Monday, 9 May 2011

Optical fiber connector

An optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so that light can pass. Most optical fiber connectors are spring-loaded: The fiber endfaces of the two connectors are pressed together, resulting in a direct glass to glass or plastic to plastic contact, avoiding any glass to air or plastic to air interfaces, which would result in higher connector losses.

A variety of optical fiber connectors are available. Typical connectors are rated for 500-1000 mating cycles.[1] The main differences among types of connectors are dimensions and methods of mechanical coupling. Generally, organizations will standardize on one kind of connector, depending on what equipment they commonly use, or per type of fiber (one for multimode, one for single-mode). In datacom and telecom applications nowadays small form factor connectors (e.g., LC) and multi-fiber connectors (e.g., MTP) are replacing the traditional connectors (e.g., SC), mainly to pack more connectors on the overcrowded faceplate, and thus reducing the footprint of the systems.

According to Telcordia Generic Requirements for Single-Mode Optical Connectors and Jumper Assemblies, optical fiber connectors are used to join optical fibers where a connect/disconnect capability is required. The basic connector unit is a connector assembly. A connector assembly consists of an adapter and two connector plugs. Due to the sophisticated polishing and tuning procedures that may be incorporated into optical connector manufacturing, connectors are generally assembled onto optical fiber in a supplier’s manufacturing facility. However, the assembly and polishing operations involved can be performed in the field, for example, to make cross-connect jumpers to size.

Optical fiber connectors are used in telephone company central offices, at installations on customer premises, and in outside plant applications. Their uses include:

* Making the connection between equipment and the telephone plant in the central office
* Connecting fibers to remote and outside plant electronics such as Optical Network Units (ONUs) and Digital Loop Carrier (DLC) systems
* Optical cross connects in the central office
* Patching panels in the outside plant to provide architectural flexibility and to interconnect fibers belonging to different service providers
* Connecting couplers, splitters, and Wavelength Division Multiplexers (WDMs) to optical fibers
* Connecting optical test equipment to fibers for testing and maintenance.

Outside plant applications may involve locating connectors underground in subsurface enclosures that may be subject to flooding, on outdoor walls, or on utility poles. The closures that enclose them may be hermetic, or may be “free-breathing.” Hermetic closures will subject the connectors within to temperature swings but not to humidity variations unless they are breached. Free-breathing closures will subject them to temperature and humidity swings, and possibly to condensation and biological action from airborne bacteria, insects, etc. Connectors in the underground plant may be subjected to groundwater immersion if the closures containing them are breached or improperly assembled.

* 1 Types
o 1.1 Notes
o 1.2 Mnemonics
* 2 Analysis
* 3 Testing
* 4 See also
* 5 References
* 6 External links

