Improvement of coupling efficiency in free-space optical communication with a multi-actuator adaptive lens.

In free-space optical communication, the propagation of a laser beam through the atmosphere causes wavefront distortions that decrease the coupling efficiency (CE) from free space to single-mode fiber. This tremendously degrades the performance of the communication channel even in the case of weak turbulence regime. In this Letter, we demonstrate that a multi-actuator adaptive lens working in closed loop with a wavefront sensor can strongly reduce the effect of turbulence while reducing the system complexity with respect to correction systems using deformable mirrors or liquid crystal spatial light modulators.

Performance evaluation of perfect optical vortices transmission in an underwater optical communication system: publisher's note.

This publisher's note identifies an error in the paper title of Appl. Opt.57, 9148 (2018)APOPAI0003-693510.

Performance evaluation of perfect optical vortices transmission in an underwater optical communication system.

In this paper, we experimentally evaluated the performance of underwater optical communications using 1 Mbit/s on-off keying signals of perfect optical vortices. Perfect optical vortices generated by Fourier transformation of the Bessel-Gaussian beam are propagated through a 2.6 m underwater medium and affected by various water conditions such as stagnant water, water flow, temperature difference, and air bubbles, so beam wander and fluctuation of the signal are studied.

Theoretical investigation of the regenerative amplification of ultrashort pulses in a high-pressure transverse electric CO laser.

We have developed a theoretical model for the regenerative amplification of ultrashort mid-infrared radiation in high-pressure transverse electric discharge CO lasers. This model is based on counter-propagating wave equations that are combined with Boltzmann equation, six-temperature, and circuit-coupled kinetic models. For the first time to our knowledge, the effect of spontaneous emission is taken into account.

Generation of perfect optical vortices using a Bessel-Gaussian beam diffracted by curved fork grating.

Perfect optical vortices (POVs) are beams whose topological charges are independent of radius, unlike conventional optical vortices. POVs are the Fourier transformation of Bessel-Gaussian (BG) beams and can be seen in the far-field diffraction of BG beams. In this paper, we present the generation of POVs of arbitrary charge using curved fork grating (CFG) illuminated by BG beam.

Chlorine measurement in the jet singlet oxygen generator considering the effects of the droplets.

A new method is presented to measure chlorine concentration more accurately than conventional method in exhaust gases of a jet-type singlet oxygen generator. One problem in this measurement is the existence of micrometer-sized droplets. In this article, an empirical method is reported to eliminate the effects of the droplets.