This PDF file contains the front matter associated with SPIE Proceedings Volume 11331, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

TOMBO is a compound-eye imaging system in which an image sensor is divided into multiple sections by small lenses. The system has notable features such as the capability of capturing various types of object signals at a time, flexibility in optical system design suitable for given purposes, and so on. Owing to the system composition, most of the previous researches were performed under specific indoor environments so that the application targets were limited.

In this study, we developed a mobile TOMBO system capable of operating in a field environment. Related to the structure of TOMBO, the baseline for distant measurement is very short. In the outdoors environment, the distance to the target objects is long, so that the parallax is too small to be detected. On the other hand, such a small parallax provides an advantage in multi-modal observation of the same object because the field-of-views of individual lenses are almost identical. Considering these properties, the mobile TOMBO system is suitable for multi-spectral imaging. A prototype system was developed with an embedded computer, Raspberry Pi 3 Model B, connecting to a multi-spectral TOMBO. The spectral channels were set as 450nm, 530nm, 660nm, 740nm, 730nm, 770nm, 850nm, 910nm, and 970nm.

The developed TOMBO system was mounted on an unmanned aerial vehicle (UAV) and aerial observation experiments were performed. Aiming at the application of plant monitoring, the observed aerial images were evaluated by a normalized difference vegetation index (NDVI) used in remote sensing. The obtained results confirmed the effectiveness and potential capabilities of the mobile TOMBO system.

Plasmonic field enhancement localized around metallic particles is useful for improving sensitivity in sensing applications. In this research, we used finite-difference time-domain modelling to study plasmonic field enhancement in an array of polystyrene particles covered with gold, to understand the effect of the incident polarization and the particle shape. The gold particle shapes were changed from a perfect sphere to an ellipsoid with the vertical height varying as 930 nm, 880 nm and 830 nm, while the horizontal diameter was fixed at 930 nm. The simulated structure was composed of gold spheres arranged in a hexagonal-close-packed array on an 80-nm thick gold film. When the metallic spheres were arranged on the gold film the plasmonic enhancement was up to 1.8 times greater than for the array without a metallic film. The plasmon resonances of the array were strongest at the bridge connections between the particles, and at the surface of the particles without connections. Where there were no particle-particle connections, the resonant field distributions had one, two, three and higher nodes. In addition, the absorption spectra for various sized rectangular structures with gold particles at the center were investigated to determine the effect of the lattice period on the wavelengths of resonance. The results showed that the lattice period did not greatly perturb the resonance modes for this structure. This study aids improved design of plasmonic-photonic crystals with micron-scale periods for sensing applications.

For establishing terahertz (THz) imaging with rapid scan, the influence of the response speed of a microelectromechanical system (MEMS) bolometer on the image quality have been evaluated and compared it with a pyroelectric detector (PED). The MEMS bolometer was operated with the frequency modulation detection mode in which the frequency shift due to the illumination of the laser light is tracked by a phase-locked loop (PLL) system. In the detection system using the PED, the laser light was chopped by an optical chopper and output signals were measured by a lock-in amplifier. Output signals from the detection systems were recorded by an analog-to-digital converter (ADC). An etched metal bookmark was used for the imaging object and imaging was made by a combination of continuous scans in the X direction and step scans in the Z direction. In imaging using the MEMS bolometer under a stage speed of 25 mm/s, the fine structures composed of very small holes much smaller than 1 mm were clearly observed. The images acquired by the MEMS bolometer were almost the same quality regardless of the stage speed, while in the case of the PED the images were distorted with increasing the stage speed. This is due to the bandwidth of the detectors. These results imply that the MEMS bolometer enables to acquire images with rapid scanning.

Holograms are rich in high frequency components with less correlation between pixels and therefore compression of holograms is a challenging area. Computer Generated Holograms (CGH) is generated by computing interference patterns represented in complex numbers with the help of computers. Currently for the representation of these complex numbers in CGH, phase-only holograms are widely used. It is an approximation of original hologram, but it suffers from noise. The proposed work deals with representation of values in complex domain into real domain based on quadrant mapping techniques. Compressed hologram representation using the proposed method provides significant increase in quality for reconstruction compared to phase-only hologram.