[edit] Types
FC connector
MIC (FDDI) connector
LC connector (duplex version)
LuxCis connector
MT-RJ connector
SC connector (duplex version)
ST connector
TOSLINK connector
Fiber connector types Short name↓ Long form↓ Coupling type↓ Ferrule diameter↓ Standard↓ Typical applications↓
Avio (Avim) Screw Aerospace and avionics
ADT-UNI Screw 2.5 mm Measurement equipment
Biconic Screw 2.5 mm Obsolete
D4 Screw 2.0 mm Telecom in the 1970s and 1980s, obsolete
Deutsch 1000 Screw Telecom, obsolete
DIN (LSA) Screw IEC 61754-3 Telecom in Germany in 1990s; measurement equipment; obsolete
DMI Clip 2.5 mm Printed circuit boards
E-2000 (AKA LSH) Snap, with light and dust-cap 2.5 mm IEC 61754-15 Telecom, DWDM systems;
EC push-pull type IEC 1754-8 Telecom & CATV networks
ESCON Enterprise Systems Connection Snap (duplex) 2.5 mm IBM mainframe computers and peripherals
F07 2.5 mm Japanese Industrial Standard (JIS) LAN, audio systems; for 200 μm fibers, simple field termination possible, mates with ST connectors
F-3000 Snap, with light and dust-cap 1.25 mm IEC 61754-20 Fiber To The Home (LC Compatible)
FC Ferrule Connector or Fiber Channel [1] Screw 2.5 mm IEC 61754-13 Datacom, telecom, measurement equipment, single-mode lasers; becoming less common
Fibergate Snap, with dust-cap 1.25 mm Backplane connector
FSMA Screw 3.175 mm IEC 60874-2 Datacom, telecom, test and measurement
LC Lucent Connector [1], Little Connector, or
Local Connector[citation needed] Snap 1.25 mm IEC 61754-20 High-density connections, SFP transceivers, XFP transceivers
LuxCis 1.25 mm ARINC 801 PC or APC configurations (note 3)
LX-5 Snap, with light- and dust-cap IEC 61754-23 High-density connections; rarely used
MIC Media Interface Connector Snap 2.5 mm Fiber distributed data interface (FDDI)
MPO / MTP Multiple-Fibre Push-On/Pull-off [1] Snap (multiplex push-pull coupling) 2.5×6.4 mm [2] IEC-61754-7; EIA/TIA-604-5 (FOCIS 5) SM or MM multi-fiber ribbon. Same ferrule as MT, but more easily reconnectable.[2] Used for indoor cabling and device interconnections. MTP is a brand name for an improved connector, which intermates with MPO.[3]
MT Mechanical Transfer Snap (multiplex) 2.5×6.4 mm Pre-terminated cable assemblies; outdoor applications[2]
MT-RJ Mechanical Transfer Registered Jack or Media Termination - recommended jack [1] Snap (duplex) 2.45×4.4 mm IEC 61754-18 Duplex multimode connections
MU Miniature unit [1] Snap 1.25 mm IEC 61754-6 Common in Japan
NEC D4 Screw 2.0 mm Common in Japan telecom in 1980s
Opti-Jack Snap (duplex)
OPTIMATE Screw Plastic fiber, obsolete
SC Subscriber Connector [1] or
square connector [1] or
Standard Connector Snap (push-pull coupling) 2.5 mm IEC 61754-4 Datacom and telcom; extremely common
SMA 905 Sub Miniature A Screw typ. 3.14 mm Industrial lasers, military; telecom multimode
SMA 906 Sub Miniature A Screw Stepped; typ. 0.118", then .089"[citation needed] Industrial lasers, military; telecom multimode
SMC Sub Miniature C Snap 2.5 mm
ST / BFOC Straight Tip[1] / Bayonet Fiber Optic Connector Bayonet 2.5 mm IEC 61754-2 Multimode, rarely single-mode; APC not possible (note 3)
TOSLINK Toshiba Link Snap Digital audio
VF-45 Snap Datacom
1053 HDTV Broadcast connector interface Push-pull coupling Industry-standard 1.25mm diameter ceramic ferrule Audio & Data (broadcasting)
V-PIN V-System Snap (Duplex) Push-pull coupling Industrial and electric utility networking; multimode 200 μm, 400 μm, 1 mm, 2.2 mm fibers
[edit] Notes

1. Modern connectors typically use a "physical contact" polish on the fiber and ferrule end. This is a slightly curved surface, so that when fibers are mated only the fiber cores touch, not the surrounding ferrules. Some manufacturers have several grades of polish quality, for example a regular FC connector may be designated "FC/PC" (for physical contact), while "FC/SPC" and "FC/UPC" may denote "super" and "ultra" polish qualities, respectively. Higher grades of polish give less insertion loss and lower back reflection.
2. Many connectors are available with the fiber endface polished at an angle to prevent light that reflects from the interface from traveling back up the fiber. Because of the angle, the reflected light does not stay in the fiber core but instead leaks out into the cladding. Angle-polished connectors should only be mated to other angle-polished connectors. Mating to a non-angle polished connector causes very high insertion loss. Generally angle-polished connectors have higher insertion loss than good quality straight physical contact ones. "Ultra" quality connectors may achieve comparable back reflection to an angled connector when connected, but an angled connection maintains low back reflection even when the output end of the fiber is disconnected.
3. Angle-polished connections are distinguished visibly by the use of a green strain relief boot, or a green connector body. The parts are typically identified by adding "/APC" (angled physical contact) to the name. For example, an angled FC connector may be designated FC/APC, or merely FCA. Non-angled versions may be denoted FC/PC or with specialized designations such as FC/UPC or FCU to denote an "ultra" quality polish on the fiber endface.
4. SMA 906 features a "step" in the ferrule, while SMA 905 uses a straight ferrule. SMA 905 is also available as a keyed connector, used e.g., for special spectrometer applications.
5. E-2000 and F-3000 are registered trademarks of Diamond SA, Switzerland. ST is a registered trademark of AT&T/Lucent Technologies.

