Abstract
Ultra-intense femtosecond vortex pulses can provide an opportunity to investigate the new phenomena with orbital angular momentum (OAM) involved in extreme cases. This paper reports a high gain optical vortex amplifier for intense femtosecond vortex pulses generation. Traditional regeneration amplifiers can offer high gain for Gaussian mode pulses but cannot amplify optical vortex pulses while maintaining the phase singularity because of mode competition. Here, we present a regeneration amplifier with a ring-shaped pump. By controlling the radius of the pump, the system can realize the motivation of the Laguerre–Gaussian [ LG 0 , 1 ( − 1 ) ] mode and the suppression of the Gaussian mode. Without seeds, the amplifier has a donut-shaped output containing two opposite OAM states simultaneously, as our prediction by simulation. If seeded by a pulse of a topologic charge of 1 or − 1 , the system will output an amplified LG 0 , 1 ( − 1 ) mode pulse with the same topologic charge as the seed. To our knowledge, this amplifier can offer the highest gain as 1.45 × 10 6 for optical vortex amplification. Finally, we obtain a 1.8 mJ, 51 fs compressed optical vortex seeded from a 2 nJ optical vortex.
Highlights
An optical vortex beam is a structured beam with a spiral phase e−ilφ in the azimuthal direction φ perpendicular to the propagation direction [1,2,3]
These applications can benefit from technologies of optical vortex generation which can be divided into external modulation outside the cavity [16,17,18,19,20] and direct generation within the cavity [21,22,23]
We develop a high gain optical vortex amplifier (OVA) whose gain reaches 106 level based on regenerative amplification
Summary
An optical vortex beam is a structured beam with a spiral phase e−ilφ in the azimuthal direction φ perpendicular to the propagation direction [1,2,3]. The spiral phase can be introduced to the ultra-short Gaussian mode laser by external modulation through spiral phase plate [19, 28], fork grating [30,31,32,33,34], and spatial light modulator [11, 35] Such methods for ultra-intense cases pose a significant challenge owing to technical difficulties like optical element damage and the dispersion hindering the synthesis of a high-power broadband optical vortex. Optical parametric amplification for ultrashort optical-vortex pulses generation makes a gain level up to 102 [44,45,46].Asfaras we know,currently,there are noOVA can reachagain level of 106 Because these amplifiers cannot make the vortex beam pass through the gain medium enough times. Base on the OVA, the 51 fs, 1.8 mJ compressed optical vortex has been obtained
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