A step-index fiber has core refractive index 1.46 and radius 4.5‚âà√≠¬¨‚à´m. Find the cutoff wavelength to exhibit single mode operation. Use relative index difference as 0.25%.$

A step-index fiber has core refractive index 1.46 and radius 4.5‚â�

1.	A step-index fiber has core refractive index 1.46 and radius 4.5‚âà√≠¬¨‚à´m. Find the cutoff wavelength to exhibit single mode operation. Use relative index difference as 0.25%.$
A.	1.326‚âà√≠¬¨‚à´m
B.	0.124‚âà√≠¬¨‚à´m
C.	1.214‚âà√≠¬¨‚à´m
D.	0.123‚âà√≠¬¨‚à´m
Answer» D. 0.123‚âà√≠¬¨‚à´m