Pulsed polarized vortex beams, a special form of structured light, are generated by tailoring the light beam spatiotemporally and witness the growing application demands in nonlinear optics such as ultrafast laser processing and surface plasma excitation. However, existing techniques for generating polarized vortex beams suffer from either low compactness due to the use of bulky components or limited controlment of pulse performance. Here, an all-fiber technique combining plasmonic metafibers with mode conversion method is harnessed to generate high-performance pulsed polarized vortex beams. Plasmonic metafibers are utilized as saturable absorbers to produce Q-switched pulses with micro-second duration, while the offset splicing method is employed to partially convert the fundamental transverse mode (LP $$_{01}$$01 ) to higher-order mode (LP $$_{11}$$11 ). Eventually, a polarized vortex beams laser is achieved at the telecom band with a repetition frequency of 116.0 kHz. The impact of geometrical parameters including period of metafibers and offset of splicing on the spatiotemporal properties of pulsed polarized vortex beams is systematically investigated. Our findings could pave the way for design, control and generation of all-fiber pulsed polarized vortex beams, and also offer insights into the development of other types of structured laser sources.

In light of the drastically-increasing demands on ubiquitous information acquisition and exchange, battery-powered devices are playing a more critical role in wireless networking, which inspires and expedites the development of energy-harvesting techniques. The sustainability requirements for such devices include two mutual-impacting dimensions: energy supply avoiding battery outage and stable transmissions avoiding buffer overflow. We in this paper propose a power-and-rate adaption scheme subject to the constraints on buffer-overflow probability and battery-outage probability in energy-harvesting enabled networks. The two probability constraints address the statistical assurance for the two-dimensional sustainability, which is suitable to dealing with the highly unpredictable energy-harvesting and channel fading statuses. Specifically, by applying the asymptotic queuing analyses to data-transmission and energy-harvesting processes, we can characterize both of the battery-outage and buffer-overflow probabilities via the effective-capacity/-bandwidth theories. Then, we formulate the effective-capacity optimization problem, which maximizes the sustainable throughput while complying with the statistical buffer-overflow and battery-outage constraints, and solve for the optimal power-adaptation scheme. We also conducted abundant simulations to evaluate our scheme's performances, demonstrate the superiority of our proposed scheme over existing baseline schemes, as well as study the impact of sustainability requirements on the performances.

The electrical characteristics and stability of indium gallium zinc oxide (IGZO) thin film transistors (TFTs) are improved through surface single crystallization of IGZO film by Cs ions adsorption at room temperature. The experimental results show that the Cs ions can bond with the oxygen ions in IGZO film, changing surface structure of IGZO film from amorphous to a single crystalline. The electrical properties and stability of surface single crystalline IGZO and a-IGZO based thin film transistors were investigated, respectively. With the introduction of the surface single crystalline of the IGZO film, the electrical properties of TFT were greatly improved, showing that the carrier mobility improved from 5.28 cm ² V ⁻¹ s ⁻¹ to 8.84 cm ² V ⁻¹ s ⁻¹ , and the threshold voltage deceased from 7.6 V to 2.3 V, accompanied with a leakage current below 10 ⁻¹⁵ A. The stability of V _th shifts in surface single crystalline IGZO based TFT was 6.3 V under V _GS = 20 V for 5000 s, improved by ∼32% compared with that of a-IGZO TFT.

To improve the performance of amorphous InGaZnO_x (a-IGZO) thin film transistors (TFTs), in this thesis, Cs⁺ ions adsorbed IGZO (Cs-IGZO) films were prepared through a solution immersion method at low temperature. Under the modification of surface structure and oxygen vacancies concentrations of a-IGZO film, with the effective introduction of Cs⁺ ions into the surface of a-IGZO films, the transfer properties and stability of a-IGZO TFTs are greatly improved. Different parameters of Cs⁺ ion concentrations were investigated in our work. When the Cs⁺ ions concentration reached 2% mol/L, the optimized performance Cs-IGZO TFT was obtained, showing the carrier mobility of 18.7 cm² V⁻¹ s⁻¹, the OFF current of 0.8 × 10⁻¹⁰ A, and the threshold voltage of 0.2 V, accompanied by the threshold voltage shifts of 1.3 V under positive bias stress for 5000 s.