Abstract: A tunable optical local oscillator is used for optical heterodyne signal detection using an electrooptic Mach-Zehnder modulator to produce a rapidly tunable optical signal from a tunable RF frequency generator. A combination of the Mach-Zehnder modulator and optical fibers for providing stimulated Brillouin scattering are used to suppress unwanted signals for providing a spectrally pure optical local oscillator waveform. Suppression of unwanted optical signals, up to 50 dB, generated by the Mach-Zehnder modulator is obtained, resulting in high spectral purity of the optical local oscillator waveform with an extended tuning range of the tunable optical oscillator equal to the operating bandwidth of up to 60 GHz of the Mach-Zehnder modulators.

Abstract: A tunable optical local oscillator is used for optical heterodyne signal detection using an electrooptic Mach-Zehnder modulator to produce a rapidly tunable optical signal from a tunable RF frequency generator. A combination of the Mach-Zehnder modulator and optical fibers for providing stimulated Brillouin scattering are used to suppress unwanted signals for providing a spectrally pure optical local oscillator waveform. Suppression of unwanted optical signals, up to 50 dB, generated by the Mach-Zehnder modulator is obtained, resulting in high spectral purity of the optical local oscillator waveform with an extended tuning range of the tunable optical oscillator equal to the operating bandwidth of up to 60 GHz of the Mach-Zehnder modulators.

Abstract: An optical fiber quadrature demodulator, for use in optical receivers, has an optical local oscillator for providing a coherent pilot tone that is mixed with an optical input signal to provide a piloted optical input signal. The pilot tone tracks phase shifts through the optical fibers for tracking the phase shift to the optical input signal as a phase shift reference in the demodulator providing coherent signal demodulation. The demodulator maintains optical phase coherence between the physically separated I and Q optical channels in the presence of unknown and time varying phase perturbations that occur in optical fibers used in photonic processing and communication systems.

Abstract: An optical fiber quadrature demodulator, for use in optical receivers, has an optical local oscillator for providing a coherent pilot tone that is mixed with an optical input signal to provide a piloted optical input signal. The pilot tone tracks phase shifts through the optical fibers for tracking the phase shift to the optical input signal as a phase shift reference in the demodulator providing coherent signal demodulation. The demodulator maintains optical phase coherence between the physically separated I and Q optical channels in the presence of unknown and time varying phase perturbations that occur in optical fibers used in photonic processing and communication systems.