Fiber Optic Wavelength Division Multiplexing Training - Mericler 2024.pptx
- 1. FIBER OPTIC WAVELENGTH DIVISION MULTIPLEXING
- 2. Unit 1 - Fiber Optic Wavelength Division Multiplexing Training ● Basic Theories ● Why Optics? ● Optical Signal Fundamentals ● How the Fiber Optic Works? ● Fiber Optic Types & Standards ● Fiber Optic Connectors Types & Categories ● Fiber Optic Accessories ● Optical Transceivers SFPs
- 3. Why Optics? ● Greater Bandwidth: Optics support higher data rates than copper wires. ● Lower Attenuation: Signal loss is significantly less in optical fiber. ● Immunity to Electromagnetic Interference: Optical signals are not affected by EMI. ● Enhanced Security: Optical fibers are difficult to tap without detection. ● Longer Transmission Distances: Signals can travel longer distances without needing amplification.
- 4. Optical Signal Fundamentals ● Light travels in waves, with peaks and troughs. ● The distance between peaks is the wavelength. ● Frequency is how many waves pass a point per second. ● Amplitude is the height of the wave from peak to trough. ● Phase describes the position of a wave relative to a reference point.
- 5. How Fiber Optics Work ● Light travels through the core of the fiber optic cable. ● The cladding, with a lower refractive index, reflects light back into the core. ● This process of total internal reflection allows light to travel long distances. ● Optical fibers can be single-mode or multi-mode. ● Single-mode fibers have a smaller core and allow only one mode of light to propagate. ● Multi-mode fibers have a larger core and allow multiple modes of light to propagate.
- 6. Fiber Optic Types & Standards ● Single-mode fiber (SMF): Smaller core, supports one mode of light, longer distances. ● Multi-mode fiber (MMF): Larger core, supports multiple modes of light, shorter distances.
- 7. Fiber Optic Connectors: Types & Categories ● Fiber optic connectors precisely align fiber cores for efficient light transmission. ● Connectors minimize signal loss/reflection, ensuring optimal performance. ● Common connector types include SC, ST, FC, and LC connectors. ● Connectors are categorized based on factors like ferrule material, polishing type, and application. ● Proper connector selection and installation are crucial for reliable fiber optic networks.
- 8. Fiber Optic Accessories ● Couplers: Combine or split optical signals. ● Attenuators: Reduce signal strength in high-power applications. ● Splice enclosures: Protect fiber splices in harsh environments. ● Patch panels: Organize and manage fiber optic cables in a structured way. ● Cable management tools: Ensure proper routing and protection of fiber cables. ● Cleaning tools and materials: Maintain cleanliness for optimal signal transmission.
- 9. Optical Transceivers SFPs ● Essential for converting electrical signals to optical signals and vice versa. ● Small form-factor pluggable modules for high-speed data transmission. ● Hot-swappable for easy installation and replacement. ● Support various distances and wavelengths. ● Used in telecommunications and data communications.
- 10. Unit 2 - OPTICAL PHYSICS / LINK CHARACTERISTICS ● Attenuation ● Dispersion ● Insertion loss and reflection loss ● Absolute Optical Power ● Power Budget Calculation ● Loss Budget Calculation ● Fiber Optic Types, Choosing Proper Type ● Metropolitan & Long Haul Networks
- 11. Unit 2 - Optical Physics / Link Characteristics ● Attenuation ● Dispersion ● Insertion loss and reflection loss ● Absolute Optical Power ● Power Budget Calculation ● Loss Budget Calculation ● Fiber Optic Types, Choosing Proper Type
- 12. Fiber Optic Attenuation ● Attenuation: The gradual loss of signal strength as light travels through the fiber. ● Measured in decibels per kilometer (dB/km). ● Caused by absorption, scattering, bending, and other factors. ● Attenuation limits the transmission distance of optical signals. ● Different wavelengths of light experience different levels of attenuation.
- 13. Dispersion ● Dispersion: The spreading of light pulses over time as they travel along the fiber. ● Measured in picoseconds per nanometer-kilometer (ps/nm-km). ● Caused by different wavelengths of light traveling at slightly different speeds. ● Modal dispersion: Different modes of light in multi-mode fibers take different paths. ● Chromatic dispersion: Different wavelengths of light travel at different speeds. ● Polarization mode dispersion (PMD): Different polarizations of light travel at different speeds.
