Abstract: An optical fiber transmission line capable of suppressing the generation efficiency of four wave mixing in transmitting wavelength multiplex signal light. The transmission line employs a single mode optical fiber in which a zero dispersion wavelength is varied in the longitudinal direction of the optical fiber more largely than manufacturing variations in manufacturing conditions of the optical fiber. The use of this optical fiber as the transmission line suppresses the generation efficiency of four wave mixing in transmitting the wavelength multiplex signal light to allow the transmission of the wavelength multiplex signal light with a reduced crosstalk.

Abstract: A head-end station (1) is provided for a passive optical network system arranged to transmit downstream TDMA frames and receive upstream TDMA frames. The head-end station (1) comprises a TDMA master (5) and a plurality of optical stages (4a, 4b) connected in common to the TDMA master (5). The TDMA master (5) assembles incoming data into downstream TDMA frames and demultiplexes upstream TDMA frames. Each optical stage (4a, 4b) is arranged to be connected to a different respective fiber network (3a, 3b) and includes an optical transmitter which modulates an optical signal with downstream TDMA frames from the TDMA master (5) together with an optical receiver arranged to detect an optical signal carrying upstream TDMA frames.

Abstract: A polarization diversity receiver system for yielding multiple heterodyne optical output signals from an incident optical beam having a p-polarized component and an s-polarized component comprises first and second sequentially-arrayed polarizing beamsplitters, and three photodetectors, each of which receives a heterodyne optical signal. The polarization diversity receiver system tracks the largest of these three signals, and uses only this largest one for subsequent signal processing. There is a minimum for this largest signal that is dependent on the input polarizations of the two optical fields whose beat note is the heterodyne signal. Thus, the object is to maximize the minimum of this largest of the three heterodyne signals.

Abstract: A comb splitting system demultiplexes and/or multiplexes a plurality of optical signal channels at various wavelengths. The comb splitting system has at least two interconnected successive stages of wavelength division multiplexers (WDMs). The first stage comprises a Fourier filter that communicates bands of channels to respective WDMs of the second stage via suitable optical paths. Each of the bands has a plurality of the individual channels that are separated by at least one other of the channels. Each second stage WDM, which is allocated to a particular band, is interconnected to respective optical paths for carrying one or more individual channels. Furthermore, in accordance with a significant feature of the present invention, the passband width and periodicity (i.e., free spectral range) associated with the first stage Fourier filter are smaller than the passband width and periodicity associated with the second stage WDMs.

Abstract: A dispersive optical waveguide tap comprises a blazed and chirped refractive index grating in the core of the waveguide, coupling means and utilization means. The grating is selected such that guided mode light of predetermined wavelength will, in the absence of the coupling means, be directed into one or more cladding modes of the waveguide. The presence of the coupling means in optical co-operation with the waveguide, changes the guiding conditions such that the cladding modes are substantially eliminated from a portion of the waveguide that includes the cladding, whereby the grating directs the guided mode light into one or more radiation modes. The blaze angle typically is .ltoreq.15.degree.. The chirp serves to bring the radiation mode light substantially to a focus in at least one dimension, the focal point (or line) depending on the wavelength of the light.

Abstract: A communication system, such as a cable television system, includes an optical transmitter (FIG. 2) that includes adaptive predistortion control circuitry (104). The adaptive predistortion control circuitry (104) measures the distortion produced by television band signals processed in the communication system. In the optical transmitter (FIG. 2), the distortion signal produced by the television signals is a relatively high-level signal from which necessary predistortion control signals may be more easily processed. Additionally, the adaptive predistortion control circuitry (104) detects both the amplitude and the polarity of distortion within the optical output (FIG. 2) of the optical transmitter, which enables the control circuit (104) to determine the correct polarity and level adjustments that should be made to the predistorter (102) included in the optical transmitter.

Abstract: An integrated coherent transceiver capable of being operated with only one below threshold FP mode is described which can be used for both receiving downstream signals and transmitting upstream signals with either FSK or ASK format. The device allows the full tuning range of distributed-Bragg-reflector ("DBR") lasers to be utilized to achieve approximately one thousand channels in a local access system with 1 GHz channel spacing. The sensitivity can be further enhanced by obtaining balanced operation (without changing the simple device structure) to cancel the laser intensity noise.

