Mohd Haniff Ibrahim

Multimode interference optical splitter based on photodefinable benzocyclobutene (BCB 4024-40) polymer

1×2 and 1×3 planar optical splitters based on Benzocyclobutene (BCB 4024-40) polymeric material are demonstrated for the first time. The devices are designed based on symmetric interference and fabricated on BK7 glass substrates with a thin layer of SiO2 as cover. A cost-effective chemical etching technique is used in the fabrication process to take advantage of the photosensitivity of the polymer. The waveguide loss was measured using the cutback method to be 3.5 dB/cm. The splitting uniformity is better than 0.02 and 1.5 dB at 1550-nm optical wavelength for the 1×2 and 1×3 splitters, respectively.

A Novel 1×2 Thermo-Optic Multimode Interference Switch Structure Based on Photodefinable Benzocyclobutene (BCB 4024-40) Polymer on Silica

A novel 1×2 multimode interference photonics switch structure based on thermal controlling effect is proposed. A ridge waveguide of photosensitive polymer, benzocyclobutene (BCB 4024-40) on silica clad is used as a design structure. A temperature changes as a result of electrode heating are analysed by employing a two-dimensional finite difference thermal model considering both conduction and convection mechanisms. The switching characteristics due to changes in effective index are analysed by the two-dimensional finite difference beam propagation method with transparent boundary condition. The proposed structure works well with low crosstalk level of -28 dB and low switching power relatively to the structural upper cladding thickness.

Single mode rib optical waveguide modeling techniques

A single mode rib optical waveguide is modeled using three distinct methods: the finite difference method (FD); effective index method (EI); two dimensional beam propagation method (2D-BPM). Starting from the fundamental Maxwells equations, the functionalities of the methods in solving the wave equation are discussed. Using a standard rib optical waveguide structure, comparisons between the methods are made in terms of normalized propagation constant values; the obtained results are shown to have good agreement.

Power Harvesting in Wireless Sensor Networks and Its Adaptation With Maximum Power Point Tracking: Current Technology and Future Directions

Wireless sensor networks (WSNs) is one of the most effective tools in collecting data autonomously going as recently as 5–10 years ago. A low deployment and maintenance cost WSN is highly recognized as one of the more advanced Internet of Things networks that can be deployed for a series of purposes namely environmental and industrial monitoring due to the majority of such systems run on expendable power source that offers WSN with a limited service lifetime. The aim of this paper is to review existing renewable energy and prospective approaches in energy harvesting strategy as a means of having a sustainable and low maintenance operation of WSN. Additionally, recent maximum power point tracking (MPPT) of solar energy harvesting is thoroughly discussed in a new perspective of the WSN framework. Semi-pilot cell fractional open-circuit voltage (SPC-FOCV) MPPT is a fairly new concept in WSN application that features less complicated configuration with reduced hardware requirements and lower cost. Recent research findings are evaluated throughout this paper leading to the SPC-FOCV MPPT materialization. A holistic discussion is made encompassing the advantages and disadvantages of the concept, its performance compared to conventional MPPT approaches and the future insight of the technology in WSN.

High Sensitivity of Balloon-Like Bent MMI Fiber Low-Temperature Sensor

A novel low cost and simple temperature sensor based on multimode interference (MMI) is formed by a successive singlemode fiber (SMF)-bent multimode fiber (MMF)-SMF structure. Due to the small curvature radius of bent MMF section mimicking a balloon shape, MMI effect from the core is spreading into coating. The high temperature sensitivity is mainly due to the large thermo-optical coefficient of the existing acrylate coating of the MMF fiber. A temperature sensitivity of up to -2060 pm/°C and -25.1 nW/°C for wavelength- and intensity-based interrogation, respectively, have been achieved in the range between 27 °C and 31 °C. This sensor is most suitable in high sensitivity and low-temperature application such as the measurement of human body temperature.

Polymer material for optical devices application

An overview of polymer materials in optical waveguiding technology is presented. This includes a review of the types of polymer being used worldwide in the development of optical devices, the track record and performances of polymer based optical devices successfully being developed as compared to other optical materials and also of the external field control of the polymer material for active devices application. Further discussion then include the current research in polymer based optical waveguiding technology held in our Photonic Research Group together with possible development and commercialization.

Measurements of ozone absorption cross section with ratiometric and non-ratiometric methods

In ultraviolet absorption spectroscopy, absorption cross section (ACS) is a parameter important for calculating ozone concentrations. In this work we have determined the ACS at the room temperature and normal pressure. The ozone con- centration has been recorded in the region 450-989 ppm, using a compact aluminium gas cell of 5 cm optical path length. We have also compared the results derived with the ratiometric and non-ratiometric methods based on the Beer-Lambert law. Our experimental results demonstrate that the non-ratiometric method can compete with the ratiometric method whenever the measuring times are relatively short.

Temperature-insensitive photonic crystal fiber interferometer for relative humidity sensing without hygroscopic coating

A novel photonic crystal fiber (PCF) interferometer RH (relative humidity) sensor is proposed and demonstrated in this paper. The sensor is made from a piece of PCF spliced to standard fibers in transmission mode, which has the advantage that it does not require the use of any hygroscopic thin film or layer. In addition, the all-silica nature of the sensing element means the sensor is insensitive to temperature. The sensor has a humidity sensitivity of 60.3 pm/%RH over the range of 60–80% RH and 188.3 pm/%RH in the region from 80 to 95% RH. A response time around ~1 s is observed for a ~2 cm long section of photonic crystal fiber interferometer (PCFI). The sensor exhibits a very low cross temperature sensitivity of around 0.5 pm/°C. The proposed sensor has potential for high humidity monitoring applications, and temperature compensation is not necessary if such a sensor is operated in normal surrounding atmosphere.

A preliminary investigation on MEMS based immunosensor for E. coli O157:H7 detection

Bio-recognition layers on sensors can be designed in various ways; however the most popular approach is to immobilise antibodies for specific capture of analytes also known as immunosensor. This paper presents a preliminary study on MEMS based immunosensor for detecting Escherichia coli 0157:H7. In this paper, the recent progress within biosensors for E. coli O157:H7 detection will be reviewed. We will discuss the strengths and limitations of current sensor technologies for the detection of E. coli 0157:H7 .This paper explores the previous methods that have been employed to detect E. coli O157:H7 based on their detection scheme, detection limit, and response time. The reasons focusing on sensor utilizing specifically defined microcantilever using piezoresistive detection scheme is also discussed. We will also explain briefly on the theoretical aspects governing the relation between surface stress and the bending of the microcantilever.

Fabrication of polymeric optical waveguides

The paper reports the fabrication of polymeric optical waveguides. Single mode planar slab waveguides and straight waveguides have been fabricated from the organic polymer B-staged bisbenzocyclobutene (BCB) from Dow Chemical. A low cost fabrication method, chemical etching, is used to form the waveguides on BK-7 glass substrates. The processing conditions required for the fabrication of single mode optical waveguides have been thoroughly investigated and are presented.