Abstract: The invention provides a wavelength multiplexing transmission apparatus includes a plurality of optical signal outputting sections for outputting optical signals having different wavelengths from each other, and a wavelength multiplexing section for wavelength multiplexing the optical signals outputted from the optical signal outputting sections and sending out a resulting optical signal. Each of the optical signal outputting sections includes a transmission light source driven by an electric signal for outputting an optical signal of a predetermined wavelength, and a wavelength filter capable of passing therethrough and sending out only an optical signal of the predetermined wavelength to be outputted from the transmission light source to prevent a wavelength drift of the optical signal outputted from the transmission light source.

Abstract: A wavelength division multiplexing device which can easily utilize existing optical fibers for increasing the transmission capacity by approximately several fold mainly in a short-range information communication network, comprising, as essential elements, a pair of 1×N optical couplers (2≦N≦16), N light emission devices in which one of peak wavelengths thereof differs from every other one by at least 30 nm and N light receivers having optical filters having light-transmission wavelength bands adjusted to correspond to said peak wavelengths, wherein the light emission devices and the light receivers having optical filters corresponding to peak wavelengths of the light emission devices form pairs, and said light emission devices of said light receivers are optically connected to N-port-side ports of one of the 1×N optical couplers.

Abstract: An apparatus for compensating for dispersion of an optical fiber in an optical line, which compensates for dispersion generated in the optical fiber when an optical signal produced by an optical transmitter is transmitted to an optical receiver via the optical line, is provided. The apparatus includes a dispersion compensation fiber for compensating an optical signal produced by an optical transmitter in order to predict and compensate for dispersion generated in the optical line, a dispersion compensation filter for controlling the dispersion value of the optical signal dispersion-compensated by the dispersion compensation fiber, to gain zero overall dispersion, and an optical amplifier for amplifying a signal having a dispersion value adjusted by the dispersion compensation filter and outputting the result to the optical line. Accordingly, it is easy to zero a dispersion value of an optical fiber in the optical line by regulation of the dispersion compensation fiber and filter.

Abstract: An apparatus for communicating, over a single transmission medium, two signals of substantially the same center frequency. The apparatus offsets in frequency one of the signals by combining the signal with the signal from a local oscillator. The apparatus then transmits the two signals, one offset from the other, as well as the signal from the local oscillator to allow for recovery of the two signals with a precise correction for the offset. In particular, the transmission medium is an optical fiber and the two signals are a main RF signal and a diversity RF signal received, respectively, by a main element and a diversity element of a diversity antenna system. The invention is of use, for example, in providing to a microbase station a main RF signal and its diversity RF signal received at a diversity antenna system remote from the microbase station and connected to the microbase station by an optical fiber.

Abstract: A method and apparatus for converting a frequency modulated lightwave into an electrical signal that is proportional to instantaneous frequency deviations of the frequency modulated lightwave. The frequency modulated lightwave is amplified by an amount equal to or greater than a desired FM processing gain to provide an amplified frequency modulated lightwave. The amplified lightwave is filtered to restrict amplifier noise added to the frequency modulated lightwave to provide a filtered lightwave. The amplitude of the filtered lightwave is limited to remove unwanted amplitude fluctuations to provide a limited lightwave. The limited lightwave is split into a first split lightwave and a second split lightwave. The second split lightwave is delayed relative to the first split lightwave, to provide a delayed second split lightwave.

Abstract: The present invention relates to a circuit for monitoring optical signals in a multiple channel system. A tunable band pass filter receives and input signal comprising multiple channels each having a different wavelength and predetermined channel spacing. Output from the tunable filter is directed to a second filter having a periodic response with wavelength, such as an etalon. The response is designed to block wavelengths of light corresponding to the channels, permitting noise in the inter-channel space to be measured by a detector. A reference circuit launches light from a broad band source through a Bragg grating into the tunable filter. The Bragg grating reflects a known reference wavelength. Light which passes from the reference source through the tunable filter is also passed through the second filter to a detector. When a notch is detected by the reference detector, the tunable filter is known to be tuned to the reference wavelength.

Abstract: An optical communications system employs a plurality of optical nodes interconnected in an optical ring transmission configuration by at least two optical transmission media, for example, optical fiber. The at least two optical transmission media, in this example, provide optical service transmission capacity and optical protection transmission capacity. Efficient restoration of optical communications between optical nodes in the optical ring transmission configuration, after an optical transmission media failure, is realized by employing an autonomous optical restoration arrangement and technique. To this end, each node autonomously controls an optical switch matrix in the node in effecting the desired restoration without the need of switch control signals transmitted from any other node in the ring, from a main controller or from a central controller.

Abstract: An extract-and-insert optical wavelength division multiplexer includes a broadcaster (D1) for applying an incoming multiplex signal to N outputs, a combiner-diffuser (D2) for broadcasting the multiplex to be inserted (MI) on N outputs, a first set of N tunable filters (FIT, . . . , FNT) for selecting the carriers of the signals which are to be used for modulating the carriers of the outgoing multiplex (MS), a second set of N tunable filters (F1E, . . . , FNE) for selecting the carriers which are to constitute the extracted multiplex (MT), N wavelength converter devices (CL1, . . . , CLN) suitable for supplying N carriers of the outgoing multiplex (MS), and N two-input, two-output optical switches (SW1, . . .

Abstract: Disclosed are a subsystem and a method for diagnosing a fiber optic network, the fiber optic network comprising a fiber having an optic stream adhering to a defined protocol of the fiber optic network, and comprising a target for receiving and responding to the optic stream. The diagnosis comprises receiving the fiber optic stream and converting the fiber optic stream to an electrical input stream with a FOSA (fiber optic subassembly), and recognizing, from the electrical input stream, a selected event (e.g., frame or command) related to the optic stream defined protocol. Then, in response to the recognition of the selected event, recognizing a selected pattern of the electrical input stream, e.g., employing mask logic, and injecting, in response to the recognition of the selected pattern, a transmission error into the optic stream, and transmitting the optic stream with the injected transmission error to the target, employing a FOSA.

Abstract: In a wavelength-division multiplex switching network having input wavelength-division multiplex (&lgr;) demultiplexers followed by a space switch and output wavelength-division multiplex multiplexers, wavelength-individual space switching matrices which are in each case connected, at the input end, via a number, corresponding to the number of wavelength-division multiplex multiplexers, of link lines to corresponding outputs of the space switch, lead to the wavelength-division multiplex multiplexers, some of the link lines leading to a space switching matrix directly connect the space switch to the respective space switching matrix and an adjustable wavelength converter is in each case inserted into the remaining link lines.

Abstract: Large-scale switching array architectures for multiwavelength routing employ absorption-switched micro-ring resonator 2×2 switches at all optical cross-points of each of a plurality of series-connected waveguide crossbar matrix switches. The architecture eliminates detrimental waveguide crossovers. Two or four coupled micro-rings made from layered III-V or II-VI hetrostructure material can aid in maintaining cross-talk at very low levels while employing simple switch addressing methods.

Abstract: In an optical receiver, a photodiode converts an optical digital input signal to an electrical signal which is fed into a differential amplifier to produce a pair of true and complementary output signals. The true output signal is received by a peak detector and the output of this peak detector is summed in a first adder with the complementary output of the differential amplifier. The true output of the amplifier is summed in a second adder with a predetermined constant voltage. Difference between the output signals of the first and second adders is detected and compared with a decision threshold to produce an output signal at one of two logical levels depending on whether the difference is higher or lower than the decision threshold. Preferably, a second peak detector having a substantially similar operating characteristic to that of the first peak detector is connected between the source of the predetermined constant voltage and the second adder.