Radio-over-fiber (RoF) including intermediate frequency-over-fiber (IFoF) technologies have been considered to be one of the effective transmission technologies for the mobile fronthaul (MFH) links in the fifth generation (5G) and beyond- 5G mobile communication systems. In this paper, we explain the concept of a MFH architecture for 5G and the future mobile services featuring cascaded IFoF and RoF links in which the functions of channel extractions and frequency conversions are implemented by the combination of analog and digital signal processing. In addition, we present our experimental results to verify the effectiveness of the cascaded IFoF-based MFH links.

We demonstrate an application of the mechanically induced long period fiber grating system for a foot plantar measurement. The system is designed as a fixed fiber grating platform that can be utilized for monitoring a subject’s foot plantar pressure distribution in static and dynamic activities. The pressure information obtained from the foot loading characteristics can be used for various application such as disease diagnosis of foot problem, foot ware design, sport biomechanics and injury prevention. The system is composed of a strand of a single mode fibers with 800 nm cut off wavelength and circular plastic grooved plates with the grating period of 0.8 and 1.0 mm made by 3 D printing. The sensing units are fixed at biomechanically significant positions; fore-foot, mid-foot and hind-foot of the foot platform for monitoring the foot plantar pressure distribution. The sensing locations are chosen appropriately to contact with sensitive areas of foot and can initially provide enough foot plantar pressure characteristics of a subject. The fiber sensing units with grating having different periods provides different sets of transmission spectra which separately respond to individual perturbed points. Preliminary result shows that the system can be used to classify different types of foot. With some advantageous properties of the optical fiber such as structural flexibility and light weight, the system can successfully be used to monitor the static and dynamic perturbations such as the movement of the body center of mass and foot actions in the stance phase. The study has demonstrated that the proposed fiber-optic sensing systems has a feasibility of being used as an alternative for insole plantar pressure detection systems.

Optical Communication system with multimode fibers at low-frequency passbands have been studied for signal transmission. In previous studies, it was found that the most commonly known bandwidth is called 3-dB modal bandwidth and is limited between 200 to 500 MHz·km. There have been several studies of low-frequency passbands which used subcarrier signals in order to increase the bandwidth for the optical communication system. Some of these possible passbands are affected by nulls of frequency response of MMF. To overcome this problem, they must be selected carefully using the methods discovered in recent studies. It was found that to achieve the proper Bit-Error-Rate (BER), the optical communication system required more optical power. In this paper, the optical communication system with MMF at low- frequency passbands is modelled by applying a 4-Amplitude Shift Keying (4-ASK) with linear block encoding. Using the subcarrier multiplexing (SCM) technique with 3 low-frequency passbands and 3-dB modal bandwidth as channels for transmitting a high data rate signal, from the simulation result, it is found that using (31, 26) linear block encoding, the data rate of 546 Mbps can be obtained with a BER lower than 10^-8 and a 6-dB coding gain is achieved. The total transmitted data rate is higher by approximately 2.73 times than the rate sent by the 3-dB modal bandwidth.

