Mathematics & Science Department
Applied Optics Group (AOG)
Research Areas | Group Members | Projects | Publications
Applied Optics Group (AOG) aims to become the national centre of excellence in the area of optics. The group shall conduct research projects and consultancy work in the area of optical method, especially in material characterizations and designing optical sensor in various applications. AOG has gradually focused on Surface Plasmon Resonance (SPR), Photoacoustic and Photothermal Method, Microwaves Physics and Fiber Grating in Biophotonics.
The SPR measurement would be the most interesting field to study in depth, as its application in highly sensitive optical sensors is evident. The method is direct, non-destructive and quantitative technique, one can work in situ without additional sample preparation. The monitoring of the molecular recognition processing is possible in real time and spends only small-volume samples per single analysis procedure. A very sensitive method has been developed for measuring the refractive index of gas, liquid, emulsion and powder that cannot be measured by using conventional method such as a minimum deviation method. SPR method also has an extensive range of applications in the analysis of metals because the resonance condition depends upon the physical properties of the metal surface on which the plasmon excited. This inherent property makes SPR well suited for nondestructive studies of surfaces, interfaces, and very thin layers. Depending on specific system design, those methods also allow a direct monitoring of fast acquisition of data which is essential for commercialization in many fields such as analytical chemistry, medical diagnostics, monitoring production process, determination of chemical concentration, food additive testing, environmental monitoring system, refractive index detector for liquid chromatography, process control microsensor, corrosion monitoring device and polarization device. In this respect, our refractive index measurement scheme can be tailored in meeting specific needs of biophysical and biochemical researches and also industrial processes.
Taking the advantages of the characteristic thermal response of a sample under light excitation, the techniques of interest in monitoring the photothermal effect of the sample are the standard photopyroelectric technique and the thermal-wave resonator cavity technique. The former is used to measure the thermal diffusivity and to study the spectroscopic response of solid sample, such as band-gap energy of ZnO. The latter allows the measurement of thermal diffusivity of liquid sample. The sample, such as an intact biological sample or palm oil, is placed in thermal contact with the pyroelectric sensor. The rectangular dielectric waveguide (RDWG) confines electromagnetic fields in two dimensions to guide electromagnetic energy from one point to another. This is a technique that supports hybrid modes and wave guidance take place because of the internal reflection at the side walls. The RDWG are usually designed with low dielectric constant materials (εr ≈ 2 – 10). This technique has been applied to measure the complex permittivity and moisture content of biological materials such as oil palm fruits. An effective permittivity model is proposed where the rectangular dielectric waveguide/sample/rectangular dielectric waveguide interfaces are represented by a homogeneous medium with an effective permittivity obtained from the solution to the wave equation in the rectangular dielectric waveguide whilst the effective permittivity of the sample was found using dielectric mixture model. The measurement system consists of a HP8720B Network Analyzer (VNA), rectangular dielectric waveguide, WR-90 standard waveguides and horn antennas. All microwave measurements were carried out using the VNA in the frequency range between 8 GHz and 12 GHz. Agilent Visual Engineering Environment Software is used to control and retrieve data from VNA. Due to the wave reflection measurement in the previous work, an interest developed in the fiber grating application. Using an electromagnetic wave, a guided wave can be transferred from one end to another in the preferable frequencies. In this work, wave reflection and transmission play important role to any electromagnetic wave solution.
Taking the advantages of the characteristic thermal response of a sample under light excitation, the techniques of interest in monitoring the photothermal effect of the sample are the standard photopyroelectric technique and the thermal-wave resonator cavity technique. The former is used to measure the thermal diffusivity and to study the spectroscopic response of solid sample, such as band-gap energy of ZnO. The latter allows the measurement of thermal diffusivity of liquid sample. The sample, such as an intact biological sample or palm oil, is placed in thermal contact with the pyroelectric sensor.
The rectangular dielectric waveguide (RDWG) confines electromagnetic fields in two dimensions to guide electromagnetic energy from one point to another. This is a technique that supports hybrid modes and wave guidance take place because of the internal reflection at the side walls. The RDWG are usually designed with low dielectric constant materials (εr ≈ 2 – 10). This technique has been applied to measure the complex permittivity and moisture content of biological materials such as oil palm fruits. An effective permittivity model is proposed where the rectangular dielectric waveguide/sample/rectangular dielectric waveguide interfaces are represented by a homogeneous medium with an effective permittivity obtained from the solution to the wave equation in the rectangular dielectric waveguide whilst the effective permittivity of the sample was found using dielectric mixture model. The measurement system consists of a HP8720B Network Analyzer (VNA), rectangular dielectric waveguide, WR-90 standard waveguides and horn antennas. All microwave measurements were carried out using the VNA in the frequency range between 8 GHz and 12 GHz. Agilent Visual Engineering Environment Software is used to control and retrieve data from VNA.
Due to the wave reflection measurement in the previous work, an interest developed in the fiber grating application. Using an electromagnetic wave, a guided wave can be transferred from one end to another in the preferable frequencies. In this work, wave reflection and transmission play important role to any electromagnetic wave solution.
1. Surface Plasmon Resonance Method as a Tool of Material Characterizing.2. Surface Plasmon Resonance Method as a sensitive optical sensor.3. Developing Software (on Optical Properties).4. Thermal diffusivity measurement.5. Photopyroelectric spectroscopy.6. Quantum Information.7. Microwaves Physics8. Applications of Fiber Grating in Biophotonics