Abstract: A communication system including a light modulator system includes a laser that produces a high frequency carrier wave signal and a laser information signal source that produces a much lower frequency information signal. The carrier wave signal passes through a first pinhole in a screen to a light mixer cavity. The information signal passes through a second pinhole in the screen to the light mixer cavity, the signals being mixed in the light mixer cavity after passing through their respective pinholes. The resulting signal components include a sum of the carrier wave signal and the information wave signal. A pickup fibre is positioned and sized to receive and transmit only the sum of the carrier wave signal and the information wave signal. The pickup fibre is connected to the local end of a fibre optic cable.

Abstract: An optical power monitor device capable of monitoring optical power with the influence of optical crosstalk eliminated, and an optical amplifier and an optical transmitter each having the monitor device. The monitor device is applied to a light source for outputting first and second beams, for example. The first beam is divided into first and second branch beams by a beam splitter. The first branch beam is supplied to a first photodetector. The first photodetector outputs a first signal having a level corresponding to the power of the first branch beam. The second beam from the light source is supplied to a second photodetector. The second photodetector outputs a second signal having a level corresponding to the power of the second beam. The first and second signals are supplied to a first subtracter. The first subtracter outputs a first error signal corresponding to the difference between the first and second signals. The first signal and the first error signal are supplied to a second subtracter.

Abstract: Disclosed is an optical network which has a plurality of subordinate optical networks, each of which being connected with a plurality of optical terminals which function as a transmitter and a receiver of a signal light, wherein multiplexing of transmission signals and demultiplexing of reception signals at the optical terminals are carried out in the subcarrier multiplexing manner; and a main optical network which is connected with the subordinate optical networks, wherein multiplexing of signal lights transmitted from the subordinate optical networks is carried out in the wavelength division multiplexing manner.

Abstract: A system of bidirectional transmission of optical signals over an optical fiber in a telecommunications network includes a transceiver unit having an optical signal transmitter and receiver coupled with each end of the fiber, and a signal monitor for detecting a predetermined deviation in the signal strength directed toward each receiver from the fiber. This predetermined deviation is indicative of a signal path disruption in the fiber resulting in at least partial signal reflection of the signals from a transmitter toward the receiver of the same set.

Abstract: The invention relates to an optical communication-transmitting system for transmitting at least one useful signal with a high bit rate, which has intermediate repeaters (ZV.sub.1 -ZV.sub.n) with optical fiber amplifiers (OV.sub.ss, OV.sub.1 -OV.sub.n, OV.sub.es) and which uses at least one additional signal of a low bit rate, for example for monitoring the intermediate repeater. For a transmission system requiring small outlay, the additional signal is transmitted on a wide band in comparison to the useful signal, for example by means of luminescence diodes (S.sub.ss, S.sub.1 -S.sub.n) and is amplified by the fiber amplifiers (OV.sub.ss, OV.sub.1 -OV.sub.n, OV.sub.es) in the same manner as the useful signal. For transmitting and receiving the additional signal, a transmitter (S.sub.1) is preferably disposed in an intermediate receiver (ZV.sub.1) upstream of the fiber amplifier (OV.sub.1) and a receiver preferably downstream thereof.

Abstract: Spontaneous emission occurring in association with direct optical amplification using an erbium-doped optical fiber is modulated with an auxiliary signal, such as a supervisory signal, for transmission of the auxiliary signal. In a first aspect of the invention, the output of an optical amplifier is passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, to modulate the spontaneous emission component contained in the optical amplifier output. In a second aspect of the invention, the output of the optical amplifier is separated by an optical branching device into a main optical signal and part of the spontaneous emission.

