Mohd Hanapiah M. Yusoff

Optimized Nano-Slot Silicon Waveguide Structures for Optical Sensing Applications

In this paper, an investigation of optimized vertical and non-vertical nano-slot silicon waveguides with different cover media (cladding) is presented. The mode properties and light confining effects for both of these slot waveguides geometry are investigated at operating wavelength of 1550nm. Light propagation of waveguide modal profiles for electric field and intensity of such slot waveguides are also presented.

New design of Y-junction coupler based on highly multimode polymer waveguide

In this paper, we demonstrate a new design of a highly multimode Y‐junction optical waveguide coupler with a v‐shaped tip compared to a standard design for better optical power splitter/combiner. The acrylic‐based waveguide contains of 1 mm×1 mm waveguide cross section, attached by 98/1000 μm polymer optical fiber (POF) as an input and outputs and NOA63 transparent adhesive polymer at the middle Y‐junction region. In the simulation of the new design, the Y‐junction branching angles and POF v‐shaped tip angles were varied. The transmission analysis was conducted using non‐sequential ray tracing technique due to the highly multimode nature of the waveguide. The output power from the two ports obtained from the simulations was about 94% with an average of 47% power splitting and percentage difference of ±0.1% between each output ports. The new design shows better splitting ratio with higher power output and maintain the excess loss of 0.27 dB.

SIMULATION OF U-SHAPED PLASTIC OPTICAL FIBER ETHANOL SENSOR

The prediction of optical loss in different bending diameter of U-shaped POF sensor toward variation of ethanol’s refractive indices was investigated using ray-tracing method perform by Zemax software. It can provide information on how the propagation ray is perturbed by different bending diameter of U-shaped POF. There are five designs of POF models were pre-drawn with different bending diameter; 2.0cm, 2.5cm, 3.0cm 3.5cm and 4.0cm. From the results, U-shaped with 2.5 cm bending diameter has shown the most sensitive bending diameter as compared to the rest. Either with the presence of cladding layer or not the sensitivity detected was 0.014 x10 -4 Watts/Vol%.

Intrinsic restructuring of defects in amorphous SiO2 in manipulating electron-trapping levels via first principles study

A model of undefected and defected amorphous SiO2 has been constructed from Rietveld Refinement to investigate the effect of defect structure to its properties. Atomic level study for both structure were carried out using plane-wave pseudo potential by density functional theory. A new electrons trapping energy level appears within the 5.853eV band gap of a-SiO2 for oxygen-excess defected structure. This defect energy level reduces as more number of excess oxygen atoms was added to the structure of a-SiO2. A spectral emission at 388nm from SiO2 glass excited with 350nm (200mW) laser demonstrates the existence of the defective states in the structure in trapping electron at 3.273eV energy level.

Matched MFD for fiber-to-vertical nanoslot waveguide couplers

The design of fiber-to-nanoslot waveguide low coupling loss is proposed and demonstrated. The light from fiber is coupled into the fiber-adapted waveguide based on an inverted taper structure with matching mode size. The parameters of taper tip width and taper length have been evaluated by means of overlap integral and 3D-FIMMPROP simulations at λ=1550 nm. Slightly larger fiber MFD of 2.9 μm found to be good match and achieved total coupling efficiency of 93% for an inverted taper tip width of 60 nm and length of 50 in TE polarized.

Fabrication and simulation of multimode symmetrical and asymmetrical Y-junction optical power splitters

This paper presents the fabrication and simulation of multimode symmetrical and asymmetrical optical power splitters based on embedded Y-junction optical polymer waveguide. Due to its highly multimode in nature, the designs were simulated using non-sequential ray tracing technique. The waveguiding which consists of 1×1 mm cross-section region was fabricated using transparent adhesive polymer (NOA63) on an acrylic plastic substrate. Experimental work on symmetrical waveguide results in 50∶50 power splitting ratios with ±2% error. A new design of asymmetrical waveguide, which utilized the main bus-line of the input port connected direct to the tap line was simulated and demonstrates a good power splitting ratios ranging from 1% to 99%.