The image on the cover of High Power Laser Science and Engineering Volume 9, Issue 1, demonstrate an all-optical method for controlling the transverse motion of an ionization injected electron beam in a laser plasma accelerator by using the transversely asymmetrical plasma wakefield. The laser focus shape can control the distribution of a transversal wakefield. The image is based on original research by Jie Feng et al. presented in their paper "Optical control of transverse motion of ionization injected electrons in a laser plasma accelerator", High Power Laser Science and Engineering 9 (1), 010000e5 (2021).
The image on the cover for Photonics Research Volume 9, Issue 8, reports on the observation of negative refraction in the PhC slab where the vertical guiding is enabled by a bound state in the continuum and essentially beyond the light cone. Such abnormal refraction and guiding mechanism are based on the synchronous crafting of spatial dispersion and the radiative lifetime of Bloch modes within the radiative continuum. The image is based on original research by Zhanyuan Zhang et al. presented in their paper "Negative refraction mediated by bound states in the continuum", Photonics Research 9 (8), 08001592 (2021).
The image on the cover for Chinese Optics Letters Volume 19, Issue 8, introduces a nanoplasmonic isolator that consists of a cylindrical resonator placed close to a metal-dielectric-metal (MDM) waveguide. The material filling the waveguide and resonator is a magneto-optical (MO) material, and the structure is under an externally applied static magnetic field.The image is based on original research by Vahid Foroughi Nezhad, Chenglong You and Georgios Veronis presented in their paper "Nanoplasmonic magneto-optical isolator [Invited]", Chinese Optics Letters 19 (8), 083602 (2021).
The image on the cover for Photonics Research Volume 9, Issue 7, indicates that wave and particle are two fundamental properties of nature. The wave–particle duality has indicated that a quantum object may exhibit the behaviors of both wave and particle, depending upon the circumstances of the experiment. The major significance of wave–particle duality has led to a fundamental equation in quantum mechanics: the Schrödinger equation. The image is based on original research by Pratyusha Chowdhury, Arun Kumar Pati and Jing-Ling Chen presented in their paper "Wave and particle properties can be spatially separated in a quantum entity", Photonics Research 9 (7), 07001379(2021).
The image on the cover for Chinese Optics Letters Volume 19, Issue 7, proposes and demonstrates the cascaded multi-wavelength mode-locked erbium-doped fiber laser (EDFL) based on ultra-long-period gratings (ULPGs) for the first time. Study found that the ULPG can be used as both a mode-locker for pulse shaping and a comb filter for multi-wavelength generation simultaneously.The image is based on original research by Bo Guo et al. presented in their paper "Ultra-long-period grating-based multi-wavelength ultrafast fiber laser [Invited]", Chinese Optics Letters 19 (7), 071405 (2021).
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 120kbT 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
We report on a mid-infrared fiber laser which uses a single-walled carbon nanotube saturable absorber mirror to realize the mode-locking operation. The laser generates 3.5 μm ultra-shor
We report on a mid-infrared fiber laser which uses a single-walled carbon nanotube saturable absorber mirror to realize the mode-locking operation. The laser generates 3.5 μm ultra-short pulses from an erbium-doped fluoride fiber by utilizing dual-wavelength pumping scheme. Stable mode-locking is achieved at the 3.5 μm band with a repetition rate of 25.2 MHz. The maximum average power acquired from the laser in the mode-locking regime is 25 mW. The experimental results indicate that carbon nanotube is an effective saturable absorber for mode-locking in the mid-infrared spectral region.show less
In this paper, we propose and demonstrate a dual-beam delay-encoded Doppler spectral domain optical coherence tomography (SDOCT) system for in vivo measurement of absolute retinal blood
In this paper, we propose and demonstrate a dual-beam delay-encoded Doppler spectral domain optical coherence tomography (SDOCT) system for in vivo measurement of absolute retinal blood velocity and flow with arbitrary orientation. The incident beam is split by a beam displacer into two probe beams of the single-spectrometer SDOCT system with orthogonal polarization states and an optical path length delay. We validate our approach with a phantom and in vivo experiments of human retinal blood flow respectively.show less
We proposed a multi-functional terahertz metasurface based on a double L-shaped pattern and a VO2 film separated by the polyimide. When the VO2 film is an insulator, a dual-band EIT eff
We proposed a multi-functional terahertz metasurface based on a double L-shaped pattern and a VO2 film separated by the polyimide. When the VO2 film is an insulator, a dual-band EIT effect is obtained, and the physical mechanism is investigated based on the current distribution and “two-particle” model. When the VO2 film is a metal, a dual-band linear-to-circular polarization converter in which the y-polarized linear wave can be effectively converted to LCP and RCP simultaneously in different bands can be achieved. By arranging the metal pattern rotating 30º, a multi-functional antenna can be obtained. When the VO2 is an insulator, the radiation of the LCP wave is divided into four beams with two beams reflected and two beams transmitted. When the VO2 is in metallic state, we can only get the co-polarized reflected wave with 21° angle. Moreover, in our design, the VO2 film doesn’t need lithography to obtain certain patterns, which improves the convenience of fabrication and experiment. Our design opens a new way for the development of multi-functional terahertz devices and has potential applications in the terahertz communication fieldshow less
Optically pumped magnetometers (OPMs) have developed rapidly in the bio-magnetic measurement field, which requires lasers with stable frequency and intensity for high sensitivity. Herei
Optically pumped magnetometers (OPMs) have developed rapidly in the bio-magnetic measurement field, which requires lasers with stable frequency and intensity for high sensitivity. Herein, we firstly stabilize a vertical-cavity surface-emitting laser (VCSEL) without any additional setup. The linewidth of the absorption spectrum as a frequency reference is broadened to 40 GHz owing to pressure broadening. To enhance performance, the VCSEL injection current and temperature are tuned simultaneously using a closed-loop control system. The experiments reveal that the VCSEL frequency stability achieves 2 × 10<sup>-7</sup> at an average time of 1 s and the intensity noise is 1×10-6 V/Hz<sup>1/2</sup> at 1–100 Hz. This approach is useful for suppressing OPM noise without additional sensor probe parts.show less