This paper focuses on extending the maximum link distance between typical optical transceivers in mobile aggregation networks. Our duplex optical amplifier is inserted between base-stations in suburban or border areas, in order to amplify 10 Gigabit Ethernet data transmitted in C-band wavelength (1530 - 1565 nm). It consists of two Conventional Erbium- Doped Fiber Amplifiers (C-EDFAs), each for unidirectional transmission. It can support 4G Long-Term Evolution (LTE)/5G network application at 10 Gb/s and higher bit-rates. The measured parameters of duplex optical amplifier are operating wavelength range, amplifier gain, and noise figure (NF). Their operating ranges of both C-EDFAs are from 1530 nm to 1562 nm. Their maximum gains are approximately 24.5 dB at 0.2-Ampere pump current and 1550-nm input wavelength. Their NFs are below 6.3 dB at -3 dBm input power and 1550-nm input wavelength. In addition, we measured a Burst-Mode EDFA (BM-EDFA) to compare with C-EDFAs. The BM-EDFA’s operating range is from 1537 to 1561 nm. Its maximum gains are approximately 24.5 dB and 31 dB at pump current of 0.175 Ampere and 0.38 Ampere respectively. Its NF is below 6 dB at the same input power and wavelength as in C-EDFAs. From these parameter results, the characteristics of C-EDFA and BM-EDFA are likely the same. However, from 10 Gb/s data transmission experiment, BM-EDFA has the lowest power variation on Ethernet packets, compared to duplex C-EDFA and another commercial EDFA. Furthermore, the effects of EDFA noises and Chromatic Dispersion (CD) over a link’s performance has been investigated and shown by Bit Error Rate (BER) measurements. The Dispersion Compensation Fiber (DCF) and 1-nm Tunable Optical Band-Pass Filter (TOBPF) were added after C-EDFAs, to reduce CD and noises respectively. Finally, the data transmission over 120 Km Standard Single-Mode Fiber (SSMF) & 15 Km DCF by using duplex optical amplifier at 10 Gb/s bit-rate was achieved with 0.5-dB power penalty at 10^-9 BER. Moreover, we can identify that BM-EDFA is more suitable for Ethernet link than C-EDFAs. Hence, we propose that C-EDFAs in duplex optical amplifier should be replaced by BM-EDFA to improve the link performance.

In this paper, we study an application of quantum key distribution (QKD) for indoor visible light communication (VLC) networks. Continuous variable QKD (CV-QKD) is used due to the fact that it is less expensive, working at room temperature, and much easier to implement. We design and analyze the security performance of the CV-QKD protocol based on sub-carrier intensity modulation (SIM) over indoor VLC systems taking into account the effects of VLC channel and other physical layer impairments. The mathematical expressions for quantum bit-error rate (QBER) and secret-key rate are derived. Based on the mathematical expressions, various systems’ metrics, including the modulation depth and the dual-threshold scale coefficient, can be determined so as to QBER and secret-key rate meet the design criteria.

This work was aimed to develop low cost devices for clear underwater exploration combined together with visible light communication (VLC) systems. This would be a new expectation of VLC application systems in the future. The complete system consisted of transmitter and receiver parts. The transmitter is responsible for transmitting sensor information data, using light emitting diode (LED). At the receiver, a photodiode is used to receive the light signal and convert into electrical signal. The pH and temperature values are displayed on the application in smartphone with Android operating system, using Bluetooth communication systems. The VLC systems work well at the maximum distance between transmitter and receiver was 80 centimeters long, and the maximum distance of Bluetooth was 10 meters.

In this paper, we propose a three-dimensional VLC indoor positioning system using smart device camera receiver whereby the rolling shutter effect of CMOS camera sensor to detect the encoded identification data and necessary information regarding transmitter positions from the individual LEDs. No prior assumptions have been made regarding each LED transmit power, this allows for non-identical LEDs and their power deterioration over time. Images of 4 LEDs are required to estimate the receiver position. In the image capturing process, it is necessary to adjust the exposure setting. The captured images are processed by converting them to black and white where the black and white stripes may be decoded. Then by applying a different threshold, we propose a method to use the white pixel area (counted in number of pixels), corresponding to each LED image, to estimate the distance between each LED and the receiver. These estimations are used in trilateration algorithm to determine the receiver position. Through proper calibration, the position error is within 10 cm.

Metamaterials (MMs) are the artificially engineered materials that can exhibit particular electromagnetic properties such as negative refractive index, left-handed behavior, extraordinary transmission, etc. These fascinating properties of MMs are of great and increasing interest to be used in various applications in the terahertz regime (0.1-10 THz). In this study, the electromagnetic property of metamaterial that we are interested is an extraordinary transmission for creating a “Metamaterial Absorber (MMA)”. Over the past decade, there has been a number of designed patterns of metamaterial absorbers having high absorptivity and also multi-absorption characteristics such as split-ring resonator, square, U-shape, T-shape and Hexagon. Most of the Hexagons are designed to have the absorption characteristics in GHz frequency. We intend to investigate the effects of the parameters regarding the absorption in the terahertz regime, especially in 0.3-5.0 THz for various applications such as security and medicine. The proposed absorber structure in this study consists of 3 layers which are a periodically arranged metallic hexagonal pattern layer, a dielectric layer, and a continuous metallic layer. Length, width, number of gaps, gap size, the position of a gap of the hexagon in the first layer are the studied parameters. The proposed hexagon metamaterial absorber of the first design having 5 gaps with gap size 5 μm each located at the corner of the hexagon provide 4 absorption bands with high absorptivity. For the other design having 6 gaps with gap size of 5 μm each located at hexagon side show not only 3 narrow bands of perfect absorption but also a broadband absorbance for the terahertz regime around 3 THz.

