Gunawan Witjaksono

WIDE RANGE OF ELECTROSTATIC ACTUATION MEMS FPOTF

By employing Microelectromechanical system (MEMS) technology, Fabry-Perot Optical Tunable Filter (FPOTF) with hybrid tuning mechanism, varying d and altering incident angle is presented. The proposed structure consists of a ∞oating dual membrane FPOTF with capability to be tuned at difierent light incident angles. Three electrostatic cavities have been designed to perform this task independently. This technique is capable to increase the tuning range up to 2/3 of capacitance gap with additional doubly range of incident angle. Optic, mechanic and electrostatic analysis of the proposed structure has been validated by simulation. Analysis in optical performance shows the tuning range enhancement is about 1.92% for §2 - mirror tilting at 6 - initial angle compared to conventional dual beam MEMS FPOTF. This analysis validates the principle of hybrid tuning method.

Design of fourier transform infrared optical sensor with manufacturing tolerance on interferometer arms for application on non-invasive hypoglycemia and hyperglycemia detection

An interferometer design employing a broadband source and based on optical fiber as waveguide implementation for contactless optical detection meant for biomedical sample is presented. The interferometer design and simulation is done using OptiSystem software. Manipulation of phase difference to produce interferogram centerburst was contributed by the optical time delay and the optical fiber length at both interferometer arms. The design is varied by time delay and it produced proper centerburst at zero optical path difference without significant affect by manufacturing tolerance length of optical fiber at both interferometer arms. It is observed that interferograms centerburst will be remained at zero nanosecond time delay up to 0.5% manufacturing tolerance length and will be shifted to the left or right position depending on the minus or plus of the tolerance length.

Fabrication of a photocurable highly sensitive optical ammonia sensor for aquaculture application

A simple sensor fabrication process for ammonia fluorescence based optical sensing has been developed by immobilizing fluorescence pair dyes in a UV-photocurable acrylate host polymer matrix. The direct process for optical sensor was designed by entrapping ammonia sensitive components in a certain ratio of acrylate monomers of methyl methacrylate (MMA) and butyl acrylate (BA). The copolymers poly(methyl metha-co-butyl acrylate) (MB) glassy transparent thin film ammonia sensor was photopolymerized under ultra-violet (UV) illumination. The acrylate based host matrix offers rapid curing, ease of preparation, excellent dyes entrapment and self-adhesive properties. The nonplasticized acrylate matrix containing ammonia sensitive components have demonstrated excellent sensitivity towards target analyte with linear sensor response to dissolved ammonia in the range of 1 to 100 μgL-1 (R2 of 0.9) with a limit detection of 1 μgL-1ammonia. The simple single step fabrication of ammonia fluorescence based optical sensor offers great manufacturing capability for aquaculture quality monitoring.

Performance of TEOS/Octyl-triethoxylane/triton x-100 on tris(4,7′-diphenyl-1,10′-phenanthroline) Ruthenium (II) sol-gel for fluorescence-based optical sensor

Fluorescence based optical sensors has become an attraction in many areas, including industrial, biomedical and environmental applications. Optical sensor developed for water quality monitoring such as dissolved oxygen sensor becomes important such as monitoring the health of aquaculture environment. This optical DO sensor use oxygen quenching luminophore as the sensor material. In this work, the performance of tris(4,7-diphenyl-1,10 phenanthroline)ruthenium(II) ([Ru(dpp)3]2+) was investigated through the thin films morphology and their luminescence spectral profile. The Scanning Electron Microscopy (SEM) images result indicates that ([Ru(dpp)3]2+) doped Octyl-triEOS/TEOS/Triton x-100 composites form uniform thin film and reduce cracks, likely to produce a reliable luminophore sensor. In addition, the spectral profile for 3 different ([Ru(dpp)3]2+) concentration were observed using high-resolution UV-VIS Spectrometer. The emission wavelength for all the samples have the same peak which seen at 610 ± 4 nm. The emission intensity shows an increasing pattern proportional to the concentration of ([Ru(dpp)3]2+). These experimental result demonstrates the ([Ru(dpp)3]2+) sol-gel thin film potentially be used for Dissolved Oxygen (DO) optical sensor luminophore.

