Journal of the American Chemical Society. Nonlinear Optics. Bibcode : Natur. Submitted manuscript. Bibcode : PhRvL.. Retrieved July 4, Nat Phys. Bibcode : NatPh Physica D: Nonlinear Phenomena. Bibcode : PhyD.. Kouzov, N. Egorova, M. Chrysos, F. Encyclopedia of Laser Physics and Technology.
Download Limit Exceeded
Boyd 3rd ed. Boyd, Nonlinear optics, Third edition, Chapter 2. Bijlani; Amr S. Helmy Optics Express. Bibcode : OExpr..
Optics Letters. Bibcode : OptL CLEO ' Pepper, Jack Feinberg, and Nicolai V. Okulov, "Angular momentum of photons and phase conjugation", J. B: At. JETP Lett. The Journal of Physical Chemistry C. ACS Macro Letters. Advances in Optics and Photonics.
Bibcode : AdOP Scientific Reports. Bibcode : NatSR Advanced Materials. Coordination Chemistry Reviews. Branches of physics. Theoretical Phenomenology Computational Experimental Applied. Continuum Solid Fluid Acoustics. Electrostatics Magnetostatics Plasma physics Accelerator physics. Quantum electrodynamics Quantum field theory Quantum gravity Quantum information.
Spara som favorit. Skickas inom vardagar. This clear and self-contained review of the last four decades of research highlights in the hot field of nonlinear optical NLO crystals, particularly of borate-based ultraviolet and deep-ultraviolet NLO crystals, covers three major subjects: the structure-property relationship in borate crystals, the structural and optical characteristics of various promising borate crystals, and their fruitful applications in a wide range of scientific and technological fields. Edited by the discoverers and users of these optical borate crystals, this is a readily accessible reading for semiconductor, applied and solid state physicists, materials scientists, solid state chemists, manufacturers of optoelectronic devices, and those working in the optical industry.
Passar bra ihop. Moreover, multiphoton processes were associated with laser-induced damage. The further interactions can lead to a local heating, and therefore structural densification during cooling and increase of the refractive index. Elliptical or roughly cylindrical cross sections are obtained when the sample is translated transversally or longitudinally to the laser beam, respectively.
Thus, at the beginning of 20 th century one of the first issues to be solved dealt with the asymmetry of the waveguides when produced by transversal writing. Such asymmetry follows the beam intensity profile where nonlinear interactions take place. In order to control the beam diameter without affecting the focal length, Osellame et al. A modification on the experimental setup became the micromachining of cylindrical waveguides simpler.
Similar beam shaping can be achieved by using a slit, positioned before the objective lens and oriented parallel to the sample translation direction. To obtain a waveguide with symmetric profile the ratio between the beam waist at perpendicular directions to the laser propagation must be at the objective entrance, where n is the refractive index and x is the waveguide axis, according to the description. Other drawback was related to the processing speed of those waveguides. The amplified laser systems employed so far own repetition rate of the order of kHz, which restricted the increase of the processing rate.
Thus, the development of long cavity Ti:sapphire oscillator provided fs-pulses at MHz rate with enough energy per pulse for such task. The inner ring represents the region achieved by laser pulses, where nonlinear effects initiated by multiphoton absorption and followed by multiphoton- and avalanche ionization take place.
Then, the melted glass resolidifies according to the temperature and pressure gradients, leaving stress-stain zone that affects the inner region and giving rise the outer rings. Furthermore, in general, kHz can be defined as the onset of repetition rate for heat accumulation effects generated by laser in glass. Because of its high band gap energy and melting temperature, pure fused silica is a particular case, requiring wavelength closer to the band gap and greater pulse energy and repetition rate.
Beam direction is normal to the image plane. In this sense, the choice of MHz or kHz laser systems substantially affects the resulting photo-written structure. If thermal effects are adverse, as in the obtainment of sub-micrometric structures, low repetition rate are appropriate, whereas high repetition rate lasers can play as a heat source, being beneficial for the reduction of waveguide loss, induced crystallization and ionic diffusion. Both, low and high repetition rate lasers enable the space-selective formation of metallic NPs.
- De La Dictadura Militar a La Democracia (Spanish Edition).
- Download Limit Exceeded?
- Related Articles.
