Ultrashort intense-field optical vortices produced with laser-etched mirrors

Abstract

We introduce a simple and practical method to create ultrashort intense optical vortices for applications involving high-intensity lasers. Our method utilizes femtosecond laser pulses to laser etch grating lines into laser-quality gold mirrors. These grating lines holographically encode an optical vortex. We derive mathematical equations for each individual grating line to be etched, for any desired (integer) topological charge. We investigate the smoothness of the etched grooves. We show that they are smooth enough to produce optical vortices with an intensity that is only a few percent lower than in the ideal case. We demonstrate that the etched gratings can be used in a folded version of our 2f-2f setup [Opt. Express 19, 7599 (2005)] to compensate angular dispersion. Finally, we show that the etched gratings withstand intensities of up to 10 12 W͞cm 2 .

Extension of filament propagation in water with Bessel-Gaussian beams

“…We kept the distance between the SLM and the glass cell as short as possible to minimize the chromatic distortions due to diffraction gratings on the SLM. 38 The beams were passed through a 13 cm-long glass cell, which was arranged vertically allowing us to measure the power and spectrum as a function of the propagation distance by changing the water level in the cell with AIP Advances 6, 035001 (2016) a programmable infuse/withdraw syringe pump (Harvard PHD 2000). A mechanical iris was used to select the central peak of the beam.…”

Femtosecond spatial pulse shaping at the focal plane

“…Other configurations such as a lens-less setup with grating and SLM assembled [16,17] and modifications based on the scheme in Fig. 1(a) have been also reported [18][19][20][21][22]. In Fig.…”

Orbital angular momentum generation in a 60GHz wireless radio channel

“…The number of phase twists produced around the vortex, in addition to the shape and behavior of fork-grating, are controlled by the topological charge (L) [16]. A holographic interference pattern is the product of the phase-only interference of an indirect plane reference wave which generates a radio vortex beam using the following formula [17,18]: (1) where, are the transverse cylindrical coordinates, is the topological charge of the radio vortex to be created, is an arbitrary phase factor and is the number of grating lines per unit length.…”