We developed an economical assembly for a silicon photonics resonator device including a device mount and lensed fiber holders for input and output fibers. The parts are fabricated by 3D printing technology using resin with digital light processing (DLP) technique and cured with UV light (405nm). The lensed fibers are aligned to the device waveguides using 6-axis aligner platform and their holders are affixed to the device mount by UV glue. Our in-house assembly module is able to firmly affix the fiber holders to the device mount and align the input and output lens fibers to the device spot size converter (SSC) of dimension 3.4 × 3.5 μm². After alignment completion, the assembly can be detached from the aligner stage to be used in un-stabilized benchtop measurement system. The benchtop measurement system for the silicon photonic sensor device consists of a tunable laser, a polarizer, an optical power meter, and a container housing the device assembly, peristalsis pump and control circuits that was developed inhouse for microfluidics control having flow rate in the level of nanoliter/minute. In addition, a software has been developed for the measurement of the device resonant wavelength and wavelength shift due to sensor activity. We have demonstrated that the silicon photonics resonator that has been mounted on our assembly in the above measurement system showed acceptable performance by comparing the results with those obtained by mounting the device on stabilized fiber alignment platform. Thus, the 3D printed assembly may be used for silicon photonics device mount in early portable sensor prototype development.

It is well-known that an explosive is defined as a material which contains a large amount of energy stored in chemical bonds. The energetic stability of gaseous products, and hence, their generation comes from the strong bond formation of carbon (mono/di)oxide and (di)nitrogen. Consequently, most commercial explosives are contained –NO₂, -ONO₂, and/or –NHNO₂ groups which, when detonate to release gases like the aforementioned ones, such as nitroglycerine, TNT, HMX, PETN, nitrocellulose, etc. It is revealed that the elemental compositions, especially nitrogen (N) is found mostly in the explosives and chemical fertilizers. It is also proved that chemical fertilizers can be used as the explosive material. In this work, the elemental composition and structure are analyzed using a scanning electron microscopy coupled with an energy dispersive X-ray spectroscopy (SEM-EDS) and a proton-induced X-ray emission spectroscopy (PIXE). The chemical fertilizer structures are also characterized using Small angle X-ray scattering (SAXS) and X-ray photoelectron spectroscopy (XPS) based on synchrotron radiation. It was shown that N was showing a relatively high amount in various samples. In addition, the elemental composition analysis revealed the presence of trace elements. Explosives and chemical fertilizers had differences in the specific elemental compositions. It can be concluded that these methods seem to be used as a fingerprint examination to identify various kinds of the explosives and chemical fertilizers.

Negative index media have a phase velocity opposite to that of the pointing vector. Therefore, if media having the same absolute value of positive and negative refractive indices are alternately arranged, standing waves are generated along the boundaries of the media because these wavelengths are the same and the directions are opposite. We propose a method of generating a stationary interference fringe that is caused by self-interference with irradiating light from a direction parallel to the positive and negative media boundaries.

This paper presents a novel method for camera calibration and image alignment of an image fusion system that consists of a thermal and a color camera. The calibration board that consists of a heated metal and an acrylic plate with asymmetric circle grid pattern was developed. The board was used to calibrate intrinsic parameters of the thermal camera and also used to find the homography to align images of the two cameras. The aligned images have been fine adjusted for their misalignment due to difference in projection centers by region of interest (ROI) setting. The visible camera was calibrated separately by using a typical calibration board with an asymmetric circle grid printed paper. The evaluation was performed in two scenarios. The first one is an indoor static scene. And the second one is an outdoor dynamic scene that is a vehicle tracking application by using CAMShift algorithm. The results validate the proposed method with high accuracy.

