quality holograms, and in the case of the chnGTP, null regions develop and frequency bands are observed favoring the formation of the holograms. The numerical simulations are presented to illustrate and discuss the influence of the frequency detuning, the beam order and the controller parameter of the waves on the modulation depths. The propose theory will be a good basis for the development of some new experiments on the holographic interferometry and it will certainly be very useful for the specialists of the studied femtosecond laser pulses.

scholarly journals Scanning near-field optical coherent anti-Stokes Raman microscopy (SNOM-CARS) with femtosecond laser pulses in vibrational and electronic resonance

2013 ◽  
Vol 21 (1) ◽  
pp. 918 ◽  
Author(s):  
Mahesh Namboodiri ◽  
Tahir Zeb Khan ◽  
Sidhant Bom ◽  
Günter Flachenecker ◽  
Arnulf Materny
Keyword(s):  
Femtosecond Laser ◽  
Near Field ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Raman Microscopy ◽  
Anti Stokes ◽  
Electronic Resonance

scholarly journals Fabrication of Periodic Nanostructures on Silicon Suboxide Films with Plasmonic Near-Field Ablation Induced by Low-Fluence Femtosecond Laser Pulses

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1495
Author(s):  
Tatsuyoshi Takaya ◽  
Godai Miyaji ◽  
Issei Takahashi ◽  
Lukas Janos Richter ◽  
Jürgen Ihlemann
Keyword(s):  
Optical Absorption ◽  
Femtosecond Laser ◽  
Absorption Coefficient ◽  
Silicon Oxide ◽  
Near Field ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Optical Absorption Coefficient ◽  
Silicon Suboxide

Silicon suboxide (SiOx, x ≈ 1) is a substoichiometric silicon oxide with a large refractive index and optical absorption coefficient that oxidizes to silica (SiO2) by annealing in air at ~1000 °C. We demonstrate that nanostructures with a groove period of 200–330 nm can be formed in air on a silicon suboxide film with 800 nm, 100 fs, and 10 Hz laser pulses at a fluence an order of magnitude lower than that needed for glass materials such as fused silica and borosilicate glass. Experimental results show that high-density electrons can be produced with low-fluence femtosecond laser pulses, and plasmonic near-fields are subsequently excited to create nanostructures on the surface because silicon suboxide has a larger optical absorption coefficient than glass. Calculations using a model target reproduce the observed groove periods well and explain the mechanism of the nanostructure formation.

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