[edit] Mnemonics

* LC connectors are sometimes called "Little Connectors".[citation needed]
* MT-RJ connectors look like a miniature 8P8C connector — commonly (but erroneously) referred to as RJ-45.
* ST connectors refer to having a "straight tip", as the sides of the ceramic (which has a lower temperature coefficient of expansion than metal) tip are parallel—as opposed to the predecessor bi-conic connector which aligned as two nesting ice cream cones would. Other mnemonics include "Set and Twist", "Stab and Twist", and "Single Twist",[citation needed] referring to how it is inserted (the cable is pushed into the receiver, and the outer barrel is twisted to lock it into place). Also they are known as "Square Top" due to the flat end face.[citation needed]
* SC connectors have a mnemonic of "Square Connector", and some people believe that to be the correct name.[1] This refers to the fact the connectors themselves are square. Another term often used for SC connectors is "Set and Click" or "Stab and Click".[citation needed]

[edit] Analysis

* FC connectors' floating ferrule provides good mechanical isolation. FC connectors need to be mated more carefully than the push-pull types due to the need to align the key, and due to the risk of scratching the fiber endface while inserting the ferrule into the jack. FC connectors have been replaced in many applications by SC and LC connectors.[4]

* There are two incompatible standards for key widths on FC/APC and polarization-maintaining FC/PC connectors: 2 mm ("Reduced" or "type R") and 2.14 mm ("NTT" or "type N").[5] Connectors and receptacles with different key widths either cannot be mated, or will not preserve the angle alignment between the fibers, which is especially important for polarization-maintaining fiber. Some manufacturers mark reduced keys with a single scribe mark on the key, and mark NTT connectors with a double scribe mark.

* SC connectors offer excellent packing density, and their push-pull design reduces the chance of fiber endface contact damage during connection; frequently found on the previous generation of corporate networking gear, using GBICs.

* LC connectors are replacing SC connectors in corporate networking environments due to their smaller size; they are often found on small form-factor pluggable transceivers.

* ST connectors have a key which prevents rotation of the ceramic ferrule, and a bayonet lock similar to a BNC shell. The single index tab must be properly aligned with a slot on the mating receptacle before insertion; then the bayonet interlock can be engaged, by pushing and twisting, locking at the end of travel which maintains spring-loaded engagement force on the core optical junction.

* In general the insertion loss should not exceed 0.75 dB and the return loss should be higher than 20 dB. Typical insertion repeatability, the difference in insertion loss between one plugging and another, is 0.2 dB.

* On all connectors, cleaning the ceramic ferrule before each connection helps prevent scratches and extends the connector life substantially.

* Connectors on polarization-maintaining fiber are sometimes marked with a blue strain relief boot or connector body, although this is far from a universal standard. Sometimes a blue buffer tube is used on the fiber instead.[6]

* MT-RJ (Mechanical Transfer Registered Jack) uses a form factor and latch similar to the RJ-45 connectors. Two separate fibers are included in one unified connector. It is easier to terminate and install than ST or SC connectors. The smaller size allows twice the port density on a face plate than ST or SC connectors do. The MT-RJ connector was designed by AMP, but was later standardized as FOCIS 12 (Fiber Optic Connector Intermateability Standards) in EIA/TIA-604-12. There are two variations: pinned and no-pin. The pinned variety, which has two small stainless steel guide pins on the face of the connector, is used in patch panels to mate with the no-pin connectors on MT-RJ patch cords.