In this paper, a measurement system using absorption spectroscopy was designed and realized. Using alternative measurement method, the system could perform with minimum calibration requirement. Features of sucrose solutions with Brix percentage from 12 ^oBrix to 16 ^oBrix were measured and extracted. Moreover, three artificial intelligent methods, namely artificial neural networks, artificial neural networks with principal component analysis, and genetic algorithm, were applied to predict unknown concentrations. The key difference between methods was the assumption on residual error’s statistical characteristics. Experimental results showed that the correlation and collinearity in structure of measured data were essential for higher prediction accuracy in artificial intelligent methods. In our experiments, genetic algorithm provided the most accurate predictions.

Grain chalkiness is an unpleasant trait adversely affecting appearance and milling quality of rice. It causes from packing of carbohydrate non-uniformly in the grain due to fluctuation of rain, humidity and heat. Chalkiness affect the quality and the price of rice directly. To categorize the rice grain chalkiness, the effective tool has not yet been implemented to be used widely in Thailand. Mostly, human detection has been carried out to classify the grain quality. Here we present the FTIR result of grain chalkiness from rice sample obtained from Department of Rice, Ministry of Agriculture of Thailand. Rice grain with chalkiness level of 1 to 5 were investigated. From FTIR result, all samples show the peaks for O-H, C=O and C-H bonds. We found no significant difference in the FTIR peak of all 5 levels of chalkiness which indicates that the cause of loose packing of carbohydrate in chalky area does not originate from microscopic level. UV- Vis spectroscopy showed the significant difference in absorption between chalky and non-chalky area in the visible range around 500-530 nm. Thus, Image processing has been carried out with green light illumination to classify level of rice chalkiness automatically in the aim to replace human detection. Two cameras were set to give perpendicular views of rice grain. Cross sectional thin slab was calculated from image analysis of perpendicular views and was integrated to obtain chalkiness volume and total rice grain volume. Thus, chalkiness level can be acquired. The algorithm was further developed as an application implementing on a mobile phone for practical use in the rice field.

Oil accidents largely occur due to mining and transport by tankers, but also due to the pipeline transport. The reason can be a leakage of the pipelines and their damage caused by their age or external influences. The leaks of oil into the soil present a high risk because of their inconspicuousness, especially in case of a slow leak, which may go unnoticed for a while. Petroleum products are soluble in water, which may lead to the contamination of the surrounding groundwater. Self-monitoring of these transport systems is an important part of their operation. This article deals with the measuring of the leak by petroleum products using optical fibers. During the measuring, we use a distributed temperature system (DTS). The DTS is based on a principle of an optical reflectometer, i.e. the light impulse is transmitted to the fiber, part of the impulse returns back to the detector due to optical scattering. The phenomenon of the returning part of the light impulse is called the Stimulated Raman Scattering. The DTS can measure temperature along the entire length of the fiber in real time. Basically, we can imagine a thousand of sensors along the measured track with the accuracy of 1 meter. In this case, we have an optical cable laid down along the testing polygon. This testing polygon is intended to simulate the transport of the oil products in the pipelines. Many different leaks are simulated here. The measuring is based on the volatility of petroleum products and their ability to evaporate. The surface of the object, from which the oil evaporates, decreases in temperature. Sudden change in temperature at a given point detects a possible leakage of petroleum products. This leak can be immediately pinpointed with the accuracy of 1 meter and necessary intervention can be performed.

Optical fiber sensors are becoming increasingly popular. Their biggest advantage is mainly resistance over electromagnetic interference and passivity in terms of power supply at the measuring point. Where the highest precision measurement and the highest responsibility is required, fiber-optic sensors are the best solution. In recent years, many studies about Bragg grating, being used in sensor applications, has been published. The development of these sensors has made a huge progress and the range of application is increasing rapidly. Bragg gratings are already widely used in industry, construction and are becoming more and more substantive in critical infrastructure. This article deals with an implementation of Bragg gratings into the geotextile and the creation of complex sensory elements. These sensor elements can be used to measure non-electric quantities (pressure stress, temperature, etc.). Selection of suitable geotextiles and combining them is an important step. From a sensory ability point of view, it is necessary to ensure the best possible transfer of the measured quantity to the geotextile and the Bragg grating. It follows to material selection and, above all, to appropriate distribution of sensory gratings within the geotextile. At the same time, it must also serve as a optical fiber protection that is very sensitive to a mechanical damage. It is necessary to ensure a correct fixation of the optical fiber with the Bragg grating. The assumption is that the geotextile will be stressed by pressure and tension. Thus, the optical fiber will be stretched in the geotextile and must not be released.

