Analysis Of Array Waveguide Based Interleaver Engineering Essay

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In the twenty first century, has massive demands in the use and availability of digital communication systems transmission ability, it has happen to an significant issues to build up thin channel spacing and larger channel number multiplexers/ demultiplexers (MUXs / DEMUXs) for dense wavelength division multiplexing (DWDM) structures. In the present-day, arrayed waveguide grating (AWG), thin-film coating, and fibre Bragg grating are major technologies for fabricating MUXs / DEMUXs.[1]

This report covers the basic operation and principles of (AWG) Array Wave Guide Based Interleaver . And the report covers the basic principle of array theory. And the performance analysis of AWG with using opti system softwear.

And also in communication networks, fibre optics networks are most rewarding communication networks. Fibre optics is channelled the transmission of light through thin glass.

The aim of this project is to investigate of the operation and function of the arrayed waveguide gratings (AWG). And the understand the performance of parameters in the device, and then we investigate those performance of parameters and try to find how those parameters can affect of the device.

Specifically, the pass band edges is more difficult to control in optical components, such as arrayed waveguide grating (AWGs), resulting in interior crosstalk performance. Interleavers assure that the originally adjacent channels are no longer present at the final filter. In addition the use of interleavers is very effective for the reduction of Rayleigh noise in bidirectional networks.

AIMS AND OBJECTIVES

Understand and familiarize the fundamental concepts and characteristics of AWG Based Interleaver

Develop and implement of AWG Based Interleaver

2. ABOUT OPTICAL FIBER

2.1 HISTORY

Fibre optics is used circumstantial in the modern world as modern technology. The principle of guiding of light through the fibbers optics possible was explained by Jacques and Mr. Daniel in Paris in 1840. [8]

In practically optical fibres are made by glass. And fibre is covered with a see-through shell to more correct of refractive index. [8]

Development of fibre then focused on fibre bundles for image transmission. Image transmission through tubes was found separately by television founder John Logie Baird and the inventor of radio Clarence Hansel in 1920. [8]

2.2 OPTICAL FIBER COMMUNICATION

Fibre optics used for communication, as transmit signals. Fibres are used as a medium for telecommunication networks. Optical fibre is very useful for transmit signals of the far away distance communications. There are benefits of using optical fibres for easy to transmit signals, [2]

High flexibility

High reliability

Adequate to its strong speed

Distance of communication network and Limit the practical speed because of attenuation and the dispersion problems in the fibre. [2] To solve and reduce attenuation problem can applied of the Erbium Doped Fibre Amplifier(EDFA) .To resolved dispersion of optical fibre still force a via media between the transmission distance and the bandwidth is making it is compulsory to refresh high speed of the signals at intervals using opto electronic repeaters.[2]

That performance use for especially long-distance communications. When compared with electrical wires small attenuation occurred in light propagates through the fibre. And the Repeaters use for long distance to modulate to transmit signal. Because they are losses signal. One fibre can be carrying many channels with different wave lengths.

Optical fibers are mostly make used of fiber optic communications or can be transmitted signals through the fibers. Because of that signals can be travel with low losses and the also resistance to electro magnetic mediation. Here fiber optic communication signals allow transmission more than higher bandwidths or data rates and longer distance. And also fibers are making use of lighting and the wrapped in bunch of fibers and they can be applied to carry images. In the short distance communication networking within a building or small area .single fiber can be transmit large number of data than the electrical wires. And also fiber has electrical interference.[8]

Fibers can be prepared by transparent plastic, glass or a mixture of the two materials. When long-distance telecommunications fibers make use of product is always glass, reason of minor optical attenuation in fibers. together of the single-mode and the multi-mode fibers are making use of communication links. Mostly Multi-mode fibers are making use of the short spaces (550m). And the single-mode fiber making used for long distance communication links. [8]

The best solution for that efficiently improves the useable bandwidth in a structure not including electronic repeaters, and permits realization of photonic networks by using Dense Wavelength Division Multiplexing (DWDM). [2]

Dense Wavelength Division Multiplexing (DWDM) is best efficient process. Reason of a number of channels can be carried. Each channel carried by dissimilar wavelengths, and they are transmitted throughout the single optical fibre. Avail of the DWDM used more available bandwidth not including dispersion effect. And the channels utilizing each channel, effectively separated from the other channels. And it cannot be dependent of the speeds, protocols and the direction of the communication networks. [2]