- 14. Insertion Loss & Reflection Loss ● Insertion loss: Signal power loss when a component is added to the fiber link. ● Caused by factors like connector misalignment, fiber mismatch, and component imperfections. ● Reflection loss: Signal power loss due to reflected light at connection points. ● Caused by differences in refractive indices between fiber and connector. ● Both losses contribute to overall signal attenuation in fiber optic systems.
- 15. Absolute Optical Power ● Absolute optical power is the measurement of light power at a specific point in the fiber optic system. ● Typically measured in units of dBm (decibel-milliwatts). ● Can be measured using an optical power meter. ● Important for ensuring that the signal strength is within acceptable limits. ● Too much power can damage equipment, too little power can result in signal loss.
- 16. Power Budget Calculation ● The optical power budget in a fiber optic communication link is the allocation of available power. ● It is the difference between the transmitter output power and the receiver sensitivity. ● The power budget determines the maximum attenuation that the signal can tolerate. ● It accounts for losses from components like connectors, splices, and the fiber itself. ● A positive power budget ensures that the signal is strong enough to be received reliably.
- 17. Loss Budget Calculation ● Allocates acceptable loss to components in a fiber optic link. ● Ensures signal strength remains within operational limits. ● Accounts for losses introduced by connectors, splices, and fiber. ● Calculated by subtracting individual losses from available power budget. ● Negative loss budget indicates insufficient power for reliable transmission.
- 18. Fiber Optic Types and Selection Criteria ● Consider transmission distance: Choose single-mode fiber (SMF) for longer distances and multi-mode fiber (MMF) for shorter distances. ● Consider bandwidth requirements: Choose SMF for higher bandwidth and MMF for lower bandwidth. ● Consider cost: MMF is generally less expensive than SMF. ● Consider future needs: Choose a fiber type that can accommodate potential future upgrades.
- 19. Choosing the Right Fiber for DWDM ● Consider transmission distance: Single-mode fiber (SMF) for longer distances. ● Consider wavelength and compatibility: Choose fibers that support the desired wavelengths for DWDM. ● Consider attenuation and dispersion: Select fibers with low attenuation and dispersion at DWDM wavelengths. ● Consider cost: Evaluate the overall cost of the fiber and its impact on the project budget. ● Consider future needs: Ensure the chosen fiber type can support potential future upgrades or expansions.
- 20. Metropolitan & Long Haul Networks ● Metropolitan Networks: Shorter distances (tens of kilometers), high capacity, lower cost. ● Long Haul Networks: Longer distances (hundreds or thousands of kilometers), high capacity, higher cost. ● Considerations: Fiber type, transmission distance, bandwidth requirements, cost, scalability. ● Network Design: Dense Wavelength Division Multiplexing (DWDM) for efficient use of fiber. ● Future Trends: Increased demand for bandwidth, 5G deployment, Internet of Things (IoT).
- 21. Unit 3 - Transmission Protocols ● SONET History ● SONET Ring Topology ● Overview of Optical Carriers ● Example of a SONET Carrier ● Agreement ● Introduction to SONET and SDH ● Advantages of SDH over older protocols ● DM, PDH, and SDH ● SONET and SDH Hierarchy ● Transport Hierarchy ● SONET Protection Ring 2 Fibers and 4 Fibers ● OTN Protocol ●
- 22. SONET Overview ● SONET = Synchronous Optical Network ● "Synchronous" meaning that only one clock source is shared by both ● Optical devices at either end of the cable ● + Atomic Clocks are used for synchronization ● + Developed in the 1980s ● + ANSI standard used in the U.S. and Canada ● + The European, Asian, and Latin American implementation of SONET is ● known as Synchronous Digital Hierarchy (SDH) standardized by the ITU
- 23. SONET Rings ● + Uses a dual-ring topology ● + One ring is the primary ring ● + A second ring (transmitting in the opposite direction) is a backup ring. ● + SONET was primarily designed to handle massive quantities of Voice ● calls ● + Because Voice is so critical, SONET has a 50ms recovery rate when the ● primary ring fails to switchover to the secondary ring.