* Hardened Fiber Optic Connectors (HFOCs) and Hardened Fiber Optic Adapters (HFOAs)

Hardened Fiber Optic Connectors (HFOCs) and Hardened Fiber Optic Adapters (HFOAs) are passive telecommunications components used in an Outside Plant (OSP) environment. They provide drop connections to customers from fiber distribution networks. These components may be provided in pedestal closures, aerial and buried closures and terminals, or equipment located at customer premises such as a Fiber Distribution Hub (FDH) or an Optical Network Terminal or Termination (ONT) unit.

These connectors, which are field-mateable, and hardened for use in the OSP, are needed to support Fiber to the Premises (FTTP) deployment and service offerings. HFOCs are designed to withstand climatic conditions existing throughout the U.S., including rain, flooding, snow, sleet, high winds, and ice and sand storms. Ambient temperatures ranging from –40°C (–40°F) to +70°C (158°F) can be encountered.

Telcordia GR-3120, Issue 2, April 2010, Generic Requirements for Hardened Fiber Optic Connectors (HFOCs) and Hardened Fiber Optic Adapters (HOFAs), contains the industry’s most recent requirements for HFOCs and HFOAs.

[edit] Testing
This section may need to be wikified to meet Wikipedia's quality standards. Please help by adding relevant internal links, or by improving the section's layout. (February 2011)

Glass fiber optic connector performance is affected both by the connector and glass. In an otherwise perfect-looking assembled connector, typical adverse factors include: connector (ferrule) concentricity tolerance, fiber diameter tolerance, fiber core concentricity tolerance (within the fiber), core optical parameter tolerance, stress in the polished fiber causing excess return loss, fiber "pistoning" eg lengthwise movement (usually poor glue), incorrect shaping of the connector tip as a result of polishing. It can be readily seen that the connector manufacturer has little control over many of these, so in-service performance may well be below the manufacturer's specification for these reasons.

Testing fiber optic connector assemblies falls into two general categories: factory testing and field testing.

Factory testing is sometimes statistical, eg a process check. For example a profiling system may be used to ensure that the overall polished shape is correct, and a good quality optical microscope to check for blemishes. Optical Loss / Return Loss performance is checked using specific reference conditions, eg against a "reference standard" single mode test lead, or using an "Encircled Flux Compliant" source for multi mode testing. Testing and rejection ("yield") may represent a significant part of the overall manufacturing cost.

Field testing is usually simpler. A special hand-held optical microscope is used to check for dirt or blemishes, and an optical time-domain reflectometer may be used to identify significant point losses or return losses. A power meter and light source or loss test set may also be used to check end-to-end loss.

International Institute of Information Technology

Established 1998
Type Deemed University, Education and Research, Private
Director Dr. Rajeev Sangal
Academic staff 47 (regular)
Undergraduates 670
Postgraduates 370
Location Hyderabad, Andhra Pradesh, India
Campus Urban, 62 Acres
Mascot Banyan Tree

International Institute of Information Technology Hyderabad [अंतरराष्ट्रीय सूचना प्रौद्योगिकी संस्थान हैदराबाद] is a prominent Research University (autonomous institute) started in 1998 with seed support from the Government of Andhra Pradesh. It was envisioned by Nara Chandrababu Naidu, the Chief Minister of the State of Andhra Pradesh from 1995-2004, to put Hyderabad on the World IT map, through the creation of a prominent IT research university. It emphasizes research from the undergraduate level, which makes it different from the other leading engineering institutes in India like the IITs. Prof. Raj Reddy, the only Indian to get the Turing Award, is the chairman of the board of governors.

The major goal is to impart a uniquely broad and interdisciplinary IT education of high academic quality. This is done through a diverse curriculum of IT courses, interdisciplinary IT research projects, interaction with industry, preparation in entrepreneurship and personality development courses.

