Q$2($a$).>$ Draw the diagram of double hetrostructure LED and explain how it offers strong

optical and electrical confinement in active region. A double hetrostructure light source emits

$3\mathrm{.}3$x$10\text{'}$ photons$/$sec at a wavelength of $650$ nm$.$ The emitted power is launched into a fiber

having NA of $0\mathrm{.}4.$ If the fiber have attenuation coefficient of $0\mathrm{.}5$ db$/$Km$,$ then what will be the

power received a distance of $10$KM$.(6)$