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This paper reports on the optimization of full-width-at-half-maximum (FWHM) of the surface plasmon resonance (SPR) curve from a graphene-based SPR biosensor. The biosensor was designed in the Kretschmann configuration which is commonly known as the most effective technique for plasmon excitation using Lumerical's finite-difference-time-domain (FDTD) analysis. The performance of the SPR biosensor can be monitored by analysing the FWHM of the SPR curves where a smaller value is desired due to a narrower resonance peak which generally corresponds to a higher transmission power resulting in a more sensitive bio-detection. To optimise the biosensor's FWHM, Taguchi's L9 orthogonal array method was utilized involving four control factors at three level values using the objective function of Smaller-the-Better (STB) signal-to-noise ratio (SNR) characteristic. The results show that the FWHM improved to 1.1261°with best settings of A3B2C3D1. The Taguchi-optimized biosensor achieved 36.98% increase in sensitivity for urea detection.

In this work, a study of two-dimensional (2D) photonic crystal (PhC) cavities on a triangular photonic crystal lattice on Gallium Nitride have been demonstrated by using the 2D Finite Different Time Domain (FDTD) method. The resonant wavelength and quality factor (Q-factor) of designed PhC structures were studied. The forbidden region or stopband observed are between 420 to 520 nm. Therefore, the resonant wavelength of GaN-based PhC cavity was observed at $\sim460$ nm for H1 and L3 cavity. Both results show a high Qfactor obtained and calculated with a value of 65 700 and 65 957 respectively.

The technique to enhance and control the sensitivity of a one dimensional photonic crystal biosensor has been investigated by using 3D FDTD and Eigen mode solver in Lumerical software. Our results show that by reducing the waveguide width, sensitivity of the ID-PhC biosensor device will increase. This can be explained by observing the evanescent field strength shown by the mode profile which differs at particular width. By using this technique, the sensitivity can be enhanced and control geometrically. The highest sensitivity obtained is 307 nm/RIU. However by shifting the light energy from inside to outside of the waveguide, light confinement is sacrificed and may result in lower quality factor device.

In this study, we designed a novel optical interconnect chip (OIC) consisting of a Fabry-Perot laser as the light source, surface plasmon resonance (SPR)-based photonic crystal waveguide as a biosensor, and a photodetector (PD). The laser output and responsivity of the photodetector were investigated based on refractive index (RI) of 1.333 and 1.335, corresponding to different urea molarities. The method used to investigate the OIC design is by simulation using INTERCONNECT solver from Lumerical. The laser emits at 800 nm wavelength. The lasing threshold current is 0.015A at output power of 0.0021W whereas the PD has marked responsivity of 1.0 A/W. Increment in the RI value from 1.333 to 1.335 increases the OIC responsivity from 0.4 A/W to 0.8 A/W at a given optical power of 0.025 μW. This OIC design is suitable for biosensor chip in medical applications to detect diseases due to changes in RI.

Optical filter is very important components in WDM network. MRR is a basic structure to design the optical filter because of easy to design for improving its performance. This paper discusses an innovative structure of the MRR, which is Polymer Triple Coupler Ring Resonators (PTCRR) for optical filter applications. Values of width between bus and ring and values of radius of the ring in the structure PTCRR were analyzed and optimized for several variations for obtaining coupling coefficient values. Therefore, wide Free Spectral Range (FSR) and high crosstalk suppression bandwidth can be obtained. As results, at the optimized width of gap of 100 nm and the optimized radiation of 8 µm, FSR of 2.85 THz and crosstalk suppression bandwidth of 60 GHz were achieved. Based on the results, this structure can be used for filtering optical signals in optical fiber communication.

