Sensitivity and quality factor improvement of photonic crystal sensors by geometrical optimization of waveguides and micro-ring resonators combination.

In this work, the process of designing and simulating optical sensors based on photonic crystal (PC) micro-ring resonators (MRRs) has been investigated. According to the PC type, different waveguides and resonators can be designed, and various topologies can be proposed from their combination, for optical sensor applications. Here, the investigated MRR is of the symmetrical micro-hexagonal ring resonator (MHRR) type. Different arrays of MHRR arrangement have been designed to investigate their effects on the output spectrum. The results of the design and simulation of different topologies have been analyzed and compared with other numerical researches. Considering all the necessary aspects of PC optical sensors, a detailed and comprehensive algorithm has been presented for designing these devices and choosing the optimal structure. In a more complementary process, the effects of reflector rods have been investigated, which indicates the existence of similarity and compatibility in the design between the distance of reflector rods and the length of MHRRs to obtain the optimal structure. Finally, the effect of different values of lattice constant and radius of dielectric rods on FWHM, transmission (TR) and resonant wavelength is studied, and the most optimal mode is presented. In order to measure the performance of the proposed optimal sensor, its application for gas detection has been analyzed. TR, FWHM, quality factor (QF), sensitivity (S) and figure of merit (FOM) of the proposed sensor were equal to 96%, 0.31 nm, 2636, 6451 nm/RIU and 2960 RIU-1 respectively. An examination of results from similar research indicates a rational and effective approach for generating diverse topologies, aiming to attain the most optimal configuration for optical sensors employing MRRs. Furthermore, employing a systematic design process based on established principles and the proposed algorithm helps prevent arbitrary parameter variations, facilitating the attainment of desired outcomes in a more streamlined and efficient manner. Given the comprehensive nature of this research, it presents a viable solution for designing optical devices based on MRRs for use in optical integrated circuits (OICs) applications.

Short-term co-ingestion of creatine and sodium bicarbonate improves anaerobic performance in trained taekwondo athletes.

BACKGROUND: Creatine (CR) and sodium bicarbonate (SB) alone improve anaerobic performance. However, the ergogenic effects of CR and SB co-ingestion on taekwondo anaerobic performance remains unknown. METHODS: Forty trained taekwondo athletes (21 ± 1 y.; 180.5 ± 7.3 cm; 72.7 ± 8.6 kg) were randomized to: (i) CR and SB (CR + SB; 20 g of CR+ 0.5 g·kg- 1·d- 1 of SB), (ii) CR, (iii) SB, (iv) placebo (PLA), or (v) control (CON) for 5 days. Before and after supplementation, participants completed 3 bouts of a Taekwondo Anaerobic Intermittent Kick Test (TAIKT) to determine changes in peak power (PP), mean power (MP), and fatigue index (FI). Blood lactate (BL) was measured before, immediately following, and 3 min post-TAIKT. RESULTS: PP and MP increased over time (P < 0.05) following CR + SB, CR, and SB ingestion, with no changes in the PLA or CON groups. There was a greater increase over time in MP following CR + SB (Absolute Δ: 1.15 ± 0.28 W∙kg67) compared to CR (Absolute Δ: 0.43 ± 0.33 W∙kg67; P < 0.001) and SB (Absolute Δ: 0.73 ± 0.24 W∙kg67; P = 0.03). There were no significant time and condition effect for FI (P > 0.05). BL increased following exercise across all groups; however, CR + SB and SB post-exercise BL was lower compared to CR, PLA, and CON (P < 0.05). CONCLUSION: Short-term CR and SB alone enhance TAIKT performance in trained taekwondo athletes. Co-ingestion of CR and SB augments MP compared to CR and SB alone, with similar PP improvements.

Wideband slab photonic crystal waveguides for slow light using differential optofluidic infiltration.

A new type of wideband slow light with a large delay bandwidth product in a slab photonic crystal waveguide with a triangular lattice of circular air holes in a silicon-on-insulator substrate based on optofluidic infiltration is demonstrated. It is shown that dispersion engineering through infiltrating optical fluids-with different refractive indices n(1f) and n(2f)--in the first two rows of the air holes innermost to the waveguide results in an improved normalized delay bandwidth product ranging from 0.187 to 0.377 with large bandwidth (12 nm<Δλ<32 nm) and group index (14.20< n(g)< 24.62) around 1550 nm. The nearly zero group velocity dispersion on the order of 10-(20) s(2)/m is achieved in all of the structures. These results are obtained by numerical simulation based on a three-dimensional-plane-wave expansion method.