phase modulation
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2022 ◽  
Author(s):  
qin liao ◽  
haijie liu ◽  
Yupeng Gong ◽  
zheng wang ◽  
qingquan peng ◽  
...  

Author(s):  
Marlon S. Ribeiro ◽  
Karen C. Ribeiro ◽  
Vinícius M. Lenart ◽  
Rozane F. Turchiello ◽  
Sergio L. Gómez

Author(s):  
Mikhail Bryushinin ◽  
Vladimir Kulikov ◽  
Alexander Petrov ◽  
Igor Sokolov ◽  
Roman Romashko ◽  
...  

Abstract We report the nonstationary holographic current excitation in a β-Ga2O3 crystal at light wavelength λ=457 nm. The material demonstrates insulating properties and high transparency for a visible light, but this, however, does not prevent the dynamic space-charge grating formation and the holographic current observation for various external electric fields - zero, dc and ac ones. The signal amplitude is measured and analyzed versus the frequency of phase modulation, spatial frequency and electric field value. The main photoelectric parameters such as specific photoconductivity, sensor responsivity and diffusion length of carriers are determined for the blue region of spectrum.


2022 ◽  
Vol 20 (1) ◽  
pp. 011901
Author(s):  
Yilin He ◽  
Jingdi Zhang ◽  
Si Xiao ◽  
Yingwei Wang ◽  
Jun He

Nanomaterials ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 153
Author(s):  
Hanlyun Cho ◽  
Heonyeong Jeong ◽  
Younghwan Yang ◽  
Trevon Badloe ◽  
Junsuk Rho

In this work, we present metalenses (MLs) designed to enhance the luminous intensity of incoherent light-emitting diodes (LEDs) within the detection angles of 0° and 10°. The detection angle of 0° refers to the center of the LED. Because the light emitted from LEDs is incoherent and expressed as a surface light source, they are numerically described as a set of point sources and calculated using incoherent summation. The titanium dioxide (TiO2) and amorphous silicon (a-Si) nanohole meta-atoms are designed; however, the full 2π phase coverage is not reached. Nevertheless, because the phase modulation at the edge of the ML is important, an ML is successfully designed. The typical phase profile of the ML enhances the luminous intensity at the center, and the phase profile is modified to increase the luminous intensity in the target detection angle region. Far field simulations are conducted to calculate the luminous intensity after 25 m of propagation. We demonstrate an enhancement of the luminous intensity at the center by 8551% and 2115% using TiO2 and a-Si MLs, respectively. Meanwhile, the TiO2 and a-Si MLs with the modified phase profiles enhance the luminous intensity within the detection angle of 10° by 263% and 30%, respectively.


Nano Letters ◽  
2021 ◽  
Author(s):  
Ivo Tanghe ◽  
Justinas Butkus ◽  
Kai Chen ◽  
Ronnie R. Tamming ◽  
Shalini Singh ◽  
...  

Robotics ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 3
Author(s):  
Takahiro Fukui ◽  
Souichiro Matsukawa ◽  
Yasushi Habu ◽  
Yasuhiro Fukuoka

We propose a method to achieve autonomous gait transition according to speed for a quadruped robot pacing at medium speeds. We verified its effectiveness through experiments with the simulation model and the robot we developed. In our proposed method, a central pattern generator (CPG) is applied to each leg. Each leg is controlled by a PD controller based on output from the CPG. The four CPGs are coupled, and a hard-wired CPG network generates a pace pattern by default. In addition, we feed the body tilt back to the CPGs in order to adapt to the body oscillation that changes according to the speed. As a result, our model and robot achieve stable changes in speed while autonomously generating a walk at low speeds and a rotary gallop at high speeds, despite the fact that the walk and rotary gallop are not preprogramed. The body tilt angle feedback is the only factor involved in the autonomous generation of gaits, so it can be easily used for various quadruped robots. Therefore, it is expected that the proposed method will be an effective control method for quadruped robots.


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