Top 29 Microwave And Optical Link Installation Interview Questions You Must Prepare 24.Jun.2024

Q1. Necessity Of Cladding For An Ofical Fiber ?

  • Provide proper light guidance inside the core.
  • Avoid leakage of light from the fiber. 

Q2. What Are Leaky Modes In Optical Fiber ?

A leaky mode or tunneling mode in an optical fiber or other waveguide is a mode having electric field that decays monotonicallv for a finite distance in the trverse direction but becomes oscillatory everywhere beyond that finite distance.

Q3. Give A Reason Behind N2 > Ni?

During manufacturing of fiber, certain impurities (dopants) are introduced in the core and cladding. so that the refractive index is slightly higher in core than cladding.

Q4. What Are The Sources Used In Optical Communication?

LEDs and L4SER diodes are the commonly used sources in optical communication systems, whether the system trmits digital or analog signal. It is therefore, often necessary to use linear Electrical to Optical converter to allow its use in intensity modulation & high quality analog trmission systems.

Q5. Define Anomalies ?

An anomaly is the smallest discrepancy that can be observed between the actual and desired characteristics of an item.

Q6. Define Mfd?

MFD ( mode field diameter) determines the fundamental mode by the radial extend of its electromagnetic field including losses at launching and joining, microbend losses, waveguide dispersion and width of radiation pattern.

Q7. What Is Photod Etector ?

Optical signal is trmitted through optical fiber it is retrieved in its original electrical form with the help of optical to electrical conversion device such as photo detector.

Q8. Uses Of Optical Fiber ?

  • To trmit the information which are in the form of coded signals of the telephone communication, computer data.
  • To trmit the optical images(ex: endoscopy).

Q9. What Is Meridional Rays ?

Rays following the zigzag path when they travel through fiber and for every reflection it will cross the fiber axis.

Q10. Advantages Of Sdh ?

  • High trmission rate.
  • Reliability.
  • High availability and capacity.

Q11. Define Lambertian Pattern?

Isotropic pattern from a surface emitter is called a lambertian pattern. In this pattern source is equally bright when viewed from any direction, but power diminishes as cose.

Q12. What Are Demountable Connectors?

These are the removable joints which allow easy, fast manual coupling and uncoupling of fiber analogous to electrical plugs and sockets.

Q13. What Is Macro Bend And Micro Bend Losses?

Macrobend losses occurs when radius of curvature that all large compared with fiber diameter microbend losses are small scale fluctuation in radius of curvature of fiber axis. 

Q14. Define Polarization?

Polarization refers to the electric field orientation of a light signal, which can vary significantly along the length of a fiber polarization state is fundamental property off an optical signal.

Q15. Define Modal Or Speckle Noise?

The speckle pattern observed in multimode fiber as fluctuation which have characteristics times longer then the resolution time of the detector is know as modal or speckle noise.

Q16. What Are The Essential Components Of Laser?

  • Amplifying medium 
  • An optical feedback 
  • Pumping source.

Q17. What Is A Fiber Optic ?

Fiber optics are long lenses. A cylinder or rod of trparent material forming a core surrounded by an external cladding with a slightly different material. Light, when entering the fiber, rebounds on the outer cladding towards the core. This way the light advances through the fiber in bounds or steps. until it exits at the other end. 

Q18. What Is Skew Rays?

Rays following the helical path around the fiber axis when they travel through the fiber and they would not cross the fiber axis at any time.

Q19. Define Tir?

At angles of incident greater than the critical angle the light is reflected back into the originating dielectric medium, which is known as Total internal reflection.

Q20. What Are The Mechanisms Of Losses Occurs In Optical Fiber?

  • Absorption (fiber material). 
  • Scattering (fiber material + structural imperfection). 
  • Radiative effects. 
  • Pulse broadening. 

Q21. Define Light Path ?

A connection between two end nodes whose traffic is switched only in the optical domain at intermediate nodes is referred to as a lightpath.

Q22. Define Bending Lass ?

Attenuation occurring as a result of either a bend in an optical fibre that exceeds the minimum bend radius or an abrupt discontinuity in the core/cladding interface is called bending loss.

Q23. What Are Degenerated Modes In Optical Fiber?

In weald guiding fibers is small then HE-EH mode pair occurs which have almost identical propagation constants and electromagnetic patterns such mode are called degenerate modes.

Q24. Define Critical Angle?

It is minimum angle angle of incident beyond which the total internal reflection occurs for light travelling from a medium of higher to one of lower refractive index is called critical angle.

Q25. Define Quantum Limit?

It is possible to find the minimum received optical power required for a specific bit error rate performance in a digital system. This minimum received power level is known as quantum limit.

Q26. What Are The Possible Noises Occur In Optical Receiver?

  • Photo detector noise.
  • Quantum noise.
  • Dark current noise (bulk dark current, surface dark current). 
  • Amplifier noise. 
  • Thermal noise or Johnson noise.

Q27. What Is Led ?

In optical fiber communication system electrical signal is first converted into optical signal with the help of electrical to optical conversion device as LED.

Q28. What Is Acceptance Angle ?

The maximum angle 4max with which a ray of light can enter through the entrance end of the fiber and still be totally internally reflected.

Q29. Define Attenuation Loss ?

Attenuation loss (or path propagation loss) is the reduction in power density (attenuation) of an electromagnetic wave as it propagates through space.