- 24. SONET Optical Transmissions ● Provides an optical circuit that implements TDM (Time Division Multiplexing) ● + Uses a single wavelength to aggregate: ● + Multiple electrical signals into a single high bitrate signal ● + Multiple optical signals (i.e. Optical Gigabit Ethernet interfaces) into a single ● high bitrate signal ● + SONET defines the physical interface standards (Layer-1) and a ● synchronous frame structure to delineate multiplexed traffic ● + SONET frame format called, “STS” (Synchronous Transport Signal) ● + SONET encapsulation ● + Supports ATM encapsulation ● + PoS (Packet over SONET) popular for transporting IP packets ● + Uses PPP encapsulation to delineate one packet from another
- 25. SONET Optical Carriers ● SONET utilizes various OC (Optical Carrier) rates to define speed and ● bandwidth ● OC-1 = 51.84Mbps ● + Other OC rates are just multiples of OC-1 ● SDH equivalent of the OC is the STM (Synchronous Transport Module) STM-0 = OC-1 ● STM-1 = OC-3 ● You select the bit-rate you wish and pay the appropriate fee
- 26. OC & STM Rates
- 27. Optical Carriers ● SONET utilizes various OC (Optical Carrier) rates to define speed and ● bandwidth ● OC-1 = 51.84Mbps ● + Other OC rates are just multiples of OC-1 ● SDH equivalent of the OC is the STM (Synchronous Transport Module) STM-0 = OC-1 ● STM-1 = OC-3 ● You select the bit-rate you wish and pay the appropriate fee
- 28. Advantages of SDH ● Increased bandwidth and capacity compared to PDH. ● Improved network efficiency and scalability. ● Standardized protocols for interoperability. ● Flexible framework for transporting various traffic types. ● Enhanced network management and monitoring capabilities. ● Support for advanced features like protection switching and network resilience.
- 29. 01 02 03 DM, PDH, and SDH Protocols Plesiochronous Digital Hierarchy (PDH) - Older tech, limited bandwidth, less efficient. Digital Multiplexing (DM) - Combines multiple digital signals. Synchronous Digital Hierarchy (SDH) - Replaced PDH, supports higher speeds, more flexible and efficient.
- 30. SONET and SDH Hierarchy ● SONET and SDH are standardized protocols for high-speed digital transmission over optical fiber ● They use a synchronous multiplexing technique to combine multiple lower- rate signals into a higher-rate signal ● SONET/SDH networks are widely used in telecommunications for their reliability, scalability, and interoperability ● Basic unit of transmission hierarchy: STS- 1 for SONET, STM-1 for SDH ● Higher-level signals are multiples of the basic unit, e.g., STS-3, STM-4, etc.
- 31. SONET Protection Ring ● SONET protection rings provide network redundancy and fault tolerance. ● Two fibers transmit data in opposite directions, forming a ring. ● If one fiber fails, the other carries the traffic, preventing service disruption. ● 4-fiber rings offer even greater redundancy with two working and two protection fibers. ● Self-healing mechanism automatically switches to the protection fiber upon failure detection.
- 32. SONET Rings: 2 Fibers vs. 4 Fibers ● 2 fibers transmit data in opposite directions, forming a ring. ● If one fiber fails, the other carries the traffic. ● 4-fiber rings offer greater redundancy with two working and two protection fibers. ● Self-healing mechanism automatically switches to the protection fiber upon failure detection.
- 33. OTN Protocol ● Flexible and efficient transport of various client signals over optical networks. ● Maps different client signals into Optical Channel Data Units (ODUs). ● Supports multiplexing and switching of ODUs for efficient bandwidth utilization. ● Uses Generic Framing Procedure (GFP) for mapping and adaptation of client signals. ● Provides a resilient and scalable infrastructure for next- generation optical networks.
