Pulse-to-pulse polarization-switching method for high-repetition-rate lasers

Abstract

We report a method that enables dynamic switching of the pulse-to-pulse linear polarization orientation of a high-pulse-rate laser. The implications for laser micromachining, where polarization direction can be important, are also discussed.

Tight focusing induces pulse delay and pulse compression of double-ring-shaped radially polarized ultrashort light pulses

“…In optical measurements with a femtosecond light pulse, the spatial and temporal properties of the focused ultrashort light pulse may influence the resolution of a produced image [22]. Likewise, the polarization of the light pulse may affect both the efficiency and the quality of ultrashort pulse micro-processes [23]. Given these considerations, it is worthwhile to investigate the tight focusing of ultrashort light pulses with double-ring-shaped radial polarization, and examine the influence of the interference of longitudinal components on the propagation velocity and pulse compression of ultrashort light pulses near the focus of high-NA objectives.…”

Real-time control of polarisation in ultra-short-pulse laser micro-machining

“…The key parameters influencing the laser process quality and efficiency are the fluence, pulse duration, wavelength, beam quality and polarisation [7][8][9]. The influence of polarisation on micro-machining has been experimentally demonstrated in [9][10][11][12], showing that drilling high-aspectratio (depth/diameter) microscopic holes in metal with linear polarised ultra-short-pulse lasers produces anisotropic profiles.…”

“…However, these methods involve mechanical rotation of optical components and could be adversely affected by vibrations and prone to mechanical failure, leading to potentially expensive maintenance. An alternative laser-specific polarisation switching method is detailed in [8]. It is based on an intra-cavity polarisation chopper wheel synchronised to the laser pulse train.…”

Real-time control of polarization in ultra-short pulse laser micro-processing

“…Industrial applications include the very precise drilling of holes for fuel-injection nozzles in the automotive industry [2,3]. The key parameters influencing the laser-machining process quality are the pulse duration, wavelength, peak power, beam quality and polarization [4][5][6].…”

“…However, these methods involve mechanical rotation of optical components and could be adversely affected by vibrations and prone to mechanical failure, leading to potentially expensive maintenance. An alternative laser-specific polarization switching method is detailed in [5]. It is based on an intra-cavity polarization chopper wheel synchronized to the laser pulse train.…”