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The complementary metal-oxide-semiconductor field effect transistor (CMOSFET) has become major challenge to scaling and integration. Innovation in transistor structures and integration of novel materials are necessary to sustain this performance trend. CMOS variability in the scaling technology becoming very important concern due to limitation of process control; over statistically variability related to the fundamental discreteness and materials. Minimizing the transistor variation through technology optimization and ensuring robust product functionality and performance is the major issue.In this article, the continuation study on process parameters variations is extended and delivered thoroughly in order to achieve a minimum leakage current (ILEAK) on PMOS planar transistor at 22 nm gate length. Several device parameters are varies significantly using Taguchi method to predict the optimum combination of process parameters fabrication. A combination of high permittivity material (high-k) and metal gate are utilized accordingly as gate structure where the materials include titanium dioxide (TiO2) and tungsten silicide (WSix). Then the L9 of the Taguchi Orthogonal array is used to analyze the device simulation where the results of signal-to-noise ratio (SNR) of Smaller-the-Better (STB) scheme are studied through the percentage influences of the process parameters. This is to achieve a minimum ILEAK where the maximum predicted ILEAK value by International Technology Roadmap for Semiconductors (ITRS) 2011 is said to should not above 100 nA/µm. Final results shows that the compensation implantation dose acts as the dominant factor with 68.49% contribution in lowering the device’s leakage current. The absolute process parameters combination results in ILEAK mean value of 3.96821 nA/µm where is far lower than the predicted value.

Arrayed Waveguide Grating (AWG) serving as a demultiplexer (demux) has been designed on SOI platform and was utilized in a Coarse Wavelength Division Multiplexing (CWDM) system ranging from 1471 nm to 1611 nm. The investigation was carried out at device and system levels. At device level, 20 nm (∼ 2500 GHz) channel spacing was successfully simulated using beam propagation method (BPM) under TE mode polarization with a unique double S-shape pattern at arrays region. The performance of optical properties gave the low values of 0.96 dB dB for insertion loss and – 22.38 dB for optical crosstalk. AWG device was then successfully used as demultiplexer in CWDM system when 10 Gb/s data rate was applied in the system. Limitation of signal power due to attenuation and fiber dispersion detected by BER analyzer =10−9 of the system was compared with theoretical value. Hence, the maximum distance of optical fiber can be achieved.

Indium oxide (In2O3) thin films annealed at various annealing temperatures were prepared by using spin-coating method for dye-sensitized solar cells (DSSCs). The objective of this research is to enhance the photovoltaic conversion efficiency in In2O3thin films by finding the optimum annealing temperature and also to study the reason for high and low performance in the annealed In2O3thin films. The structural and morphological characteristics of In2O3thin films were studied via XRD patterns, atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), EDX sampling, and transmission electron microscopy (TEM). The annealing treatment modified the nanostructures of the In2O3thin films viewed through FESEM images. The In2O3-450°C-based DSSC exhibited better photovoltaic performance than the other annealed thin films of 1.54%. The electron properties were studied by electrochemical impedance spectroscopy (EIS) unit. The In2O3-450°C thin films provide larger diffusion rate, low recombination effect, and longer electron lifetime, thus enhancing the performance of DSSC.

UV polymerization of perfluorinated acrylic polymer (ZPU12) for optical waveguide is studied by FTIR spectroscopy. With 15 μm planar thickness of the polymer material ZPU12-450 and 6 μm thickness of ZPU12-456 requires 8 and 3 min repectively to be fully UV cured with low intensity of 14 mW/cm2 at room temperature in the presence of nitrogen flowing. These results show the delay of curing reaction with increasing thickness or depth in the optical waveguide. Besides, a thickness of 6 μm of ZPU12-456 requires about 4 min to be fully UV cured with intensity of 12 mW/cm2. The conversion rate slows down on the decreasing of curing intensity. The polymerization also shows that the UV induced polymerization is faster than thermal curing reaction. The refractive indices of ZPU12-450 is around 1.450 and most of the refractive indices of ZPU12-456 are between 1.455 and 1.456. On the other hand, the thermooptic coefficient of ZPU12-456, dn/dT is −2.105×10−4/°C and −2.090×10−4/°C for TE and TM polarization, respectively. The thermooptic coefficient of ZPU12-450, dn/dT is −2.737×10−4/°C and −2.465×10−4/°C for TE and TM polarization, respectively.

