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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.

Areas of Interest

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 Physics
8. Applications of Fiber Grating in Biophotonics

Group Members
Group Coordinator : Rosmiza Mokhtar [1,2,3]
Tel No : + 60 3 8921 2298
Fax No : + 60 3 8921 2115
E-mail :
Completed Research Projects
  • Rosmiza Mokhtar, “Pengukuran Ketelusan Logam Emas dan Cecair dengan Kaedah Resonans Plasmon Permukaan”, Master Degree (1999). 
  • Liaw Hock Sang, “Photopyroelectric Technique in Thermal Diffusivity Determination and Spectroscopic Response of Solid Samples”, Master Degree (2003).
  • Roslina Mokhtar, Zulkifly Abbas, Kaida Khalid & Jumiah Hassan, “A New Rectangular Dielectric Waveguide Technique For Ripeness Determination of Palm Fruits”, Master Degree (2004).
On-Going Research Projects
  • Rosmiza Mokhtar, “Multilayers Analysis Using the Phenomenon of Surface Plasmon Resonance”, PhD.
  • Liaw Hock Sang, “Efficiencies of Optical Elements for Quantum Logical Operations”, PhD.
Selected Recent Publications
  • W. Mahmood Mat Yunus, Zainal Abidin Talib, Mohd Maarof Moksin, Zaidan Abd. Wahab, Rosmiza Mokhtar, and Azmi Zakaria (1996). “An Annealing Effect on the Surface Modes Supported by Gold Thin Film Deposited on Silicon Substrates - A Computer Simulation Based on ATR Technique.” Bulletin S & T Kead. Pej. Mal., 6, 17 -24.
  • W.Mahmood Mat Yunus, Mohd Maarof Moksin, and Rosmiza Mokhtar (1997). “Surface Plasmon Study for Detection of Ethanol in Water and Moisture Content of Hevea Latex.” Technical Digest (Refereed), CLEO-The Pacific Rim Conference On Laser and Electro-Optics, pg. 236-237 (IEEE Conference).
  • Rosmiza Mokhtar, W. Mahmood Mat Yunus, Mohd Maarof Moksin, Zainal Abidin Talib, Azmi Zakaria, and Lee Seng Yap (1998). “Determination of the Refractive Index Using ATR Surface Plasmon Resonance.” Sci. Int. (Lahore), 10(3), 1-3.
  • Rosmiza Mokhtar, and W. Mahmood Mat Yunus (2000). “Determination of Refractive Index of Palm Oil Using a Surface Plasmon Resonance Technique.” Solid State Science & Technology, 8(1 & 2), 86-92.
  • Rosmiza Mokhtar, and W.Mahmood Mat Yunus (2000). “Optical Characterization of Thin Film Using Surface Plasmon Resonance.” J. Solid St. Sci. & Technol. Letters, 7(1 & 2), 56-62.
  • Rosmiza Mokhtar, Mohd Maarof Moksin, and W. Mahmood Mat Yunus (2000). “Pencirian Resonan Plasmon Permukaan dan Pengunaan Saput Tipis Emas sebagai Lapisan Aktif Sensor Optik.” PERTANIKA, J. Sci. Technol., 8(1), 1-14.
  • W. Mahmood Mat Yunus, Rosmiza Mokhtar, Mohd Maarof Moksin, Chong Boon Peng, and Lee Woei Yeh (2000). “Optical Sensor Based on Surface Plasmon Resonance Measurements.” Asean Journal on Science and Technology for Development, 17(2), 31-38.
  • Rosmiza Mokhtar, Zainul Abidin Hassan, and W. Mahmood Mat Yunus (2000). “A Study of Chemical Gas Effect on Gold Surface Using Surface Plasmon Resonance (SPR) Measurements.” Prosiding Fizik 2000 : Seminar Fizik Kebangsaan,234-239.
