Optical Fiber Waveguides MCQ || Types of Optical fiber Waveguides Questions and Answers

Answer: 1. Insulator

Explanation: 

Optical fibers are made up of silica-based glass or plastic that are insulators and therefore have no currents flowing in them. As a result, fibers are immune to electromagnetic interference. In addition, no tapping of information is possible with fiber communications.

Answer: 3. Selenides

Explanation: 

• Glass fiber is made by fusing mixtures of metal oxides, sulfides, or selenides.
• The resulting material is a randomly connected molecular network rather than a well-defined ordered structure as found in crystalline materials.
• When glass is heated up from room temperature, it remains a hard solid up to several hundred degrees centigrade.
• As the temperature increases further, the glass gradually begins to soften until at very high temperatures it becomes a viscous liquid.

Answer:4. All of the above

Explanation: 

• Fibers are used instead of metal wires because signals travel along with them with less loss.
• In addition, fibers don’t suffer from the electromagnetic interference that troubles metal wires.
• Fibers are also used for illumination and imaging and are often wrapped in bundles.
• Specially designed fibers are also used for a variety of other applications, some of them being fiber optic sensors and fiber lasers.
• Another advantage of optical fibers is that they do not corrode and can be placed near a chemical environment.
• The bandwidth and speed of optical fiber communication systems are large, compared with any other communication system that exists today.

Answer:3. 1.45 to 850 nm

Explanation: 

The most common material for optical fiber is silica (Si0₂), which has a refractive index of 1.458 at 850 nm.

Answer:3. 1.45 to 850 nm

Explanation: 

The most common material for optical fiber is silica (Si0₂), which has a refractive index of 1.458 at 850 nm. To produce two similar materials that have slightly different indices of refraction for the core and cladding, either fluorine or various oxides (referred to as dopants), such as B₂O₃, GeO₂, or P₂O₅ are added to the silica.

Answer:4. All of the above

Explanation: 

The following are the advantages of glass optical fiber:

• Glass optical fibers are durable and withstand low to high temperatures in the range -40^oF to +900^oF. For that reason, they are useful for high-temperature appliances such as ovens, furnaces, condensers, and more as well as low-temperature areas such as cold storage warehouses.
• Due to lower loss per kilometer, glass fibers are best for long-distance communication.
• Glass fiber optics can support high bandwidth signal transmission. As a result, it is ideal for home networking.
• Glass optical fiber cable is immune to electromagnetic interference (EMI) and radio magnetic interference (RMI).
• Glass optical fibers are thin and light in weight. Therefore, they are optimal for small spaces and small targets.

Answer:4. All of the above

Explanation: 

Plastic optical fiber, polymer optical fiber or POF, is an optical fiber that is made out of plastic. Traditionally, it comprises PMMA (acrylic as the core (96% of the cross-section in a fiber 1mm in diameter) that facilitates the transmission of light, and fluorinated polymers as the cladding material.

Answer: 4. All of the above

Explanation: 

Advantages of Plastic fiber

• it is generally less expensive and makes use of less costly connectors.
• It is substantially tougher – it can be looped more tightly than glass in a wire closet.
• Plastic fiber is extremely easy to troubleshoot because it uses visible light, rather than infrared light: a user can actually look into the connector and see whether data is flowing on the line.
• Traditionally come in a wide variety of diameters ranging from 0.15-2 mm (small core) and even up to 20 mm (large core) 
• More flexible and able to bend farther without cracking or breaking 
• Able to withstand vibration and unsteady environments.

Answer: 4. All of the above

Explanation: 

Disadvantages  of Plastic fiber

• Signal attenuation and dispersion are very high. Hence they are not useful for long-distance communication systems.
• The Refractive index of the core and cladding part varies rapidly at higher temperatures. Hence NA and mode pattern of the plastic fiber deviates.
• It offers low quality compare to glass optical fiber.
• It is flammable and hence needs to be used in selected applications after proper analysis.
• More narrow numerical aperture – 0.48 – .063 
• Not able to withstand harsh environments and will easily degrade/yellow over time 
• Can only transmit a narrow spectrum of visible light (400 – 700 nm) 

Answer: 1. Used in Illumination

Explanation: 

Application of Plastic Optical Fiber

• The largest application of POF has been in digital audio interfaces for short-distance (5 m), low-speed communication between amplifiers, and built-in digital-to-analog converter and digital audio appliances, such as CD/MD/DAT players and BS tuners.
• The noise-immune nature of POF contributes to creating the sound of high quality and low jitter. Because of its flexibility and immunity to factory floor noise interference, rugged and robust POF communication links have been successfully demonstrated in a tough industrial manufacturing environment.
• Lightweight and durable POF networks could link the sophisticated systems and sensors used in automobiles, which would increase performance and overall efficiency.
• POF could be used to incorporate video, minicomputers, navigational equipment, and fax machines into a vehicle. Another short-haul application for POF is home networking, where appliances, entertainment and security systems, and computers are linked to create a smart home.
• Plastic fibers are preferred for more illumination and decorative applications, such as backlighting and trim lighting. Due to the flexibility and vibration resistance of plastic fibers, they are also great for automotive and industrial lighting purposes.