Wan Maisarah Mukhtar

Influence of annealing temperature on optical properties of Al doped ZnO nanoparticles via sol-gel methods

Zinc oxide (ZnO) thin films have become technologically important materials due to their wide range of electrical and optical properties. The characteristics can be further adjusted by adequate doping processes. The effect of dopant concentration of Al, heating treatment and annealing in reducing atmosphere on the optical properties of the thin films is discussed. Undoped and aluminum-doped zinc oxide (AZO) thin films are prepared by the sol-gel method. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine are used as precursor, solvent and stabilizer. In the case of AZO, aluminum nitrate nanohydrate is added to the precursor solution with an atomic percentage equal to 0 %, 1 %, 2 % and 3 % of Al. The multi thin layers are transformed into ZnO upon annealing at 450 °C and 500 °C. The optical properties such as transmittance, absorbance, band gap and refractive index of the thin films have been investigated by using UV-Visible Spectroscopy (UV-Vis). The results show that the effect of aluminium dopant concentration on the optical properties is depend on the post-heat treatment of the films. By doping with Al, the transmittance spectra in visible range increased and widen the band gap of ZnO which might due to Burstein-moss effects.Zinc oxide (ZnO) thin films have become technologically important materials due to their wide range of electrical and optical properties. The characteristics can be further adjusted by adequate doping processes. The effect of dopant concentration of Al, heating treatment and annealing in reducing atmosphere on the optical properties of the thin films is discussed. Undoped and aluminum-doped zinc oxide (AZO) thin films are prepared by the sol-gel method. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine are used as precursor, solvent and stabilizer. In the case of AZO, aluminum nitrate nanohydrate is added to the precursor solution with an atomic percentage equal to 0 %, 1 %, 2 % and 3 % of Al. The multi thin layers are transformed into ZnO upon annealing at 450 °C and 500 °C. The optical properties such as transmittance, absorbance, band gap and refractive index of the thin films have been investigated by using UV-Visible Spectroscopy (UV-Vis). The results show that the effect of aluminium dop...

Optimization of gold thin films thicknesses in enhancing SPR response

Nowadays, surface plasmon resonance (SPR) sensor has been widely used in biosensing applications to detect the wide diversity of biomolecular interactions. There are few parameters need to be concerned in order to optimize the performance of SPR sensors such as film thicknesses, type of thin films and their configurations. In this study, we seek to determine the optimum thicknesses of hybrid thin films which consist of gold-graphene oxide layers for the enhancement of SPR sensor sensitivity. By using a theoretical approach, a WINSPALL 3.02 simulator had been used to investigate the effects of various thicknesses of hybrid configurations thin films towards the excitation of surface plasmon polaritons (SPP). A layer of 3 nm protein was added to compare the maximum adsorption of the SPR sensor based on their configuration. It was found that the optimum thicknesses of gold and graphene oxide are 50 nm and 0.68 nm respectively for achieving best sensitivity. Thus, the sensitivity value for gold-GO thin films is higher than silver-GO which are 19.42 °/RIU and 5.45 °/RIU with FWHM = 2.28° and 0.64° respectively.

Fabrication of gold strip thin film on glass substrate for plasmonic demodulation application

Plasmonic demodulation is a process where an optical signal due to the generation of surface plasmon polaritons (SPP) reacts with electrical domain, resulted an inverse relationship between them. In this study, fabrication processes of gold strip thin films on the glass substrates are presented. For an optimization purpose of electro-optics effect observation, the width of gold strip thin film is set as 0.5mm, which is equal to the laser beam spot diameter. First, the strip pattern is printed on a commercial transparent plastic slide. The pattern transfer process from plastic slide to glass slide is performed using UV light. Once the pattern is formed on the glass substrate, gold thin film with varies thicknesses namely 30nm, 50nm and 100nm are deposited by monitoring the sputtering time; via d.c. sputtering on the glass substrate which is partly coated with the positive photoresist. The photoresist is removed by immersing the coated glass slide in acetone solution for 15 minutes, follow with DI water for three seconds in an ultrasonic bath. This yields to the establishment of gold strip thin films with dimension of width 0.5mm × length 10mm. An optimal plasmonic demodulation process is successfully acquired by using gold metal strip with thickness of 30nm and higher laser power level, namely P=1.5mW. In a conclusion, we believe that the output of this study will contribute a significant impact to the development of the plasmonic demodulator as an active device.

On the performance of Mach-Zehnder-Interferometer (MZI) optical modulator on silicon-on-insulator (SOI)

In recent years, there has been a significant interest in the development of optical waveguide modulators using Silicon-On-Insulator (SOI) substrates motivated by the potential to provide a reliable low-cost alternative to other photonic materials. Objective: In this paper, Multimode Interference (MMI) device is used to develop the MZI structure of the optical modulator. Meanwhile, the electrical part of the modulator utilizes the forward biased P-I-N structure. The effect of varying MMI width to the performance of the MZI optical modulator on SOI was investigated. The effect of varying MMI width to the insertion loss (IL), extinction ratio (ER) and modulation efficiency (VπL) of the device were carried out. Results: The investigated MMI widths are 22, 30 and 38 μm. Smallest MMI width, which is 22 μm has recorded the lowest value of insertion loss with 3.30 dB and the best extinction ratio of 25.60 dB. However, the best modulation efficiency was observed for the MMI width of 38 μm with 0.1696 V.cm. Conclusion: Appropriate selection of MMI width is vital to ensure optimum performance of the MZI modulator.