Nanometer Material Processing Using NSOM-delivered Femtosecond Laser Pulses

2004 ◽  
Vol 850 ◽  
Author(s):  
Chen-Hsiung Cheng ◽  
Ming Li
Keyword(s):  
Substrate Surface ◽  
Near Field ◽  
Laser Pulses ◽  
Optical Microscope ◽  
Femtosecond Laser Pulses ◽  
Surface Topology ◽  
Field Range ◽  
Field Coupling ◽  
Nanometer Material ◽  
And Performance

ABSTRACTNanometer-scale surface topology modification has been demonstrated using NSOM (near-field scanning optical microscope) delivered femto-second pulses. The ablation laser has a pulse width of 150 femto-second and wavelength of 387-nm. The laser pulses are coupled into the free end of a multimode optical fiber that a nanometer-size NSOM probe was fabricated on the other end with small orifice. The transmitted laser pulses from the probe orifice illuminates and machines the substrate surface when the probe is in near-field range of the substrate surface. The produced feature on Silicon surface is as least 200-nm deep with hole diameter around 200-nm. Near-field coupling of the laser has the potential to achieve ablation of feature size less than diffraction limit. Using NSOM delivery method also allows us to take advantage of nanometer metrology in precision surface ablation or other type of preformed surface modification. The ability of monitoring surface topology of substrate in real time enables us to accomplish the in-situ surface processing. We have demonstrated the technique of drilling 200-nm air holes on a pre-formed 600-nm wide wave guide. This method can be used to fabricate one-dimensional photonic crystal on a waveguide in ambient environment. The experiment design and performance evaluation will be discussed.

Nanostructuring Borosilicate Glass With Near-Field Enhanced Energy Using a Femtosecond Laser Pulse

2006 ◽  
Vol 129 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Alex Heltzel ◽  
Arvind Battula ◽  
J. R. Howell ◽  
Shaochen Chen
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Borosilicate Glass ◽  
Substrate Surface ◽  
Near Field ◽  
Planck Equation ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Avalanche Ionization ◽  
Avalanche Process

A model based on the evolution of electron density derived from the Fokker-Planck equation has been built to describe ablation of dielectrics during femtosecond laser pulses. The model is verified against an experimental investigation of borosilicate glass with a 200fs laser pulse centered at 780nm wavelength in a range of laser energies. The ablation mechanisms in dielectrics include multi-photon ionization (MPI) and avalanche ionization. MPI dominates the ionization process during the first stages of the laser pulse, contributing seed electrons which supply avalanche ionization. The avalanche process initiates and becomes responsible for the majority of free-electron generation. The overall material removal is shown to be highly dependent upon the optical response of the dielectric as plasma is formed. The ablation model is employed to predict the response of borosilicate glass to an enhanced electromagnetic field due to the presence of microspheres on the substrate surface. It is shown that the diffraction limit can be broken, creating nanoscale surface modification. An experimental study accompanies the model, with AFM and SEM characterizations that are consistent with the predicted surface modifications.

scholarly journals Optical Sensitivity of Waveguides Inscribed in Nanoporous Silicate Framework

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 123
Author(s):  
Zhong Lijing ◽  
Roman A. Zakoldaev ◽  
Maksim M. Sergeev ◽  
Andrey B. Petrov ◽  
Vadim P. Veiko ◽  
...  
Keyword(s):  
Refractive Index ◽  
Near Field ◽  
Experimental Studies ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Direct Writing ◽  
Sensor Applications ◽  
Refractive Index Contrast ◽  
Optical Sensitivity ◽  
Index Contrast

Laser direct writing technique in glass is a powerful tool for various waveguides’ fabrication that highly develop the element base for designing photonic devices. We apply this technique to fabricate waveguides in porous glass (PG). Nanoporous optical materials for the inscription can elevate the sensing ability of such waveguides to higher standards. The waveguides were fabricated by a single-scan approach with femtosecond laser pulses in the densification mode, which resulted in the formation of a core and cladding. Experimental studies revealed three types of waveguides and quantified the refractive index contrast (up to Δn = 1.2·10−2) accompanied with ~1.2 dB/cm insertion losses. The waveguides demonstrated the sensitivity to small objects captured by the nanoporous framework. We noticed that the deposited ethanol molecules (3 µL) on the PG surface influence the waveguide optical properties indicating the penetration of the molecule to its cladding. Continuous monitoring of the output near field intensity distribution allowed us to determine the response time (6 s) of the waveguide buried at 400 µm below the glass surface. We found that the minimum distinguishable change of the refractive index contrast is 2 × 10−4. The results obtained pave the way to consider the waveguides inscribed into PG as primary transducers for sensor applications.

