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Simulation Ekert quantum key distribution protocol using Qiskit for verifying entanglement and security
(2026-03-05)
Khotphuthon, Wasuphon
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Buranasiri, Prathan
Bell’s Theorem provides a theoretical foundation for understanding the non-locality of quantum mechanics, particularly through the concept of quantum entanglement. This project implements and simulates the Ekert quantum key distribution protocol using IBM’s quantum hardware via Qiskit. Based on Bell’s Theorem, the protocol employs entangled qubit pairs distributed to two parties, Alice and Bob, who perform measurements in randomly chosen bases. The results are analyzed using a Bell test to verify entanglement. A violation of Bell’s inequality confirms secure, uncompromised key generation. If entanglement is disturbed, the key is discarded.
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Micro-nanoscale metrology for reference material size from speckle pattern images
(2026-03-05)
Sirikarntayuprakit, Pakkhanan
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Plaipichit, Suwan
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Ngansalung, Benjarat
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Buranasiri, Prathan
Recently, the fabrication of micro- and nanoscale materials has become necessary in daily life. The sizes and compositions of those materials need to be explored, as the products will be used in other industries. Therefore, micro-nanoscale metrology is necessary for quality control, as some processes require the use of reference materials for comparing the size of industrial micro-nano-sized products. This study investigates the feasibility of using laser speckle imaging. Since the laser speckle setup is relatively inexpensive, the system is a good choice for installation in small factories. Combined with the Gray-level Co-occurrence Matrix (GLCM) analysis method, this technique has been used to compare the size of reference materials that are fabricated by the National Institute of Metrology of Thailand. Two sizes of reference materials, 100 nm and 1,000 nm, were of interest. The particles are composed of polystyrene, and their certified mean diameter and size distribution were determined using transmission electron microscopy (TEM), validated through international comparison, and served as the basis for testing the technique. Clear differences in GLCM contrast, dissimilarity, energy, and correlation were observed between the two particle sizes, reflecting their distinct scattering characteristics. The results demonstrate that speckle-based texture analysis provides a sensitive response to particle size variation, offering a promising pathway toward low-cost, non-invasive micro-nano metrology.
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Photorefractive Effect in an Imperfect Cerium Doped Barium Titanate Crystal: Reflection Grating Case
(2026-01-01)
Khotphuthon, Wasuphon
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Plaipichit, Suwan
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Suchat, Suebtarkul
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Buranasiri, Prathan
The photorefractive (PR) effect, a nonlinear optic phenomenon, occurs in materials that have electro-optic (EO) properties. When two coherent beams of light interfere with each other in a PR material, donor electrons between valence band and conduction band, caused by material impurity, absorb the photon and are excited into the conduction band and generate electron-hole pairs. This process induces a periodic electric field called a space charge field that alters the material’s refractive index due to the EO effect. In this research, we explored reflection grating (RG) in an imperfect Ce-doped BaTiO3 crystal and then showed optical image correlation using the RG. Two beam coupling was investigated using two non-Gaussian incident beams on the opposite surface of an imperfect Ce-doped BaTiO3 crystal. Light at green wavelengths from a semiconductor laser was used as the source of the incident beams and entered at certain angles relative to the crystal c-axis. Large beam coupling power was observed in both incident directions when the angle between both incident beams is at Bragg’s angle in the direction of the c-axis. The diffraction light was found to be in the same polarization as the incident beam. In addition, interesting results for the optical correlation using reflection grating were demonstrated. These results suggest that by doping BaTiO3 with cerium, strong beam coupling or photorefractive grating can be observed with certain incident writing angles on the crystal, which could be utilized in future flexible holographic devices in the future.
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Comparison of Interferometry Applications: Michelson vs. Sagnac Interferometers
(2025-05-14)
Wannasri, Thanawat
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Yindeesuk, Witoon
;
Buranasiri, Prathan
An interferometer is a crucial instrument for collecting information on interference patterns, widely used in both scientific and industrial applications. This paper was focused on comparing the interferometric applications of the Michelson and Sagnac interferometers. The Michelson interferometer, characterized by its double-path setup, and the Sagnac interferometer, which operates on a common-path principle, were analyzed. Experiments were conducted to capture interference patterns of different samples using both interferometers. In the first experiment, the image fringes of the alphabet characters (K, M, I, T, and L) were captured, while in the second, fingerprint patterns were captured. The results showed that both interferometers produced similar fringes for the alphabet characters, although the Sagnac interferometer exhibited a higher circular frequency. In the fingerprint experiment, the Michelson interferometer produced linear fringes. This study highlights the distinct fringe patterns generated by each interferometer when different samples are analyzed, providing valuable insights into their diverse applications.