And also DWDM helps to the all optical fibre networks architectures. Where on signals are routed by using their wavelengths. As the result of that, this type of networks are probable more flexible and faster, and that can be low costly to keep up when the compared with other ways.[2]

3. ARRAY WAVEGUID GREATINS

3.1 INTRODUCTION ABOUT AWG

Arrayed Waveguide Grating (AWG) is multiplexers / demultiplexers are planar waveguide devices .Image and dispersive properties are basic foundation on an array waveguides. They imaging the field in an input and output waveguide on to array waveguides in such a way that the various wavelength signals are presented. [3]

In recent years, Arrayed Waveguide Grating (AWG) was first discovered by Smit in 1988 and later by Takahashi in 1990 and after that Dragone in 1991. They are known by under different names: Phased Arrays (PHASARs), Arrayed Waveguide Gratings (AWGs), and the Waveguide Grating Routers (WGRs).[3] And waveguide grating router (WGR) has happen to more and more trendy as wavelength multiplexers / demultiplexers (MUX / DEMUX) for dense wavelength division multiplexing (DWDM) applications (Vellekoop and Smit, in 1991).

The acronym AWG invented by Takahashi is the most normally used up name now a days. Fibre Bragg Gratings and Thin-Film Filters, AWGs are the mainly significant kind of filter type used in WDM networks. They are accepted turn out to be the mainly significant develop of Photonic Integrated Circuits (PIC) technology.[4]

Recent world the mainly significant technologies are used for AWGs.

Indiumphosphide (InP) based semiconductor technology

Silica-on-silicon technology

As well to that they investigate on lithium niobate and silicon-based polymer technologies have been shown up as well. Silica-on-silicon (SoS) AWGs have been presented to the sell in 1994 and at present grip the major part on the AWG market.[3]

This modal equals with fibre and so it comparatively simple to pair them to fibres. High fibre-coupling efficiency of (losses in use of 0.1 dB) and low propagation loss (less than 0.05 dB/cm) with they joined.[3]

The major difficulty is they are comparatively big because of their fibre compared waveguide properties. They are prohibiting the use of small curves. This is for the present being got better by using upper index disparity and the doted-size converters to maintenance fibre coupling low losses. [3]

3.2 ABOUT AWG

This is a latest technology make uses of an integrated array of waveguides as a interleaving and grating.[5] The arrayed waveguide grating (AWG) is a planar waveguide device.[6] And the beam going from side to side a device grating shall create an interference sample, signifying the beam is diffracted just at clear angles.

The spatial strength of giving out is a function of the grating, the wavelength and the angle of occurrence. In here different wavelengths will be diffracted in the different angles (spatially separated). Arrayed waveguide grating (AWG) is producing a tiny grating with lithographic technology and with low losses. [5]

Functions in AWG:-

Transmissive diffraction and grating in largest part of fiber optics

According o the wave length diffracting the beam at the angle

The primary application of arrayed waveguide gratings is WDM. By developing AWG, used for demultiplexing and WDM wavelength-division multiplexing (WDM). Initially, developers are identified that AWGs could be mix with other planar waveguide apparatus. And the other various functions like,[6]

Wavelength-selectable lasers.

Including dynamic gain

Reconfigurable optical add/drop multiplexers

Equalization

Figure 3.2.1 In an arrayed waveguide grating [6]

Dense Wavelength Division Multiplexing (DWDM) is an effective way. Where the number of channels, but different wavelengths are in each channel. Through a single optical fibre allows transmitted signals, without raising the cause of dispersion by using additionally on hand bandwidth. [2]

Each channel, while it is efficiently divided from the others, could be free in protocol, direction of communication and speed, all-optical network architecture are understood by helps of DWDM without want for electro-optical conversion where transmit signals are routed according to wavelength. Therefore, this kind of network has below characterises when compared to other types, [2]

Less costly to maintain

More flexible

Potentially faster

Figure 3.2.2 An Add / Drop Multiplexer (ADM). [2]

Figure 3.2.3 An Optical Cross Connect (OXC) using a space division switch [2]

In DWDM is done optical wavelength multiplxers / demultiplexers by Arrayed Waveguide Gratings (AWG). As well as multiplexing and the demultiplexing functions are performing by DWDM. It can be joint with other apparatus to make put or out multiplexers, used to pipe one wavelengths on and off the network, and the make use of for the routing, and Cross Connects. These components can be inert, according to wavelength where the signal routing should be fixed, or activated. Where the optical switches are utilised to dynamically route the signals. [7]

