A reliable method for measurement of the nonlinear refractive index through application of multi wavelength phenomenon. Multi wavelength realisation based on Erbium doped fibre laser (EDFL) is proposed and experimentally demonstrated. A combination of 15 m high efficiency Erbium doped fibre (EDF) and a 20 m Photonic Crystal Fibre (PCF) as main catalyst to suppress the homogenous broadening of EDF and to obtain highly stability of multi wavelength through insertion of a set of fibre Bragg gratings (FBGs) in the cavity. This PCF has zero dispersion of 1040 nm which mismatch from transmission window of 1550 nm. A reliable repeatability of multi wavelength based on multiple configuration of FBGs less than 0.2% obtained. This consistent results influence in determination of nonlinear refractive index by relation of four wave mixing (FWM).
Arrayed Waveguide Grating (AWG) functioning as a demultiplexer is designed on SOI platform with rib waveguide
structure to be utilized in coarse wavelength division multiplexing-passive optical network (CWDM-PON) systems. Two
design approaches; conventional and tapered configuration of AWG was developed with channel spacing of 20 nm that
covers the standard transmission spectrum of CWDM ranging from 1311 nm to 1611 nm. The performance of insertion
loss for tapered configuration offered the lowest insertion loss of 0.77 dB but the adjacent crosstalk gave non-significant
relation for both designs. With average channel spacing of 20.4 nm, the nominal central wavelength of this design is
close to the standard CWDM wavelength grid over 484 nm free spectrum range (FSR).
A linear tapered double S-shaped arrayed waveguide grating (AWG) was designed as an alternative to a U-shaped AWG, and a complete transmission spectrum for 18 channels of coarse wavelength-division multiplexing (CWDM) was demonstrated. The silicon-on-insulator based AWG with a rib waveguide structure with a broad channel spacing of 20 nm was designed to serve as a multiplexer/demultiplexer. A beam propagation method modeling simulation under transverse electric mode polarization over a free spectrum range of 700 nm was used for the design process. The geometrical dimensions of the AWG rib structure were optimized to achieve the lowest reported insertion loss of 1.07 dB and adjacent crosstalk of −38.83 dB. The influence of different etching depths on the top Si layer of the AWG for a constant core width of 0.6 μm as well as birefringence effects were also investigated. A transmission spectrum response at the output port close to the standard CWDM wavelength grid range of 1271 to 1611 nm with an average channel spacing of 2485 GHz was obtained.
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.
An acrylic-based 1x2 Y-Branch POF coupler consists of input POF waveguide, a middle high index contrast waveguide
taper and output POF waveguides has been developed. The optical device is based on a 1x2 Y-branch coupler design
with a middle high index contrast waveguide taper. Device modeling has been performed using non-sequential ray
tracing with an insertion loss of 4.68 dB and coupling ratio of 50:50. Low cost acrylic material has been used for the
device substrate. This middle waveguide taper region is constructed on the acrylic block itself without using any
additional optical waveguiding medium injected into the engraved taper region. Fabrication of the devices is done by
producing the device structures on an acrylic block using high speed CNC machining tool. Input and output POF fibers
are inserted in to this device structure in such a way that they are passively aligned to the middle waveguide taper
structure. The measured insertion loss is 7.5 dB and with a splitting ratio of 50:50.
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.
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.
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.
A novel 3D modeling of a lateral PIN photodiode (LPP) is presented utilizing In0.53Ga0.47As as the absorbing layer. The LPP has profound advantages compared to the vertical PIN photodiode (VPD) 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. The device has an interdigitated electrode structure to maximize optical absorption. At a wavelength of 1550 nm, optical power of 5 Wcm-2 and 5 V reverse bias voltage, the device achieved responsivity of 0.5 A/W. The -3dB frequency response of the device was at 14 GHz and it is able to cater for 10 Gbit/s optical communication networks.
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