In this study, we investigated the surface plasmon resonance (SPR) sensing based on photonic crystal structures which are designed using a single graphene sheet and multilayer metal oxides (Al 2 O 3 and ZnO) for detection sensitivity and the absorption of molecules through excitation wavelength when using air and water as analytes. The refractive index (η) of air is 1.0 and water is 1.33. The method used to investigate the design structure is by simulation using finite difference time domain (FDTD). The wavelength is fixed at 0.8µm (near-infrared region) to excite a transverse electric (TEM) surface plasmon polaritons using Kretschmann configuration. Both analytical and numerical SPR spectra were in a good agreement. When using air as analyte, the reflection of incident angle for Al 2 O 3 and ZnO are 59.6° and 62°. While, the reflection of incident angle for Al 2 O 3 and ZnO are 69.6° and 71.8° when using water as analyte. The change in the refractive index of the analytes gave a change in the incident angle hence graphene and metal oxides can be used to form a SPR-based biosensor for biomedical applications.

Epiretinal membrane is a common disease of the eye which can cause severe loss of vision. Membrane peeling is the promising treatment in which surgeons use a miniature needle with a pick to peel off the membrane. However, due to the fragility of the retinal tissues and lack of force perception have made the procedure too risky to perform. Hence, development of smart tools/needles that use fiber Bragg grating (FBG) force sensors has been extensively reported. The main challenge was and yet is to decouple completely between axial and transverse forces. In this paper for the first time, we propose theoretically a novel method to decouple with high accuracy between the two force components. For the sake of holding out the method, only 2-DOF is considered here. Simulation was carried out to simulate 2-D needle integrated with two FBGs. One of which is a tapered FBG placed at the neutral axis of the needle for axial force measurement, while the second is normal FBG bonded on the needle's surface to mind the lateral force. As the strain applied, the bandwidth of the FBGs is only analyzed. A mathematical model is developed to show how force vectors can be measured in reality.

This paper aims to study the effect of process parameter variation on a nano-scaled planar p-type MOSFET (metal-oxide-semiconductor field-effect transistor) device for 22 nm technology using Taguchi's L9 orthogonal array. The device was constructed with high-k/metal gate consisting of Titanium dioxide (TiO2) and Tungsten silicide (WSix) metal gate using an industrial-based numerical simulator. Using Taguchi's Signal-to-noise ratio (SNR) of nominal-the-best (NTB), the compensation implantation has been as identified as the dominant factor influencing the Vth value with 67.77% while the Halo implantation tilting angle has been identified as the adjustment factor. Upon optimization, the Vth value is −0.29538 V which is within the requirements of the International Technology Roadmap for Semiconductors (ITRS) 2012 which is −0.289 V ± 12.7 %.

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.

In this paper, a multi-path optical ring resonator (MpORR) on silicon-on-insolator (SOI) is proposed for sensitivity enhancement in liquid chemical sensing applications. It is designed on Silicon Dioxide (SiO2) substrate and Silicon material as the core of optical waveguides. The proposed multi-path optical ring resonator can be realized with a wide free spectral value (FSR) of 3 THz. Therefore, the sensitivity of the sensor can be enhanced. Analysis and optimization of the proposed multi-path optical ring resonator are discussed and reported for optical wavelength operation of 1550 nm. The proposed device can be used for identifying different liquid material precisely.

We numerically investigated 3-dimensional (3D) sub-wavelength structured metallic nanohole films with various thicknesses using wavelength interrogation technique. The reflectivity and full-width at half maximum (FWHM) of the localized surface plasmon resonance (LSPR) spectra was calculated using finite-difference time domain (FDTD) method. Results showed that a 100nm-thick silver nanohole gave higher reflectivity of 92% at the resonance wavelength of 644nm. Silver, copper and aluminum structured thin films showed only a small difference in the reflectivity spectra for various metallic film thicknesses whereas gold thin films showed a reflectivity decrease as the film thickness was increased. However, all four types of metallic nanohole films exhibited increment in FWHM (broader curve) and the resonance wavelength was red-shifted as the film thicknesses were decreased.

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.

One reasonable and cost-effective method to sense chemicals such as ammonia is to use optical waveguides. In this work, the simulation of an optical single-mode splitter waveguide was executed to detect ammonia on the sensing arm. OptiBPM and Ionex softwares were used for the waveguide and ion exchange simulations respectively. The deepest and widest optical channel was produced when a concentration of Ag+ of 0.2 moles/m3 was used at a temperature of 350°C for duration of 35 minutes. The optical splitter designed in OptiBPM showed a change in the optical power with the presence of ammonia on the gold-coated sensing arm of the splitter. Therefore, the thermal ion change method is an alternative cost-effective method for the fabrication of optical biosensors.