In this paper, we present our recent progress on the characterisation and process optimisation of photoresist-like fluorinated acrylate and Cyclomer acrylate copolymers. Different acrylate formulations from cyclized acrylic copolymers (Cyclomer) have been exploited and compared with fluorinated acrylate, ORMOCER from available sources. Refractive indices of the Cyclomer acrylate at transverse electric (TE) mode is 1.56 while refractive index of fluorinated acrylate at TE is 1.52 at room temperature. Both acrylates show negative thermooptic (TO) effect with temperature. The thermooptic coefficient, dn/dT of the polymers are as high as the order of 10−4, which is comparable to those of available optical polymers. Higher values of dn/dT are shown by the Cyclomer acrylate compared to that of the fluorinated acrylate. Thermal stability determination were measured using Thermal Gravimetric Analysis and decomposition were evaluated at 5 and 10% decomposition. It was found that Cyclomer is more stable than ORMOCER. From glass transition and specific heat capacity values obtained using Differential Scanning Calorimeter, fluorinated acrylate has more specific heat capacity than Cyclomer. Characterisation of pre baked and UV cured polymer samples had been analysed using FTIR. The time and intensity of UV curing were optimised to obtain waveguide channel of width between 40 and 10 μm for Cyclomer. For fluorinated acrylate, only the UV curing time parameter had been optimised. The development techniques of these acrylates are also different; the Cyclomer used the aqueous based developers while fluorinated acrylate used hydrocarbon solvent. Microstructural channel waveguide had also been analysed via scanning electron microscope (SEM), which shows the channel waveguide structures.

This paper highlights the study of carrier injection effect on silicon-on-insulator phase modulator with various sloped wall waveguide structure. By default, the sloped angle 54.74° arises from anisotropic chemical etching with the waveguide aligned to the 〈111〉 crystal direction. However, etched surfaces cannot be consistent depending on many variables such as reaction temperature and etchant concentration. Therefore, different possible angles are studied in this report. The characterization of the phase modulator was carried out by 2D Silvaco CAD software under different applied voltages. The n + p + n + structure was employed to study the device performance in terms of modulation efficiency and absorption.

Ion-exchange technology on glass substrates for the fabrication of optical waveguides is a cost-effective and low loss method to produce biosensors. In this paper, the thermal ion-exchange process was simulated using a commercial software where various concentrations of AgNO3/NaNO3 salt-melt was deposited on Corning glass substrates at different temperatures and duration. Subsequently, a Mach-Zehnder Interferometer (MZI) was designed on glass substrates using OptiBPM software and the effect of the branching angle, a towards the power losses in the MZI was evaluated. Guided light suffers loss owing to the tapered andseparating structure of the MZI.

A Vitreoretinal microsurgery force sensing technology has been rapidly emerging as the extremely small and delicate tissue structures of the eye interior dictates a precise and sensibly manipulation. Excessive applied forces during tool-tissue interaction manipulation lead to irreversible tissue damage. Fiber Bragg grating (FBG) based sensors are an excellent candidate as they meet all the constraints required by the retinal microsurgies; by being small size, provides sub-millinewton resolution, covering working range, etc. Significant progress leads researchers to move up from 1-DOF force sensor to 2-DOF and lately a 3-DOF that can measure tri-axis forces of mN scale in very restricted dimensions. Decoupling completely between the axial and transverse force components was the most challenge that could result in errors and less accuracy. In this study, we propose a linear chirp FBG (LCFBG) to be located in the middle of the device for axial measurement. Instead of commonly wavelength shifted decoding; we rather would retrieve applied forces using optical power measurement of the reflected peak of centre wavelength. A Simulation results using Matlab have showed linear relationship with adequate sensitivity around 6.8dB/N (0.0068dB/mN), and a resolution of

A study on the effect of balance and imbalance fraction ratio of nonlinear optical loop mirror (NOLM) to produce multiwavelength erbium-doped fiber laser (MWEDFL) is presented. Based on the study, generation of multiwavelength fiber laser with 60dB OSNR value and 0.42nm mode spacing are realized from the effect of the laser interference using sagnac loop mirror and light interference It is shown that the transmittance value for imbalance fraction ratio obtained from the experiment is 0.36 thus fraction ratio of NOLM is an important parameter in producing multiwavelength fiber laser.

