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Optical fibre Basic physics of OFC Merits & Demerits of OFC Nomenclature of OFC Absorption & attenuation Jointing & termination of OFC Optical sources & Detectors FBG & Applications


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A “ SEMINAR ON ” Submitted to:- Ravi Goyal Sir Submitted by:- Ram Niwas Bajya GOVT. ENGG. COLLEGE AJMER OPTICAL FIBER


Contents RAM NIWAS BAJIYA Optical fibre Basic physics of OFC Merits & Demerits of OFC Nomenclature of OFC Absorption & attenuation Jointing & termination of OFC Optical sources & Detectors FBG & Applications

Century Gothic:

OPTICAL FIBER OFC have Fibres which are long, thin strands made with pure glass about the diameter of a human hair RAM NIWAS BAJIYA


Total internal reflection At some angle, known as the critical angle θc , light traveling from a higher refractive index medium to a lower refractive index medium will be refracted at 90° i.e. refracted along the interface. If the light hits the interface at any angle larger than this critical angle, it will not pass through to the second medium at all. Instead, all of it will be reflected back into the first medium, a process known as total internal reflection Incident angle = RAM NIWAS BAJIYA

Wingdings 3:

Optical fiber mode Fibbers that carry more than one mode at a specific light wavelength are called multimode fibres. Some fibres have very small diameter core that they can carry only one mode which travels as a straight line at the centre of the core. These fibres are single mode fibres. RAM NIWAS BAJIYA


Optical fiber's Numerical Aperture(NA) Multimode optical fiber will only propagate light that enters the fiber within a certain cone, known as the acceptance cone of the fiber. The half-angle of this cone is called the acceptance angle θmax . For step-index multimode fiber, the acceptance angle is determined only by the indices of refraction: Where n is the refractive index of the medium light is traveling before entering the fiber nf is the refractive index of the fiber core nc is the refractive index of the cladding RAM NIWAS BAJIYA


Merit of OFC Medium / Link Carrier Information Capacity Copper Cable (short distance) 1 MHz 1 Mbps Coaxial Cable (Repeater every 4.5 km) 100 MHz 140 Mbps (BSNL) UHF Link 2 GHz 8 Mbps (BSNL), 2 Mbps (Rly.) MW Link (Repeater every 40 km) 7 GHz 140 Mbps (BSNL), 34 Mbps (Rly.) OFC 1550 nm 2.5 Gbps (STM-16 – Rly.) 10 Gbps (STM-64) 1.28 Tbps (128 Ch. DWDM) 20 Tbps (Possible) RAM NIWAS BAJIYA


Frequency Vs Attenuation In Various Types of Cable • More information carrying capacity fibbers can handle much higher data rates than copper. More information can be sent in a second RAM NIWAS BAJIYA


Limitations of OFC Difficulty in jointing (splicing) Highly skilled staff would be required for maintenance Precision and costly instruments are required Tapping for emergency and gate communication is difficult. Costly if under- utilised Special interface equipment’s required for Block working Accept unipolar codes i.e. return to zero codes only. RAM NIWAS BAJIYA

Times New Roman:

Nomenclature for Optical Interface X can be I or S or L or V or U & denotes haul I for intra station (up to 2 km) S for short haul (15 km) L for long haul (40 km at 1310 nm & 80 km at 1550 nm) V for very long haul (60 km at 1310 nm & 120 km at 1550 nm) U for ultra-long haul (160 km at 1550 nm) Optical Interface specified as X.Y.Z RAM NIWAS BAJIYA


• Y can be 1 or 4 or 16 or 64 & denotes STM Level – 1 for STM-1 – 4 for STM-4 – 16 for STM-16 – 64 for STM-64 • Z can be 1 or 2 or 3 & denotes fibre type – 1 for 1310 nm over NDSF (G.652 fibre) – 2 for 1550 nm over NDSF (G.652 fibre) – 3 for 1550 nm over DSF (G.653 fibre) – 5 for 1550 nm over NZDSF (G.655 fibre) RAM NIWAS BAJIYA


