Continuously tunable CW single-frequency Nd:YAP/LBO laser with dual-wavelength output

We present a continuously tunable high-power continuous wave(CW)single-frequency(SF)Nd:YAlO_(3)/lithium triborate(Nd:YAP/LBO)laser with dual-wavelength output,which is implemented by combining an optimized and locked etalon with an intracavity nonlinear loss.The obtained output powers of the stable SF 1080 and 540 nm lasers are 2.39 and 4.18 W,respectively.After the etalon is locked to an oscilating mode of the laser,the wideband continuous frequency tuning and long-term stable single-longitudinal-mode operation of the laser are successfully realized,which can be well used for the applications of quantum information and quantum computation.To the best of our knowledge,this is the first realization of the continuously tunable high-power CW SF 1080/540 nm dual-wavelength laser.

Autonomous trajectory tracking control method for an agricultural robotic vehicle

To address the nonlinearities and external disturbances in unstructured and complex agricultural environments,this paper investigates an autonomous trajectory tracking control method for agricultural ground vehicles.Firstly,this paper presents the design and implementation of a lightweight,modular two-wheeled differential drive vehicle equipped with two drive wheels and two caster wheels.The vehicle comprises drive wheel modules,passive wheel modules,battery modules,a vehicle frame,a sensor system,and a control system.Secondly,a novel robust trajectory tracking method was proposed,utilizing an improved pure pursuit algorithm.Additionally,an Online Particle Swarm Optimization Continuously Tuned PID(OPSO-CTPID)controller was introduced to dynamically search for optimal control gains for the PID controller.Simulation results demonstrate the superiority of the improved pure pursuit algorithm and the OPSO-CTPID control strategy.To validate the performance,the vehicle was integrated with a seeding and fertilizing machine to realize autonomous wheat seeding in an agricultural environment.Experimental outcomes reveal that the vehicle of this study completed a seeding operation exceeding 1 km in distance.The proposed method can robustly and smoothly track the desired trajectory with an accuracy of less than 10 cm for the root mean square error(RMSE)of the curve and straight lines,given a suitable set of parameters,meeting the requirements of agricultural applications.The findings of this study hold significant reference value for subsequent research on trajectory tracking algorithms for ground-based agricultural robots.

Realization of a continuous-wave single-frequency tunable Nd:CYA laser

We demonstrate an all-solid-state continuous-wave(CW)single-frequency tunable 1.08μm laser,which is realized by employing a disordered laser medium Nd:CaYAI0_(4)(Nd:CYA)crystal.The maximal output power of single-frequency 1.08μm laser is 1 W.By rotating the incident angle of the intracavity etalon(IE),the maximal tuning range of 183.71 GHz is achieved.After the IE is locked to the oscillating longitudinal mode of the laser,the continuous tuning range of 60.72 GHz for 1.08μm laser is achieved by scanning the cavity length.To the best of our knowledge,this is the first demonstration of a CW single-frequency widely tunable 1.08μm laser based on Nd:CYA crystal.

调控分子间的电子耦合效应实现多彩超长有机室温磷光

有机超长室温磷光聚合物因其优异的可加工性、灵活性和可重复性等特点,在各种光电应用中表现出巨大的应用潜力.然而,实现全彩的室温磷光仍然是一个挑战.在本文中,我们通过在聚乙烯醇中掺杂不同浓度的三苯基膦盐,成功制备了一系列余晖颜色可调的有机室温磷光聚合物(从蓝色到红色).实验和理论计算证明:室温磷光聚合物颜色的宽范围调控归因于掺杂体膦盐分子间的电子耦合作用大小.此外,这些多彩的磷光聚合物可应用于柔性3D显示和防伪.

Generation of tail-free short pulses using high-pressure CO_(2) laser

The spectral linewidth of a transversely excited pulsed CO_(2) laser is broadened at high working pressures.This phenomenon causes a decrease in the upper-level lifetime such that the pulse width is significantly compressed.Although the tail part of CO_(2) laser pulses owns a non-negligible proportion of total energy,it has minor effects during the interaction process between photons and materials due to its low amplitude.Thus,it is of great significance to yield the tail part and generate a narrow pulse in most applications.In this study,a continuously tunable pulsed CO_(2) laser with a low nitrogen proportion in the mixture is developed to generate tail-free short pulses;a minimum pulse width of 30.60 ns with a maximum pulse energy of 481 mJ is synchronously achieved at a pressure of 7 atm,and the estimated peak power is above 15 MW.A numerical simulation is also conducted for comparison with the experimental results.The contribution of the spectral gain toward the compression of the pulse width is discussed in the last section of this paper.