10^-8 sec

10^-7 sec

10^-10 sec

10^-3 sec

N2=N1

N1>N2

N2>N1

N1=N2

Integer multiple of half of the wavelength

Integer multiple of the wavelength

Half of the wavelength always

Three times the wavelength always

DIODE LASER

He:Ne LASER

Semiconductor LASER

Nd:YAG LASER

Equal to

Greater than

Less than

Total Internal Reflection of Light

Refraction of Light

Reflection of Light

Scattering of Light

Step Index Fibre

Graded Index Fibre

$$n_1\sqrt[]{2\Delta}$$

$$2n_1\sqrt[]{\Delta}$$

$$\sqrt[]{n_1^2-n_2^2}$$

$$\sqrt[]{n_2^2-n_1^2}$$

Single Mode Fibre

Multimode Mode Fibre