Abstract: In an optical data transmission system, high frequency pulsed optical signals are transmitted along an optical fibre. These pulses are attenuated and distorted by transmission over long optical fibres, making detection of data difficult at the receiving end. The allowable pulse profile is determined by an eye diagram, and the invention uses an eye diagram which is non-symmetrical with respect to logic 1 and 0 levels. By positioning the eye diagram closer to the logic 0 level, detection in the presence of noise introduced during transmission of the optical pulses, can be significantly improved.

Abstract: The present invention has an object to provide a WDM optical transmission system for effectively compensating such as wavelength dispersions of respective wavelength bands, by a simple constitution making use of a hybrid transmission path in case of transmitting a broadband WDM signal light containing a plurality of wavelength bands. To this end, wavelength dispersion characteristics of a hybrid transmission path utilizing a 1.3 &mgr;m zero-dispersion SMF and an RDF in the present WDM optical transmission system, are set such that compensation ratios of wavelength dispersion and dispersion slope become approximately 100% for a reference wavelength band which is one of a plurality of wavelength bands; and dispersion compensation fibers capable of compensating wavelength dispersions caused within the hybrid transmission path are inserted into propagation paths, respectively, within an optical amplifier, for the wavelength bands except for the reference wavelength band.

Abstract: An operation unit of a PMD compensation module includes a PBS, a compensated part and a combiner. The PBS separates an optical input into a first polarized signal and a second polarized signal. The compensated part includes a fixed prism and a movable prism. The first polarized signal outputted from the PBS travels through the fixed prism and the movable prism in series. The light path of the first polarized signal in the movable prism is elongated or shortened according to a position of the movable prism. A continuously variable delay can thus be applied between the first and second polarized signals. The combiner recombines the first polarized signal received from the compensated part and the second polarized signal received from the PBS into an optical output signal.

Abstract: Methods and systems for higher-order PMD compensation are implemented by developing an effective mathematical model and applying economical design techniques to the model. By assuming a constant precession rate for a narrow band of frequencies in an optical signal, a simplified model of a higher-order PMD compensator can be derived. The model can be used produce an economical compensator by making multiple uses of selected optical components.

Abstract: A method and device is disclosed for dispersion compensation of an optical signal. By providing two filters having a sloped dispersion and opposite in sign over a wavelength band wherein one filter is tunable, a controllable amount of dispersion can be introduced to offset or compensate dispersion. Preferably one of the filters is a tunable periodic device in the form of a multi-cavity GT etalon. In a preferred embodiment of the filters can be designed to provide various controllable but different constant amounts of dispersion.

Abstract: A parallel monitored and controlled optical PMD compensator comprises a branch optical signal split from an optical signal path. A polarization controller (PC) and differential group delay are disposed in each of the paths. A controller adjusts polarization compensation of the PCs in response to PMD dispersion of the branch optical signal. A PMD monitor is preferably disposed in the branch path providing a monitor signal to the controller for use in adjusting the PCs. A polarization rotator may inject a reference signal into the paths with the PC disposed in the branch path acting as a polarization scrambler. A state of polarization (SOP) of the reference signal may be monitored by polarimeters disposed in both paths and the SOP of the reference signal in the branch path may be provided to the controller for adjusting polarization compensation of the inline PC.

Abstract: An optical link is described for transmission of an RF signal using an optical fiber having opposing ends and configured such that unwanted distortion signals are produced when optical signals pass through the optical fiber. At least first and second optical signals are transmitted through the optical fiber, where the optical signals have been modulated with an RF signal in such a way that a predetermined relationship is produced between the RF signals modulated on the first and second optical signals. At the opposing end of the optical fiber, a receiving arrangement receives the modulated first and second optical signals including the unwanted distortion signals produced during the transmission through the optical fiber. The receiving arrangement then regenerates the RF signal from the modulated first and second optical signals while causing the unwanted distortion signals to be canceled based on the predetermined relationship between the RF signals modulated on the first and second optical 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: A system and method for achieving, while using a multimode diode laser and polarization-maintaining fibers, high signal-to-noise ratio in a magneto optical storage system. In particular, the system splits an incoming main light signal into two orthogonal polarization states, which then propagate over different distances before recombining. By pulsing the laser on and off at a high frequency and choosing an appropriate path difference for the polarization states, which is dependent upon the modulation frequency of the laser, the system eliminates first-order spectral polarization noise arising from a potential error in a key optical component.