Examples of Nomenclature for Optical Interface I.16.1 – Intra station STM-16 link on 1310 nm fibre S.16.2 – Short haul STM-16 link on 1550 nm fibre (G.652) L.16.2 & L.16.3 – Long haul STM-16 link on 1550 nm fibre (G.652 & G.653) S.4.1 – Short haul STM-4 link on 1310 nm fibre L.4.1 – Long haul STM-4 link on 1310 nm fibre (40 km) S.1.1 – Short haul STM-1 link on 1310 nm fibre L.1.1 – Long haul STM-1 link on 1310 nm fibre (40 km) RAM NIWAS BAJIYA

Microsoft Photo Editor 3.0 影像:

Absorption & Attenuation Scattering of light due to molecular level irregularities in the glass Light absorption due to presence of residual materials, such as metals or water ions, within the fiber core and inner cladding. These water ions that cause the “water peak” region on the attenuation curve, typically around 1380 nm. RAM NIWAS BAJIYA

Microsoft Excel 圖表:

Three peaks in attenuation  a). 1050 nm b). 1250 nm c). 1380 nm  • Three troughs in attenuation (Performance windows) a.) 850 nm: 2 dB/km b). 1310 nm: 0.35 dB/km c). 1550 nm: 0.25 dB/km Absorption loss & Scattering loss RAM NIWAS BAJIYA


JOINTING AND TERMINATION OF OFC There are two methods for jointing Optical fibre cable. a). splicing b.) connectors a). splicing Fusion Splicing- • Fusion splicing provides a fast, reliable, low-loss, fibre-to-fibre connection by creating a homogenous joint between the two fibre ends. • The fibres are melted or fused together by heating the fibre ends, typically using an electric arc. • Fusion splices provide a high-quality joint with the lowest loss (in the range of 0.01 dB to 0.10 dB for single-mode fibres) and are practically non-reflective. RAM NIWAS BAJIYA


2. Mechanical Splicing- • Mechanical splicing is of slightly higher losses (about 0.2 db) and less-reliable performance • System operators use mechanical splicing for emergency restoration because it is fast, inexpensive, and easy. • Mechanical splices are reflective and non-homogenous RAM NIWAS BAJIYA


b). Basics about connectors- • Fibre optic connector facilitates re-mateable connection i.e. disconnection / reconnection of fibre • Connectors are used in applications where – Flexibility is required in routing an optical signal from lasers to receivers – Reconfiguration is necessary – Termination of cables is required • Connector consists of 4 parts: – Ferrule – Connector body – Cable – Coupling device RAM NIWAS BAJIYA

Total internal reflection:

Optical sources An optical source is a major component of optical transmitters. Fiber optic communication systems often use semiconductor optical sources such as Light emitting diodes ( LEDs) and semiconductor lasers. Some of the advantages are: Compact in size · High efficiency · Good reliability · Right wavelength range · Small emissive area compatible with fibre core dimensions · Possibility of direct emulation at relatively high frequencies RAM NIWAS BAJIYA

Optical fiber mode:

Optical Detectors The role of an optical receiver is to convert the optical signal back into electrical signal and recover the data transmitted through the optical fibre communication system. Its vital component is a photo detector that converts light into electricity through the photoelectric effect. Some the advantages are: · high sensitivity · fast response · low noise · low cost · high reliability RAM NIWAS BAJIYA

Optical fiber's Numerical Aperture(NA):

FBG and Applications The F ilter that B ragg G rading

PowerPoint Presentation:

Fiber Grating Fiber grating is made by periodically changing the refraction index in the glass core of the fiber. The refraction changes are made by exposing the fiber to the UV-light with a fixed pattern. Glass core Glass cladding Plastic jacket Periodic refraction index change (Gratings) RAM NIWAS BAJIYA

Frequency Vs Attenuation In Various Types of Cable:

Fiber Grating Basics When the grating period is half of the input light wavelength, this wavelength signal will be reflected coherently to make a large reflection. The Bragg Condition   r = 2n eff  in Reflection spectrum reflect Transmission spectrum trans.  n (refraction index difference) RAM NIWAS BAJIYA

Limitations of OFC :

Creating Gratings on Fiber One common way to make gratings on fiber is using Phase Mask for UV-light to expose on the fiber core. RAM NIWAS BAJIYA

Nomenclature for Optical Interface :

Characteristics of FBG It is a reflective type filter Not like to other types of filters, the demanded wavelength is reflected instead of transmitted It is very stable after annealing The gratings are permanent on the fiber after proper annealing process The reflective spectrum is very stable over the time It is transparent to through wavelength signals The gratings are in fiber and do not degrade the through traffic wavelengths, very low loss It is an in-fiber component and easily integrates to other optical devices RAM NIWAS BAJIYA

PowerPoint Presentation:

Temperature Impact on FBG The fiber gratings is generally sensitive to temperature change (10pm/°C) mainly due to thermo-optic effect of glass. Athermal packaging technique has to be used to compensate the temperature drift RAM NIWAS BAJIYA

Examples of Nomenclature for Optical Interface:

Types of Fiber Gratings TYPES CHARACTERS APPLICATIONS Simple reflective gratings Creates gratings on the fiber that meets the Bragg condition Filter for DWDM, stabilizer, locker Long period gratings Significant wider grating periods that couples the light to cladding Gain flattening filter, dispersion compensation Chirped fiber Bragg gratings A sequence of variant period gratings on the fiber that reflects multiple wavelengths Gain flattening filter, dispersion compensation Slanted fiber gratings The gratings are created with an angle to the transmission axis Gain flattening filter RAM NIWAS BAJIYA

Absorption & Attenuation:

Typical FBG Production Procedures Select Proper fiber H2 loading Laser writing Annealing Athermal packaging Testing Different FBG requires different specialty fiber Increase photo sensitivity for easier laser writing Optical alignment & appropriate laser writing condition Enhance grating stability For temperature variation compensation Spec test RAM NIWAS BAJIYA

PowerPoint Presentation:

Current Applications of FBG FBG for DWDM FBG for OADM FBG as EDFA Pump laser stabilizer FBG as Optical amplifier gain flattening filter FBG as Laser diode wavelength lock filter FBG as Tunable filter FBG for Remote monitoring FBG as Sensor …. RAM NIWAS BAJIYA


Possible Use of FBG in System Multiplexer Dispersion control EDFA OADM Switch EDFA Demux ITU FBG filter Dispersion compensation filter Pump stabilizer & Gain flattening filter ITU FBG filter Tunable filter ITU FBG filter Pump stabilizer & Gain flattening filter E/O Wave locker Monitor Monitor sensor RAM NIWAS BAJIYA

PowerPoint Presentation:

ITU FBG Filter for DWDM l 1 , l 2 … l n FBG at l 1 l 1 l 2 Circulator Circulator FBG at l 2 l 3 Circulator FBG at l 3 ... l 1 , l 2 … l n FBG at l 1 l 1 l 2 Circulator Circulator FBG at l 2 l 3 Circulator FBG at l 3 ... Multiplexer De-multiplexer RAM NIWAS BAJIYA

PowerPoint Presentation:

ITU FBG Filter for OADM Circulator Circulator FBG Through signal Dropped signal Added signal Outgoing signal Incoming signal RAM NIWAS BAJIYA

PowerPoint Presentation:

Dispersion Compensation Filter Dispersed pulse circulator Chirped FBG RAM NIWAS BAJIYA

PowerPoint Presentation:

Pump Laser Stabilizer 980 spectrum Focal lens Fiber 980 Stabilizer + - Pump Laser RAM NIWAS BAJIYA

FBG and Applications:

Gain Flattening Filter Gain profile GFF profile Output RAM NIWAS BAJIYA

Fiber Grating:


Fiber Grating Basics:


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