Both circuits are shown apparent to the format of data, can permit function completely in the optical field and both directional transmit of information. These tasks permit the creation of dissimilar apparent optical network. Examples of the three main kinds of these are explained in the coming subsections. [2]

It can put up several input fibres same time. Input and output port link policy were experimentally verified and formulated. The device same time removes the two main faults observed in the before built up device; reduction of every waveguide crossings between AWGs and taking away of the condition to accurately tally the characteristics of the two AWGs. This suggestion will be helpful in reduce device cost. [9]

This is because of the information that AWG based components that have been shown to be able of the exactly demultiplexing and a large number of channels, with comparatively little loss. Main characters of the N (output) x N (input) AWG MUX / DEMUXes are little loss of fibre to fibre, accurate and the narrow channel spacing, and the polarization insensitivity, then the big channel number, high reliability and stability, and being appropriate for the huge production (Dragone in 1991).[4]

Because of the manufacture the AWG is established on ranked photolithographic technology, in the combination of the AWG gives so many benefits. Such as,

Reduced packaging and fabrication costs

Reliability

Large fabrication

Tolerances

Compactness

The most valuable benefits of the AWG also include the controlled channel and precisely and the spacing, uniform the insertion loss and simple and accurate wavelength in stabilization.[4]

3.3. ABOUT INTERLEAVER

3.3.1 INTERLEAVER FUNCTIONL TYPES

All functions and filter types are mutual and periodic in frequency

(a) Partition of channels output to 1:4 or higher

(b) Two different ports are used to separate even and odd channels from Original interleaver.

(c) Asymmetric interleaver separates one channel.

(d) Separates even and odd bands of channels from banded interleaver,

Figure 3.3.1.1 (a) Partition of channels output to 1:4 or higher [10]

Figure 3.3.1.2 (b) Two different ports are used to separate even and odd channels from Original interleaver. [10]

Figure 3.3.1.3 (c) Asymmetric interleaver separates one channel. [10]

Figure 3.3.1.4 (d) Separates even and odd bands of channels from banded interleaver [10]

In the optical communication the effective method for increase the transmission capacity, was Dense wavelength division multiplexing (DWDM). [10]

The cyclic signals of the interleaver can be filter decreases the number of channels. Fourier apparatus are necessary to the flat pass band (out put signal) and high isolation rejection band. [10]

These intreleavers contrasts in to only channel drop and add filters. It can be creating a single narrow band of the filter more than a large rejection band. As a result of the interleaver needs for lesser Fourier apparatus, then the sharp edge response higher order and same flat top and narrow band filters can be understood with use few sections. [10]

There are many varieties of the blocks of the interlever according to their functions. The initial design of combines (or separates) an odd channels from even channels through the DWDM combiner. It is indicated by a 1:2 interleaver. In every channel there is cyclic separation and logical extension. Like as the 1:4 function Shown. The dissimilar variant of the banded interleaver. Where the channel bands are separated and periodically. [10]

This is the very hard to create and filter due to filters are roll off must be steeper in the relative to the filter time. At last, in compare with the previous in three filters. The asymmetric filters can cyclically separate one channel. [10]

Array Waveguide Gratings (AWG)s , and the DWDM devices such as thin film filters (TFFs) and Fibre Bragg Gratings (FBG)s , are mainly used for in systems with channel spacing to the no less than 100 GHz.[11]

Can be expand the transmission ability, with decrease in the channel spacing. It is also named interleaver. The input of the DWDM wavelengths can be separated by using Interleaver. Each individual channel is transmitted very high bit rate of traffic channels. Also the chromatic dispersion of the component is very low.[11]

4. BASIC PRINCIPLE OF AWG

The arrayed waveguide grating base interleaver is includes of an array of narrow waveguides. Between a pair of Coupling zones or mixing regions the signals are running closed each other. When cyclic waveguides running up to the second mixing region, that input signals first enter the mixing region and where they are coupled. [6]

After that the light transmitted to the second mixing region. That region the wave signal diffraction and in different angles of different wavelengths, it is similar to a diffraction grating.[6]

The combining region works as a lens to focus the diffracted beam in to a series of output ports on the opposed side. Helpful mediation focuses beam of a odd wavelength at only one position on the opposite side, with the ports set up to gather beam at the expected wavelength span, such as typical optical channel slots for WDM.[6]

