Abstract: A device for compensating for PMD occurring in a transmission optical fiber in an optical transmission system. An output beam from an optical fiber link changes its polarization state by a polarization controller (PC) to be applied to a PBS. A first polarization component passes through a variable delay line, rotates by a predetermined angle, and is inputted to the PBS. A portion of a second polarization component is transmitted by a predetermined mirror. The reflected second polarization component is applied to the PBS to be combined with the first polarization component inputted to the PBS. The transmitted second polarization component passes through a photo-detector and a BPF. The filtered signal is inputted to a PC controller to select the smaller value among the currently and previously measured power values.

Abstract: An apparatus for compensating a polarization mode dispersion including a polarization adjusting means for adjusting polarization states of an optical beam having a differential group delay based on a polarization adjusting feedback control signal; a polarization beam splitting means for splitting principal states of polarization of the adjusted optical beam into a first polarization and a second polarization; a time delaying means for the first polarization based on a time delay feedback control signal; a polarization adjustment controlling means for controlling the polarization adjusting means based on a polarization adjusting feedback control signal; a time delay controlling means for controlling the time delaying means based on a time delay controlling feedback signal; and an electric combining means for combining a time-compensated first polarization and the second polarization transmitted through the optical tap.

Abstract: The present invention provides a clock extraction apparatus and method for an optical signal. The clock extraction apparatus includes optical branching means, optical filtering means, and clock extraction means. The optical branching means branches an optical signal, which has been transmitted from a transmitting end to a receiving end, into a plurality of optical signals to be transmitted to a plurality of paths. The optical filtering means simultaneously reflects the center wavelength and a specific side peak wavelength of the optical signal, which has been transmitted to a first path of the plurality of paths, to the optical branching means, the specific side peak wavelength being spaced apart from the center wavelength by a clock frequency. The clock extraction means extracts a clock by detecting and bandpass filtering the beating signal from the center wavelength and the specific side peak wavelength reflected to the optical branching means.

Abstract: A device for compensating for PMD occurring in a transmission optical fiber in an optical transmission system. An output beam from an optical fiber link changes its polarization state by a polarization controller (PC) to be applied to a PBS. A first polarization component passes through a variable delay line, rotates by a predetermined angle, and is inputted to the PBS. A portion of a second polarization component is transmitted by a predetermined mirror. The reflected second polarization component is applied to the PBS to be combined with the first polarization component inputted to the PBS. The transmitted second polarization component passes through a photo-detector and a BPF. The filtered signal is inputted to a PC controller to select the smaller value among the currently and previously measured power values.

Abstract: Provided are a polarization mode dispersion (PMD) compensator and method for automatically and rapidly compensating PMD occurring in an optical transmission fiber in a high-speed optical transmission system. The polarization mode dispersion compensator includes a separator and a differential time delay remover. The separator aligns orthogonal first and second polarization components of a received optical signal with respect to two orthogonal axes of a polarization beam splitter using optical signal information output via a second path of a first path and the second path of the two outputs of the polarization beam splitter, splits the first and second polarization components, and transmits the first polarization component via the first path and the second polarization component via the second path. The differential time delay remover receives the first and second polarization components that have been split to remove a differential time delay between the first and second polarization components.

Abstract: Method for compensating polarization mode dispersion, The method includes: transforming states and directions of polarization components of an optical signal received from the optical transmission line, rotating the polarization components of the optical signal output from the polarization controller, separating two orthogonal polarization components of the output from the polarization rotator so that a first polarization component is transmitted to an output path and a second polarization component is transmitted to a monitoring path, controlling the PC using a feedback control to minimize an electrical power filtered at a specified frequency so that the two orthogonal polarization components of the optical input signal to the polarization beam splitter are aligned to two axes of the PBS, and controlling the polarization rotator by comparing an optical power of the first polarization component transmitted to the output path with an optical power of the second polarization component transmitted to the monitor

Abstract: A method for compensating polarization mode dispersion (PMD) occurring in optical transmission fiber in a high speed optical transmission system and an apparatus therefore are provided.

Abstract: The present invention relates to a Sagnac interferometric sensor array for acoustic sensing and method of sensing acoustic signal that is able to observe acoustic signals coming from several sources simultaneously. The acoustic sensor of the present invention is a Sagnac interferometric sensor array employing a depolarizer. Unlike a single Sagnac interferometric sensor, two light signals traveling in the opposite directions from each other pass through the off-center position of the loop at different times in the Sagnac loop when they are pulses, and thus, it is possible for the light pulses to be maintained at a constant phase difference by giving arbitrarily a certain amount of phase to them. By using the fact, the interferometer is constructed in such a way that the interference light output coincides with the applied acoustic signals in waveform. This invention suggests a way of fabricating an array of fiber-optic acoustic sensors that is easy to be made and is highly sensitive at some frequency band.

Abstract: A heat generating type ink-jet print head including an ink supply passage for receiving an ink from an ink container, a micro chamber for storing the ink and nozzles, all being directly formed on a substrate, and a method for fabricating the ink-jet print head using an electrolytic polishing process, and a method for fabricating the ink-jet print head. The ink-jet print head is fabricated using an electrolytic polishing process, thereby achieving an accurate and inexpensive fabrication.

Abstract: A heat generating type ink-jet print head including an ink supply passage for receiving an ink from an ink container, a micro chamber for storing the ink and nozzles, all being directly formed on a substrate, and a method for fabricating the ink-jet print head using an electrolytic polishing process, and a method for fabricating the ink-jet print head. The ink-jet print head is fabricated using an electrolytic polishing process, thereby achieving an accurate and inexpensive fabrication.