Transverse and axial resolution of femtosecond laser ablation

Femtosecond lasers are capable of precise ablation that produce surgical dissections in vivo. The transverse and axial resolution of the laser damage inside the bulk are important parameters of ablation. The transverse resolution is routinely quantified, but the axial resolution is more difficult to measure and is less commonly performed. In some in vivo samples, fine dissections can also be difficult to visualize, but in vitro samples may allow clear imaging. Using a 1040-nm, 400-fs pulsed laser, we performed ablation inside agarose and glass, producing clear and persistent damage spots. Near the ablation threshold of both media, we found that the axial resolution is similar to the transverse resolution. We also ablated neuron cell bodies and fibers in C. elegans and demonstrate submicrometer resolution in both the transverse and axial directions, consistent with our results in agarose and glass. Using simple yet rigorous methods, we define the resolution of laser ablation in transparent media along all directions.

KALANA IS THE ONLY SOURCE OF CREATION AND SOURCE OF ENERGY IN THIS UNIVERSE

One side, most of the researches going on Universe, Space, Black holes, white holes, development of technology etc. and on the other side world is ending due to pollution. The transparent media, to which I’m calling as “Kalana”, that exists during sunlight and disappears at night, is actually brighter then sunlight. But due to pollution, it is looking dark. Wherever pure Kalana exists, there sunlight or any other source of light or Energy have no value. As Pollution increase, darkness also increases and reduces the presence of Kalana. Kalana itself is the source of creation and source of Energy in this universe. Each and everything that exist in this universe is created from Kalana. The outcome of Universal arrangements in Kalana is called “truth”. Truth has its own significant value in our society and everyone wish to be truthful for peaceful life. This is the main reason that, our ancestor was always tried to follow the truth and had advance technology then today what we have. Today’s technologies are not based upon the principle of truth and hence everything has its own side effects

THz-Photonics Transceivers By All-Dielectric Phonon-Polariton Nonlinear Nanoantennas

The THz spectrum (spanning from 0.3 THz to 30 THz) offers the potential of a plethora of applications, ranging from the imaging through non transparent media to wireless-over-fiber communications and THz-photonics. The latter framework would greatly benefit from the development of optical-to-THz wavelength converters. Exploiting Difference Frequency Generation in a nonlinear all dielectric nanoantenna, we propose a compact solution to this problem. By means of a near-Infrared pump beam (at ω1), the information signal in the optical domain (at ω2) is converted to the THz band (at ω3 = ω2 − ω1). The approach is completely transparent with respect to the modulation format, and can be easily integrated in a metasurface platform for simultaneous frequency and spatial moulding of THz beams.

Refraction of electromagnetic waves in pseudo-passive media

The problem of reflection and refraction of a plane monochromatic wave is considered in the most general formulation for a flat interface of two isotropic pseudo-passive media using the vector covariant approach of F.I. Fedorov. The generalized Fresnel coefficients for the perpendicular and parallel polarizations turn out to be complex values, except for cases when the phase difference of the permeabilities of the two media is zero or 180 degrees. The critical Brewster angles also turn out to be complex quantities. The phenomenon of total reflection, in contrast to passive transparent media, is not realized in pseudo-passive media. The energy coefficients of reflection and transmission are calculated and analyzed. Restrictions imposed on the values of the material parameters of the problem are indicated, which should be taken into account when studying refractive wave phenomena involving pseudo-passive metamaterials.

Propagation of laser beams through curved interfaces of transparent media

Mathematical models of propagation of Gaussian, collimated and structured laser beams in transparent optically homogeneous media in the presence of curved interfaces are presented. Experimental techniques which are used for reconstruction of the interfaces profiles are described.

Transverse and Axial Resolution of Femtosecond Laser Surgery

Femtosecond lasers are capable of precise ablation inside transparent media, including glass and in vivo samples. The transverse and axial resolution of damage inside the bulk are important parameters of ablation. The transverse resolution is straightforward to measure, but the axial resolution is much more difficult to measure and rarely performed. Using a 1040-nm, 400-fs pulsed laser, we performed ablation inside glass with a transverse and axial resolution of 0.75 µm. By fitting damage spot measurements to theoretical predictions, we find an ablation threshold of 6.4 x 1012 W/cm2. We also ablated neuron cell bodies and fibers in C. elegans and demonstrate submicrometer resolution in both the transverse and axial directions, consistent with our results in glass. Using simple yet rigorous methods, we define the resolution of laser ablation in transparent media along all directions.