The number of channels and the number of output ports are divided; when the channel spacing is multiplied by the number of channels can be obtained free spectral range of the device. The waveguides going among the two combination regions is larger than the number of channels.[6]

AWG is a planar-waveguide devise carrying out of high transmission gratings. Arrayed waveguides made in plastic, silicon, silica or semiconductor materials like as indium phosphates. AWG as a planar waveguide device, it could be made monolithically and integrated with other components. [6]

4.1 MULTIPLXER / DEMULTIPLEXER

Arrayed waveguide gratings have obtained approvals for WDM with high channel calculates as their arrangements permit low cost per channel than the methods basis on discrete optics. When in the laboratory editions have reached very ultimately high channel calculates and the spacing, with channel spacing to 10 GHz and hundreds of channels in a single device. [6]

Demultiplexing is the main purpose of the AWGs, with using a single input delivering a WDM signal and which is demultiplexed and the output of the optical channels are divided among various output waveguides. For multiplexing in AWGs, the component could be reversed with signals at isolated wavelengths. And incoming isolated port combined inside of the AWG. [6]

Typical AWGs have pass bands. It is closely in Gaussian form. They are powerful attenuate beam from the nearby pass bands. Though, the perfect pass band for WDM has a flat top conversely than the arched Gaussian peak. The simplest channel to smoothing the peak is convenient filtering by correcting way beam of light is carried to the input port, or by correcting the lengths of the array arms of the AWG. [6]

One option is to affix an interleaver to divide signals between pair of AWGs. Once is accepting the even channels and the other odd channels. Another waveguide component or AWG is for extra filtering. [6]

As the AWG demultiplexer Wavelength routing is the same principles. The of the arrayed waveguide gratings diffraction angle depends geometry of the grating technology as well as on the angle of the incidence. All the optical channels have to the same angle of incidence when they are entering through the single fibres. [6]

On the other hand, those inputs signals have different incidence angles if the light enters to the input mixer through the two or more input ports, hence they are diffracted at the dissimilar angles as they appear from the arrayed waveguides gratings in the output of the mixer. When reroute and the rearrange to optical channels delivered by multiple inputs of fibres this effect can be used to be easily. [6]

According to that the routing arrangement is rigid, channels with the same wavelength won't interfere with the each other or to be routed in out of the same waveguide. [6]

4.2 APPLICATIONS OF AWG

Arrayed waveguide gratings (AWG)s are mainly experimental used in optical fibre communication systems or networks. In particular those based on the multi-channel transmission with wavelength division multiplexing (WDM).

In individual wavelength channels or channels must be used in combined or separated. It can be the part of the more complex photonic integrated circuits (e.g. WDM transmitters).

Arrayed waveguide grating can be used for separating or interleaving the lines in the spectrum of a super continuum source, or in a pulse shaper for ultra short pulses.

5. OPERATION OF AWG

Figure 5.1 Array waveguide Gratings[10]

Figure 5.2 Lens setup of an AWG[10]

Waveguide configuration is formed on a substratum in the Arrayed waveguide grating. Include the following options in the waveguide configuration.

In to the first slab can be arranged One or more optical input waveguides, and the output side can be connected in to the first slab, one or more optical output channel Arrayed waveguides, and that waveguides connected to the input side of the second slab.

From the catching light beginning the outside to the first slab and the waveguide propagate light there through. In the arrayed waveguide enough many of waveguides in various lengths.

And the 2nd slab waveguides are linked to output edge of the arrayed waveguide.Then the single or more of the optical output waveguides can organized.

In the array waveguide grating of claim (fibre optics) where different in length from each other. And fibre optics is (sliding) construct in mutually-different materials.

In the arrayed waveguide grating, fibers are separate from each other.

Figure 5.3 Schematic representation view of the N X N AWG.[33]

Figure 5.4 The Input / Output Free Propagation Region.[34]

In normally AWG gadgets such as serve the multiplexers, add-drop devices, demultiplexers and filters and the optical Wave Division Multiplexing (WDM) and the Dense Wave Division Multiplexing (DWDM) uses.

