An optical demodulator for use as a pulse position demodulator. The
demodulator has one or more semiconductor optical amplifiers coupled to
receive an optical signal to be demodulated at first end thereof and for
receiving optical control pulses at a second end therefore, the optical
signal to be demodulated and the optical control pulses
counter-propagating in said one or more semiconductor optical amplifiers
in order to determine a delay or phase shift there between; and a
detector coupled to the one or more semiconductor optical amplifiers for
recovering, as an electrical output signal, the delay or phase shift in
the optical signal.