Abstract: A conversion method for converting a unipolar voltage data stream into a carrier-suppressed return-to-zero (CSRZ) optical data stream includes modulating a continuous optical wave with an encoded nonreturn-to-zero (NRZ) voltage data stream for providing a CSRZ optical data stream of full-width at half-maximum (FWHM) pulse width less than one-half of the transition time of the encoded nonreturn-to-zero (NRZ) voltage data stream between logical states for a reduced pulse width. The modulating circuit is either a duobinary modulator driven with a swing of ±2V? or an optical time domain multiplexed plurality of nonreturn-to-zero (NRZ) modulators with phase shifting and differential encoding.

Abstract: A semiconductor ridge laser for coupling to a single-mode optical fiber has a ridge with a narrow parallel region, a diverging region, and then a wide parallel region that is adjacent to an output facet. A pump region for the laser may be less than the entire area of the ridge and have a “T” shape. Preferably, the ridge has a depth of about 350 to 550 nm and the narrow parallel region has a length of more than 0.4 times the overall length of the ridge. The wide parallel region at the output enables the laser to obtain low thermal resistance, which leads to a low operating temperature, a low power density in the laser cavity, and low astigmatism.

Abstract: A conversion method for converting a unipolar voltage data stream into a carrier-suppressed return-to-zero (CSRZ) optical data stream includes modulating a continuous optical wave with an encoded nonreturn-to-zero (NRZ) voltage data stream for providing a CSRZ optical data stream of full-width at half-maximum (FWHM) pulse width less than one-half of the transition time of the encoded nonreturn-to-zero (NRZ) voltage data stream between logical states for a reduced pulse-width. The modulating circuit is either a duobinary modulator driven with a swing of ±2V&pgr; or an optical time domain multiplexed plurality of nonreturn-to-zero (NRZ) modulators with phase shifting and differential encoding.

Abstract: A bidirectionally pumped optical amplifier (200) comprises an active fibre (201), a first WDM coupler (204) and a second WDM coupler (205), a first pump: branch (220) coupled to said first WDM coupler (204) comprising a first laser (202) and a first grating (210), for introducing pump radiation into said active fibre (201) in a first direction, a second pump branch (230) coupled to said second WDM coupler (205) comprising a second laser (203) and a second grating (212), for introducing pump radiation into said active fibre (201) in a second direction, opposite to said first direction. The second laser has an output power PF. A first pump residual, having a power Pinj, is coupled into said second pump branch (230) from the active fibre (201) and injected into said second laser (203). The first pump branch (220) further comprises an optical isolator (211) for the pump radiation. The output power of the injected laser and the injected pump power residual are such that PF/Pinj>2.

Abstract: A semiconductor ridge laser for coupling to a single-mode optical fiber has a ridge with a narrow parallel region, a diverging region, and then a wide parallel region that is adjacent to an output facet. A pump region for the laser may be less than the entire area of the ridge and have a “T” shape. Preferably, the ridge has a depth of about 350 to 550 nm and the narrow parallel region has a length of more than 0.4 times the overall length of the ridge. The wide parallel region at the output enables the laser to obtain low thermal resistance, which leads to a low operating temperature, a low power density in the laser cavity, and low astigmatism.

Abstract: A double-passage acousto-optical device including an acousto-optical switch having a first polarization conversion region connected between first input and output ports, and a second conversion region connected between second input and output ports; and an optical combination connected between the first output port and the second input port via optical fibers and including an optical isolating element. The double-passage acousto-optical device may alternately include an acousto-optical switch including a single polarization conversion region connected between first input and output ports and also connected between second input and output ports. A bandpass filter, a notch filter, and add/drop and a tunable laser generator may be formed using the acousto-optical device.

Abstract: The invention relates to optical birefringent waveguides, acousto-optical devices using such optical waveguides and an acoustic waveguide as well as a manufacturing method therefore. The optical waveguides of the invention exhibit a small birefringent variation with respect to a change of waveguide parameters, if the fundamental mode propagating in the optical waveguide has a propagation constant near to the cut-off condition. The optical waveguide dimensions are typically chosen such that the cut-off wavelength of the waveguide is below 1650 nm for an operating wavelength in the window between 1530 nm and 1656 nm. The acousto-optic mode converter using such optical waveguides have a superior conversion characteristic over the conversion frequency with reduced side lobes. Therefore, using the thin and narrow optical waveguides of the invention, a superior performance of the acousto-optical devices using such an optical waveguide can be obtained.

Abstract: A double-stage acousto-optical waveguide device comprises two polarization conversion stages, a polarization selective input element, a polarization selective output element and two intermediate polarization selective elements that have two branches connected together and two branches not connected together that are located on opposite sides of the branches connected together and extend in lateral waveguides that reach the edges of the substrate.

Abstract: An acousto-optical waveguide device with compensation of polarization mode dispersion (PMD) comprises at least one first and one second optical path in optical waveguide and at least one compensation optical path connected to the first and second optical path. The compensation optical path has a prefixed PMD such that the passage time of a first polarization component of an optical signal in the first optical path and in the compensation optical path is substantially equal to the passage time of a second polarization component in the second optical path and in the compensation optical path.

Abstract: A method of adjusting the operation of optical networks in terms of propagation constants of guided modes in integrated optical devices, allowing a considerable number of out of tolerance devices to be recovered by depositing on the surface where the optical guides are manufactured, once the normal fabrication process is completed, a further layer of transparent material of suitable size and refractive index.

Abstract: Apparatus for measuring the effective refractive index in optical fibers, in which a source sends light radiation, the wavelength of which can be varied within a predetermined interval, into a fiber span, and a detector collects the radiation intensity of the radiation collected by the detector as the wavelength varies, in order to determine the oscillation period of the fiber transmittance or reflectivity and to obtain the effective refractive index from such period.

Abstract: Integrated optical devices are fabricated by field-assisted ion exchange on a starting substrate, wherein the substrate is first prepared to be connected to a source of potential difference, is duly masked as a function of the optical circuit to be implemented and is dipped in a melted salt, which is an ion source for the exchange, with another electrode for applying the electric field capable of inducing ion exchange.

Abstract: A pump system for lasers or amplifiers made of a waveguide presenting a monomode active region, in which the pump radiation is launched into a multimode guide surrounding the active region. The radiation is obtained as a sum of the radiations emitted by a plurality of independent sources.

Abstract: A method of adjusting the operation of bimodal optical networks in terms of propagation constants of guided modes in integrated optical devices, allowing a considerable number of out of tolerance devices to be recovered by depositing on the surface where the optical guides are manufactured, once the normal fabrication process is completed, a further layer of transparent material of suitable size and refractive index.

Abstract: An optical coupler adapted to feed a plurality of optical fibers with light radiation coming from a single fiber or, conversely, to transmit to a single fiber the radiation coming from a plurality of fibers. A round paraboloid receives the optical beams condensed by hemispherical lenses placed in front of the fiber end faces and concentrates them on the end face of the output fiber through a hemispherical lens.