Figure 5.3 shows a schematic illustration of the N x N AWG. The instrument includes of two curved in slab waveguide star couplers (free space range or free propagation ranges, FSR), linked by a go away array waveguide with the same length variation among nearby Array waveguides.[4]

The processing theory of the AWG multiplexers/demultiplexers can be explained in brief as below. In the input waveguide Light propagating is diffracted in coupled into the arrayed waveguide and the slab region by the 1st FSR. The arrayed waveguides has been planned like as the optical pathway of the length variation between nearby array waveguides equivalent an figure many of middle wavelength of the demultiplexer. As a result, the field delivery at the input opening will be recreated at the output opening. [4]

So, at this middle wavelength, the beam of light concentrates in the middle of the image surface (presented that the input waveguide is middle in the input surface). If the input wavelength is re tuned from this middle wavelength, changes of phase happen in the array branches. Because of this steady pathway of the length in variation between nearby waveguides, this phase vary get higher linearly array wave-guides from the inner to outer , That may happen the wave front to be slanting at the output opening.[4]

As a result, the central point in the plane of image is moved left from the centre. The pointing of the output waveguides in the plane of image permits the suitable parting of the various among wavelengths. The input includes of a number of channels, normally among 8 or 40 in industrial devices, transmitted on individual frequencies. Channel spacing is common in commercial devices.[2]

Frequency spacing in has been attained according to laboratory situations. The functioning wavelength is usually roughly 1.55 μm which attenuation is least in fibre optics. Every waveguides in the AWG be likely to one mode to make sure expected propagation throughout the machine.[2]

5.1 BASIC DESIGN PARAMETERS OF AWG

When knowing of the functioning theory of AWG take in, it depends on the various materials, like as polymeric materials or silica, and design conditions. like as diffraction, length difference of nearby arrayed waveguides, main length of the slab waveguide, free spectral range (FSR), and maximum value of input and the output wavelength channels, the maximum number of the array waveguides. The basic design parameters are summarized in analytical equations as follows: [28]

5.1.1 LENGTH DIFFERNCE OF AJACENT ARRAY WAVEGUID

The path length variation among nearby arrayed waveguides ∆L is given by the below expression [13]

Where

nc - is the effective refractive index of AWG,

∆L - is the path length difference between adjacent arrayed waveguides

0 - is the centre wavelength of the arrayed waveguide,

m - is the diffraction order,

5.1.2 FREE SPECTRAL RANGE (FSR)

Free spectral range (FSR) is a significant property of the AWG , demultiplexer periodicity is the similar name to the FSR. This periodicity is because of the information that create interface at the outside FSR can happen for a amount of wavelengths. The free spectral span indicates the frequency spacing and the wavelength among the maximum of the interface model due to the cyclic qualities of the AWG transfer function, and could be get as follows .[4]

Where,

FSR - free spectral range

nc - effective refractive index of AWG

m - order of diffraction

ng - group refractive index

0 - centre wavelength of the arrayed waveguide

5.2 TECHNICAL FIELD

In the communication field of optical fibre, there can be used an arrayed waveguide grating while specified. In the current invention connects for arrayed waveguide grating is managing the task of the wavelength demultiplexing and multiplexing of optical signals of many wavelengths.[14]

In the arrayed waveguide grating can be arranged one or more optical fibre input waveguides .In the first slab waveguides are linked to the optical input waveguides which is in the output sides . And arrayed waveguide is linked to the output side waveguides of first slab. And the 2nd slab waveguide are linked to the output side of the arrayed waveguides. And there can be

Arranged one or more optical fibre output waveguides. [14]

The arrayed waveguide is provided by the propagating of the light output from and the plurality of waveguides and the first slab waveguide arranged. Nearby channel waveguides are various in lengths by predefined lengths. And the arrayed waveguide provides to the each one of signal for a phase variation is in the arrayed waveguide gratings. Normally, a large number of channel waveguides are included the arrayed waveguide.[14]

On the array waveguide grating, when the wavelength division multiplexed of optical signal including signals can be having wavelengths λ1, λ2, λ3......to.... λn. One optical input waveguide can be entered those wavelengths. Then after that this signal forwards to the optical input waveguides and in to the first slab waveguides. Then the signal is diffracted and spread by the first slab waveguide and it is transmitted to the arrayed waveguide to propagate there through. [14]

After arrayed waveguide passing through, the signals enter the second slab of waveguide in join of and then the output from the optical waveguides. And the channel of the waveguides in the arrayed waveguides are all different in lengths, the phase difference between appears in each of the signals are that have passed through out of the arrayed waveguides. In Oder to this phase differences, the wave forms fronts of the signals are tilt. And this tilt angles are determines of the focal points of the signals. [14]

In this reason of the cardinal points of the signals are having different different wavelengths differ from each other and the accordingly optical output of the waveguides are formed at the respective in the focal points. Within this configuration, the signals are different the wavelengths are an extracted by the optical output waveguides respectively. Then the completing of the function as a wavelength division demultiplexer of an arrayed waveguide grating. [14]