Abstract: The apparatus includes a first housing (10) defining a first chamber (26), the first chamber sized to enclose an electronic device. The first housing has an inner surface (22) and an outer surface (24), and at least a portion of the first housing is transparent. A light-generating device (14) is disposed at least in part between the inner surface and the outer surface of the transparent portion of the first housing. The light-generating device has a first end and a second end. The first end is responsive to electrical signals (18) and the second end is responsive to optical signals (20). When a first electronic device (45) is disposed in the first chamber, the first electronic device transmits electrical signals to the first end, the second end translates the electrical signals to optical signals and transmits the optical signals through the outer surface.

Abstract: It is an object of the invention to provide a light-receiving module, in which characteristic of a semiconductor amplifier unit mounted thereon is inspected on the course of fabrication and an outside photosensor do not come to nothing, and a method for fabricating the same. In the package of the light-receiving module, a semiconductor chip, which comprises an amplifier and a inside photosensor for inspecting it, and an outside photosensor for receiving a light signal are allocated. First, the inside photosensor is irradiated with a light for inspecting amplifier, and the output of the amplifier is investigated. In case that the amplifier is recognized as normal, an Al pattern communicated with the input port of the amplifier is cut, and the output port of the outside photosensor is connected with the input port of the amplifier by a bonding wire. Thus, the light-receiving is completed.

Abstract: Disclosed is an optical switching system with a combined space and wavelength division multiplex based on the repeated contention technique. The present invention has effects on high capacity in required in the optical switch module, by performing the contention resolution over a two consecutive cell time slot which repeatedly employs the present and previous state information. According to the present invention, the input cells make use of a switching opportunity two times. As a result, the present invention maintains the desired probability of cell loss, keeping up the state values L small. Also, the present invention can decrease the number of filters because it is possible to decrease the number of wavelength used for the wavelength conversion. Furthermore, the present invention has an effect on the high capacity based on the extension of the optical switch modules.

Abstract: An optical receiver suitable for use in a wavelength division multiplexing (WDM) system is able to tolerate shifts in the transmitting lasers' wavelength. During a periodically repeated wavelength synchronization phase, only a single transmitter laser is operating, and a peak finder locks onto the wavelength having greatest power and notes the corresponding detector pixel's position. Thus, the receiver knows the relative wavelength of the transmitting laser in terms of the detector pixel illuminated with the brightest light, and can store this information for later reference. The active transmitter lasers take turns synchronizing their wavelengths during successive synchronization phases. During the multi-wavelength data transmission phase, many lasers in the system transmit information at the same time, at different wavelengths.

Abstract: A method and apparatus is provided of locating a portable remote station transceiving a diffuse infrared communicated signal within an enclosed area containing a plurality of stationary infrared transceivers interconnected with a central controller. The method includes the steps of detecting a particular transmission of the diffuse infrared communicated signal from the portable remote station within the enclosed area by the plurality of stationary transceivers and measuring a parametric value of the particular signal received by each stationary transceiver of the plurality of stationary transceivers. The method further includes the step of locating the portable remote station based upon differences in the parametric value measured at each stationary transceivers.

Abstract: For transmitting received signals from an antenna (A) to a base station (BS) of a radio system, optical signals, which are transmitted to the base station (BS) via a light guide (L), are generated in an antenna unit (AE) connected to the antenna (A). An optical carrier is generated in the base station (BS) and is fed to the antenna unit (AE). There, the optical carrier is modulated, using an electro-optical modulator (EO), in a way corresponding to the received signals coming from the antenna (A) and is transmitted to the base station (BS) via a light guide (L). The present invention dispenses with the need for dedicated lasers in the antenna units (AE).

Abstract: A device for driving a light emitting element, including a DC power source for generating a DC current, a signal driving unit for controlling, in an on-off manner, the DC current generated in the DC power source on the basis of signal data with timing in accordance with the signal data, a light emitting element which is driven by the DC current controlled in the on-off manner by the signal driving unit and emits light when the DC current flows thereto, a high-speed pulse controlling unit for controlling, in an on-off manner, the DC current which drives the light emitting element at a sufficiently short period in comparison with the signal data to pulse the DC current, and a driving control unit for controlling the timing of on-off control of the high-speed pulse controlling unit in accordance with a required mean optical output.