* 1 Centers
* 2 Location
* 3 Governing Council Members
* 4 Research Areas
* 5 Academic programs
o 5.1 Under Graduate Programs
o 5.2 Dual Degree Programs
o 5.3 Post Graduate Programs
o 5.4 PhD
o 5.5 Admissions
+ 5.5.1 Under Graduate and Dual Degree
+ 5.5.2 Post Graduation
* 6 Campus
* 7 Conferences
* 8 Workshops
* 9 Ranking
* 10 Curriculum
* 11 Students Parliament
* 12 Felicity
* 13 Sports
* 14 See also
* 15 External links

[edit] Centers

* Language Technologies
* Center for VLSI and Embedded Systems Technologies
* Data Engineering
* Visual Information Technology
* Center for Security, Theory and Algorithmic Research
* Communications
* Robotics research Lab
* Cognitive science lab

[edit] Location

The institute is in Gachibowli, Hyderabad. It is close to HITEC City (a centre housing software development centres of companies like Microsoft, Oracle Corporation, Motorola, Infosys and GE Capital) and the presence of IT majors from across the globe right on the campus through their schools and research centers.
[edit] Governing Council Members

* Prof Raj Reddy,University Professor of Computer Science & Robotics, School of Computer Science, Carnegie Mellon University (CMU), Pittsburgh, USA
* Prof Rajeev Sangal (Ex-officio), Director, IIIT-H
* Prof Kamalakar Karlapalem (Ex-officio), Dean (Academic), IIIT-H
* Prof P J Narayanan (Ex-officio), Dean (R&D), IIIT-H
* Prof Narendra Ahuja, Director (International), IIIT-H, Donald Biggar Willet Professor of Engineering, University of Illinois
* C.R. Biswal, IAS, Principal Secretary to Govt, Higher Education Dept, Secrectrait, Hyderabad
* Shri M Gopi Krishna, IPS (Ex-officio), Special Secretary to Government of Andhra Pradesh, Information Technology & Communications Department, Hyderabad
* Shri C Srini Raju, Managing Director, Peepul Capital Advisors P Ltd., Hyderabad
* Shri S Ramadorai, Managing Director, Tata Consultancy Services, Mumbai
* Prof K C Reddy, Chairman, Andhra Pradesh State Council of Higher Education (APSCHE), Hyderabad
* Dr. D.N Reddy, Vice - Chancellor, JNTU, Kukatpally, Hyderabad
* Shri Som Mittal (Ex-officio), President, NASSCOM, New Delhi
* Prof N Balakrishnan, Associate Director, Division of Information Science, Indian Institute of Science (IISc), Bangalore
* Prof U B Desai, Director, Indian Institute of Technology, Hyderabad

[edit] Research Areas

The research areas of the institute are:

* Language Technologies
* Speech Technologies
* Information Extraction
* Computer Vision & Image Processing
* Data Engineering
* Cognitive Sciences
* Information Security, Theory & Algorithms
* Robotics
* Signal Processing & Communications
* Building Sciences
* Power Systems
* Agriculture & Rural Development
* Software Engineering
* Computational Natural Sciences
* Bioinformatics
* Exact Humanities
* Earthquake Engineering
* VLSI & Embedded Systems
* Spatial Informatics
* Compilers
* IT for Education

[edit] Academic programs

The institute is a centre of learning for both under graduate and post graduate courses. The course pattern lays stress on research at both graduate and under graduate levels. The Curriculum and the academic programmes are altered and maintained to suit the upcoming and present changes in the Industry.
[edit] Under Graduate Programs

The Undergraduate programmes offered here are as follows :-
1) (Bachelor of Technology) in Computer Sciences (CSE).
2) B.Tech in Electronics and Communications (ECE).
3) B.Tech Honors in the above fields - A programme offered at the end of second year to allow research oriented students to focus on the research orientation of their academic field.
[edit] Dual Degree Programs

