Comments (0) Cite this document
They are used in wavelength-stabilized lasers, Raman amplifiers, phase conjugators, fiber lasers, wavelength converters, passive optical networks, wavelength division multiplexers,…
Download full paperFile format: .doc, available for editing
GRAB THE BEST PAPER93.5% of users find it useful
Read TextPreview


Fiber Bragg gratings have emerged as important components in a variety of lightwave applications. They are used in wavelength-stabilized lasers, Raman amplifiers, phase conjugators, fiber lasers, wavelength converters, passive optical networks, wavelength division multiplexers, and gain equalizers.
Lightwave networks enable high capacity interconnections of information on many parts of earth. What has stimulated their development is the demand for increased bandwidth. Commercial point-to-point wavelength division multiplexers operating in the 1550nm wavelength region may have 8, 16, and more connections, each carrying 2.5 or10 Gb/s traffic and proposals for finer granularity.
Accompanying the evolution from copper wire or wireless connection to lightwave networks is the proliferation of new optical devices. Discoveries in optical transmitters, amplifiers, frequency converters, filters and multiplexers enable ways to generate, condition, and detect light.
The study of wave interactions with periodic structures has yielded convenient methods of analysis and the results have been extended to gratings in wavelengths such as those in distributed feedback lasers, acousto-optic modulators and filters, and other diffracted waveguide devices. The fiber Bragg gratings is readily analyzed by coupled mode and transfer matrixes analysis. the two modes of the waveguide Bragg grating are the counter propagating waves in the fiber which are coupled through the grating reflection. In the absence of the grating, the spatial dependence of the polarization currents for the forward wave are proportional to. Perturbations by a grating having spatial period ٨ create new sidebands that result in wave coupling i.e. exp( jβz)cos(2πz/٨) = ½{exp[j(β-2π/٨)z]+exp[j(β+2π/٨)z]} and mode coupling to the backward coupling wave. Exp[-jβz] described by the first term on the right-hand side, occurs when -β~(β-2π/٨). Then the forward propagating wave is reflected (coupled) into the backward propagating wave.
Coupled mode equations are readily derived upon substitution by the grating refractive index function into the wave equation +[]2E(٤)=0 where ٤=koz is the normalized axial dimension and n(٤)/no=1+σ(٤)+2h(٤)cos[2٤+2ǿ(٤)]. Here, no is the effective index of the propagating waves, and k0=٤onok is the nominal Bragg wave number, for constant ǿ, the Bragg wavelength is λbragg=2πn0/k0. Change in the local average refractive index is defined by σ, the peak-to-peak index variation is 4h and corresponds to grating chirp; linear chirp has ǿα٤2. Defining a detuning parameter about the nominal Bragg wavelength, Δ= (w-w0)/w0=λbragg/( λ-1) and expanding ( βn/k0no)2 to first orders
+[1+2(α+Δ)+2hexp(iχ)+2hexp(-iχ)]E(ﯕ)=0 where χ=2ﯕ +2ǿ. Assuming slowly varying field amplitudes and expressing the field as the sum forward and backward propagating waves E(ﯕ)= a +(ﯕ)exp(iﯕ)+a-(ﯕ)exp(-iﯕ) is substituted and only first derivatives retained. Grouping yields the coupled mode equations for the field amplitudes in the forward and backward-propagating waves. Therefore coupling between waves is directly proportional to the grating amplitude and change in the average refractive index has a similar effect as grating chirp.
Fiber gratings are of interest to lightwave communications as either auxiliary components or as network elements
Fiber lasers
These can be constructed using fiber Bragg gratings as wavelength selective resonator mirrors and erbium-doped fiber as the gain medium. These fiber lasers are optically pumped, often directly without the use of pump wavelength division multiplexers.
The output behavior is described by a simple above threshold two mirror model of the erbium fiber laser derived from rate equations. For an undepleted pump, the laser’s output power PL as a function of pump power PP is
PL= .{.[ where α, g and ﯕ designate fiber parameter R is the reflectivity of the fiber Bragg grating cavity mirrors and n2=(αl-ln )/(αl+gl) is the normalized metastable population. The laser threshold and slope efficiency are easily calculated whether pumped at 650, 980, or 1480nm wavelength.
Reflectors in fiber amplifiers
Placing a single broadband reflector at the output of an erbium-doped fiber amplifier double-passes the input signal, increasing the small-signal gain and recycles remnant pump light. The equation for reflected wavelengths is obtained.
Exp[ ()-2αiL].
Raman-shifted lasers and Raman amplifiers
These enable efficient conversion of short-wavelength light into longer wavelengths suitable for long-distance fiber transmission.
Pump reflector in a phase conjugator- Blocking filter in a programmable wavelength converter
The phase conjugator compensates chromatic dispersion in optical fiber. Dispersion-induced signal distortion from the first half of the span is cancelled by dispersion in the second half. Efficient phase conjugation may be obtained through 4-wave mixing in semiconductor lasers or optical fibers, though the efficiency must be independent of the input signal polarization for its practical use in a lightwave system.
Isolation filters in bidirectional lightwave transmission
These are used in long-distance systems where fiber is scarce. There are 1300/1550nm bidirectional systems.
Having a minimum fiber count requirement for bidirectional systems may allow improved path diversity, smoother upgrade transitions and marginal growth in congested routes.
WDM demultipliers
The channels in a wavelength division multiplexer are combined in a multiplier, traverse the fiber link and then are separated with a demultiplier to direct each channel to its receiver.
1. R Kashysp, ‘Photosensitive optical fibers: Devices and applications,’ Optic Fiber Technol.vol1 pp.17-34, 1994.
2. M. Yamada and K. Sakuda, ‘Analysis of almost-periodic distributed feedback slab waveguides via a fundamental matrix approach,’ Appl. Opt. vol. 26, no. 16, pp 3474-3478, 1987.
3. H.A. Haus: Waves in optoelectronics: Englewood cliffs, NJ: Prentice Hall, 1984 Ch. 8.
4. A. Hamakawa, T. Kato, G. Sasaki, and M. Higehara, ‘wavelength stabilization of 1.48μm pump laser by fiber grating,’ in Proc. ECOC ’96, Oslo, Norway, 1996, paper MoC3.6. Read More
Cite this document
  • APA
  • MLA
ECE 4332 ELECTR OOPTIC DEVICES AND SYSTEMS Assignment. Retrieved from
  • Cited: 0 times
Comments (0)
Click to create a comment or rate a document