The arrayed waveguide gratings are taken by advantage of principle and the reversibility of optical circuits. And the arrayed waveguide grating also handles in the function of the wavelength division multiplexers. And as well as wavelength division demultiplexer. The reversing in the above described in the procedure, when the signals are having differing wavelengths λ1, λ2, λ3...to....λn enter respective optical output of the waveguides. The signals are passes through the above mentioned of the propagation path in reverse. And in the second waveguide slab, signals are multiplexed. And the arrayed waveguide and the first slab waveguides and output of the optical fibre input waveguides.

In generally, as an arrayed waveguide gratings are mainly made of the silica based with glass.[14]

6. LABORATORY EXPERIMENTS

In the laboratory experiment Opti system software was used to analysing performance of Array Waveguide Based Interleaver. In here I used to AWG N x N multiplexer.

An AWG N x N multiplexer structure is shown in Figure 6.1

Figure 6.1 Soft ware structure of AWG.

Figure 6.2 Soft ware properties of AWG

Mainly in AWG can be configure as,

Size - with N inputs between 2 and 1000

Configuration - Mux and De-mux

Frequency - Between 30 and 300000 THz.

Bandwidth - Numeric value between 0 and 1e+100 GHz.

Frequency Spacing - Numeric value between -10000 and 10000 GHz.

In practically we use of following bands and the wavelength ranges,

Band

Description

Wavelength Range

O band

Original

1260 to 1360 nm

E band

Extended

1360 to 1460 nm

S band

Short Wavelengths

1460 t0 1530 nm

C band

Conventional ("erbium window")

1530 to 1565 nm

L band

Long Wavelengths

1565 to 1625 nm

U band

Ultra long Wavelength

1625 to 1675 nm

* (1530 nm t0 1650 nm Dense WDM)

Table 6.1 Wavelength ranges [8]

To the AWG can be input in N frequencies. Each channel will exit through a different output, according to its wavelengths and frequency. AWG input with an suitable design, the channels will be exit and separated through various outputs.

In this experiment used the C band for practical.

6.1 AWG WORK AS MULTIPLEXER

Figure 6.1.1 Setup of AWG use as Multiplexer

Figure 6.1.2. Output of the five channels

This section, is described the experimental results of the multiplexer using an AWG. Figure 6.1.3 shows of the experimental setup in basics. In the experiment, separated two channel optical signals (With using optical Trans meters) multiplexed by using AWG. And the observation can be taken by the optical spectrum analyzer.

Figure 6.1.3 simple structure of the Simulation of AWG use as mux.

Figure 6.1.4 one of the outputs of the two channels with spacing.

Figure 6.1.5 one of the outputs of the two channels with increase spacing.

Input frequencies- 1530nm & 1565nm

In AWG,

Configure Mux , Frequency- 1550nm.

Change the frequency spacing of the optical transmitter.

Wavelength (µm)

Frequency spacing (nm)

Figure 6.1.6 frequency spacing and wavelength diagram

The diagram shows the variation of frequency spacing and wavelength. That is linear diagram.

6.2 AWG WORK AS DE-MULTIPLEXER

Figure 6.2.1 Setup of AWG use as De Multiplexer

Figure 6.2.2 Output of the three channels

In this section, described the experimental results of the AWG using de multiplexer. Figure 6.2.3. shows the simple experimental setup. In this experiment, separated two channels input the multiplexer. In the output of multiplexer in put the AWG .After that observes the output of signal diagrams of optical spectrum analyzer.

The carrier wavelength of the channels 1 and 2 are 1530 nm and 1540 nm respectively. For the Demux scheme, we used opt system soft ware a commercially available in AWG.

The centre frequency of the AWG was set to the 1560 nm. And they perform desired to the Demux operation.

Figure 6.2.3 simple structure of the Simulation AWG use as de mux.

Figure 6.2.4 two optical output of the AWG de mux

The figure shows the Separation between the carriers and the two sidebands. There can be seen by a considerable amount of the unsuppressed optical carriers.

In this experiment, first filtered the carrier signal and the lower sideband of the channels 1 and 2 with using the AWG as shown in Figure6.2.3 because we used an AWG, each demultiplexed channel cannot be simultaneously detected. The channel selection was made by adjusting the input ports of the AWG. The carrier and the sideband of the undesired channel are suppressed by the desired carrier and the sidebands of the channels respectively.