- 34. Understanding OTN Protocol ● Flexible and efficient transport of various client signals over optical networks ● Maps different client signals into Optical Channel Data Units (ODUs) ● Supports multiplexing and switching of ODUs for efficient bandwidth utilization ● Uses Generic Framing Procedure (GFP) for mapping and adaptation of client signals ● Provides a resilient and scalable infrastructure for next-generation optical networks
- 35. Unit 4: Wavelength Division Multiplexing (WDM) ● What is Multiplexing and Why Multiplexing? ● Multiplexing Types ● WDM, CWDM and DWDM ● Spectral Width ● Optical Windows
- 36. Dense Wavelength Division Multiplexing (DWDM) ● Originally used as a Carrier technology to aggregate optical signals ● + Now also provided as an Enterprise WAN solution ● + Provides many more channels than CWDM (up to 192 ● channels) ● + Each channel can carry a 100Gbps multiplexed signal ● + Typically, the minimum bandwidth you would get when connecting an ● office to a DWDM circuit is 10Gbps
- 37. Dense Wavelength Division Multiplexing (DWDM) ● DWDM (using different multiplexed wavelengths) can be used to aggregate several SONET signals onto a single fiber strand ● + Enterprise WANs can increase their required bandwidth at any time when using DWDM without the need for installation of additional fiber cables ● + Per Spectrum Enterprise: ● + "Wavelength Services provides a non-shared, point-to-point circuit for ● connecting locations. Traffic passes seamlessly across the network, separated from other data streams and encapsulated inside wavelength frequency."
- 38. Course Wavelength Division Multiplexing (CWDM) ● + Designed for short-range communications (80km or less) ● + Generally, less expensive than DWDM ● + Uses cheaper lasers that are less precise ● + Provides between eight (8) and eighteen (18) channels of ● optical wavelengths
- 39. CWDM Contrasted With DWDM
- 40. Multiplexing (WDM) Explained ● Multiplexing combines multiple signals for transmission over a shared medium. ● Increases bandwidth efficiency and lowers cost. ● WDM is a multiplexing technique that uses different wavelengths of light. ● CWDM uses wider spacing between wavelengths, allowing for fewer channels. ● DWDM uses denser wavelength spacing, enabling more channels and higher capacity.
- 48. What is Multiplexing and Why Use It? ● Multiplexing is a method by which multiple analog or digital signals are combined into one signal over a shared medium. ● Multiplexing increases the amount of data that can be sent over a network within a specific time frame. ● Different types of multiplexing include frequency-division multiplexing (FDM), time-division multiplexing (TDM), and wavelength-division multiplexing (WDM). ● WDM is a technique used to increase bandwidth over existing fiber networks. ● WDM works by combining multiple signals on laser beams at various infrared wavelengths and transmitting them through a single optical fiber.
- 49. Multiplexing Types ● Frequency Division Multiplexing (FDM): Divides the available bandwidth into multiple channels, each carrying a separate signal. ● Time Division Multiplexing (TDM): Divides the available time slots into multiple channels, each transmitting a portion of each signal in a fixed sequence. ● Wavelength Division Multiplexing (WDM): Combines multiple signals on laser beams at various infrared wavelengths and transmits them through a single optical fiber. ● Code Division Multiplexing (CDM): Employs spread-spectrum techniques where each signal is assigned a unique code.
- 50. WDM, CWDM, and DWDM Explained ● WDM combines multiple signals on laser beams at various infrared wavelengths. ● CWDM uses wider spacing between wavelengths, allowing for fewer channels. ● DWDM uses denser wavelength spacing, enabling more channels and higher capacity.
- 51. Spectral Width in DWDM ● Spectral width measures the range of wavelengths occupied by a light signal. ● It is typically measured in nanometers (nm) or picometers (pm). ● DWDM systems require precise control of spectral width to prevent interference between channels. ● Narrow spectral width lasers are essential in DWDM systems to maximize channel density. ● Factors like temperature and modulation can affect spectral width.
- 52. Optical Windows in DWDM ● Optical windows are wavelength ranges with low attenuation loss. ● DWDM systems primarily use the C-band (1530nm - 1565nm) and L-band (1565nm - 1625nm) windows. ● The choice of optical window depends on factors like transmission distance and desired capacity. ● C-band offers lower attenuation, making it suitable for long-haul transmission. ● L-band offers higher capacity, but with slightly higher attenuation.
- 53. Unit 5: WDM Site Components ● Optical Transponders ● Optical Filters ● Dispersion Compensation Modules (DCM) ● Coherent Transmission
- 54. Optical Transponders in DWDM ● Essential for converting electrical signals to optical signals and vice versa. ● Used in DWDM systems to transmit and receive different wavelengths of light. ● Can be tuned to specific wavelengths, allowing for flexible network configurations. ● Amplify optical signals, enabling long-distance transmission. ● May incorporate multiplexing and demultiplexing functions for combining and separating wavelengths.
