For suitable power confinement of fundamental mode, the normalized frequency v should be maintained in the range 1.5 to 2.4μm and the fractional index difference must be linearly increased as a square function while the core diameter is linearly reduced to keep v constant. This confinement is achieved by?

Optoelectronics and Optical Communication 

For suitable power confinement of fundamental mode, the normalized frequency v should be maintained in the range 1.5 to 2.4μm and the fractional index difference must be linearly increased as a square function while the core diameter is linearly reduced to keep v constant. This confinement is achieved by?

a) Increasing level of silica doping in fiber core 
b) Increasing level of germanium doping in fiber core 
c) Decreasing level of silica germanium in fiber core 
d) Decreasing level of silica doping in fiber core

Answer : - Increasing level of germanium doping in fiber core

The tailoring of fiber parameters provides suitable power confinement. These parameters may be diameter, index-difference, frequency etc. The doping level of germanium contributes to the tailoring of fiber parameters; which in turn provides suitable power confinement.