Pichet Limsuwan

This work demonstrates that the As₂Se₃-on-CaF₂ waveguide can enable optical integration with three distinct mid-infrared (mid-IR) light sources on silicon emitting at wavelengths of 3.6, 4.8, and 7.4 μm, while sustaining a competitive waveguide-based sensing figure of merit within a mid-IR spectral range of 3–8 µm. Despite considerable variations in lasing optical mode sizes and polarizations from three different laser chips, the As₂Se₃-on-CaF₂ waveguide can facilitate efficient butt-coupling with each source while maintaining the same As₂Se₃ waveguide thickness. This permits the implementation of As₂Se₃-on-CaF₂ waveguides, in which the waveguide width can be tailored to achieve both competitive optical coupling performance with the light sources and a high sensing figure of merit across the entire wavelength range of interest. This work demonstrates the attractiveness of the chalcogenide As₂Se₃-on-CaF₂ waveguide in terms of design flexibility for chip-scale optical integration in the important mid-IR wavelength ranges.

This research investigates the intersection of construction innovation and cultural heritage through the lens of tourist perceptions of the world’s largest carved golden Buddha, situated at Khao Chi Chan Mountain, Pattaya, Thailand. Positioned as an emerging tourism destination, this site contributes to the rebranding of Pattaya as a globally significant hub for religious tourism. This study highlights how this monumental Buddha statue fosters spiritual experiences, promotes the conservation of art and culture, and encapsulates a historical narrative tied to Thailand’s royal lineage. Notably, the statue’s creation employed a pioneering technique—the only one of its kind worldwide—involving laser-guided carving by artisans, followed by gold leaf application to enhance its aesthetic magnificence. A mixed-methods research approach was adopted, integrating historical document analysis with narrative accounts of the statue’s construction using modern technology, complemented by quantitative data collected through tourist questionnaires. By documenting the historical use of laser technology in creating this iconic Buddhist landmark, this research corrects misconceptions about its construction process and highlights the innovative application of a 20 W Argon ion laser for drawing the image of Buddha on the cliff. This study evaluates tourist perceptions using the DHARMA model, revealing how Destination Identity, Heritage Values, and Memorable Experiences foster emotional connections and spiritual enrichment (β = 0.801, p < 0.001). The findings underscore Khao Chi Chan’s potential to reposition Pattaya as a hub for Buddhist tourism, diversifying its image beyond nightlife-centric tourism. This work contributes to sustainable tourism by demonstrating how sacred sites can balance cultural preservation and economic vitality, offering insights for heritage management and urban tourism development in Southeast Asia.

Fe and Cu powders were mixed at a 50:50 ratio. Then, Fe-Cu alloys were prepared using the ball milling technique with different milling times of 6, 12, 18, 24, 30, 36, and 42 h. The crystalline structure was analyzed using X-ray diffraction (XRD), and it was found that the optimum milling time was 30 h. The homogeneity of the Fe and Cu elements in the Fe–Cu alloys was analyzed using the scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDX) mapping technique. Additionally, the crystal orientation of the Fe–Cu alloys was investigated using transmission electron microscopy (TEM). To fabricate the cathode for nitrate removal via electrolysis, an Fe–Cu alloy milled for 30 h was deposited onto a copper substrate using mechanical milling, then annealed at 800 °C. A pulsed DC electrolysis method was developed to test the nitrate removal efficiency of the Fe–Cu-coated cathode. The anode used was an Al sheet. The synthesized wastewater was prepared from KNO₃. Nitrate removal experiments from the synthesized wastewater were performed for durations of 0–4 h. The results show that the nitrate removal efficiency at 4 h was 96.90% compared to 74.40% with the Cu cathode.