- 55. ● Essential components in DWDM systems for managing wavelengths. ● Selectively transmit or block specific wavelengths of light. ● Multiplexers combine multiple wavelengths onto a single fiber. ● Demultiplexers separate wavelengths at the receiving end. ● Optical add-drop multiplexers (OADMs) selectively add or drop wavelengths at intermediate points. ● Improve signal quality by reducing crosstalk and noise. ● Enable efficient use of available bandwidth. Optical Filters in DWDM
- 56. Overcoming Dispersion in DWDM ● Dispersion Compensation Modules (DCMs): Counteract dispersion by introducing an opposite dispersion effect. ● Coherent Transmission: Uses advanced modulation and detection techniques to mitigate dispersion effects. ● Fiber Bragg Gratings (FBGs): Reflect specific wavelengths of light to manage dispersion. ● Electronic Dispersion Compensation (EDC): Employs digital signal processing algorithms to correct for dispersion.
- 57. Unit 6: DWDM Architectures & Protection ● Unidirectional and Bi-directional DWDM ● Single Fiber Working ● OADM & ROADM ● CDC ● The ITU G.692 Grid ● Filter-less architecture ● Coherent DWDM ● Optical Cross-Connects (OXCs)
- 58. Unit 6: DWDM Architectures & Protection, Cont ● Light path Topology Design (LTD) ● Routing & Wavelength Assignment (RWA), Graph coloring ● Optical protection, and reliability (MTBF, MTTR). ● Optical control and management ● Performance management, optical overhead. ● Optical Transport Network (OTN)
- 59. Widely Deployed Fiber Types G.652.widely used, need d1spers1on compensation tor high rate transmI':>sion . 1d FWM. le for DWDM Dispersion coefficient 17ps/nmkm SMF (G.652) Ok for DWDM with dispersion management Bad for DWDM (C-Band) Good for DWDM (C+L Bands 1310n m E 1550n m G.653: Zero dispersion at 1550nm window. DSF (G.653) NZDSF (G.655)
- 60. Unidirectional vs. Bidirectional DWDM ● Unidirectional DWDM: All channels transmitted in a single direction. ● Bi-directional DWDM: Channels transmitted in both directions on a single fiber. ● Requires wavelength filtering to separate transmit and receive signals. ● Reduces fiber usage compared to unidirectional DWDM. ● More complex to implement and manage.
- 62. Single Fiber Working in DWDM ● Employs a single optical fiber for both transmitting and receiving data. ● Uses wavelength division multiplexing (WDM) to separate transmit and receive channels. ● Requires components like circulators or diplexers to isolate wavelengths. ● Offers cost savings by reducing fiber usage. ● Can be more complex to implement and manage than dual-fiber systems.
- 63. OADM & ROADM in DWDM ● OADMs: Add/drop multiplexers for specific wavelengths in DWDM networks. ● Fixed or reconfigurable to alter wavelength routing. ● ROADMs: Reconfigurable OADMs offer dynamic wavelength routing and switching. ● Remotely configurable to adapt to network changes. ● Essential for flexible and scalable DWDM networks.
- 68. 2) Fixed Optical Add/Drop Multiplexer (FOADM) • Add/drop pre-determined wavelengths at the intermediate sites • Pass remaining channels through without demultiplexing • No power loss for pass through wavelengths • Less costly hardware but manual patching to connect dropped wavelength with transponder
- 70. 3) Re-configurable Optical Add Drop Multiplexers (ROADMs) • Add/drop/pass-through wavelengths remotely • Uses Wavelength selective switch inconjunction with Amplifier to - Dynamically balance power between all wavelengths sharing a fiber - Reconfigure add/drop/pass through wavelength - Switch wavelengths to multiple directions (degrees) e.g, North/south/ east
- 76. ROADM Based DWDM Networks Simplify Opex, Simplify Network Architecture, Simplify Network Planning Improve Opex Efficiency, FOADM Based Architecture •Re-plan the network every time •new services is added •Extensive man hours to retune •network ROADM Based Architecture - Plan the network only once - Can be reconfigured remotely
- 77. ROADM Mesh Benefits •n OEO transponder •I 2°ROADM •Ring Based Architecture - Traffic must follow ring - Inefficient traffic routing • More regeneration - Expensive Transponders • Limited protection • • • • • • -8 0 ROADM Mesh Based Architecture - Load balancing • More capacity Shorter distance less • Regeneration - Eliminate transponders - More protection Options
- 85. CDC in DWDM ● CDC stands for Colorless, Directionless, and Contentionless. ● It refers to the ability of ROADMs to switch any wavelength to any port, regardless of direction or color. ● This flexibility simplifies network design and management. ● It allows for dynamic provisioning of wavelengths and efficient use of network resources. ● CDC enhances the scalability and adaptability of DWDM networks.