Design of MEMS Based Energy Harvester to Profile Environmental Parameter Using Autonomous WSN Components

With the rapid development on micro electro mechanical system (MEMS) and wireless transmission technology, wireless sensor networks (WSN) are becoming an emerging technology with a number of potential applications. One such application is the monitoring of agricultural environmental parameter. Such an application requires an infinite-life power source that will harvest energy continuously from the ambient environment. This paper describe about the design, and development consideration of an energy harvester for an autonomous sensing system. The sensing components of WSN are connected with the energy harvester on the same structure to generate required energy from the ambient environment. As a case study, the power requirement by MIMOS Berhad [1] developed WSN components are measured from real time deployment. Based on the power requirement an autonomous system is designed (patent granted [2]) and proof of concept (POC) of the system is implemented. The POC shows from 1 cm2 area of the energy harvester a potential difference of 0.6 V and current of 0.25mA can be achieved. These results shows, by cascading several unit area of the energy harvester and integrating it with WSN components, it is possible to achieve autonomous WSN system, which is very essential for realistic deployment of WSN.

The Effect on Physical, Electrical and Structural Parameters of RF Sputtered Molybdenum Thin Film

In this study, the physical, electrical, and structural parameter on radio frequency (RF) sputtered molybdenum thin film is investigated as a function of two deposition parameters: rf power, and argon (Ar) pressure. Films are sputtered onto the substrates nominally held in room temperature in a RF sputtering system at partial argon (Ar) pressure. A number of 10 films are deposited at 8 sccm of Ar pressure while varying the rf power from 90 to 360 watt. Besides, another set of 7 films are deposited at 240 watt RF power while varying the Ar pressure from 8 to 32 watts. All the films are characterized using FESEM, AFM, XRD, and four points probe. The analysis results substantiate that, to fabricate a low resistive thin layer of molybdenum (Mo) both sputtering power, and deposition time Ar pressure plays significant rules. It is found that, with the increase of the RF power (90 to 280 watt) the deposition rate increase from 1.2 A0/sec to 4.4 A0/sec. But at a RF power higher than 280 watt the deposition rate saturated and it does not increase as linear as before. Also resistivity continuously decreases as the RF power increases from 90 watt up to 270 watt, after that the resistivity remain almost same regardless the RF power increased. Besides, by varying the Ar pressure it is found that with the increase of the Ar pressure the deposition rate increase until 20 sccm (up to 2.4 A0/sec). With further increase of the Ar pressure deposition rate start reducing and reached 2.1 A0/sec at 32 sccm. Based on the above investigation and analysis optimized film is deposited and further analyzed. The surface roughness is analyzed using AFM characterization tool and found 27.4519 nm. The FESEM and XRD analysis along with the resistivity of the film is used to measure the strain of the deposited film and found a strain of less than 0.01% on the optimized film, which is essential for MEMS/NEMS device fabrication and energy harvesting applications.

Biphoton generation using multistate quantum key distribution technique

In this paper, we present a method to prepare pairs of photons (biphotons) for multistate quantum key distribution by investigating a pulsed laser diode driver system based on MOSFET current mirror and digital signal controller (DSC). The design is able to emit stream pairs of photons from three semiconductor laser diodes. The DSC is capable to switch between the three laser diodes at constant rate. The duty cycle is maintained at 1% in order to reduce its thermal effect and thus prolong the laser diodes life cycle. This laser driver system is capable to generate biphotons automatically with bit rate of about 5.5kbps for µ equal to 1.

Improvement on advanced security network module on real telecommunication infrastructure

We successfully implement and improved Advanced Security Network Module on real fiber optic test-bed by riding on existing laid telecommunication fiber. Transmitting through dark fiber was achieved with a maximum key rate of 2056 bit/s that unconditionally protects the establishment of shared keys between two remote distances. Mixing of Telecom standard single mode fiber type which consist of normal G652 and low water peak fiber G652D, Fresnel reflection and the effect of train passing by on some portion of the entire 44.5km length are among the obstacles while deploying the security network module equipment.

FEM simulation on MEMS FP OTF using Al metallic mirror

MEMS Fabry Perot Optical Tunable Filter (FP OTF) is widely used in WDM application. Most of this device is developed using DBR mirror in order to achieve high reflectivity. However, the usage of this mirror will increase the cost and complexity of MEMS FP OTF fabrication. Some application requires minimal bandwidth where it needs only 95% mirror reflectivity. This can be achieved using metallic mirror. The usage of metallic mirror reduces the complexity of MEMS FP OTF fabrication process. Therefore, FEM simulation model for MEMS FP OTF using Al metallic mirror is developed using CoventorWare 2006 software in order to investigate the performance in terms of optical Intensity and output spectrum within 1200nm to 1600nm wavelength range. Thickness of Al thin film is varied from 100nm to 1000nm to investigate the absorbance, A for a slice of metallic thin film mirror without substrate. MEMS FP OTF using LAI;=200nm and LAI;=500nm Al thin film are developed and simulated using Coventor Ware2006 software. Results are analyzed in terms of transmittivity, Free spectral Range (FSR) and Bandwidth (FWHM).