In technologies operating at light wavelengths for wireless communication, sensor networks, positioning, and ranging, a dynamic coherent control and manip

In technologies operating at light wavelengths for wireless communication, sensor networks, positioning, and ranging, a dynamic coherent control and manipulation of light fields is an enabling element for properly generating and correctly receiving free-space optical (FSO) beams even in the presence of unpredictable objects and turbulence in the light path. In this work, we use a programmable mesh of Mach–Zehnder (MZI) interferometers to automatically control the complex field radiated and captured by an array of optical antennas. The implementation of local feedback control loops in each MZI stage, without global multivariable optimization techniques, enables an unlimited scalability. Several functionalities are demonstrated, including the generation of perfectly shaped beams with nonperfect optical antennas, the imaging of a desired field pattern through an obstacle or a diffusive medium, and the identification of an unknown obstacle inserted in the FSO path. Compared to conventional devices used for the manipulation of FSO beams, such as spatial light modulators, our programmable device can self-configure through automated control strategies and can be integrated with other functionalities implemented onto the same photonic chip.show less

We demonstrated a 202 W Tm:YLF slab laser using a reflecting volume Bragg grating (VBG) as an output coupler at room temperature. Two kinds of active heat

We demonstrated a 202 W Tm:YLF slab laser using a reflecting volume Bragg grating (VBG) as an output coupler at room temperature. Two kinds of active heat dissipation methods were used for the VBG to suppress the shift of wavelength caused by its increasing temperature. The maximum continuous wave (CW) output power of 202 W using the microchannel cooling was obtained under the total incident pump power of 553 W, the corresponding slope efficiency and optical-to-optical conversion efficiency were 39.7% and 36.5%, respectively. The central wavelength was 1908.5 nm with the linewidth (full width at half maximum) of 0.57 nm. Meanwhile, with the laser output increasing from 30 to 202 W, the total shift was about 1.0 nm, and the wavelength was limited to two water absorption lines near 1908 nm. The beam quality factors M² were measured to be 2.3 and 4.0 in x and y directions at 202 W.show less

A counter-surface plasmon polariton lens (CSPPL) is proposed to perform stable nanoparticle trapping by providing up to 120kbT optical potential depth. Th

A counter-surface plasmon polariton lens (CSPPL) is proposed to perform stable nanoparticle trapping by providing up to 120k_bT optical potential depth. The optical potential depth is related to the incident angle and phase difference of the light incident on two gratings of CSPPL. The depth of optical potential can be manipulated with negligible displacement by the incident angle less than 20°. Both the depth and the center position of the optical potential well can be manipulated by the incident phase difference. The study of stable and manipulatable optical potential on the CSPPL promotes the integration of optical tweezers.show less

In amplitude-modulation-type electroholography, the binary-weighted computer-generated hologram (BW-CGH) facilitates the gradation-expressible reconstruct

In amplitude-modulation-type electroholography, the binary-weighted computer-generated hologram (BW-CGH) facilitates the gradation-expressible reconstruction of three-dimensional (3D) objects. To realize real-time gradation-expressible electroholography, we propose an efficient and high-speed method for calculating bit planes consisting of BW-CGHs. The proposed method is implemented on a multiple graphics processing unit (GPU) cluster system comprising 13 GPUs. The proposed BW-CGH method realizes eight-gradation-expressible electroholography at approximately the same calculation speed as that of conventional electroholography based on binary computer-generated holograms. Consequently, we were able to successfully reconstruct a real-time electroholographic 3D video comprising approximately 180,000 points expressed in eight gradations at 30 frames per second.show less