Figure6.2.5 frequency spacing and wavelength diagram

The diagram shows the variation of frequency spacing and wavelength. That is linear diagram.

In here more clearly and shows the shifted in output signals of the middle wavelength through to the outside guides. Figure proves the enlarged version of the middle channel.

AWG is includes of a diffraction of the lens and the grating and the slim output split with a spatially modeled of the mask on peak of the gratings. This requisite provides an output of the temporal waveform. But that is a exactly scaled version of the input spatial profile at the grating.[15]

In precious of a cyclically peaked input of the spatial shape creates a regularly spaced explode of pulses. An AWG could be thought about to the incorporated pulse form where the array waveguide relates to the gratings of the lens grouping in the bulk equipment and the AWG output waveguide groups to the greater part optics output.[15]

The spatial waveguide model next to the output of the AWG array part is analogous to the cyclically moderated spatial light on the greater part grating the optics; this clarifies the close match among the extremely high speed pulse explodes made here via lighting of an AWG and previously using pulse shapers . And also the greater part optics such as the AWG is able of generating numerous spatially divided and wavelength moved but else the same copies of the pulse explode.[15]

As this attitude for make use of an AWG is before undiscovered, it is significant to in brief express the optical power effectiveness. Referring to the effectiveness for a only output channel is roughly known by the pass band width separated. When the apparatus is planned so that output channels are spaced by, the numerous output channels is roughly. So, the total optical power effectiveness is known by the efficiency for a single channel period the number of channels as the result. [15]

In review of the experiment, we have to reveal in the 1st time for our learning, the generation of trains of the pulses at terahertz repetition speed is likely from an AWG. The key conditions are that the device must be modified. And the multiple filters of pass bands of the signal fit within the input of the laser bandwidth. And the output pulse repetition frequency is equal to the free spectral range, or equally the opposite of the delay of an increase per direct in of the array waveguide region.[15]

The output temporal profile is invariant across different outputs of the same device, but the middle wavelength moves from one output to the next with the quantity of shift given by the channel spacing of the device.[15]

In the pulse spectrum width of an individual pulses in the output train is verified by the input pulse width. These exclusive properties are permit for generation of the same wavelength shifted and very high speed of the pulse trains for hybrid TDM (Time Division Multiplexing) and the WDM ( Wavelength Division Multiplexing) communications and photonic signal processing. In the future, we anticipate that similar experiments may be performed with a high-repetition-rate of the source (tens of gigahertz), which lead to very closely spaced or even continuous terahertz pulse should burst.[15]

6.3 AWG WORK AS INTERLEAVER

Figure 6.3.1 simple structure of the simulation of AWG use as Interleaver.

In this simmulation input the sevaral frequncy by using optical transmetters. And join the ideal mux and AWG. Out put of the ideal mux showen in figure 6.3.2. there is seven (7)frequncies with multiplexed out put.

Figure 6.3.2 optical output of Mux

Figure 6.3.3 optical output of optical spectrum Analyzer.

In this figure can identify main output of four (4) frequencies are interleaving.

Figure 6.3.3 optical output of optical spectrum Analyzer-1.

In this figure can identify main output of other three (3) frequencies are interleaving.

7. TIME PLANE

8. CONCLUTION

In the changing world, most things are changing into electronic based systems and the easy part of the operations. As the result of this, optical fibers are use to communication. Now a day's optical fibers are overlap with applied science and engineering designs and the applications of the equipments.

In this project is investigated theoretically the basic design parameters of arrayed waveguide grating (AWG) with using opti system software. In the experiments used the C-band's spectral range (from 1530 nm to 1565 nm). And have been demonstrated theoretically that the minimum of the diffraction order and the maximum number of the input and the output wavelength channels, and then the maximum number of the arrayed waveguides. Also have to investigate the optimization design and the parameters of AWG for a C-band application.

By using opti system software comparing the variation of frequency spacing and wavelength configuration with AWG. That configures with two types, multiplexer and the de multiplexers. Got readings with changing frequency spacing. Those are linear diagrams. The reason for that frequency spacing variation is linear for both multiplexrs and de multiplexer configurations in AWG. The knowledge was gain about the how to work with the soft ware and the components can be use in simulating process by using opti system software.

