An optical threshold device including an input, an output, first and second radiation
guiding branches, each branch having first and second terminals, at least one of
the first and second branches having a non-linear optical element, first and second
optical couplers, at least one of the first and second optical couplers having
an asymmetric optical coupler, the first optical coupler configured to split an
input signal of radiation from the input into a first radiation portion propagating
through the first branch and a second radiation portion propagating through the
second branch, the second optical coupler configured to combine the first and second
radiation portions from the second terminals of the first and second branches,
respectively, into an output signal at the output, wherein the non-linear optical
element produces a phase shift between the first and second radiation portions
and wherein the first and second radiation portions interfere at the second coupler
in response to the phase shift.