Matter-wave near-field interferometric experiments require interference contrast as high as possible in order to extract information from the interference patterns. One of the tasks to accomplish this requirement is to align the distances between gratings and detection. We present here a method for this precision alignment. An electron beam as a matter-wave source, a diffraction grating, and mask grating were used in this study. The simulations show that the longitudinal scanning of the mask grating with the detection can specify the exact location of the near-field or so-called Talbot distance with the condition of using the gratings with small open fractions. Therefore, the various open fractions were done in the calculation. Due to the lack of commercial gratings with small open fractions, a technique of two overlapping gratings can be applied for changing arbitrary grating shapes and open fractions. We conclude that smaller open fraction of the gratings gives better longitudinal alignment. The results show that the Talbot distance is located at the highest throughput behind the gratings. The present study can provide a method for implementing matter-wave diffraction experiments in the future.

We explore the possibility of using transition energies of a doubly excited helium atom to describe the absorption lines of interstellar medium. We follow the method of approximated separation of variables in hypersperical coordinate in solving the energy levels of doubly excited helium. Although the results do not exactly match with the absorption spectrum of the diffuse interstellar bands, they show some correlation. We have also shown that the distribution of the difference between observed spectrum and the calculated result can be fit by normal distribution with the mean value close to zero. Furthermore, we argued that the distribution obtained from randomly generated lines are significantly different from the calculated result.

Due to an exponential growth of utilizing laser, light, and RF for medical and medical dermatology, there have been many issues regarding the use of those technologies. Modern devices are straightforward to use, but they are very powerful and are capable of considerable damage when used incorrectly, especially pulse laser, with high intensity. Since there has been an increasing use of pulse laser in medical and cosmetic applications in Thailand, and the laser pulse power and energy are needed to be calibrated. National Institute of Metrology, Thailand (NIMT) has set up a laser energy system and provide calibration service to customers. The service supports calibration of low-level laser pulse at wavelength of Nd-YAG laser at 1064 and 532 nm and at energy range 1 mJ-100 mJ. The laser energy standard was calibrated by National Metrology Institute of Japan (NMIJ) and compared with National Metrology Institute of Germany (PTB) measurement system under scientific collaboration MOU between NIMT & PTB.

Compact atomic magnetometer (AM) has potential applications in biomedical devices to measure magnetic signals from human organs, e.g. magnetocardiography and magnetoencephalography. Reducing the size of Helmholtz coils is an essential step for a design of compact AM, which also leads to lower cost in manufacturing processes. However, the homogeneity and magnitude of the magnetic fields and the size of a rubidium vapor cell must be considered for the decrease of the coil size. Here, we report a design of compact AM with square Helmholtz coils of 24×24×24 cm³ housing a rubidium vapor cell of 7.5 cm in length. The coils were calculated to induce a constant magnetic field of 0.5 gauss covering the length of 10 cm along the axis of symmetry of the coils. The field gradient was measured to be less than 4% of the magnitude over the distance of 6 cm. For zero-field condition, the field gradient was no more than 1 mgauss in all axes. Further developments of square Helmholtz coils for improving the field gradients are still needed before implementing in the compact AM.

