Patent ID: 8218977

Claim:
An optical device comprising: a first optical port for inputting a received optical differential phase shift keying (DPSK) signal, and for outputting a first equalized optical output signal; a second optical port for outputting a second equalized optical output signal; an interferometer for separating constructive and destructive paths of the received optical differential phase shift keying DPSK signal; a first equalizer located at the first optical port, and a second equalizer located at the second optical port; the first and second equalizers integrated with said interferometer for reducing from optical filtering effects an interference by signal bits of the DPSK signal with signal bits of a contiguous DPSK signal; said first and second equalizers being within said interferometer in the constructive and destructive optical paths of said interferometer; wherein no fiber, fusion splice, or connectors and adapters are needed between elements of the interferometer and equalizers, therefore enabling an overall insertion loss less than a combined loss of separate interferometer and equalizers; said interferometer and equalizers exhibit similar wavelength drift from temperature change thereby increasing more tolerance to temperature variation than separate interferometer and equalizers.