Abstract
We report on a high-power passively mode-locked radially polarized Yb:YAG thin-disk oscillator providing 125 W of average output power. To the best of our knowledge, this is the highest average power ever reported from a mode-locked radially polarized oscillator without subsequent amplification stages. Mode-locking was achieved by implementing a SESAM as the cavity end mirror and the radial polarization of the LG*01 mode was obtained by means of a circular Grating Waveguide Output Coupler. The repetition rate was 78 MHz. A pulse duration of 0.97 ps and a spectral bandwidth of 1.4 nm (FWHM) were measured at the maximum output power. This corresponds to a pulse energy of 1.6 µJ and a pulse peak power of 1.45 MW. A high degree of radial polarization of 97.3 ± 1% and an M2-value of 2.16 which is close to the theoretical value for the LG*01 doughnut mode were measured.
Highlights
And azimuthally polarized laser beams have attracted a great interest within different fields of scientific applications such as optical trapping, imaging or plasmon excitation [1]
We report on a high-power passively mode-locked radially polarized Yb:YAG thin-disk oscillator providing 125 W of average output power
Mode-locking was achieved by implementing a SESAM as the cavity end mirror and the radial polarization of the LG*01 mode was obtained by means of a circular Grating Waveguide Output Coupler
Summary
And azimuthally polarized laser beams have attracted a great interest within different fields of scientific applications such as optical trapping, imaging or plasmon excitation [1]. The advantages of radially and azimuthally polarized beams over circularly or linearly polarized beams have been theoretically outlined for cutting with CO2 lasers in [2]. An increase of the cutting speed of up to a factor of 2 for radially polarized beams in comparison to circularly or linearly polarized beams was predicted. An increase of the cutting speed of 37.5% by using a radially polarized rather than a circularly polarized CO2 laser was demonstrated [3]. Using a wavelength of 1.03 μm an increase of the cutting speed of 42.9% for a radially polarized beam in comparison to an unpolarized beam was shown [4]. A better quality of micro holes in fused silica and silicon was obtained using femtosecond laser beams with radial polarization [6]. Biomimetic structures giving rise to e.g. the water repellent lotus-leaf effect on metallic surfaces were fabricated with radially and azimuthally polarized femtosecond laser pulses [7]
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