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Asymmetrical resonant cavity thin film devices designed for vanadium dioxide applications
(2025-01-01)
Padungatthakij, Chettanat
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Wicharn, Surawut
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Buranasiri, Prathan
Vanadium dioxide (VO2) is a volatile phase change material (PCM) that undergoes a rapid structure transition when heated above and reverts when cooled below its transition temperature. This transition alters its optical properties significantly when compared to normal materials, making it possible to design a thin film device with switching operation mode. In this paper, we redesign VO2-based devices with two different use cases to introduce an asymmetrical resonant cavity (AsymReca) structure. The redesigned process aimed to enhance the optical performance of the central VO2 layer and gave it an antireflection property. Using simulation, we discuss the advantages and limitations of this design approach and highlighting its potential use case.
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Measurement of the degree of polarization using FTO in a rectangular-type Sagnac interferometer
(2025-01-01)
Usman, Abdullahi
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Bhatranand, Apichai
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Jiraraksopakun, Yuttapong
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Buranasiri, Prathan
This paper presents a modified Sagnac interferometer using a self-referenced polarization and phase-shifting technique for real-time measurement of rotating polarized light and the degree of polarization (DOP). The setup achieved a high DOP of 98.97%, enabling accurate reference signals for measuring the effective thickness in the samples deposited on the FTO glass substrate.
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Speckle imaging of graphene oxide and reduced graphene oxide
(2025-01-01)
Sirikarntayuprakit, Pakkanhan
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Yindeesuk, Witoon
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Buranasiri, Prathan
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Rattanasirawit, Chinnapat
Laser speckle imaging is a non-contact technique for analyzing materials' surface roughness and scattering characteristics. This study investigated the speckle patterns of graphene oxide (GO) in sheet form and reduced graphene oxide (rGO) in powder form under coherent laser illumination. The intensity distributions were recorded using a CMOS camera and analyzed statistically to determine key surface parameters, including speckle contrast and roughness. The results show that GO produces a finer, more uniform speckle pattern with lower contrast and roughness values than rGO, which exhibits coarser and more irregular patterns. These differences reflect the distinct structural characteristics of the two materials. The findings demonstrate the potential of speckle imaging for non-destructive optical characterization of graphene-based materials.
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Optimizing indoor digital holography for photovoltaic surface analysis: A novel approach for solar PV testing conditions
(2025-01-01)
Bako, Abdullahi
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Voochaiphum, Bunyarit
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Suchat, Suebtarkul
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Buranasiri, Prathan
The sun is a clean, inexhaustible, free energy source, and it is environmentally safe. The rapid expansion of the solar photovoltaic (PV) industry demands innovative quality control techniques for defect detection and efficiency optimization of solar cells. Traditional methods such as electroluminescence, photoluminescence, and infrared thermography have limitations in detection resolution, real-time monitoring, and surface characterization. In this research, a novel approach digital holography-based non-contact method for detecting and analyzing defects in solar cells, such as micro-structural defects, surface roughness, dust, scratch, and cracks, was investigated. Laser module was used as our light source to optimize indoor test conditions. An integrated recognition system was developed to automate and improve accuracy using real hologram images. Reconstruction images and Fourier transforms were used to extract the phase and amplitude across the solar PV cell. This preserved the module's integrity and providing detailed defect information from the solar surface.
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Digital Holography Technique for exposing Defect on Photovoltaic Cell
(2025-01-01)
Bako, Abdullahi
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Voochaiyaphum, Bunyarit
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Buranasiri, Prathan
We employed digital holography techniques to detect surface anomalies from photovoltaic cell. The approach allowed for precise spatial mapping of micro-crack features without requiring physical contact or electrical biasing compared to conventional methods.
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Digital Holography Technique for exposing Defect on Photovoltaic Cell
(2025-01-01)
Bako, Abdullahi
;
Voochaiyaphum, Bunyarit
;
Buranasiri, Prathan
We employed digital holography techniques to detect surface anomalies from photovoltaic cell. The approach allowed for precise spatial mapping of micro-crack features without requiring physical contact or electrical biasing compared to conventional methods.

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