The Dual Degree Programmes are as follows :-
1) B.Tech and MS (Master of Science) by Research in Computer Science and Engineering.
2) B.Tech and MS (Master of Science) by Research in Electronics and Communication Engineering.
3) B.Tech in Computer Science and Masters in Computational Natural Science.
4) B.Tech in Computer Science and Masters in Computational Linguistics.
5) B.Tech in Computer Science and MS by Research in Exact Humanities.
[edit] Post Graduate Programs

The postgraduate programmes offered here are as follows :-
1) M.Tech Computer Science Engineering (CSE).
2) M.Tech Computer Science & Information Security (CSIS).
3) M.Tech Computer Aided Structural Engineering (CASE).
4) M.Tech Bioinformatics.
5) M.Tech Computational Linguistics (CL).
6) Master of Science in Information Technology (MSIT)

There are also programmes in computational linguistics like M.Phil (Master of Philosophy), MSc in computational natural sciences and Post BSc.
[edit] PhD

1) PhD courses provided here are as follows :-

2) PhD Computer Science Engineering (CSE).

3) PhD Computational Natural Sciences (CNS).
4) PhD Electronics and Communication Engineering (ECE).
5) PhD Computational Linguistics (CL).
6) PhD Computer Aided Structural Engineering (CASE).
7) PhD Bio-informatics.
8) PhD IT in Power Systems.
9) PhD Spatial Informatics.
10) PhD Cognitive Science.
11) PhD Exact Humanities.
Also courses including Post graduate diploma in Applied Agriculture and Information Technology(PGDAAIT), and in computational linguistics are provided.
[edit] Admissions
[edit] Under Graduate and Dual Degree

Admissions were taken solely through AIEEE i.e. CCB (Central Counseling board) counseling until the year 2009. From the academic batch 2010 (known as UG2k10) the institute revised the admission procedure and decided on independent selection students though still considering the merit achievements of AIEEE.
[edit] Post Graduation

Admissions are on the basis of Post-graduate Entrance Exam (PGEE) conducted by IIIT-H.
Admissions to the MSIT programme [1] run at this institute are based on a test conducted every year from April to May.
[edit] Campus

The Institute is situated on a campus of 62 acres (250,000 m²). There are 4 buildings that house the corporate schools and research centers. In addition to this, the academic building has the lecture halls, tutorial rooms, computer and electronics labs and offices of the administration and faculty.

All students are provided hostel rooms. Few students have to share rooms (double occupancy) whereas most of the students have single occupancy. The Institute has a Guest House with four air conditioned suites. Two hostels for men and one for women have a total of about 1200 rooms. There is an optical fiber network connecting all buildings on campus including the hostels.

The Institute has well-equipped air-conditioned computer laboratories allocated batch-wise to students. The labs are equipped with modern hardware and software. The PC to students ratio is about 1:2. All computers are part of an intranet (1 Gbit/s Backbone). The Institute has high bandwidth (8 Mbit/s) Internet connectivity round the clock. Research students have 24 hours access to the computer facilities. The students administer their own computer systems. The research centers and corporate schools provide specialized equipment for research and development.

Selected areas of the institute like Few parts of Boys' Hostel, Nilgiri and Library Building are connected by WiFi. IIIT maintains its own proxy Server.
[edit] Conferences

1. PAKDD 2010
2. IJCAI 2007, the premier international conference on Artificial Intelligence (an A+ grade conference)
3. FSTTCS 2005
4. ICDE RIDE 2003 (Multi-Lingual Information Management)

[edit] Workshops

1. Robocamp [2] 2010, 2009 and 2008
2. R & D showcase - The research and project exhibition showcasing the research work and projects carried out in the institute.

[edit] Ranking

IIIT Hyderabad is consistently ranked in the top 10 of most national rankings among engineering colleges. It ranks right after the Old IITs and is usually in the top five in the category of placements.

IIIT Hyderabad was ranked among the Best 6 Universities in South Asia, in terms of "scholarly papers" on the Internet, by Cybermetric Lab, Spain's largest public research institution in 2009.