ECE teacher's Reflection on practice

...?REFLECTION Analyse: Being the first time I met Ryan, I needed to establish good rapport with him. Knowing that he came from a trip, I used that asa springboard to begin a conversation. The sharing of recent experiences is an appropriate ice-breaker as it shows that one is interested in the other person (Brewer, 2001). I think Ryan appreciated the fact that I gave him my attention and consideration. My patience and interest in him paid off as he rewarded me with a show of affection at the end of the day. It made me feel good that I was successful in establishing a good rapport with this boy. Theorize: The episodes with Ryan reflected the Te Whaariki principle of Relationships. Ryan was indeed responsive and reciprocated my... Analyse: Being...
3 Pages(750 words)Essay

Handling devices

...?Handling devices Roller conveyor: One of the materials handling devices found in my organization belongs to the category of transport, i.e. roller conveyor. It is used to shift goods from one place to another. The material may be moved from one workplace to another or from a dock to another. The benefit of using the roller conveyor is that no matter how heavy the load may be, it gets moved with minimal inconvenience and time as it has to be moved mechanically by rollers. No manual work is involved in it. The smallest thing to be transported has to be broad enough to cover the width of at least three rollers in order to be moved (MHE Taxonomy, 1999). I would like to reduce the diameter of the rollers so...
1 Pages(250 words)Essay

Cloning Devices

.... In fact, the term cloning can be used for a variety of types such as electronic devices excluding computers that work similar to other electronics (TechTerms, 2013; The SCO Group, Inc., 2004). The research has shown that the development of a clone provides a variety of advantages. Some of the common uses of cloning are outlined below: Reinstatement of computer after a crash Without a doubt, a clone of boot drive is believed to be a critical tool for retrieval from a state that occurs due to a system crash or failure. If a person or a company does not develop a clone, then the recovery from a system crash or failure can take a lot of time (i.e. from a few hours to a few weeks), even...
10 Pages(2500 words)Research Paper

