Abstract: An optical communication system has a transmitter generating a phase-modulated optical signal (Sa, Sb, . . . , Sk); a receiver for receiving the phase-modulated optical signal; an optical communication link between the transmitter section and the receiver section. The optical communication link is a dispersion-managed optical communication link having dispersion-compensating elements propagating the phase-modulated optical signal at substantially constant optical power. The receiver has a dispersive element having a prescribed dispersion, the dispersive element receiving and converting the phase-modulated optical signal into a corresponding intensity-modulated optical signal, and an optical intensity detector fed with the intensity-modulated optical signal.

Abstract: Wavelength converter device for generating a converted radiation at frequency ?g through interaction between at least one signal radiation at frequency ?g and at least one pump radiation at frequency ?g, with an input for the at least one signal radiation at frequency ?g; a pump light source for generating the at least one pump radiation at frequency ?g, an output for taking out the converted radiation at frequency ?g, a structure for transmitting the signal radiation, the structure including one optical resonator having a non-linear material, having an optical length of at least 40*?/2, wavelength ? being the wavelength of the pump radiation, and resonating at the pump, signal and converted frequencies ?p, ?s, and ?g.

Abstract: A hybrid waveguide structure having a combination of buried waveguide sections and ridge waveguide sections on the same substrate, share a common core layer. The buried waveguide sections provide the low index contrast desirable for couplers and other device components. The ridge waveguide sections provide the high index contrast needed for efficient low-loss tightly curved waveguides. The devices are fabricated starting from a low index contrast buried waveguide. Cladding material is then selectively removed by etching down from an upper surface either side of the waveguide core to a lower surface. This forms an enhanced index contrast ridge section of the waveguide. The other sections of the waveguide core remain buried and thus retain lower index contrast.

Abstract: Waveguide bends are specially designed according to a matching condition in order to suppress mode distortion and other undesirable effects. The bend is structured having regard to its length and curvature to ensure that at its end the first and second bend modes are substantially in phase with each other having completed approximately an integer number of beats. By being in phase at the end of the bend, the two modes are able to properly reconstruct the first mode of the straight waveguide and propagate on with a minimum of distortion, whether it be into a straight section, a further curved section of arbitrary curvature, into a free space propagation region and the like. This approach suppresses mode distortion, transition losses and other negative effects of waveguide bends. Device applications include couplers, Y-branches and Mach-Zehnder interferometers, all of which include waveguide bends.

Abstract: A hybrid waveguide structure having a combination of buried waveguide sections and ridge waveguide sections on the same substrate, share a common core layer. The buried waveguide sections provide the low index contrast desirable for couplers and other device components. The ridge waveguide sections provide the high index contrast needed for efficient low-loss tightly curved waveguides. The devices are fabricated starting from a low index contrast buried waveguide. Cladding material is then selectively removed by etching down from an upper surface either side of the waveguide core to a lower surface. This forms an enhanced index contrast ridge section of the waveguide. The other sections of the waveguide core remain buried and thus retain lower index contrast.

Abstract: An optical intensity modulator for high-speed RZ and NRZ data modulation based on a balanced three-arm Mach-Zehnder interferometer. The three arms are joined at the input and output sides of the device by three-way couplers. The input coupler is structured to couple approximately equal powers into the first and third arms and no more than 50% power into the second arm. In the straight sections of the arms, there is arranged an AC electrode structure for applying an RF modulation signal and a DC electrode structure for biasing the device at a working point. The AC electrode structure is arranged so that an applied modulation signal induces a negative phase shift (−&Dgr;&phgr;) in the first arm in relation to the second arm and a positive phase shift (+&Dgr;&phgr;) in the third arm in relation to the second arm.

Abstract: An optical intensity modulator for high-speed RZ and NRZ data modulation based on a balanced three-arm Mach-Zehnder interferometer. The three arms are joined at the input and output sides of the device by three-way couplers. The input coupler is structured to couple approximately equal powers into the first and third arms and no more than 50% power into the second arm. In the straight sections of the arms, there is arranged an AC electrode structure for applying an RF modulation signal and a DC electrode structure for biasing the device at a working point. The AC electrode structure is arranged so that an applied modulation signal induces a negative phase shift (−&Dgr;&PHgr;) in the first arm in relation to the second arm and a positive phase shift (+&Dgr;&PHgr;) in the third arm in relation to the second arm. Large notch widths of up to 12 times the notch width of a conventional two-arm Mach-Zehnder modulator are achievable.