Reconfigurable and tunable twisted light laser

Abstract

Twisted light, having a helical spatial phase structure and carrying orbital angular momentum (OAM), has given rise to many developments ranging from optical manipulation to optical communications. The laser excitation of twisted light in a reconfigurable and tunable way is of great interest. Here, we propose and experimentally demonstrate an OAM reconfigurable and wavelength tunable twisted light laser with achievable high-order OAM modes on a hybrid free-space and fiber platform. The excited twisted light laser is enabled by a ring resonator incorporating spatial light modulators (SLMs) and bandpass filter (BPF). By appropriately switching the phase pattern loaded onto SLMs and adjusting the BPF, twisted light laser with reconfigurable OAM and tunable wavelength is implemented. In the experiment, the OAM value is varied from −10 to +10 and the wavelength is adjusted from 1530 to 1565 nm covering the whole C band. The obtained results indicate successful implementation of a reconfigurable and tunable twisted light laser with favorable operation performance. Reconfigurable and tunable twisted light laser may open up new perspectives to more extensive OAM-enabled applications with improved flexibility and robustness.

Optical vortices 30 years on: OAM manipulation from topological charge to multiple singularities

“…Recently, Wang et al 167 improved the output efficiency and reduced the threshold of a similar system by using a Z-cavity and a birefringent plate in the cavity design, and a 14.5-nm wavelength-tunable width and a 0~±14ℏ OAM range were achieved. Wang’s group 168 designed and implemented a fibre-space coupling vortex laser system, where a wavelength-tunable range of 1530–1565 nm and an OAM of 0~±10ℏ were achieved.

Fig. 9Generation of wavelength- and OAM-tunable CW VBs (I).Generation methods of wavelength- and OAM-tunable VBs using an acousto-optic fibre grating ( a ), along with the experimental results 161 ( b ), an SPP-embedded MEMS filter system 162 ( c – e ), and a VBG in a hollow-pumped solid-state laser 163 ( f ).

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“…161–163 , OSA Publishing

Fig. 10Generation of wavelength- and OAM-tunable CW VBs (II).Generation methods of wavelength- and OAM-tunable VBs using a dual-off-axis pumped Yb:CALGO laser system 165,166 ( a ), intracavity birefringent plate rotation 167 ( b ), and a “Gauss-OAM-Gauss” beam conversion system in a fibre laser 168 ( c ). a From refs.

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Structured Light from Lasers

“…It is not surprising then that phase‐only approaches have taken center stage. For example, in the case of Bessel beams, the use of phase‐only elements for their creation was first proposed in the late 1990s, later implemented with refractive axicons and diffractive axicons, with the suggestion that combinations of these approaches could be seen with metasurfaces . Flat‐top beams too have seen such developments, created by diffractive mirror structures in single step approaches as well as in a two‐step approach for a cavity that transforms a Gaussian mode at one end to a flat‐top at the other .…”

“…The result was the demonstration of virtually any structured light field from the same device, with some examples of the output modes shown in Figure . This work was extended to demonstrate arbitrary lateral shapes by multibeam superpositions, tunable twisted light, dynamic fiber lasers, and the use of a dual cavity to excite two spatial modes which could be combined to form arbitrary vector beams from a digital laser . Additions of acousto‐optic modulators have likewise allowed dynamic selection of various structured light beams .…”

Detection and elimination of pulse train instabilities in broadband fibre lasers using dispersion scan

“…Fibre lasers are unique light sources that have an increasing number of applications in industry 1 , nonlinear 2 and multiphoton 3 microscopy, micro-processing 4 , generation of optical vortices 5 , vector beams 6 , high power laser development 7,8 , and imaging 9 , among many others. Important efforts have been devoted to generating ultrashort pulses from these lasers [10][11][12][13][14][15][16] .…”