Off-axis spiral phase mirrors for generating high-intensity optical vortices

Abstract

In this work, we present a novel and practical method for generating optical vortices in highpower laser systems. Off-axis spiral phase mirrors are used at oblique angles of incidence in the beam path after amplification and compression allowing for the generation of high-power optical vortices in almost any laser system. An off-axis configuration is possible via modification of the azimuthal gradient of the spiral phase helix and is demonstrated with a simple model using a discrete spiral staircase. This work presents the design, fabrication, and implementation of off-axis spiral phase mirrors in both low and high-power laser systems.

Kilo-Tesla axial magnetic field generation with high intensity spin and orbital angular momentum beams

“…With the recent demonstration of high intensity OAM modes in high-power laser facilities with parameters similar to those assumed in this work, experimental verification of the magnetic fields could now be feasible [16]. Generation and control of multi-kT magnetic fields will open up new opportunities in a number of areas of high energy density physics and laboratory astrophysics including particle acceleration schemes, magnetic re-connection, fast ignition and fundamental physics.…”

“…Circularly polarizing large diameter, high power laser beams is not trivial requiring fragile and costly optics. However, with the new generation of PW class lasers coupled with off-axis spiral phase mirrors [16], axial magnetic fields on the order of 10's of kT may be feasible using LP OAM modes. Ultimately, the field strength will depend on the absorption rate of the laser which may diverge from our simple model when using ultrahigh intensity beams (I 0 10 21 W cm −2 ), high | | beams, and ultra-short pulse durations (τ < 100f s).…”

“…OAM has also been shown to couple more efficiently to free electrons due to an optimal overlap between the laser intensity profile and the angular momentum density yielding greater coupling at larger radial distances [15]. Additionally, high intensity OAM beams have recently been produced in high power lasers using off-axis spiral phase mirrors mitigating nonlinear effects like temporal distortions and B-integral present with transmissive optics such as quarter waveplates [16].…”

Measuring the orbital angular momentum of high-power laser pulses

“…That way, they can be as thick as needed to make them stable and they can be made from materials that withstand even the most powerful lasers in operation. They can even be fabricated in such a way so as to operate off-axis 14 , reflecting the beam at an angle and avoiding any geometrical issues with their inclusion in experimental setups.…”

Optimal Laguerre–Gaussian modes for high-intensity optical vortices

“…Recent advances have enabled the generation of high-power OAM beams for exploring these new and interesting phenomena [25][26][27]. A robust and pulse-shape preserving method has been more recently demonstrated using an off-axis spiral phase mirror (OASPM) which could practically introduce OAM to many HPL facilities [28]. The OASPM imprints a helical wavefront onto the near-field of the laser after pulse amplification and compression via a nano-structured staircase on its surface.…”