Micro Milling Process for the Rapid Prototyping of Microfluidic Devices

Micro milling process has become an attractive method for the rapid prototyping of micro devices. The process is based on subtractive manufacturing method in which materials from a sample are removed selectively. A comprehensive review on the fabrication of circular and rectangular cross-section channels of microfluidic devices using micro milling process is provided this review work. Process and machining parameters such as micro-tools selection, spindle speed, depth of cut, feed rate and strategy for process optimization will be reviewed. A case study on the rapid fabrication of a rectangular cross section channel of a microflow cytometer device with 200 um channel width and 50 um channel depth using CNC micro milling process is provided. The experimental work has produced a low surface roughness micro channel of 20 nm in roughness and demonstrated a microflow cytometer device that can produce hydrodynamic focusing with a focusing width of about 60 um

S-bend silicon-on-insulator (SOI) large cross-section rib waveguide for directional coupler

S-bend contributes the high losses in the silicon-on-insulator (SOI) large cross-section rib waveguide (LCRW). The objective of this work is to investigate S-bend SOI LCRW with two different single-mode dimensions named symmetrical and asymmetrical. The S-bend SOI LCRW has been simulating using beam propagation method in OptiBPM software. The asymmetrical waveguide with two different dimension arc given the best performance if compared to others dimension with 3 μm of waveguide spacing. It achieved 92.24% and 91.10% of normalized output power (NOP) for 1550 nm and 1480 nm wavelength respectively. Moreover, the minimum of S-bend spacing between the two cores is 0.9 μm for both 1550 nm and 1480 nm. Therefore, asymmetrical waveguide with two different dimension arc and 0.9 μm of S-bend spacing are chosen. This analysis is important to determine the right parameter in order to design the SOI passive devices. However, future work should be done to see the performance by designing the coupler and implement in the real system. Copyright © 2017 Institute of Advanced Engineering and Science. All rights reserved

Intensity Loss of ZnO Coated on Fiber Optic

Macrobends are optical fiber structures suitable for detecting motion changes. This structure has been developed using single-mode fibers and a combination of single-mode and multimode fibers called hetero-core. In this study, a new macrobending structure was designed and developed by adding a nano-ZnO element to the fiber optic core based on Revolution 4.0. The addition of nanomaterial elements involves an etching process that uses harmful chemicals or high-cost laser technology. Therefore, hetero-core was applied in this study to replace the etching process. The ZnO-coated fiber optics with 10 (ZnO1), 20 (ZnO2), and 30 (ZnO3) times of dip coating were developed using the dip-coating method and characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Sensitivity measurement was conducted with glued optical fiber in the form of bending using a tape with a bending dimension of 2.5 cm × 1.5 cm and a wavelength of 1,550 nm. Morphological characterization using SEM proves that nanoparticles are attached to the optical fiber, and the EDX characterization confirms that the nanoparticles are ZnO elements. Optical fiber sensor sensitivity using core sizes 9, 50–9–50, 50–9–50 (ZnO1), 50–9–50 (ZnO2), and 50–9–50 (ZnO3) achieved sensitivity values of 0.91, 1.61, 2.98, 3.34, and 3.51, respectively. This study successfully produced ZnO-coated optical fiber sensors with a hetero-core structure without performing the etching process and successfully increased the sensitivity of the sensors

Investigation of AWG demultiplexer based SOI for CWDM application

9-channel Arrayed Waveguide Grating (AWG) demultiplexer for conventional and tapered structure were simulated using beam propagation method (BPM) with channel spacing of 20 nm. The AWG demultiplexer was design using high refractive index (n~3.47) material namely silicon-on-insulator (SOI) with rib waveguide structure. The characteristics of insertion loss, adjacent crosstalk and output spectrum response at central wavelength of 1.55 μm for both designs were compared and analyzed. The conventional AWG produced a minimum insertion loss of 6.64 dB whereas the tapered AWG design reduced the insertion loss by 2.66 dB. The lowest adjacent crosstalk value of -16.96 dB was obtained in the conventional AWG design and this was much smaller compared to the tapered AWG design where the lowest crosstalk value is -17.23 dB. Hence, a tapered AWG design significantly reduces the insertion loss but has a slightly higher adjacent crosstalk compared to the conventional AWG design. On the other hand, the output spectrum responses that are obtained from both designs were close to the Coarse Wavelength Division Multiplexing (CWDM) wavelength grid