Active and passive optical devices for modulators on silicon on insulator (SOI) is becoming very popular now due to easy fabrication and downscaling factors. Mach-Zehnder interferometer (MZI) for modulator, microring oscillator (MRO) for filter and arrayed waveguide grating (AWG) for multiplexing and demultiplexing wavelengths are among popular devices used for sensor or optical communication components. MZI modulator using injection of minority carrier in parallel with the optical signal propagation is an alternative which could offer easy design and fabrication compared to transverse injection current. This type of design, where p and n region are on the same MZI arm is predicted to offer many fabrication and operating benefit than the current transverse p-n junction.

We demonstrate the design, fabrication and characterization of silicon-on-insulator (SOI)-based Arrayed Waveguide Grating (AWG) with broad channel spacing of 20 nm (∼2500 GHz) which has a unique double S-shaped pattern at the arrayed region. Beam propagation method (BPM) under TE polarization at a central wavelength of 2431GHz and Complementary-Metal Oxide Semiconductor (CMOS) technology are used to simulate and fabricate the AWG device with 340 nm thick top silicon (Si) guiding layer. Performance comparison of insertion loss and optical crosstalk between the simulated and fabricated AWG was discussed. SOI-based AWG is employed in the Coarse Wavelength Division Multiplexing (CWDM) system to investigate the functionality of the device at a system level as well as to analyse signal degradation using a bit-error rate (BER) analyzer when 10 Gb/s and 40 Gb/s data rates are applied.

This paper describes the performance measurement of a Coarse Wavelength Division Multiplexing (CWDM) system with Erbium Doped Fiber Amplifier-Semiconductor Optical Amplifier (EDFA-SOA) in post - amplifier configuration. The results are acquired from experimental work where 8 CWDM channels ranges from 1471 nm to 1611 nm wavelengths are being transmitted and the total link distance is 65 km. The proposed amplified system causes a great increase in the measured input power to the receiver subsystem compared to when no amplifier has been utilized. The proposed amplified system is useful to support the transmission in metro access network (MAN) scenario.

We characterized the performance of the transmission spectrum in terms of insertion loss for 4 -channel silicon-on-insulator (SOI)-based arrayed waveguide grating (AWG) device ranging from 1471 nm to 1531 nm with 20 nm (∼2500 GHz) channel spacing. The characterization was carried out using standard optical waveguide alignment system incorporated with butt-coupling method. Our main objective is to reduce coupling loss caused by the different mode-field diameter (MFD) between single mode fiber (SMF) and AWG device when butt-coupling method was used. Hence, fiber with conical tip of 2.0 µm spot diameter at 1/e2 was introduced and the performance of coupling loss between standard 9/125 µm SMF and fiber with conical tip was compared where the latter reduced the optical coupling loss by 10%.

Silicon-on-insulator (SOI) has become one of the popular material that is widely used to develop passive or active devices in application for modern photonics communication. Using SOI, we proposed a new double S-shaped Arrayed Waveguide Grating (AWG) with broad channel spacing of 20 nm (∼2500 GHz). This SOI-based AWG device performed with low insertion loss of

The localized surface plasmon resonance (LSPR) properties are numerically analyzed using finite-difference time domain (FDTD) method, which is a reliable technique in solving Maxwell's equations in dispersive medium. Optical properties and LSPR characteristics were analyzed with Titanium Nitride (TiN) as an adhesion layer at gold(Au)/silver(Ag) interface. The reflection spectra of bimetallic layer nano-holes was compared with various metallic layer thicknesses of Au and Ag, hole radii and lattice period. When compared between single and bimetallic Ag/TiN/Au nano-hole layers, it showed that the layer with 70nm-thick Ag/5nm-thick TiN/50nm-thick Au (Ag70/TiN5/Au50) gave greater LSPR-based sensor performance with narrower plasmonic line width and better full width at half maximum (FWHM). Change in geometrical parameters such as lattice period and hole radii was affected the sensitivity and detection accuracy of Ag70/TiN5/Au50 nano-hole layer, which maximum of 90.9% reflection intensity and minimum of 18nm FWHM were obtained.