- 86. The ITU G.692 Grid ● The ITU-T G.692 grid is a standardized frequency grid for Dense Wavelength Division Multiplexing (DWDM) systems. ● It defines the specific wavelengths (channels) that can be used in DWDM transmission. ● The grid helps to ensure interoperability between DWDM equipment from different vendors. ● It also helps to prevent interference between channels and maximize spectral efficiency. ● The ITU-T G.692 grid is essential for the planning and deployment of DWDM networks.
- 87. Filter-less Architecture in DWDM ● Eliminates the need for fixed optical filters. ● Uses tunable lasers and receivers for flexible wavelength selection. ● Enables dynamic provisioning of wavelengths. ● Reduces cost and complexity compared to traditional DWDM architectures. ● Enhances scalability and adaptability of DWDM networks.
- 88. Coherent DWDM Explained ● Uses advanced modulation and detection techniques to improve signal quality and reach. ● Employs phase and amplitude modulation to increase spectral efficiency. ● Can transmit multiple bits per symbol, increasing data capacity. ● Requires more complex components and algorithms than traditional DWDM. ● Offers improved performance and scalability for next-generation optical networks.
- 89. Optical Cross-Connects (OXCs) in DWDM ● Network nodes that switch high-speed optical signals in a DWDM network. ● Can switch individual wavelengths between different fibers. ● Enable dynamic reconfiguration of optical connections. ● Improve network flexibility and efficiency. ● Essential for building scalable and adaptable DWDM networks.
- 90. Light Path Topology Design (LTD) in DWDM ● Planning the physical route of optical paths in a DWDM network. ● Considers factors like distance, available fiber, and equipment placement. ● Aims to minimize signal loss, dispersion, and cost. ● Ensures efficient use of network resources and scalability for future expansion. ● LTD is crucial for optimizing DWDM network performance and reliability.
- 91. Routing & Wavelength Assi (RWA) ● RWA is the process of assigning wavelengths and routes to optical connections. ● It aims to optimize network performance while minimizing blocking and maximizing resource utilization. ● RWA is modeled as a graph coloring problem, where wavelengths are colors and connections are vertices. ● The goal is to assign colors to vertices without assigning the same color to adjacent vertices. ● This ensures that signals on different wavelengths do not interfere with each other. ● Efficient RWA algorithms are crucial for scalable and dynamic DWDM networks.
- 92. Optical Protection & Reliability in DWDM ● Optical protection mechanisms ensure network survivability in case of failures. ● Mean Time Between Failures (MTBF) measures the average time between failures in a system. ● Mean Time To Repair (MTTR) measures the average time to restore a system after a failure. ● High MTBF and low MTTR are desirable for reliable DWDM networks. ● Protection mechanisms can be hardware-based (e.g., redundant components) or software- based (e.g., restoration protocols).
- 93. Optical Control & Management in DWDM ● Network management system for DWDM elements. ● Monitors performance and detects faults. ● Configures wavelengths, power levels, and routing. ● Remotely controls optical switches and amplifiers. ● Ensures efficient and reliable network operation.
- 94. Optical Transport Network (OTN) ● Flexible, efficient transport of client signals over optical networks ● Maps different client signals into Optical Channel Data Units (ODUs) ● Supports multiplexing and switching of ODUs for efficient bandwidth utilization ● Uses Generic Framing Procedure (GFP) for mapping and adaptation of client signals ● Provides a resilient and scalable infrastructure for next-generation optical networks
- 95. Unit 7: DWDM Passive Components ● RC Splitter ● Diffraction Grating ● FBG ● Thin Film Filter ● AWG ● Optical Isolator
- 96. RC Splitters in DWDM ● Passive device that splits incident light into multiple output fibers ● Evenly distributes optical power among output fibers ● Used to create multiple copies of a signal or for power monitoring ● Does not require external power source ● Low insertion loss, high reliability, and compact size
- 97. Diffraction Gratings in DWDM ● Optical component that disperses light into its constituent wavelengths. ● Employs diffraction to separate wavelengths based on their angle of incidence. ● Enables wavelength selective switching, routing, and filtering in DWDM systems. ● Can be used for multiplexing and demultiplexing wavelengths. ● Offers high efficiency, low insertion loss, and compact size.