A polyethylene flow-injection mechanism coupled with polymer optical fibre is developed to determine nitrite in aqueous solution based on direct absorbance spectrophotometric method. Sample of nitrite concentration ranging from 0.2156 μg/mL to 3.45 μg/mL is prepare for experiment. The result shows that peak wavelength of the absorbance is obtained at 545nm with a standard deviation range of 0.0004 to 0.0107 and precision of 0.5% to 0.03%. Meanwhile, limit of quantitation and limit of detection are found to be 0.158 μg/mL and 0.0052 μg/mL respectively. There results indicate satifactory parameters for analytical analysis with the sensor displays moderate overall sensitivity.

This paper provides the enhancement of 22nm planar PMOS transistor technology through downscaling, design parameter simulation and optimization process. The scaled down device is optimized for its process parameter variability using Taguchi method. The aim is to find the best combination of fabrication parameters in order to achieve the target value of the threshold voltage (V th ). A combination of high permittivity material (high-k) and metal gate is utilized simultaneously in replacing the conventional SiO 2 /Poly-Si technology. For this, Titanium dioxide (TiO 2 ) was used as the high-k material and tungsten silicide (WSi x ) was used as the metal gate. The simulation results show that the optimal threshold voltage (V th ) of −0.289 V ± 12.7% is achieved in accordance to the ITRS 2012 specifications. This provides a benchmark towards the fabrication of 22 nm planar PMOS in future work.

This paper presents an investigation of the most influential parameters in designing a Mach Zehnder Interferometer (MZI) on Silicon-On-Insulator (SOI) using Taguchi method. The symmetric Y-junction is employed in designing the MZI. Meanwhile, parameters affecting the design of a MZI such as the area of the waveguide, offset in X direction (lx), offset in Z direction (lz) and the arm length were considered and varied for optimization purposes. Design and optimization of passive MZI structure is crucial prior to implementation of active devices.

This paper proposes a measurement of nonlinear refractive index in the course of multi wavelength technique. We have generated a multi wavelengths formation by utilising a photonic crystal fibre (PCF) which mismatches zero dispersion wavelength from transmission wavelength at 1550 nm. We provide an experimental set-up in generating the multi wavelength phenomenon. A fibre ring laser configuration consists of erbium doped fibre amplifier (EDFA) set up and arrangement of FBGs is described. Encouraging results obtained from the set up proves the relations of signals generated through FBGs and new wavelengths. These findings shows, multi wavelengths able to present valuable inputs in determination of nonlinear refractive index parameter.

We demonstrated multiwavelengths formation by utilising a combination of fibre ring laser, three fbgs and 20 m of photonic crystal fibre (PCF) with zero dispersion wavelength at 1040 nm. Although it characteristics efficiently interacts in 1040nm range lasers in efficiency of non linear effects, we determined to exploit four wave mixing (FWM) effect in generating multiwavelength at C band transmission window. Prior, the Erbium Doped Fiber Amplifier (EDFA) spectrum was performed in order to identify its performance and suitable FBG. Two FBGs at the end of C band amplification and one fibre Bragg grating (FBG) at gain spectrum are selected. The FBGs assigned are FBG 1, 2 and 3 with its own specifications (1530.47 nm and reflectivity 89.9%), (1561.42 nm and reflectivity 91.6%) and (1563.95 nm and reflectivity 96.7%) respectively. Through FWM effect, new wavelengths generated successfully at gain spectrum range 1530nm to 1540nm. These findings show, multiwavelengths able to be generated even though the separation between signals which are not consistent at lengths and far among each other able to induce by sufficient energy level. The findings give a valuable impact and prospective relevance towards sensors and optical communications.

This chapter investigates the performance of enhanced double weight (EDW) code for spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) system using different detection techniques. EDW code possess ideal cross-correlation properties such as the maximum cross correlation of one that are important characteristics in the optical CDMA systems since these can eliminate multiple access interference and reduce noise. The EDW code has numerous advantages including the efficient and easy code construction, simple encoder/decoder design, existence for every natural number \(n\), and weight, which can be any odd number greater than one. The experimental simulation results as well as the transmission performances are presented in this chapter.