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.

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.

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%.

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.

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 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.

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.

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.

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.

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.

We apply the arrayed waveguide grating (AWGs) method for encoder and decoder design for complete transmitter and receiver system. The encoder and decoder module will be using the AWG to encode and to decode optical source into useful signal to carry the data and transmit it using a single optical fibre. This module was designed to suite the zero cross correlation (ZCC) code. In this paper the study conduct to design of encoder/decoder for optical code division multiple access (OCDMA) system based AWGs and performance of ZCC code using this system. Results demonstrate that the encoder/decoder design of ZCC code using AWGs is capable of up to 100 km with BER less than 10-9 which is typically allowed in optical communications.

This paper presents the security performance of spectral amplitude code OCDMA systems. We examine factors affecting data security such as system capacity and its influences on the eavesdropper SNR. The eavesdropper probability of error-free code detection for Modified Double Weight (MDW) OCDMA scheme is investigated. The eavesdropper performance is based on observing the authorized transmitted signal based on classical detection theory. For probability of correct detection of 0.5, an eavesdropper receiver would need to detect SNRs of 8, 9.3 and 10 dB for MDW (9, 4), MDW (18, 6) and MDW (30, 8) respectively.

The optimum transmit power for an optical code division multiple access (OCDMA) system based on enhanced double weight (EDW) code is evaluated for various transmission distances considering the nonlinear stimulated Brillouin scattering (SBS) effects. It has been observed through computer simulation 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. It has been shown that the longer transmission distance have low Brillouin threshold power value and the power launched require must not excess the threshold power in order to overcome SBS effects. Also in this paper, we investigate and demonstrate how the attenuation coefficient and effective core area of optical fiber transmission influence the Brillouin threshold power in optical CDMA system.

The purpose of this paper is to design and characterize the wavelength selective coupler (WSC). The device which use the concept of coupled mode theory is designed using SU-8 polymer on silica substrate parameters with compliance of FTTH wavelength such as wavelengths 1310 nm (upstream data/voice), 1480 nm (downstream data/voice), 1550 nm (video) and 1625 nm (testing). The performance of the devices was modeled using the beam propagation method (BPM-Cad) product from the Optiwave Inc. This paper also highlights the parameter studies and the effect to the design specification and performance. We analyze the following parameters such as: wavelength, separation between waveguides, waveguide width and refractive indices for substrate (n2) and waveguide (n1).

Analysis of material composition effect and material gain are performed to investigate GaInNAs quantum wells performance for application in long wavelength Vertical-Cavity Surface-Emitting Laser (VCSEL) operating at 1310 nm wavelength. The optimized GaInNAs active region is then incorporated into double intracavity device structure for VCSEL analysis. The long wavelength GaInNAs VCSEL exhibits sub-miliampere operating current and single-mode emission at 1310 nm wavelength.

Flake-like particle of ZnO had been synthesized through pyrolitic reaction of hydrozincite as chemical bath deposition product. The decomposition of hydrozincite is studied by sample IR spectra of calcined samples at 200degC, 300degC and 500degC. The calcinations at 300degC transformed hydrozincite into ZnO and kept the flake-like structure. Morphologic study showed spherical particles at early deposition grew to form flake-like structure and diffraction pattern showed that sample consist of dominantly perpendicular plane.

The In0.53Ga0.47As interdigitated lateral p-i-n photodiode (ILPP) is a a cheap and affordable device to meet growing demands of optical communication networks operating at speeds below 10 Gbps. A ILPP model utilizing In0.53Ga0.47As 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 signal-to-noise (SNR) ratio of ILPP devices as a function of design factors. The analytical equation was used to predict SNR values for experimentally developed devices from the literature.