  • Rosmiza Mokhtar, Zainul Abidin Hassan, and W.Mahmood Mat Yunus (2001). “A Study of H2S Effect on Gold Surface Using Surface Plasmon Resonance (SPR) Measurements.” Technical Digest (Refereed), CLEO-The 4th Pacific Rim Conference On Laser and Electro-Optics, vol. II, 222-223 (IEEE Conference).
  • Rosmiza Mokhtar, Zainul Abidin Hassan, W. Mahmood Mat Yunus, Anuar Kasim, and Zainal Abidin Talib (2002). “A Study Of Chemical Gas Sensor For The Detection Of Carbon Monoxide Gas Using The Surface Plasmon Resonance (SPR) Measurement.” Proceeding of the 4th Postgraduate Seminar, 158 –162. (16 July 2002, Universiti Putra Malaysia).
  • Rosmiza Mokhtar, Zainul Abidin Hassan, and W. Mahmood Mat Yunus (2002). “A Study Of H2s Effect On Gold Surface Using Surface Plasmon Resonance (SPR) Measurements II.” J. Solid State Science & Technology, vol.10, no. 1&2, pg. 320-325.
  • Rosmiza Mokhtar and Zainul Abidin Hassan (2006). “Surface Plasmon Resonance (SPR) Technique as a Tool for Toxic Gas Detection.”  The Research Development Newsletter of the College of Engineering (COE), Universiti Tenaga Nasional, Volume 3, Number 1, Pg 6(Mac 2006).  
  • Rosmiza Mokhtar and Zainul Abidin Hassan (2007). “Multilayers analysis using the phenomenon of Surface plasmon resonance.” The Research Development Newsletter of the College of Engineering (COE), Universiti Tenaga Nasional, Volume 4, Number 1&2, Pg 9, March 2007.
  • B. Z. Azmi, H. S. Liaw, and Z. Abbas (2005). Thermal-wave interferometry of gas-liquid applied to a thermal-wave resonator cavity technique”, Review of Scientific Instruments 76, 074901.
  • B.Z. Azmi, H.S. Liaw, W.M.M. Yunus, M. Hashim, M.M. Moksin, W.M.D.W. Yusoff (2004). “Normalisation procedure in thermal wave approach of thermal diffusivity measurement of solids using pyroelectric sensor.”
    Infrared Physics & Technology 45(4), 315-321.
  • B.Z. Azmi, H.S. Liaw, M. Hashim, M.M. Moksin, W.M.M. Yunus, W.M.D.W. Yusoff (2001). “Effects of CoO impurities in ZnO semiconductor on photopyroelectric spectra and band-gap energy determination.” J. Fizik Malaysia, 23(1-4), 110-112.
  • B.Z. Azmi, H.S. Liaw, M.M. Moksin, M. Hashim, W.M.M. Yunus and W.M.D.W. Yusoff (2001). “Photopyroelectric spectra of methyl red doped poly (methyl methacrylate).”
    J. Solid State Sci. and Tech. Lett., 9(1), 226-232.
  • Roslina Mokhtar, Zulkifly Abbas, Kaida Khalid & Jumiah Hassan (2003). “RDWG Technique of Determination of Complex Permittivity of Oil Palm Fruits”. In 5th Putra Physics Seminar Proc., 220-225
  • Roslina Mokhtar, Zulkifly Abbas, Kaida Khalid & Jumiah Hassan (2003). Microwave Reflection Measurements of Oil Palm Fruits Using RDWG Technique. In MSTC Proc. (CD-ROM version)., 1310-1316
  • Roslina Mokhtar, Zulkifly Abbas, Kaida Khalid & Jumiah Hassan (2004). RDWG Technique for Determination of Complex Permittivity & Moisture Content of Oil Palm Fruits. In The 4th Annual Seminar of National Science Fellowship 2004 Proc. 45.
  • Z.Abbas, R. Mokhtar, K.Khalid, M.Hashim & S.Abdul Aziz (2007). RDWG Technique of Determination of Moisture Content in Oil Palm Fruits. Springer, EDP Sciences, Società Italiana di Fisica in European Physical Journal.
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