This report presents a large dynamic operation of wavelength numbers of laser lines that have been periodically filtered using an MZI-SI filter effect. A 70 nm span range for a wider periodic comb filter with 0.60 nm wavelength spacing was achieved through an advanced triple-loop ring-cavity fiber laser with a combination of MZI-SI. Almost all of the best 95 numbers of wavelengths are flattened at 6 dB of peak power fluctuation in a 52 nm range. By adjusting the rotation angles of a polarization controller (PC), the ultra-wide range multiwavelength spectrum has been shifted by 36 nm in a range from 1522.8–1558.6 nm.

Long-wavelength VCSELs (LW-VCSEL) operating in the 1.55 μm wavelength regime offer the advantages of low dispersion and optical loss in fiber optic transmission systems which are crucial in increasing data transmission speed and reducing implementation cost of fiber-to-the-home (FTTH) access networks. LW-VCSELs are attractive light sources because they offer unique features such as low power consumption, narrow beam divergence and ease of fabrication for two-dimensional arrays. This paper compares the near field and far field effects of the numerically investigated LW-VCSEL for various design parameters of the device. The optical intensity profile far from the device surface, in the Fraunhofer region, is important for the optical coupling of the laser with other optical components. The near field pattern is obtained from the structure output whereas the far-field pattern is essentially a two-dimensional fast Fourier Transform (FFT) of the near-field pattern. Design parameters such as the number of wells in the multi-quantum-well (MQW) region, the thickness of the MQW and the effect of using Taguchi's orthogonal array method to optimize the device design parameters on the near/far field patterns are evaluated in this paper. We have successfully increased the peak lasing power from an initial 4.84 mW to 12.38 mW at a bias voltage of 2 V and optical wavelength of 1.55 μm using Taguchi's orthogonal array. As a result of the Taguchi optimization and fine tuning, the device threshold current is found to increase along with a slight decrease in the modulation speed due to increased device widths.

We analyze the effects of the mole fraction variation of III-V heterostructures employed as the active region in an InP-based multi-quantum-well (MQW), long-wavelength vertical-cavity surface-emitting laser (LW-VCSEL). The VCSEL model which utilizes an air-post design for electrical current confinement is equipped with GaAs/AlGaAs and GaAs/AlAs top and bottom distributed Bragg reflectors(DBR) mirrors respectively. The changes in the quantum well band-gap energy is evaluated against the laser performance in terms of its threshold current, gain, lasing wavelength and emission power by means of an industrial-based numerical simulator. The simulated device achieved lasing powers up to 4.9 mW with modal gain of 25 cm-1, lasing wavelength of 1.56 μm and threshold current

We present relevant bounds for the case of weak+vacuum decoy state and one decoy state for a two-way four states Quantum Key Distribution (QKD) protocol. The numerical simulation result is significant given that an improvement in maximum secure distance of nearly twice the original one is achieved.

A hybrid WDM and SAC/Optical CDMA System is proposed to enhance the data network security and to exploit the capacity of an optical system. Code pulses of SAC/Optical CDMA are overlaid onto a multichannel WDM system. Modified Quadratic Congruence (MQC) code is as the signature address code for SAC/Optical CDMA. In general, OCDMA improves service availability for data of a network. With the use of WDM channels in a hybrid scheme, an eavesdropper faces another challenge for intercepting and decoding the coded signal. The interference that is the main factor limits the performance of the proposed system. So that, the notch filters and APD photo detectors instead of PIN photo detectors are used in order to improve the SAC/OCDMA performance. A simulation is presented as a demonstration of the concept.

Since 1980's, silicon photonic devices have been extensively studied, however a submicrometre-size photonic devices have been realized only in the last few years. Silicon properties namely the transparency in the range of optical telecommunications wavelengths and high index of refraction, have enabled the fabrication of low loss submicron waveguide. Photonic devices such as splitter, coupler, and filter have been demonstrated in silicon but once the device has been fabricated, the properties of the device are predetermined. A silicon based modulator can be used to control the flow of light, where the refractive index of the silicon waveguide can be varied thus, induce a change in the transmission properties.