9. REFERENCES

[1] Yinchieh Lai. "Arrayed waveguide grating DWDM interleaver", OFC 2001 Optical Fiber

Communication Conference and Technical Digest Postconference Edition (IEEE) , 2001

[2] http://www.nottingham.ac.uk/ggiemr/downloads/SL_chapt2.pdf

[3] Xaveer J. M. Leijtens. "Arrayed Waveguide Gratings", Springer Series in Optical Sciences,

2006

[4] http://www.apollophoton.com/apollo/APNT/APN-APSS-AWG.pdf

[5] http://www.comsoc.org/ci/private/1998/dec/Sadot.html

[6 ] Hecht, Jeff. "New family of components emerge from arrayed waveguide gratings: designer are using AWGs to create a", Laser Focus World, Dec 2003 Issue

[7] http://www.scipub.org/fulltext/ajeas/ajeas22317-323.pdf

[8] http://en.wikipedia.org/wiki/Optical_fiber

[9] O. Moriwaki. "Interleaved Waveband MUX/DEMUX Developed on Single Arrayed-Waveguide Grating", OFC/NFOEC 2008 - 2008 Conference on Optical Fiber Communication/National Fiber Optic Engineers Conference, 02/2008

[10] S. Cao. "Interleaver Technology: Comparisons and Applications Requirements", Journal of Lightwave Technology, 2004

[11] Wang, Q.. "Optimal design of a flat-top interleaver based on cascaded M-Z interferometers by using a genetic algorithm", Optics Communications, 20030901

[12] Qin, Z.-K.. "Analysis for fabrication errors of arrayed waveguide grating multiplexers", Optics and Laser Technology, 200803

[13 ] D.E. Leaird. "Generation of high-repetition-rate WDM pulse trains from an arrayed-waveguide grating", IEEE Photonics Technology Letters, 3/2001

[14] A. Kaneko et al, "Recent progress on AWGs for DWDM applications," IEICE trans.

Vol.E83-C, no.6, 2000.

[15] ITU-T specification report G.709 and G.975

[16] Journal of Light wave Technology, Vol.21, No.8,Aug 2003

[17] E. S. Koteles, "Integrated planar waveguide demultiplexers for high density WDM

applications," Fiber and Integrated Optics, vol.18, pp. 1999.

[18] John M. Senior " Optical FiberCommunication"

[19] IEEE Photonics Technology Letters, Vol. 13, No. 3, March 2001

[20] http://en.wikipedia.org/wiki/Optical_fiber

[21] Y. Inoue, H. Takahashi, and et al: "Elimination of polarization sensitivity in silicabased

wavelength division multiplexer using a polyimide half waveplate," J.

Lightwave Technology, vol.15, no.3, pp1947-1957, 1997.

[22] http://www.freepatentsonline.com/7539368.html

[23] C. Doer et al., IEEE Photon. Tech. Lett.11, 581 (1999).

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[25] C. Dragone- optical multiplexer and planar arrangement of two star

couplers, IEEE Phot. vol. 3, no. 9, pp. 812-815, 1991.

[26] M. K. Smit and A. R. Vellekoop - Four channel integrated-optic wavelength

multiplexer with weak polarization dependence, Lightwave Technology., vol. 9, no. 3,

pp. 310-314, 1991.

[27] http://www.aero.org/publications/crosslink/winter2002/04.html

[28] Rajiv Ramaswami & Kumar N. Sivarajan., " Optical Networks"

[29] M. K. Smit and C. van Dam, "PHASAR-Based WDM-Devices: Principles, Design

and Applications", IEEE J. of Sel. Topics in Q.E., vol. 2, no. 2, pp. 236-250, 1996.

[30] IEEE Photonics Technology Letters, Vol.17, No.12, Dec 2005

[31] Faculty of Electrical Engineering,Universiti Teknologi Malaysia-VOL. 10, NO. 2, 2008.

[32] K. Okamoto, Fundamentals of optical waveguides, New York: Academic, pp. 359,

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[33] P. MuËœnoz, D. Pastor and J. Capmany, "Analysis and design of arrayed waveguide

gratings with MMI couplers"Optical Communications Group Universidad Polit´ecnica de

Vera s/n, 4607

[34] S.Musa, Borreman,"Multimode arrayed waveguide greating demultiplexer', University of Twente, Light wawe Devices Group.

[35] H. Takahashi, "Arrayed waveguide grating for wavelength division multiplexer with

nanometer resolution," Electron. Lett., vol. 26, pp. 87-88, 1990.

[36]www.oplink.com/shop/images/uploads/AWG50.JPG

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