Abstract: A long-distance, high bit-rate optical communications link is described comprising an optical transmitter, an optical receiver, and an index-guiding microstructured optical fiber between the optical transmitter and the optical receiver, the microstructured optical fiber having a majority of the cross-section of the core and cladding regions occupied by voids. The voids are dimensioned such that an effective index of refraction of the cladding region is less than an effective index of the core region, the optical fiber propagating light by an index-guiding effect. The attenuation and dispersion characteristics of the microstructured optical fiber, when expressed in dB/km and ps/(nm-km), respectively, each decrease in approximate proportion to the percentage of cross-sectional area occupied by the voids.

Abstract: A dispersion compensating (DC) fiber preferably including a central segment having a relative refractive index, a depressed moat segment, an intermediate segment, an annular ring segment and a cladding layer. The relative refractive index profile of the DC fiber is selected to provide negative dispersion, negative dispersion slope, a &kgr; value of less than or equal to about 100, and MPI of less than −40 dB at 1550 nm. The DC fiber preferably has a pin array bend loss of less than or equal to about 30 dB at a wavelength of about 1550 nm.

Abstract: A compensation arrangement for addressing the problem of first-order and second-order polarization mode dispersion (PMD) in an optical fiber communication system includes separate, independent elements for each type of PMD. First-order PMD may be compensated using conventional techniques related to adjusting the transit time differential between the polarization states. The second-order polarization mode dispersion is compensated by recognizing the separate sources of second-order PMD (pulse broadening analogous to chromatic dispersion, additional pulse broadening due to optical filtering (narrowing), and coupling of a portion of the optical signal into the orthogonal polarization relative to the main pulse with a different transmit time. A chirped fiber grating with a variable temperature gradient, a complementary optical filter with variable spectral transmission and a polarizer, respectively, can be used to compensate for these three sources of second-order PMD.

Abstract: The frequency-selective optical multiplexer comprises, an LC polarization controller, a spectral demux/mux and input/output optics including two ports, a first optical path spatially separated from a second optical path and polarization-dispersive optics. The polarization dispersive optics are disposed between the ports and the optical paths; generate from an optical signal a pair of polarization components, composed of a first polarization component and a second polarization component having orthogonal polarizations; and output the first and second polarization components via the first and second optical paths, respectively. The first and second polarization components have first and second polarizations when the optical signal is received at one port, and have the second and the first polarizations, respectively, when the optical signal is received at the other port.

Abstract: A dual wavelength optical fiber distributed feedback laser comprises a pump laser coupled to a birefringent fiber in which a first grating device (two co-located single phase-shift fiber Bragg gratings (FBGs)) is provided. The grating device gives the laser two potential lasing modes in each of two orthogonal polarization states. A polarization mode coupling FBG selects two orthogonally polarized modes on which the laser oscillates. In a photonic data carrying signal source, the laser is coupled to a polarization dependent, optical modulator operable to apply a modulation, at a data signal frequency, to one polarization mode of the laser output. In an optical waveguide based electronic signal transmission system the modulated and un-modulated polarization modes output from the source are transmitted across a fiber transmission line to a polarizing optical fiber in which the two modes heterodyne to generate an electronic carrier signal in the optical domain.

Abstract: A polarization scrambler and a polarization mode dispersion (PMD) compensation system compensate for PMD on an active optic fiber. The polarization scrambler scrambles a state of polarization of an optical signal that carries user information. The PMD compensation system then receives the optical signal over the active optic fiber. The PMD compensation system measuring a differential group delay and principal states of polarization of the PMD in the active optic fiber. The PMD compensation system then determines a modification of the optical signal based on the differential group delay and the principal states of polarization of the PMD. The PMD compensation system modifies the optical signal in the active optic fiber to compensate for PMD based on the determination of the modification. The PMD compensation system then transmits the optical signal.

Abstract: In an optical transmission system, a first modulated signal is generated at the transmitting end by modulating a first carrier signal with a first data signal and a second modulated signal is generated by modulating a second carrier signal, which differs from the first carrier signal by a differential frequency, with a second data signal. The first and second modulated signals are polarized orthogonally with respect to one another and combined to form an optical multiplex signal and are transmitted. At the receiving end, the optical multiplex signal is conducted via a polarization control element to a polarization splitter which splits the optical multiplex signal into the first and second modulated signals.

Abstract: A method and a device for compensating the polarization mode dispersion (PMD) of a transmitted optical signal comprise means of a polarization controller (3) coupled to a differential group delay (DGD) generator (5). The polarization controller (3) is controlled by a feedback loop, said feedback loop implementing an optimisation algorithm to optimize a feedback parameter of the output signal of the DGD generator (5). The algorithm takes into account the state of polarization (SOP) of an optical signal determined from the output signal of the polarization controller (3)) or from the output signal from the DGD generator (5).

Abstract: To extend a distance of polarization-multiplexing, an optical transmitter in an optical transmission system has a first signal light output unit (24A, 124A) to output a first signal light (S1) of linear polarization to carry a first data (D1) using VSB modulation having one of sideband on a short wavelength side and sideband on a long wavelength side, a second signal light output unit (24B, 124B) to output a second signal light (S2) of linear polarization to carry a second data (D2) using VSB modulation having the other of sideband on a long wavelength side and sideband on a long wavelength side, and an optical coupler (26, 126) to couple the first signal light (S1) and the second signal light (S2) under different polarizations and output the coupled signal lights onto the optical transmission line (12, 112).

Abstract: A polarization of at least one modulated optical signal is varied at the transmitter side. Upon receiving the signals, propagation time variations of at least one optical signal are detected at the receiver side. These propagation time variations are determined preferably by evaluating the variations of the integral of the control signal of a voltage-controlled oscillator in the clock recovery and are a measure for existing polarization mode dispersion, which may be compensated by means of a polarization mode dispersion compensator.

Abstract: A micro-optical delay element for a polarization time-division multiplexing scheme is disclosed wherein two light beams are provided to a polarization beam splitter/combiner (PBS/C) in the absence of optical fiber. At least one beam exiting a modulator is collimated and reaches the (PBS/C) unguided as a substantially collimated beam. In this manner the polarization state of the beam is substantially unchanged. This obviates a requirement for polarization controllers.

Abstract: A spread polarization transmitter for transmitting at least one light signal comprises a spread-spectrum communication apparatus and a polarization modulator. The spread-spectrum communication apparatus modulates the at least one light signal according to a spread-spectrum modulation technique. The polarization modulator comprises a polarizer and a magnetic bubble waveguide. The polarizer is capable of polarizing the at least one spread-spectrum modulated light signal in a polarized direction. And the magnetic bubble waveguide, which is configured in accordance with a pseudo-random polarization code sequence such that the plurality of magnetic bubble domains assume a time varying position representative of the pseudo-random polarization code sequence, is capable of receiving at least one polarized, spread-spectrum modulated light signal.