Silicon as a photonic medium has a unique advantages. It is transparent in the range of optical telecommunications wavelengths (1.3 and 1.55µm) and has a high index of refraction, which allows for the fabrication of high-index-contrast submicrometer structures. The key elements for the development of silicon microphotonics is the silicon-based optical modulators which have earned a great interest in the recent years. High-speed optical modulation can be achieved by free carrier concentration variations. Electron and hole injection in PIN diodes has been widely used but generally leads to bandwidths lower than a few 100MHz.

Silicon high-speed waveguide-integrated electro-optic modulator is one of the critical devices for on-chip optical networks. The device converts data from electrical domain to the optical domain. Most studies for high speed modulation method in Si or Si based device are based on free carrier concentration variations (injection or depletion of free carriers) which are responsible for local refractive index variations and then phase modulation of a guided wave traveling through the active region. A change in the refractive index/absorption can be achieved by injection or depletion of both electron and holes into the intrinsic region of a silicon p-i-n diode.

Single transverse mode control is achieved for multimode GaAs-based VCSEL by utilizing photonic crystal design and etched trench structure. Theoretical analysis is initially performed for photonic crystal design with various lattice constant and air holes diameter. The fabricated photonic crystal VCSEL with etched trench structure exhibits single mode output power of 0.7 mW, threshold current of 3.5 mA, slope efficiency of 0.10 W/A, and continuous single mode output spectrum throughout a wide operating current range. Comparison of typical oxide VCSEL, trench oxide VCSEL, and photonic crystal oxide VCSEL employing trench structure is presented. By combining photonic crystal and trench structure, single transverse mode operation of photonic crystal VCSEL can be much more strictly controlled.

In this paper, 1.25 Gb/s GPON downstream link is presented. All the optical distribution network (ODN) classes are implemented, using Optisystem, to investigate the transmission capability and performance of the proposed downstream physical media (PM) GPON model. Some of the design constraints involved in an optical network design such as fiber span analysis, power budget and margin calculations are taken into consideration with worst case. The quality or performance of a digital communication system is specified by its BER or Q value with respect to other parameters such as receiver sensitivity. The simulated model can support 18, 50 and 128 number of users for classes A, B, and C respectively.

In this paper, tradeoffs between security and performance in optical CDMA is presented. Confidentiality against eavesdropper interception strategies for optical CDMA is considered. Coherent detection and combining signals shows better confidentiality than the incoherent one. Spectral amplitude optical CDMA based on Modified Double Weight (MDW) systems, with different code dimension, is investigated. Increasing the network system capacity or maximizing authorized specified SNRs will lead the eavesdropper to detect high SNRs.

An enhancement of data networks security using a hybrid WDM and SAC/Optical CDMA System is proposed. Secure transmission for dedicated users is achieved by overlaying a covert channel onto a multichannel WDM network. The covert channel is spectrally encoded using spectral amplitude coding (SAC) with unipolar Modified Double Weight (MDW) as the signature address code. OCDMA improves service availability in the presence of physical infrastructure attacks. With the use of WDM channels, the difficulty for an eavesdropper to intercept and decode the secure signal is increased. A simulation is presented as a demonstration of the concept.

We report characterization result using weak coherent pulses on four states polarization flipper utilizing two Pockels cells. Visibility of nearly 90% and above was achieved for each four linear polarization input states. A good polarization contrast between not flipped and flipped states shows that this configuration can be applied for single photon applications.

This paper reports the effect of doping concentration to the electrical characteristic performance of the phase modulator in the carrier injection mode at wavelength 1.55µm. The phase modulator device has been integrated in the silicon-on-insulator (SOI) rib waveguide with the p-i-n diode structure. The electrical device performance is predicted using the 2-D semiconductor package SILVACO (CAD) software under DC operation. The least doping concentration of p+ and n+ region produces the least change of refractive index of the modulator. Meanwhile, results show that by increasing the doping concentrations, the value of Iπ decreases. This means that the phase modulator performance is better with increased doping concentrations.

