Continuous 40 GW/cm$^2$ laser intensity in a near-concentric optical cavity

TL;DR

This paper demonstrates achieving a record CW laser intensity of 40 GW/cm$^2$ in a near-concentric optical cavity, enabling potential applications in electron wave manipulation and phase contrast transmission electron microscopy.

Contribution

It introduces a near-concentric cavity setup that focuses high-power laser beams to unprecedented intensities, paving the way for advanced electron-optical elements.

Findings

Achieved 40 GW/cm$^2$ laser intensity in a near-concentric cavity.

Focused 7.5 kW of circulating power into a 7 μm waist.

Established a pathway for ponderomotive phase contrast TEM.

Abstract

Manipulating free-space electron wave functions with laser fields can bring about new electron-optical elements for transmission electron microscopy. In particular, a Zernike phase plate would enable high-contrast imaging of soft matter, leading to new opportunities in structural biology and materials science. A Zernike plate can be implemented using a tight, intense CW laser focus that shifts the phase of the electron wave by the ponderomotive potential. Here, we use a near-concentric cavity to focus 7.5 kW of circulating laser power at 1064 nm into a 7 $\mu$m waist, setting a record for CW laser intensity and establishing a pathway to ponderomotive phase contrast TEM.