e 1 t and e 2 t from 3 db coupler 10 can be expressed as equ3 where u03c6 t and u03c6 r are the phase shift components introduced by coupler 10 due to the nature of the 3 db coupler and conservation of energy u03c6 t u03c6 r u03c0 2 output signals e 1 t and e 2 t subsequently travel along a separate pair of signal paths where e 1 t is applied as an input to a first 90 u00b0 hybrid component 12 and e 2 t is applied as an input to a second 90 u00b0 hybrid component 14 hybrids 12 and 14 can also be considered as polarization selective beam splitters which will split the input signal into 34 horizontal 34 and 34 vertical 34 components therefore in accordance with equations 3 6 the four outputs from hybrids 12 and 14 will be equ4 where u03b4 is defined as the phase shift introduced by hybrid components 12 and 14 the 34 vertical 34 outputs e 1v t and e 2v t are subsequently applied as a pair of inputs to a first balanced receiver 16 in particular for the arrangement shown in the figure balanced receiver 16 comprises a pair of photodiodes 18 and 20 each photodiode responsive to a separate one of the signals e 1v t and e 2v t for example photodiode 18 is responsive to signal e 1v t and photodiode 20 is responsive to signal e 2v t thus the lightwave signal is transformed into a current where the pair of currents are applied.