We report experimental result on passive compensation on standard single mode optical fiber. The states of polarization (SOP) were analysed and the six main states normally used for QKD system are investigated. Passive control of SOP approach seems very unpractical, but through simple setup, compensation at each communicating arm seems to be a potential method. The results show that the SOP state remains similar to the source after compensation and the passive compensation setup compensate all 6 SOPs source value over time. We achieved to maintain the related stoke value (S 1 , S 2 , S 3 ) at each SOP state above 93%.

Optical devices are components which require sophisticated equipment and technically skilled manpower for device fabrication and assembling and most of the production costs are on the device assembly. However, the next generation optical components may not be devices assembled at the production line but it will be based on the concept of 'do-it yourself' optical devices. We proposed a simple low-cost acrylic-based Y-branch POF coupler which can be assembled easily by the end users themselves. The device is composed of three sections: an input POF waveguide, an intermediate adjustable hollow waveguide taper region and output POF waveguides. Low cost acrylic-based material has been used for the device material. A desktop high speed CNC engraver is utilized to produce the mold inserts used for the optical device. In addition to the engraved device structure, 4 holes are drilled at each corner to allow a top plate to be screwed on top and enclosed the device structure. Included with this POF coupler assembly kit will be the mold insert, top acrylic block, input and output POF fibers (cleaved and stripped with different stripping lengths) and connecting screws. The short POF fibers are inserted into the engraved slots at the input and output ports until the fibers are positioned just before or butt-coupled to each other. The assembling is completed when the top plate is positioned and the connecting screws are secured. The POF coupler has an average insertion loss of 5.8 ± 0.1 dB, excess loss of 2.8 dB and a good coupling ratio of 1:1.

This paper presents the security enhancement for spectral amplitude coding optical CDMA. The eavesdropper probability of error-free code detection based on hybrid code system is investigated. Enhancement Double Weight (EDW) optical CDMA scheme and M-sequence codes are used as a hybrid code system. The eavesdropper performance is based on observing the authorized transmitted signal based on classical detection theory. The eavesdropper taps a coded transmission of a particular user and performs the necessary calculations to derive the transmitter's code word from these transmissions. If an eavesdropper could be forced to tap code pulses with low SNRs, a security enhancement can be obtained. An eavesdropper would need SNR of 9.2 dB to correctly detect encoded pulses with a probability of 50 % for the hybrid scheme, which is 5 and 3 dB higher than M-sequence and EDW schemes respectively. The difference in performance of the eavesdropper's receiver with envelope detection is getting small, especially at higher SNRs.

Zn1−xMnxO thin films with different doping concentration (x = 0, 0.02, 0.04, 0.06, 0.08) were synthesized by sol gel method using the spin coating technique. Zn1−xMnxO thin films are prepared using 2‐methoxyethanol solution of zinc acetate dehydrate and manganese acetate tetrahydrate. The effects of the doping concentration on the structural and optical properties were investigated. The AFM images showed many spherical shaped nanoparticles on the surface morphology and surface roughness is increased by Mn doping. Meanwhile, the transmittance spectra are decreased by Mn doping and absorption edge shifted to longer wavelength. The photoluminescence spectra shifted to lower energy gap at low concentrations of Mn. These films achieve tunable band gap characteristics by means of changing the dopant concentration.

this paper presents the implementation of enhanced double weight optical code division multiple access codes (EDW-OCDMA) on Point-to-multipoint access network for FTTH applications, the design is based on EDW code. Simulation experiment performed to study the performance of the code, the new algorithm to generate the higher weighted EDW code enable the performance study of EDW in Point-to-multipoint for higher weights too. In this paper there is a new design to implement the code into Point-to-multipoint Access network FTTH. Multiple weighted EDW code implemented and designed to fit into FTTH application. Performance of the code on FTTH is presented through eye diagram and comparison graph from the simulation results.