Rhetorical Devices

...Teacher Rhetorical devices in Othello’s Act I, Scene 3, lines 149-197 Shakespeare’s another tragic play en d Othello is rich with rhetorical devices that made it favorite subject to study literature. In this piece of work, Othello is peppered by soliloquy mostly by another character Iago but in in Act I, scene 3, lines 149-197, it was Othello himself who did the soliloquy. Soliloquy is a rhetorical device common in Shakespearean tragedy where a character utters or narrates his or her own thoughts in a personal discourse (talking to nobody but himself or herself) that would reveal the character or the dilemma of the narrator or his/her motive. Soliloquy is used as the best way to give...
2 Pages(500 words)Essay

Mnemonic devices

...Mnemonic Devices Introduction Loss of memory is one of the prime factors affecting excellent performance of activities to carry out. There is increased desire to advance the ability to recall previous information concerning essential educational schools and industrial organizations. This essay principally entails knowledge about mnemonic devices. In addition, this piece of writing brings to light the various types of mnemonic devices. Further, the article educates individuals on the importance of mnemonic devices. Finally, there are limitations regarding the use of mnemonic devices and ways of ensuring that individuals have a positive perception...
5 Pages(1250 words)Research Paper

Compare Devices

...Comparison of Poetic Devices William Shakespeare is one of the renowned playwrights and poets in the globe. His poems from previous centuries have remained influential in the modern times. Notably, they are still rich in poetic devices and have been the focus of many analysts in the modern times. Without doubt, Shakespeare’s work is highly influential to modern poets. On the other hand, Andrew Marvell also wrote poems that have proved to be influential up to date inspiring modern poets. The themes and devices used by both of these poets have remained aspects of analysis as more and more artists venture into analyzing their work. This paper will compare Shakespeare’s poem titled, “Shall I...
2 Pages(500 words)Essay

ECE 330 Assignments 1 & 2

..., outbreak in the world. There have been reported cases of Ebola in the United States of America. The case of Ebola is a good example of new information that has had to pass through my human memory system. The disease is quite dangerous and is spread by direct contact with infected persons. Storing of this new information and organizing it in my memory, is a process which is systematic. Ebola being a disease had to be stored next to other similar words which are diseases such as HIV and STI’S. My human memory system then broke down this information further by classifying Ebola as an infectious disease that is spread by direct contact with an infected person’s blood or fluids. This information was, thus,...
6 Pages(1500 words)Essay

ECE 330 Discussion 2-4

...ECE 330 Discussion 2-4 ECE 330 Discussion 2-4 Discussion 2 Experiences which support children in connecting knowledge domains impact on their neural works in the brain. This implies that early childhood educators must plan their classroom curriculum and environments in ways that cater for their thinking as it develops (Robeson, 2012). Therefore, to apply higher-order thinking, a suggested method would be one that links thinking to memory. Agreeably, thinking may not just entail recalling of memories, but researchers have also shown that thinking is difficult to do without the involvement of past memories. In this manner, as the children’s thinking is developed, it is crucial to include items or materials...
2 Pages(500 words)Essay

Electro, Pneumatic and Hydraulic Systems and Devices

...Electro, Pneumatic and Hydraulic Systems and Devices By Affiliation Task There are a number of Health and Safety regulations and pieces of Health and safety legislation applicable to working with fluid power equipment and systems. List the aspects of health and safety legislation and regulations that apply when working with fluid power equipment and systems or in groups of three deliver a presentation on 3 health and safety regulations. Fire Precautions Act 1971 The fire precautions act of 1971 deals with all types of protective measures regarding the health and safety precautions that premises should observe. The Act provides various aspects of building and use of...
4 Pages(1000 words)Assignment

ECE 410 Assessment Assignment

...Assessment Assignment Assessment Assignment Background information I assessed a child d Paul. Paul is a five-year-old male child. He can speak one language, his mother tongue, and English. Paul can read three to five letter English words. I assessed Paul on four different abilities including ECE early literacy assessment, concepts about print assessment, alphabet knowledge assessment, and oral language assessment. ECE early child literacy assessment I performed this test by giving Paul a list of names. First, I asked him his name, and he answered correctly. I then wrote several names on paper and asked him to point at his name. He did it successfully. I then performed a series of assessments like asking...
3 Pages(750 words)Essay
sponsored ads
We use cookies to create the best experience for you. Keep on browsing if you are OK with that, or find out how to manage cookies.

Let us find you another Assignment on topic ECE 4332 ELECTR OOPTIC DEVICES AND SYSTEMS for FREE!

Contact Us