IIIT Hyderabad was ranked overall 7th in 2008 and 5th in 2010 among the top technology schools in India Dataquest Magazine[3]

Placement 2010 Top 3 in campus placements, among all technology schools in the country, by Dataquest -IDC T-School Survey in 2010.

Placement 2009 Top 2, among all technology schools in India, as per Mint-Cfore carried out Best Engineering Colleges’ Survey 2009, with an average compensation of Rs.6.1 lac, despite IIIT-H being the last among all engineering colleges in the country to open placement season

Placement 2008 Top 2, among all technology schools in India, as per Outlook-Synovate Survey; average compensation: Rs.7.2 lac per year, which is second highest in India, after IIT-Kharagpur’s

Placement 2007 Top 5, in India, among all categories of engineering colleges, as per Dataquest-IDC’s Best Engineering Colleges’ Survey

Placement details -
[edit] Curriculum

IIIT Curriculum can be said to be one of the best out of the engineering colleges in India. Students have the independence of choosing the subjects they want to study from the second year onwards. Eminent members of the industry are regularly invited to teach at the institute. The classroom for many courses is a mix of under graduate students, post graduate students and working professionals registered for the course. Students in under graduate programs are required to study limited number of cross departmental subjects, which they can choose from a large selection. Thus improving their knowledge beyond the regular curriculum. Students in third year onwards are encouraged to work in one of the research labs, thus making them work aware, and thus helping them choose their future field of work.
[edit] Students Parliament

The student representatives of each batch constitute the student parliament of IIIT, the student parliament is given powers by the administration to form laws regarding student life in IIIT. The constitution of the college has been drafted by the students parliament. It acts as a governing body for the students. Student issues are addressed to the administration through the parliament. It acts as an intermediary between students and the administration.
[edit] Felicity

Each year IIIT holds its annual cultural and technical festival Felicity [4], in the month of February. Since its inception, Felicity has gone from strength to strength and is now one of the most eagerly awaited college festivals in Hyderabad. Felicity attracts students from all major engineering and degree colleges across the country. ent was a major new addition to the Felicity 2010.

Renowned music bands like Strings[5], Parikrama[6], Motherjane [7], Indian Ocean, Ganesh & Kumaresh, Euphoria, Demonic Resurrection, Bombay Vikings, Sledge have performed at Felicity over the past few years.

Solo performances by Mohit Chauhan of Masakali Fame and Kumar Vishwas, a popular comedian, were huge hits in the recent years.

Dr I V Subba Rao, Chief Electoral Officer of Andhra Pradesh gave the inaugural address at Felicity 2010, while noted Telugu film director Sekhar Kammula, delivered the commencement address.

Jayaprakash Narayan, founder of the Lok Satta Party, gave an inaugural address at Felicity 2009.

Lecture - 10 Fiber Optic Components

Wednesday, 4 May 2011

Transmission windows

Transmission windows

Each effect that contributes to attenuation and dispersion depends on the optical wavelength. The wavelength bands (or windows) that exist where these effects are weakest are the most favorable for transmission. These windows have been standardized, and the currently defined bands are the following:[11]
Band Description Wavelength Range
O band original 1260 to 1360 nm
E band extended 1360 to 1460 nm
S band short wavelengths 1460 to 1530 nm
C band conventional ("erbium window") 1530 to 1565 nm
L band long wavelengths 1565 to 1625 nm
U band ultralong wavelengths 1625 to 1675 nm

Note that this table shows that current technology has managed to bridge the second and third windows that were originally disjoint.

Historically, there was a window used below the O band, called the first window, at 800-900 nm; however, losses are high in this region so this window is used primarily for short-distance communications. The current lower windows (O and E) around 1300 nm have much lower losses. This region has zero dispersion. The middle windows (S and C) around 1500 nm are the most widely used. This region has the lowest attenuation losses and achieves the longest range. It does have some dispersion, so dispersion compensator devices are used to remove this.