This paper presents security performance for incoherent unipolar and bipolar Optical CDMA Network Systems. The eavesdropper performance is investigated, by simulation, based on Modified Double Weight (MDW) Spectral Amplitude Optical CDMA. Our results show that using unipolar OCDMA code schemes based on MDW code system enhances the security with a low cost implementation in comparison to the bipolar ones

A 1X2 POF splitter based on a Y-branch metal hollow POF coupler design has been developed. The device is composed of three sections: an input POF waveguide, an intermediate hollow waveguide taper and output POF waveguides. Simulation based on non-sequential ray tracings have been performed on the POF splitter. Low cost aluminum based material has been used for the device substrate. Fabrication of the POF splitters are done by producing the device mold insert using high speed CNC machining tool and short POF fibers at the input and output sections are inserted inside the mold insert before the interfaces of the hollow waveguide taper. The POF splitter has an average insertion loss of 5.8 ± 0.2 dB, excess loss of 2.8 dB and coupling ratio of 1:1. A video-over POF system test-bed consisting of a POF video transmitter and receiver has been constructed with a total transmission length of 10 m. The POF splitter has been tested in the video-over POF system and shows no significant signal degradation.

A successive interference cancellation optical (O-CDMA) system with spectral amplitude coding is investigated. It has been shown that SIC/SAC scheme has potential to suppress MAI, and improve the system performance as compared with conventional receiver.

The work presented here shows the effect of wavelength conversion experiment on Four Wave Mixing (FWM) by utilising photonic crystal fibre(PCF). This configuration consists of dual pump and a few sets of Fiber Bragg Gratings (FBGs). Selective conversion is also possible by adjusting on one of pump laser. However, phase matching conditions plays vital roles in this experiment. This phenomenon is the major cause of FWM.

An optical code generating device using plastic optical fiber (POF) coupler for portable optical access card system is presented. The code generating device constructed using asymmetric hollow POF coupler design provides a unique series of output light intensities which are successively used as an optical code. Each coupler will be assigned with a unique optical code based on the asymmetrical waveguide design. Non-sequential ray tracing simulation of various coupler designs showed a linear relationship between the tap-off ratio (TOFR) and the waveguide tap width. The results for the simulated and fabricated 1x2 asymmetric couplers show the same linear characteristics between the TOFR and the tap width. The simulated devices show a TOFR variation from 18.6% to 49.9% whereas the TOFR for the fabricated metal-based devices varies from 10.7% up to 47.7%, for a tap width of 500 μm to 1 mm. The insertion loss for the 1x2 asymmetric coupler at the tap line varies from 12.7 dB to 21.2 dB whereas for the bus line, the average insertion loss is about 12 dB.

This paper focused on developing a fully passive device prototype named Passive In-line Monitoring (PIM) device, which used to tap out a small ratio of triple-play signals for monitoring purpose without affecting the transmission in fiber-to-the-home (FTTH) access network. This device will be installed with the main lines in FTTH permanently to allow the field engineers or technicians to simply connect it to a portable tester unit for transmission surveillance and failure detection. The PIM device is used to sharply determine the location of break point before repairing. A passive tapper circuit is required to obtain the optical signals to provide a visual way of monitoring the receiving signal performance. The entire optical components that had been used in the circuit design including connectors, splices, optical isolators, and optical couplers. This device is potentially to improve the service reliability and reduce the repairing cost and time.

This paper focuses on developing a Passive In-line Monitoring (PIM) device prototype, which used to tap out a small ratio of triple-play signals for in-service monitoring and failure identifying against fiber fault in fiber-to-the-home (FTTH) access network. This device will be installed with the main lines in FTTH permanently to allow the technicians to simply connect it to a portable tester unit for transmission surveillance and failure detection. The PIM device is used to sharply determine the location of break point before repairing. A passive taper circuit is required to obtain the optical signals to provide a visual way of monitoring the receiving signal performance. This device is potentially to improve the service reliability and reduce the repairing cost and time.

The interdigitated lateral p-i-n photodiode (ILPP) has profound advantages compared to the vertical p-i-n photodiode (VPD) structure mainly due to the ease of fabrication where diffusion or ion implantation can be used to form the p+ and n+ wells in the absorbing layer. A novel ILPP model utilizing In 0.53 Ga 0.47 As (InGaAs) as the absorbing layer was developed and optimized statistically using fractional factorial design (FFD) methodology. Seven model factors were investigated and a new analytical equation was developed to predict the responsivity of ILPP devices as a function of design factors. Comparison between the simulated and calculated responsivity values yielded error ratios of less than 3 %. A statistically optimized ILPP model with -3 dB frequency of 7.5 GHz, responsivity of 0.61 A/W and signal-to-noise ratio (SNR) of 20 dB was developed at an operating voltage of 5 V, wavelength of 1.55 μm and optical input power of 10 Wcm -2 . Hence the model qualifies to be used as a cheap and affordable device in fiber-to-the-home based on passive-optical-networks (FTTH-PON) operating at a minimum speed of 2.5 Gbps.

