• Connectors are mechanisms or techniques used to join an optical fiber to another fiber or to a fiber optic
  • Different connectors with different characteristics, advantages and disadvantages and performance parameters are Suitable connector is chosen as per the requirement and cost.
  • Various fiber optic connectors from different manufactures are available SMA 906, ST, Biconic, FC, D4, HMS-10, SC, FDDI, ESCON, EC/RACE, LC, MT.
  • Three different types of connectors are used for connecting fiber optic cables. These are –
  1. Subscriber Channel (SC)
  2. Straight Tip (ST)
  3. MT-RJ
    • SC connectors are general purpose It has push-pull type locking system. Fig.

4.8.1 shows SC connector.

  • ST connectors are most suited for networking It is more reliable than SC connector. ST connector has bayonet type locking system. Fig. 4.8.2 shows ST connectors.

  • MT-RJ connector is similar to RJ45 Fig. 4.8.3 shows MT-RJ connector.

 

 

 

 

Principles of Good Connector Design

 

  1. Low coupling

 

  1. Inter-changeability – No variation is loss whenever a connector is applied to a

 

  1. Ease of

 

  1. Low environmental

 

  1. Low cost – The connector should be in expensive also the tooling required for

 

  1. Reliable

 

  1. Ease of

 

  1. Repeatability – Connection and reconnection many times without an increase in loss.

 

Connector Types

 

  • Connectors use variety of techniques for coupling such as screw on, bayonet-mount, puch-pull configurations, butt joint and expanded beam fiber

Butt Joint Connectors

 

  • Fiber is epoxied into precision hole and ferrules are used for each fiber. The fibers are secured in a precision alignment sleeve. But joints are used for single mode as well as for multimode fiber Two commonly used butt-joint alignment designs are :
  1. Straight-Sleeve.
  2. Tapered-Sleeve/Biconical.
    • In straight sleeve mechanism, the length of the sleeve and guided ferrules determines the end separation of two fibers. Fig. 4.8.4 shows straight sleeve alignment mechanism of fiber optic connectors.

 

 

  • In tapered sleeve or biconical connector mechanism, a tapered sleeve is used to accommodate tapered ferrules. The fiber end separations are determined by sleeve length and guide Fig. 4.8.5 shows tapered sleeve fiber connectors.

Installing Fiber Connectors

 

  • The method of attaching fiber optic connectors to optical fibers various among connector Following are the basic steps for installing fibers –
  1. Cut the cable one inch longer than the required finished
  2. Carefully strip the outer jacket of the fiber with ‘no nick’ fiber Cut the exposed strength members and remove fiber coating.
  • Thoroughly clean the bared fiber with isopropyl alcohol poured onto a soft, lint free cloth such as Never clean the fiber with dry tissue.
  1. The connector may be attached by applying epoxy or by
  2. Anchor the cable strength members to the corner This prevents direct stress on the fiber.
  3. Prepare the fiber face to achieve a good optical finish by cleaning and polishing the fiber

Connector Return Loss

 

  • At the connection point of optical link low reflectance levels are desired since the optical reflections can be source of unwanted feed back into the laser Due to this unwanted feedback the optical frequency response may degrade, also it generates internal noise within the source affecting overall system performance. Fig. 4.8.6 shows the connection model.

  • The return loss for the index-matched gap region is given by,

 

                                                    … (4.8.1)

where,

 

D is the separation between fiber end. n1 is index-matching matrial.

R is reflectivity constant.

 

Recommended Questions

 

  1. State the considerations for power coupling and power launching in a fiber optic
  2. Derive the expression for power coupling to a step index fiber by a surface emitting
  3. Derive the expression for power coupling to a graded index fiber by a surface emitting
  4. Explain various types of misalignments in fiber
  5. Derive the expression for power received by fiber for axial
  6. Give the expressions for various fiber-related
  7. State the steps involved in cleaving process
  8. Explain controlled fracture technique of cleaving.
  9. Define finer Explain different types of splicing.
  10. State the considerations for power coupling and power launching in a fiber optic
  11. Derive the expression for power coupling to a step index fiber by a surface emitting
  12. Derive the expression for power coupling to a graded index fiber by a surface emitting
  13. State the factors on which the power launching capability of source is dependent.
  14. What is lensing schemes? With simple sketch show different lensing State the drawback of lensing schemes also.
  15. Explain equilibrium numerical
  16. Write note on laser diode to fiber
  17. State the principles of good connector
  18. List the steps involved in process of installing fiber optic