Once nonlinear optical processes promoted the nucleation, a heating source is necessary to promote the diffusion and aggregation of those metallic atoms. Therefore, space-selective formation of metallic NPs is achieved using only direct laser writing when MHz fs-laser is applied, while an additional annealing, usually carried on temperatures close to the glass transition, is required for the case of low repetition rate.
A practical way to check if the precipitation of metallic nanoparticles occurred is through the absorption spectrum, which must present the surface plasmon resonance at visible region. Figure 7 shows the extinction spectra of an Au 2 O 3 doped silicate glass after the irradiation using three different intensities from a nm, fs, 1 kHz laser and subsequently annealing.
The effect of irradiation with intensities of 6. The bands seen on spectra Figures 7a and 7b are due to surface plasmon resonance SPR of Au nanoparticles, whereas the spectrum in Figure 7c has been assigned to undecagold compounds with small Au clusters. It is important to note that in this example two steps were applied: i fs-laser micromachining and ii heat treatment. As mentioned before, if a high repetition laser had been employed the second step could be ruled out.
We have reported the differences concerning the usage of kHz or MHz laser systems for the space-selective formation of silver and copper NPs in borosilicate glass. When kHz repetition rate laser is applied, such effects are observed in the absorption spectrum through color centers, defects and other induced electronic states.
Passar bra ihop
Then, this preferential light absorption gives rise to the plasmon band after the suitable annealing. On the other hand, metallic nanoparticles readily precipitate when thermal effects associated with high repletion rates are presents, and the SPR band is observed even without heat treatment. An detailed study about the ionic species and clusters of silver induced by femtosecond laser was recently reported.
The inset shows the picture of this sample and the corresponding irradiated areas adapted from reference Metallic nanoparticles have been exploited for improvement of the nonlinear optical properties in different material systems. An increase of the refractive index of 4.
- A Different Shade of Colonialism: Egypt, Great Britain, and the Mastery of the Sudan (Colonialisms).
- Heinrich Heines „Romanzero“ als Text des literarischen Biedermeier (German Edition).
- Der Ehe-Code: Wie Sie eine erfüllte Partnerschaft führen. Über 100 glückliche Ehepartner verraten ihr Geheimrezept (German Edition).
- Death Rides a Pink Horse.
- Nonlinear Optical Borate Crystals, Principles and Applications.
Figure 8 displays a 3D-waveguide containing metallic silver nanoparticles in its core, produced by femtosecond laser irradiation in phosphate glass. Nonetheless, all benefits related to Ag NPs, like short lifetimes, high quantum yield and stability against photobleaching, 55 are integrated in the waveguide, bringing new prospects for the development of all-optical devices. For instance, 2D and 3D nonlinear architectures with second harmonic generation has been demonstrated. We have discussed the effects of longitudinal and transversal laser write as well as the influence of repetition rate over the fabrication of waveguides in glass.
Among the experimental parameters, pulse duration also affects the laser-induced damage in transparent materials. Experiments and modeling on fused silica are studied, 57 , 58 for regimes of short and ultra-short pulses respectively, in which contributions from multiphoton, tunnel, impact and avalanche ionizations are thoroughly described.
Also investigating fused silica, Mazur group found a dependence of NA with the damage caused by fs-laser pulses. Such threshold energy is well below the critical power for self-focusing for a regime of high NA greater than 0. Most of the key works concerning laser-induced damage and waveguides are performed using standard or commercial glasses. Nevertheless, studies on optical nonlinearities, addressed in the former section, demonstrate the importance of tailoring material properties through the composition, stimulating the usage multicomponent glass for direct laser write.
In this paper we presented a survey of results obtained by our and other research groups on the study of the nonlinear refraction and absorption in special glasses, as well as on the processing of such materials by femtosecond laser pulses. From the point of view of nonlinear spectroscopy, very interesting results have been obtained, revealing a clear interdependence between the glass composition and the nonlinear refraction and absorption that can lead to tailoring the material's optical properties for applications in optics and photonics.
Considering the processing of such special glasses, the results here compiled demonstrate that femtosecond laser is a powerful tool to change glassy materials properties by micromachining, which led to obtaining, among other applications, the waveguide fabrication and the controlled production of metallic nanoparticles.