Sol gel-self assembly technique is presented to produce nanocrystals thin films. This combined technique was applied because more convenient, faster, simpler and less costly than others method. FESEM images show that the Mn doped ZnS exhibit the spherical type. The ZnS:Mn colloidal performs the high bandgap in visible region. Furthermore, the optical properties of the nanocrystals thin films are also studied by photolumines (PL). PL spectrum show the blue and orange emission due to 4T1–6A1 of Mn2+ transition.

A new application of an asymmetric hollow optical waveguide coupler is presented. The asymmetrically-design hollow waveguide coupler provides a unique series of output power which successively is used as an optical code in a portable access card system. The output power are arranged in a way that it will represent a unique optical code. The waveguide design combines two major structures which are asymmetric Y-junction splitter and linear taper. The use of a basic lx2 asymmetric waveguide coupler design together with a cascaded design technique allow more complex and higher level hollow waveguide coupler to be constructed. The code combination generated by the waveguide coupler theoretically provides the access card system with millions of possible code combination as the number of output ports increases. The code combination of the waveguide coupler is derived using combinatory number theory where the combination is dependable on the number of output ports.

This paper presents the eavesdropper performance to tap and detect encoded spectral chips from optical CDMA networks. The probability of correctly detecting encoded spectral chip pulses is investigated based on Modified Double Weight (MDW) Spectral Amplitude Optical CDMA. For probability of correct detection of 0.5, an eavesdropper receiver would need to detect SNR of 8 dB. The eavesdropper performance is investigated by simulation. Tapping efficiency of 20 % is enough to tap encoded spectral chips with reasonable sensitivity.

We conducted a computer simulation study to assess the effects of Stimulated Brillouin Scattering (SBS) on performance analysis of optical CDMA based on Enhanced Double Weight (EDW) code. It has been observed that SBS causes backward scattering of transmit signal and this in turn causes a reduction of received power and limitation improvement for the bit error rate. The maximum transmission distance is evaluated for optical CDMA based on BER equal to 10 -9 and transmitted power into fiber below SBS threshold power. Also in this paper, we demonstrate how the speed of data transfer, directly modulated technique and effective core area of optical fiber transmission influence the Brillouin threshold power in optical CDMA system.

Mn doped ZnS is a semiconductor that can exhibit good quality in their properties due to the wider band gap. In this present work, sol gel method with self assembled technique were used to perform a good quality of ZnS:Mn nanocrystals layer depend on the different of doping concentration. The nanocrystals of the prepared Mn doped ZnS have been analyzed using Field Emission Scanning Electron Microscopy (FESEM), Photoluminescence (PL) and UV-Vis spectrophotometer. The appearance of the nanocrystals from FESEM micrograph was smooth and homogenous with the average size was measured around 25 nm. From the measurements of transmittance of the films, the bandgap increases with the increase of Mn concentration same as the PL performance. Based on these properties that were obtained from nanocrystals layer, it is suitable and has tendency to use in photonic crystals applications.

Illuminance scale is one of the fundamentals in the realisation of candela in optical radiation. The en route of the realisation is based on the fundamental process from the unbroken chain of traceability which includes from the primary standard disseminated to working standard and lastly the end user. There are many variations towards this realisation even though some of the national metrology institutes (NMI) does not have the primary standard but their traceability still valid. The realisation of National Metrology Laboratory SIRIM (NML‐SIRIM), Malaysia illuminance scale is based on detector. The scale is traceable to National Physical Labortaory (NPL), United Kingdom (UK) by annually calibrating photometers and luminous intensity lamp. This paper describes measurement method and the system set‐up was previously crosschecked with Korea Research Institute Standards and Science (KRISS), Republic of Korea. The agreement between both laboratories is within 0.5% the uncertainty maintained at NML‐SIRIM. Furthermore, the basic measurement equation for illuminance realisation is also derived.