Optical encryption device for software protection

An optical-based hardware encryption device for software protection is proposed. Software piracy and illegal usage require that software operation is secured through a form of hardware protection. Electronic-based hardware keys such as dongle keys may be vulnerable to attacks through reverse engineered technology. A simple optical device can be included as part of the hardware key where it can be used as an encryption device. Software users will require specific hardware key with built optical device in order to operate the software. The LED activated optical device can produce encrypted signals via generated optical codes solely based on the geometrical feature of the optical device. A suitable form of optical code generating device is presented in the form of 1xN asymmetric waveguide coupler

Chemical tapering of polymer optical fiber

Polymer optical fibers (POFs) have significant advantages over numerous sensing applications. The key element in developing sensor is by removing the cladding of the fiber. The use of organic solvent is one of the methods to create tapered POF in order to expose the core region. In this study, the etching chemicals involved is acetone, methyl isobutyl ketone (MIBK), and acetone-methanol mixture. The POF is immersed in 100%, 80%, and 50% of acetone and MIBK dilution. In addition, the mixture of acetone and methanol is also used for POF etching by the ratio 2:1 of the volume. Acetone has shown to be the most reactive solvent towards POF due to its fastest etching rate compared to MIBK and acetone-methanol mixture. The POF is immersed and lifted from the solution for a specific time, depending on the power loss properties for the purpose of producing unclad POF. In comparison to silica fiber optic, the advantages of POF in terms of its simple technique and easy handling enable it to produce unclad POF without damaging the core region. The surface roughness of the POF is investigated under the microscope after being immersed into different solvent. This method of chemical tapering of POF can be used as the fundamental technique for sensor development. Next, the unclad fiber is immersed into ethanol solutions in order to determine the reaction of unclad POF towards its surrounding. The findings show that this particular sensor is sensitive towards concentration changes ranging between 10 wt% to 50 wt%

Large cross-section rib silicon-on-insulator (SOI) S-bend waveguide

S-bend SOI waveguide is known as the most critical part for SOI device design. Normalized output power for the different parameter of the S-bend waveguide has been analyzed using OptiBPM simulator in 1.55 μm communication wavelength. Dimension of 5 × 5 μm2 single-mode rib waveguide is chosen. The variable parameters are transition offset and lateral offset, given the waveguide length of 100 μm–5000 μm. The maximum normalized output power achieved at the waveguide length of 550 μm for the 10 μm S-bend offset is 95.81%. Moreover, the ideal lateral offset is 2.7 μm with 2.52% normalized output power improvement

Investigation of AWG demultiplexer based SOI for CWDM application

9-channel Arrayed Waveguide Grating (AWG) demultiplexer for conventional and tapered structure were simulated using beam propagation method (BPM) with channel spacing of 20 nm. The AWG demultiplexer was design using high refractive index (n~3.47) material namely silicon-on-insulator (SOI) with rib waveguide structure. The characteristics of insertion loss, adjacent crosstalk and output spectrum response at central wavelength of 1.55 μm for both designs were compared and analyzed. The conventional AWG produced a minimum insertion loss of 6.64 dB whereas the tapered AWG design reduced the insertion loss by 2.66 dB. The lowest adjacent crosstalk value of -16.96 dB was obtained in the conventional AWG design and this was much smaller compared to the tapered AWG design where the lowest crosstalk value is -17.23 dB. Hence, a tapered AWG design significantly reduces the insertion loss but has a slightly higher adjacent crosstalk compared to the conventional AWG design. On the other hand, the output spectrum responses that are obtained from both designs were close to the Coarse Wavelength Division Multiplexing (CWDM) wavelength grid

Sensitivity Enhancement of Heterocore Macrobend Fiber Optics by Adding a ZnO Film

Optical fibers with high sensitivity are in demand due to their great potential in sensor application. Semiconductors, such as ZnO, are good materials. Using them as a second cladding offers opportunities in realizing next-generation multimaterial fiber optics. COMSOL Multiphysics is used to simulate heterocore macrobend fiber optics with the same curvature radius but different values of refractive index and thickness of ZnO films. The optimum thickness of ZnO films is identified by determining the loss of optical fibers. Macrobend heterocore fiber optics by adding ZnO thin film has been established by simulating and interpreting the relationship in terms of transmission and refractive index in the evanescent field. These results will provide a reliable fundamental to guide the performance in practice