After the evolution of laser in 1960, implementation of LED in the optical communication systems could take place in 1970.
At the heterojunction (extrinsic semiconductor layers used as interfaces between two homojunction materials), the guiding principle for optical power is total internal reflection, which guides the power out at the emitting facet of LED via a path that is parallel to the junction.
When provided with forward biasing using a DC source, recombination of electrons and holes at the thin n-AlGaAs would occur.
The voltage-current characteristic curve represents that beyond the threshold biasing voltage, current increases exponentially.
Sensitivity to lateral misalignment in the acute direction to the junction plane of the LED rises by at least a factor of three, regardless of the coupling scheme used.
A reciprocal relationship between peak coupling efficiency and sensitivity to misalignment could also be observed.