Optical devices based on silicon photonic technology are very important as supporting current and future communication systems in terms of their scale of integration and productivity. Although various devices have been proposed and realized using silicon photonics technology, this paper describes an optical path switch combining a large number of 2×2-unit-switches loaded with electrical heaters on a Mach-Zehnder interferometer (MZI). We have been developed 8×8 and 32×32 optical matrix switches, which employ a path-independent-insertion-loss (PILOSS) configuration that has a feature of the same device count on the any path of the connection. The PILOSS structure has a feature of Strictly-nonblocking, which can connect any input port to any output port without changing existing connections when making a new connection. Each heater of the optical switch is driven by pulse-width-modulation (PWM) generated by a Field Programmable Gate Array (FPGA). The calibration of the pulse width according to the 2×2-unit switch state (Cross or Bar) is performed on all of the MZIs in advance, and the values are stored in a table of the FPGA. Separately, Cross / Bar state tables corresponding to the connection pattern of the optical input port and output port are prepared, and the pulse width switching according to the state table is simultaneously performed based on a switching command from the upper layer controller. It takes a certain amount of time to change the heater temperature of the MZI arm for switching. However, it is possible to shorten the switching time by applying a signal named “Turbo pulse” for a short term at the transition. When the temperature is raised by the heater, the switching can be speeded-up by applying a continuous high-level voltage to the heater temporarily. Even in the case of the temperature drops, the switching time can be accelerated by applying a continuous high-level voltage to the heater on the other arm of the MZI. The switching time, which was actually 30μs without Turbo pulse, could be reduced to 2.5 μs with Turbo pulse. The fabricated silicon photonics switch chip was mounted to the chip-carrier, assembled on a printed circuit board, and housed in a 19-inch wide 1-rack unit (RU) height blade. In addition to measuring the various characteristics of the device in our laboratory, it has also been installed and operated at the telecommunication carrier's collocation space to confirm long-term operation in the field. This shows that the technology related to the large-scale silicon photonics devices shown here can be adopted to practical use.

Malaria is a disease generally found in a tropical area including Thailand. It is widely known that the biological technique such as PCR normally used for an accurate detection of malaria-infected blood requiring a considerable period to repeat the process. Raman spectroscopy is considered to be an alternative method for the malaria infected blood detection. Theoretically, Raman spectroscopy is based on the scattering process that is less likely in a normal situation. Therefore, an enhancing technique known as “surface-enhanced Raman scattering (SERS)” is required for the signal augmentation. The SERS provides the enhancement of the electric field near the surface of the substrate. With the application of the technique, the main target of this research focuses on the comparison of the SER Raman spectra of the normal red blood cell and malaria infected red blood cell. However, only a single spectrum cannot provide a clear difference between the normal and the infected blood. An additional tool for even more effective discrimination was provided by using PCA analysis. In the sample preparation stage, the spin coating process was applied to spread the red blood cells uniformly on the surface. In addition, the spectra of the red blood cells including media were collected in various conditions in terms of the excitation wavelengths and the types of substrate. This additional information can be used as references for any red blood cell related investigation using Raman spectroscopy.

We validated applicability to actual measurement of a method proposed by Iuchi et al. to estimate blood concentration in skin tissue by conducting an experiment with 3 subjects. In the previous study, the method was proposed to estimate melanin and blood concentration in human skin tissue with a 7-layered model of skin. In order to validate applicability to actual measurement of the method, they conducted an experiment that forearm was given by 2 stimuli of warm bathing or carbonated bathing and estimated the blood concentration and melanin concentration in the forearm skin tissue with the proposed method. The results of 2 stimuli were consistent with a fact that warm bathing prompts blood flow in shallow layers of the skin tissue but carbonated bathing prompts blood flow not only in shallow layers but also in deep layers of the skin tissue. Based on the result, they concluded that the method they proposed was applicable to actual measurement. However, since the experiment was conducted with only one subject, the experiment result is considered to be not enough to conclude that the method is applicable to actual measurement because influence of individual difference could not be considered in the experiment with only one subject. Therefore, in this research, we conduct the same experiment as the previous study with three subjects. According to the results of the experiment, we can find that even after increasing the number of subjects, the results are still as same as before. Therefore, we conclude that the method is applicable to actual measurement.