Tiered umbrella or in Thai called Chat means a high decoration or decoration of honor, a type of umbrella that is stacked up in layers along a single axis. At present, in Thailand, the tiered umbrellas are seen in three important places including (1) on the top of the pagoda of various temples, (2) inside the ordination hall of temples, and (3) inside the Grand Palace for the king and the royal family. In the past, a tiered umbrella was made from brass because its color was similar to gold. Constructing each set of tiered umbrellas requires a skilled technician and takes a lot of time. At present, laser cutting of metals has been widely used in the production section of the industry. This is due to the advantages of laser cutting that include narrow kerf width, smooth cutting edges, high cutting speed, reduced material waste, no tool wear, and easy automation and manipulation even for complex shapes. In this work, an example for the construction of seven-tiered umbrellas from stainless steel sheets using a high-power CO2 laser was reported. The results show that the total working time for the construction of a seven-tiered umbrella is about 113 h, which is much less time compared to 3–6 months taken by craftsmen. Therefore, this method can preserve the construction of tiered umbrellas in Thailand even though craftsmen are scarce at present.

Metal contamination from farming, inadequate wastewater treatment, and poor disposal of municipal garbage are major threats to public health. This research aimed to (1) assess the extent of heavy metal contamination in sediment samples, (2) describe the distribution of heavy metals by locating likely pollution sources using a positive matrix factorization (PMF) model, and (3) quantify the potential ecological consequences associated with these metals at six different places around the Chan Thnal Reservoir. The findings indicated steady degradation and suggested moderate to high metal contamination. Fe > Zn > Cr > Cu > Pb > Co > As > Mn > Cd was the trend of metal concentrations in the sediment. Various soil pollution indices showed that most of the studied sediment samples were clean, moderately clean, or slightly contaminated. However, Co and Cd reached high-risk conditions posing a severe problem to the local population living in and around the Chan Thnal Reservoir. Principal component analysis (PCA) was used to estimate primary factors in PMF analysis. It was found that the contamination of As, Cu, Zn, Cd, and Pb originated from agricultural and traffic vehicle sources; however, Zn, Fe, Mn, Cr, and Cu were derived from natural sources (e.g., atmospheric deposition and compost amendment). Furthermore, Fe, Cd, Mn, Co, Pb, and Cr were generated from urban and industrial sources (metal coatings, plastic burning, wastewater irrigation, and sewage sludge). Accordingly, this research improves our knowledge of the prevalence of heavy metal pollution in agroecosystems, which may be used to foresee and mitigate the risks of heavy metal exposure to humans and other organisms.

We report on 3-D FDTD simulation of waveguide-integrated plasmonic Ge/SiGe MQWs photodetectors. Despite several significant works on Ge/SiGe MQW optical modulators, Ge/SiGe MQW photodetectors still show improvable performance, limiting the potential to employ them for both optical modulation and detection. In this paper, we investigate the use of plasmonic concept to enhance electromagnetic field confinement inside the Ge/SiGe MQWs absorbing region with a view to having a compact and low-voltage waveguide-integrated Ge/SiGe MQWs photodetectors. Optical responsivities in term of applied electric fields, device dimensions of width and length, optical bandwidth, fabrication misalignment, and number of QWs periods are taken into account. The investigation shows that using plasmonic enhancement, a waveguide-integrated Ge/SiGe MQWs photodetector that is as short as 5 μm could be obtained with comparable responsivity and bias voltage values to some of the state-of-the-art bulk Ge-based devices, increasing the potential usage of Ge/SiGe MQWs for both optical modulation and detection in low-energy optical interconnects.

We theoretically explore the potential of Si₃N₄ on SiO₂ waveguide platform toward a wideband spectroscopic detection around the optical wavelength of 2 μm. The design of Si₃N₄ on SiO₂ waveguide architectures consisting of a Si₃N₄ slot waveguide for a wideband on-chip spectroscopic sensing around 2 μm, and a Si₃N₄ multi-mode interferometer (MMI)-based coupler for light coupling from classical strip waveguide into the identified Si₃N₄ slot waveguides over a wide spectral range are investigated. We found that a Si₃N₄ on SiO₂ slot waveguide structure can be designed for using as optical interaction part over a spectral range of interest, and the MMI structure can be used to enable broadband optical coupling from a strip to the slot waveguide for wideband multi-gas on-chip spectroscopic sensing. Reasons for the operating spectral range of the system are discussed.