Abstract: There are provided an apparatus and method for recovering a clock signal from a burst mode signal. A first delay delays an input data signal for half of a time period of the input data signal, and produces a first delay signal. An XOR gate adds the input data signal and the first delay signal provided from the first delay, and provides an inverted signal of the added signal. An OR gate adds an output signal of the XOR gate and a second delay signal, and provides the added signal as a recovered clock signal. A second delay delays the added signal provided from the OR gate for an integer multiple of a time period of the input data signal, and produces the second delay signal that is provided to the OR gate. The frequency of the recovered clock signal is not limited by any delay in the gate elements due to a phase transition of the input data signal occurring when every other packet is provided.

Abstract: A method capable of optical packet switching even in a case where physical optical data in an optical packet switch has not the shape of a packet but the shape of continuous data, and a system therefore are provided. The optical switching method includes the steps of (a) detecting input terminals into which an optical packet is input, of an optical switch and switching the optical packet to destination output terminals of the optical packet, and (b) when there are the input terminals into which the optical packet is not inputted in step (a), detecting other input terminals into which the optical packet, which direct an output terminal among the plurality of output terminals connected to the input terminals, is inputted, and searching a blank output terminal and switching dummy data from the input terminal to the blank output terminal.

Abstract: A multi-dimensional optical cross-connect switching system. The system is capable of multi-dimensionally using wavelength resources, such as in the forms of optical fibers, optical wavelength bands and optical wavelengths. The system can three-dimensionally use the wavelength resources by being matched with an optical transport network through the optical fiber layer, optical wavelength band layer and optical wavelength layer. In addition, the multi-dimentional optical cross-connect switching system is constructed in such a way that two cross-connect switches are symmetrically arranged and an insertion/extraction switch is added to switch addition/dropping links between the two switches.

Abstract: Disclosed is a multiwavelength locking method and apparatus using an acousto-optic tunable filter in an optical communication system including optical transport networks, in which output wavelengths of light sources are monitored under the condition in which pilot signals are applied to the acousto-optic tunable filter, so as to lock the wavelengths of the light sources, thereby eliminating an wavelength instability of the light sources for an improvement in transmission characteristics. The acousto-optic tunable filter receives light beams of N different frequencies respectively outputted from N light sources, along with N pilot signals having different frequencies, and converts respective frequencies of beam components of the output beam corresponding to the N pilot signals, thereby outputting N frequency-converted output beams to be applied to a photo-detector.

Abstract: There are provided an apparatus and method for recovering a clock signal from a burst mode signal. A first delay delays an input data signal for half of a time period of the input data signal, and produces a first delay signal. An XOR gate adds the input data signal and the first delay signal provided from the first delay, and provides an inverted signal of the added signal. An OR gate adds an output signal of the XOR gate and a second delay signal, and provides the added signal as a recovered clock signal. A second delay delays the added signal provided from the OR gate for an integer multiple of a time period of the input data signal, and produces the second delay signal that is provided to the OR gate. The frequency of the recovered clock signal is not limited by any delay in the gate elements due to a phase transition of the input data signal occurring when every other packet is provided.

Abstract: An apparatus for controlling cycles of optical pulse streams based on a time correlation is disclosed. The feedback optical pulses and the input optical pulses are subjected to a time interleaving so as to make them not overlapped together, and then they are subjected to a time correlation, thereby considerably reducing the polarized beam dependence of the input optical pulse streams. The apparatus includes a clock generating means for generating clocks, and an optical pulse generating means for receiving the clocks from the clock generating means to generate optical pulses in synchronization with the pulses of the clock generating means. An input optical pulse distributing means distributes the feedback optical pulses of an output optical pulse distributing means, and distributes the optical pulses of the optical pulse generating means.

Abstract: Disclosed herein is a multidimensional optical cross-connect switching system. The system includes an optical fiber layer switching unit that cross-connect switches input/output optical fibers, extracts some of the input optical fibers, and inserts optical fibers from the upper layer into the output optical fibers. An optical waveband layer switching unit cross-connect switches the input/output optical wavebands, obtains wavebands by demultiplexing optical signals coming up from the lower layer, extracts some of the obtained wavebands and the input wavebands to route them to the upper layer, inserts wavelengths from the upper layer, and multiplexes the cross-connect switched wavebands and sends some of them to the output waveband ports and the rest to the lower layer.

Abstract: Disclosed is a multiwavelength locking method and apparatus using an acousto-optic tunable filter in an optical communication system including optical transport networks, in which output wavelengths of light sources are monitored under the condition in which pilot signals are applied to the acousto-optic tunable filter, so as to lock the wavelengths of the light sources, thereby eliminating an wavelength instability of the light sources for an improvement in transmission characteristics. The acousto-optic tunable filter receives light beams of N different frequencies respectively outputted from N light sources, along with N pilot signals having different frequencies, and converts respective frequencies of beam components of the output beam corresponding to the N pilot signals, thereby outputting N frequency-converted output beams to be applied to a photo-detector.

Abstract: A method capable of optical packet switching even in a case where physical optical data in an optical packet switch has not the shape of a packet but the shape of continuous data, and a system therefore are provided. The optical switching method includes the steps of (a) detecting input terminals into which an optical packet is input, of an optical switch and switching the optical packet to destination output terminals of the optical packet, and (b) when there are the input terminals into which the optical packet is not inputted in step (a), detecting other input terminals into which the optical packet, which direct an output terminal among the plurality of output terminals connected to the input terminals, is inputted, and searching a blank output terminal and switching dummy data from the input terminal to the blank output terminal.

Abstract: A method of fabricating a thermooptic tunable wavelength filter of optical communication systems using WDM is provided, which includes the steps of forming a polymer optical waveguide on a semiconductor substrate using a polymer material, forming a polymer Bragg grating on the optical waveguide using O2 RIE and polymer spin coating, and forming a thermooptic tuning electrode over the polymer optical waveguide in which the Bragg grating is integrated. This provides the thermooptical tunable wavelength filter which has very narrow wavelength band width of transmission signal, low crosstalk with optical signals adjacent thereto, stable wavelength tuning characteristic using thermooptic effect and wide tuning ranges. Furthermore, the optical devices using the polymer optical waveguide can be fabricated with low cost. Thus, they have advantages in terms of economy and marketability.

Abstract: The present invention relates to a subscriber control module having a test apparatus suitable for testing internal routes in an Asynchronous Transfer Mode ATM exchange system for improved reliability and effective maintenance thereof. A subscriber control module having testing functions makes it possible that internal whole routes in the exchange system under the control by maintenance control module inside the system can be tested through the use of subscriber switching network and connection switching network. Further, a test apparatus of the present invention placed inside the exchange system can test ATM subscribers with individually different rates, configured in such a way to be identical with boards used in the exchange system so that the test apparatus can be installed inside the exchange system.