We present the design of a high birefringence hollow core with nested anti-resonance nodeless fiber (HC-NANF). This model is designed for terahertz guidance made by TOPAS copolymer. The finite element method is used to study the properties of the proposed fiber: effective material loss, confinement loss, and birefringence. In this model, the cladding consists of four circular anti-resonant tubes: two tubes aligning in the horizontal axis and two tubes aligning in the vertical axis. Each circular anti-resonant tube consists of two circular nested tubes. First, we optimize the thickness of circular nested tubes due to anti-resonance reflecting guidance mechanism to achieve the lowest loss. The simulation results show that the thickness of 0.09 mm is suitable for operating at 1 THz. To achieve the birefringence, we attempted to rotate the inner circular nested tube with two patterns: symmetric and asymmetric rotations. The simulation results show that only the asymmetric rotation can provide the birefringence in the structure. It also shows that the birefringence can be adjusted by rotating the inner circular nested tube with respect to the core radius. Finally, the orthogonal birefringence of the proposed design from HC-NANF is found to be higher than 10^-4. This study offers an alternative model to provide the birefringence in THz regime, which might be relevant for future polarization related applications.

The FDTD simulation is performed with a system in which the front-surface is a concave lens, the inside of bulk is a zero refractive index medium in which positive and negative refractive index cells are randomly arranged, and a reflector is placed over the back-surface plane. In a zero-index medium, an outgoing wavefront is always parallel to the outgoing-surface, is independent of either the incident wavefront or the shape of the incoming-surface. After waiting for a while after entering pulsed light into this structure, the light reflected from the back-surface is focused at the focal point of the concave lens over the front-surface.

The purpose of the study was to investigate of photorefractive Bragg gratings within iron-doped lithium niobate crystals with the size of seven cubic millimeters. Polarized helium-neon laser beams with a wavelength of 633 nm have been separated into two beams and then incident on the crystal with different angles. Both beams were used for writing the grating in the crystal with the incident angle (2θ). and the angle between both beams has been founded the highest efficiency of diffraction beams. Then the transport of intensity method was used to explore the grating characteristics by using the opposite polarization of the writing helium-neon laser beam. Images in focus and defocus before and after the focal plane was recorded on a Canon digital camera. Then, these images were used to process by computer programing based on the principle of transport of intensity equation. By using this technique, the grating characteristics in lithium niobate crystals would be investigated.

We introduce a model of nonlinear multimode fibers with losses and gain. The model is based on the (3+1)-dimensional cubic-quantic complex Ginzburg-Landau equation (CGLE) with conservative and dissipative nonlinearities and a 2- dimensional transverse trapping potential. It applies to passively mode-locked lasers in the short-pulse operation regime. Systematic numerical analysis of the model reveals a variety of stable modes, including stable fundamental solitons and breathers, as well as solitary vortices with winding number n =1 , while vortices with n = 2 are unstable, splitting into persistently rotating bound states of two unitary vortices. An essential finding is biostability between the fundamental and vortex solitons.

In this study, we numerically investigated the absorption properties in one-dimensional photonic hypercrystal (PHC), which was consisted of a periodically alternating layers of hyperbolic metamaterial and dielectric material. The first layer of the unit cell of the PHC is a hyperbolic metamaterial (HMM), which made of the two-dimensional square lattice arrangement of gold (Au) nanowire embedded in indium tin oxide (ITO) host and the second layer is the same dielectric material used in metamaterial system. First, the nanowire array hyperbolic metamaterial was designed for providing high extinction coefficient in visible light to near infrared region by optimizing the radius of each Au nanowires. Then, a transfer-matrix method (TMM) was used as the numerical tool for calculating the absorption spectrum of the PHC for both TE- and TM-polarization. The numerical results showed that the PHC structure provides the widest absorption spectrum in the range of 500 to 1,000 nm for TE-polarized wave incidence. The bandwidth of interesting absorption spectrum is increased when increasing the layer thickness of the composed dielectric material. The level of absorbance of PHC is enhanced by increasing the number of periods. Conversely, the absorbance of PHC structure is decreased with the greater incident angle. Finally, the fill factor of nanowire hyperbolic metamaterial will make the shifting of absorption spectrum into long-wavelength region when it is decreased. Meanwhile, the absorption of TM-polarized wave in PHC structure is too low when comparing with TE-wave case. Due to the influence of the above parameters on the absorption spectrum for TE-polarized wave, so the PHC may be used as the TE broadband absorber for energy harvesting application.