Tuesday, 3 May 2011


Daniel Colladon first described this "light fountain" or "light pipe" in an 1842 article titled On the reflections of a ray of light inside a parabolic liquid stream. This particular illustration comes from a later article by Colladon, in 1884.

Fiber optics, though used extensively in the modern world, is a fairly simple and old technology. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London a dozen years later.[1] Tyndall also wrote about the property of total internal reflection in an introductory book about the nature of light in 1870: "When the light passes from air into water, the refracted ray is bent towards the perpendicular... When the ray passes from water to air it is bent from the perpendicular... If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be totally reflected at the surface.... The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27', for flint glass it is 38°41', while for diamond it is 23°42'."[2][3] Unpigmented human hairs have also been to shown to act as an optical fiber.[4]

Practical applications, such as close internal illumination during dentistry, appeared early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. The principle was first used for internal medical examinations by Heinrich Lamm in the following decade. In 1952, physicist Narinder Singh Kapany conducted experiments that led to the invention of optical fiber. Modern optical fibers, where the glass fiber is coated with a transparent cladding to offer a more suitable refractive index, appeared later in the decade.[1] Development then focused on fiber bundles for image transmission. The first fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, and Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers; previous optical fibers had relied on air or impractical oils and waxes as the low-index cladding material. A variety of other image transmission applications soon followed.

In the late 19th and early 20th centuries, light was guided through bent glass rods to illuminate body cavities. Alexander Graham Bell invented a 'Photophone' to transmit voice signals over an optical beam.[5]

Jun-ichi Nishizawa, a Japanese scientist at Tohoku University, also proposed the use of optical fibers for communications in 1963, as stated in his book published in 2004 in India.[6] Nishizawa invented other technologies that contributed to the development of optical fiber communications, such as the graded-index optical fiber as a channel for transmitting light from semiconductor lasers.[7][8] Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables (STC) were the first to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer (dB/km), making fibers a practical communication medium.[9] They proposed that the attenuation in fibers available at the time was caused by impurities that could be removed, rather than by fundamental physical effects such as scattering. They correctly and systematically theorized the light-loss properties for optical fiber, and pointed out the right material to use for such fibers — silica glass with high purity. This discovery earned Kao the Nobel Prize in Physics in 2009.[10]

NASA used fiber optics in the television cameras sent to the moon. At the time, the use in the cameras was classified confidential, and only those with the right security clearance or those accompanied by someone with the right security clearance were permitted to handle the cameras.[11]

The crucial attenuation limit of 20 dB/km was first achieved in 1970, by researchers Robert D. Maurer, Donald Keck, Peter C. Schultz, and Frank Zimar working for American glass maker Corning Glass Works, now Corning Incorporated. They demonstrated a fiber with 17 dB/km attenuation by doping silica glass with titanium. A few years later they produced a fiber with only 4 dB/km attenuation using germanium dioxide as the core dopant. Such low attenuation ushered in optical fiber telecommunication. In 1981, General Electric produced fused quartz ingots that could be drawn into fiber optic strands 25 miles (40 km) long.[12]

Attenuation in modern optical cables is far less than in electrical copper cables, leading to long-haul fiber connections with repeater distances of 70–150 kilometers (43–93 mi). The erbium-doped fiber amplifier, which reduced the cost of long-distance fiber systems by reducing or eliminating optical-electrical-optical repeaters, was co-developed by teams led by David N. Payne of the University of Southampton and Emmanuel Desurvire at Bell Labs in 1986. Robust modern optical fiber uses glass for both core and sheath, and is therefore less prone to aging. It was invented by Gerhard Bernsee of Schott Glass in Germany in 1973.[13]

The emerging field of photonic crystals led to the development in 1991 of photonic-crystal fiber,[14] which guides light by diffraction from a periodic structure, rather than by total internal reflection. The first photonic crystal fibers became commercially available in 2000.[15] Photonic crystal fibers can carry higher power than conventional fibers and their wavelength-dependent properties can be manipulated to improve performance.