scholarly journals Graphene Oxide-Based Silico-Phosphate Composite Films for Optical Limiting of Ultrashort Near-Infrared Laser Pulses

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1638 ◽  
Author(s):  
Adrian Petris ◽  
Ileana Cristina Vasiliu ◽  
Petronela Gheorghe ◽  
Ana Maria Iordache ◽  
Laura Ionel ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Femtosecond Laser ◽  
Near Infrared ◽  
Substrate Surface ◽  
Sol Gel ◽  
Composite Films ◽  
Laser Pulses ◽  
Optical Limiting ◽  
Femtosecond Laser Pulses ◽  
Glassy Matrix

The development of graphene-based materials for optical limiting functionality is an active field of research. Optical limiting for femtosecond laser pulses in the infrared-B (IR-B) (1.4–3 μm) spectral domain has been investigated to a lesser extent than that for nanosecond, picosecond and femtosecond laser pulses at wavelengths up to 1.1 μm. Novel nonlinear optical materials, glassy graphene oxide (GO)-based silico-phosphate composites, were prepared, for the first time to our knowledge, by a convenient and low cost sol-gel method, as described in the paper, using tetraethyl orthosilicate (TEOS), H3PO4 and GO/reduced GO (rGO) as precursors. The characterisation of the GO/rGO silico-phosphate composite films was performed by spectroscopy (Fourier-transform infrared (FTIR), Ultraviolet–Visible-Near Infrared (UV-VIS-NIR) and Raman) and microscopy (atomic force microscopy (AFM) and scanning electron microscopy (SEM)) techniques. H3PO4 was found to reduce the rGO dispersed in the precursor’s solution with the formation of vertically agglomerated rGO sheets, uniformly distributed on the substrate surface. The capability of these novel graphene oxide-based materials for the optical limiting of femtosecond laser pulses at 1550 nm wavelength was demonstrated by intensity-scan experiments. The GO or rGO presence in the film, their concentrations, the composite films glassy matrix, and the film substrate influence the optical limiting performance of these novel materials and are discussed accordingly.

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

Filament damage and channel waveguide fabrication in Yb-doped phosphate glass

2020 ◽  
Vol 34 (29) ◽  
pp. 2050325
Author(s):  
Jing Lv ◽  
Kedian Wang ◽  
Guanghua Cheng
Keyword(s):  
Phosphate Glass ◽  
Continuous Wave ◽  
Single Mode ◽  
Laser Pulses ◽  
Optical Microscope ◽  
Femtosecond Laser Pulses ◽  
Circular Aperture ◽  
Optical Pump ◽  
Channel Waveguides ◽  
Waveguide Fabrication

We report on the fabrication of filament damages in Yb-doped phosphate glass by femtosecond laser pulses. The uneven index modification was obtained using a 20× optical microscope objective with 0.4 numerical apertures. The multimode fields of original channel waveguides were investigated and in good agreement with the simulation results, whose structures can be regarded as a kind of beam splitters. Under the optical pump at 976 nm, the end region of the original filament shows continuous wave laser oscillation. The elongated and uniform filaments were fabricated by introducing a circular aperture, so that the guiding performance of tradition-channel single mode was achieved. Both large-mode-area waveguides are expected to find applications in optical communications and high-power lasers and amplifiers.

Experimental and Theoretical Analysis of the Nanoscale Crater Generation With a Near Field Scanning Optical Tip

2008 ◽  
Author(s):  
Sy-Bor Wen
Keyword(s):  
Theoretical Analysis ◽  
Light Absorption ◽  
Light Propagation ◽  
Order Approximation ◽  
Near Field ◽  
Optical Microscope ◽  
Femtosecond Laser Pulses ◽  
Photoexcited Electron ◽  
Pure Silicon ◽  
Near Field Scanning

Different nano-patterns have been generated with the same near field scanning optical microscope (NSOM) tips with multiple femtosecond laser pulses in different background gases. It is demonstrated that significant energy was transferred from the NSOM probe to a pure silicon surface for the generation of nano-protrusions and nano-craters, which shows the possibility of nano-fabrication with the present experimental configuration. In order to understand the heating effect of the target and the relationship between the generations of nano-craters, a corresponding theoretical analysis considering the wave format light propagation within a single tapering NSOM probe (first order approximation) and the subsequent light absorption in a target is established. This analysis show that electron temperature of around the nano-scale laser spot of target can be very high (>∼10,000 K) during the laser pulse. However, both the photoexcited electron number density and lattice temperature are much less the threshold for a thermal and non-thermal evaporation. Therefore, supplementary mechanisms in additional to pure pulsed light absorption are required for generation of nano-craters on a target if a single tapering angle NSOM probe is applied.

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
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