Intrinsic attenuation occurs due to something inside or inherent to the fiber. It is caused by impurities in the glass during the manufacturing process.

2)What is scattering loss?

Rayleigh scattering accounts for the majority (about 96%) of attenuation in optical fiber. Light travels in the core and interacts with the atoms in the glass. The light waves elastically collide with the atoms, and light is scattered as a result.

3)what is Extrinsic attenuation?

Extrinsic attenuation can be caused by two external mechanisms: macrobending or microbending.

4)what is Macrobending ?

If a bend is imposed on an optical fiber, strain is placed on the fiber along the region that is bent. The bending strain will affect the refractive index and the critical angle of the light ray in that specific area. As a result, light traveling in the core can refract out, and loss occurs.

5)what is Microbending ?

The second extrinsic cause of attenuation is a microbend. This is a small-scale distortion, generally indicative of pressure on the fiber.

6)what is fiber bandwidth?

The fiber bandwidth is defined as the lowest frequency at which the magnitude of the fiber Frequency response has decreased to one-half its zero-frequency value. This is the -3 decibel (dB) optical power frequency (f3dB). This frequency is referred to as the fiber bandwidth.

7)what is the basic structure of optic fiber?

The basic structure of an optical fiber consists of three parts; the core, the cladding, and the coating or buffer. The basic structure of an optical fiber is shown in figure 2-9. The core is a cylindrical rod of dielectric material. Dielectric material conducts no electricity. Light propagates mainly along the core of the fiber. The core is generally made of glass. The core is described as having a radius of (a) and an index of refraction n1. The core is surrounded by a layer of material called the cladding.For extra protection, the cladding is enclosed in an additional layer called the coating or buffer. The coating or buffer is a layer of material used to protect an optical fiber from physical damage. The material used for a buffer is a type of plastic.

8)What is critical angle?

The angle at which total internal reflection occurs is called the critical angle of incidence.

The basic optical property of a material, relevant to optical fibers, is the index of refraction. The index of refraction (n) measures the speed of light in an optical medium. The index of refraction of a material is the ratio of the speed of light in a vacuum to the speed of light in the material itself.

10)What are the properties of ideal opotic detectors?

Fiber optic communications systems require that optical detectors meet specific performance and compatibility requirements. Many of the requirements are similar to those of an optical source. Fiber optic systems require that optical detectors:

• Be compatible in size to low-loss optical fibers to allow for efficient coupling and easy packaging.
• Have a high sensitivity at the operating wavelength of the optical source.
• Have a sufficiently short response time (sufficiently wide bandwidth) to handle the system's data rate.
• Contribute low amounts of noise to the system.
• Maintain stable operation in changing environmental conditions, such as temperature.

The numerical aperture (NA) is a measurement of the ability of an optical fiber to capture light. The NA can be defined from the refractive index profile or the output far-field radiation pattern.

12)what is cutoff wavelength?

The CUTOFF WAVELENGTH of a single mode fiber is the wavelength above which the fiber propagates only the fundamental mode. The cutoff wavelength of a single mode fiber varies according to the fiber's radius of curvature and length.

13)What is total internal reflection?

TOTAL INTERNAL REFLECTION occurs when light rays are totally reflected at the boundary between two different transparent materials. The angle at which total internal reflection occurs is called the critical angle of incidence.

14)What is acceptance angle?

The ACCEPTANCE ANGLE is the maximum angle to the axis of the fiber that light entering the fiber is bound or propagated.

15)What are the types of fibers?

FIBERS are classified by the number of modes that propagate along the optical fiber. Single mode fibers propagate only one mode because the core size approaches the operational wavelength. Multimode fibers can propagate over 100 modes depending on the core size and numerical aperture.

16)What are the advantages of fiber optics?

The ADVANTAGES of fiber optic systems include improved system performance, immunity to electrical noise, signal security, and electrical isolation. Advantages also include reduced size and weight, environmental protection, and overall system economy.

17)What are the disadvantages of fiber optics?

The DISADVANTAGES of fiber optic systems include problems with the relative newness of the technology, the relatively expensive cost, and the lack of component and system standardization. However, these disadvantages are already being eliminated because of increased use and acceptance of fiber optic technology.

18)what is Snell's law?

SNELL'S LAW OF REFRACTION describes the relationship between the incident and the refracted rays when light rays encounter the boundary between two different transparent materials.

19)what is the wavelength of operation in optic fibers?

The WAVELENGTH OF OPERATION in fiber optics is between 700 nm and 1600 nm. The wavelength of operation is between the ultraviolet (below 400 nm) and infrared (above 2000 nm) intrinsic absorption regions.

20)What is step index fiber?

In STEP-INDEX fibers, the refractive index of the core is uniform and undergoes an abrupt change at the core-cladding boundary.

21)What is graded index fiber?

In GRADED-INDEX fibers, the refractive index of the core varies gradually as a function of radial distance from the fiber center.

22)What is Fresnel reflection?

FRESNEL REFLECTION occurs twice in a fiber-to-fiber connection. A portion of the optical power is reflected when the light first exits the source fiber. Light is then reflected as the optical signal enters the receiving fiber.

23)What are optic sources?

An OPTICAL SOURCE converts electrical energy (current) into optical energy (light).The principal LIGHT SOURCES used in fiber optics are semiconductor light-emitting diodes (LEDs) and laser diodes (LDs).

24)What is dynamic range?

DYNAMIC RANGE refers to the range of optical power levels over which the receiver operates within the specified values. It usually is described by the ratio of the maximum input power to the sensitivity.

25)What is an optical detector?

An OPTICAL DETECTOR is a transducer that converts an optical signal into an electrical signal. It does this by generating an electrical current proportional to the intensity of incident optical radiation.