- 98. FBGs in DWDM ● Reflects specific wavelengths of light while transmitting others. ● Acts as a filter or mirror for precise wavelength management. ● Enables dispersion compensation, add/drop multiplexing, and other functions. ● Offers low insertion loss, high reflectivity, and compact size. ● Can be inscribed in various types of optical fibers.
- 99. Thin Film Filters in DWDM ● Uses alternating layers of high and low refractive index materials. ● Produces interference effects to selectively transmit or reflect specific wavelengths. ● Offers narrow spectral width and high precision filtering. ● Requires careful design and manufacturing to achieve desired performance. ● Can be used for wavelength multiplexing, demultiplexing, and channel isolation.
- 100. AWGs in DWDM ● Combines/separates multiple wavelengths of light in DWDM systems. ● Uses interference effects from multiple waveguides. ● Offers high channel count, low insertion loss, and compact size. ● Requires precise design and manufacturing for optimal performance. ● Different AWG types include Gaussian, Flat-Top, and Athermal AWGs.
- 118. Unit 8: LASERS ● How Laser Works? ● LASERS Performance characteristics ● Laser Types ● Fiber Non-linearity ● Mode-locked lasers ● Laser vs. LED
- 119. Laser Diode HOW DOES IT WORK?
- 120. Laser vs. LED in Fiber Optics ● Lasers provide a more focused and directional light source compared to LEDs. ● LEDs emit light over a wider area, leading to greater dispersion and signal loss. ● Lasers offer higher power levels and longer transmission distances than LEDs. ● LEDs are generally more cost-effective and have a longer lifespan compared to lasers. ● The choice between lasers and LEDs depends on the specific requirements of the fiber optic system.
- 121. LASER Performance Characteristics ● Output Power: The amount of optical power emitted by the laser. ● Wavelength: The specific wavelength or range of wavelengths at which the laser operates. ● Spectral Width: The range of wavelengths contained within the laser emission. ● Modulation Bandwidth: The maximum frequency at which the laser output can be modulated. ● Polarization: The orientation of the electric field of the emitted light. ● Relative Intensity Noise (RIN): The fluctuation of the laser output power over time.
- 122. Laser Types in Fiber Optics ● Semiconductor Lasers: Commonly used, compact, and efficient. ● Gas Lasers: Helium-Neon (HeNe), Argon, and Carbon Dioxide lasers are examples. ● Solid-State Lasers: Nd:YAG and Erbium-doped fiber amplifiers (EDFAs) are examples. ● Fiber Lasers: Doped with rare-earth elements, high power and efficiency. ● Mode-Locked Lasers: Produce ultra-short pulses, used in high-speed communications.
- 123. Fiber Non-Linearity ● Occurs when high-intensity light interacts with the fiber material. ● Causes signal distortion and crosstalk in DWDM systems. ● Effects include Stimulated Raman Scattering (SRS) and Stimulated Brillouin Scattering (SBS). ● SRS is the transfer of energy between different wavelengths. ● SBS is the reflection of light caused by acoustic vibrations. ● Mitigation techniques include power management and dispersion compensation.
- 124. Mode-Locked Lasers in Fiber Optics ● Generate ultra-short optical pulses. ● Used in high-speed communications and precision measurements. ● Can create pulses with durations of femtoseconds or even attoseconds. ● Achieved by locking the phases of different longitudinal modes in a laser cavity. ● Requires precise control of cavity length and dispersion.
- 125. Unit 9: DETECTORS ● How to Detect the Optical Signal? ● Types of Detectors ● Detectors Sensitivity ● Optical Wavelength Conversion
- 126. Unit 10: OPTICAL AMPLIFIER ● How to Detect the Optical Signal? ● Types of Detectors ● Detectors Sensitivity ● Optical Wavelength Conversion
- 127. Unit 9: DETECTORS ● How to Detect the Optical Signal? ● Types of Detectors ● Detectors Sensitivity ● Optical Wavelength Conversion