Showing papers on "Optical Carrier transmission rates published in 1987"
TL;DR: In this paper, the authors reported the intensity modulation of an optical carrier at frequencies as high as 40 GHz using a Ti:LiNbO3 optical waveguide switch and a self-electrooptic sampling technique was used to observe the modulation.
Abstract: We report the intensity modulation of an optical carrier at frequencies as high as 40 GHz using a Ti:LiNbO3 optical waveguide switch. A self-electrooptic sampling technique is used to observe the modulation.
110 citations
TL;DR: In this article, a 12.5 Gbit/s fiber-optic network is implemented with a central mode-locked laser clock, integrated optical waveguide modulators, optical time-multi/demultiplexing and an optical reservation protocol.
Abstract: A 12.5 Gbit/s fibre-optic network is implemented with a central mode-locked laser clock, integrated-optic waveguide modulators, optical time-multi/demultiplexing and an optical reservation protocol. The network accommodates 125 stations transmitting at 100 Mbit/s each, using receiver-fixed assignment time-division multiple access.
55 citations
Patent•
01 May 1987TL;DR: In this article, a technique for applying selected phase delays to an optical carrier signal, the phase delays being referenced to a radio-frequency (RF) subcarrier signal, is presented.
Abstract: A technique for applying selected phase delays to an optical carrier signal, the phase delays being referenced to a radio-frequency (rf) subcarrier signal. The optical signal to be phase delayed is introduced into a phase delay network comprising multiple optical paths and multiple electro-optical switches, controllable by signals generated in switching logic. The selected delays can be introduced for purposes of data modulation, or for steering an antenna beam in a phased-array antenna. As applied to the phased-array antenna system, the invention includes a data modulator, a series of star couplers for splitting the optical carrier into multiple elemental carriers, and multiple phase shifters for applying selected phase shifts to the elemental carrier signals, to effect antenna beam steering.
46 citations
Patent•
23 Oct 1987TL;DR: In this paper, an optical signal source is split into a carrier signal and a reference signal, and the carrier signal is phase modulated with the radio-frequency signal by means of a Pockels cell, producing a phase-modulated signal devoid of evenharmonic distortion, and containing only relatively small odd-harmonic components.
Abstract: Apparatus, and a corresponding method for its use, for modulating an optical carrier signal with a radio-frequency signal and providing a desirably high dynamic range. An optical signal source is split into a carrier signal and a reference signal, ideally with an optical star coupler, and the carrier signal is phase-modulated with the radio-frequency signal by means of a Pockels cell, producing a phase-modulated signal devoid of even-harmonic distortion, and containing only relatively small odd-harmonic components. In the preferred embodiment of the invention, the phase-modulated signal has its carrier signal suppressed. Then the resulting double-side-band suppressed-carrier signal is combined with the reference signal, preferably with another optical star coupler, to produce the desired modulated optical signal with high dynamic range.
30 citations
Patent•
09 Apr 1987
TL;DR: In this paper, a heterodyne coherent detection system with orthogonally-polarized components was proposed, in which at the transmitting side the polarization of an optical carrier is modulated, and at the receiving side the beam resulting from the combination of the modulated beam and the beam emitted from a local oscillator (12) is split into two orthogonal polarized components.
Abstract: Optical-fibre transmission system with heterodyne coherent detection, in which at the transmitting side the polarization of an optical carrier is modulated, and at the receiving side the beam resulting from the combination of the modulated beam and the beam emitted from a local oscillator (12) is split into two orthogonally-polarized components. The two optical signals are detected and sent to an electronic mixer (19a, 19b) which receives the two components and carries out a synchronous demodulation eliminating the effects of the linewidth of the source (1) and of the local oscillator (12).
24 citations
Patent•
26 Jun 1987TL;DR: In this paper, a broad spectrum optical carrier from a source is divided over at least two paths and the carrier in at least one path is modulated in accordance with information, and the paths are recombined with delay multiplexing.
Abstract: A broad spectrum optical carrier from a source is divided over at least two paths and the carrier in at least one path is modulated in accordance with information. The paths are recombined with delay multiplexing. At a distribution point, the recombined paths are divided and the modulated carrier in at least one of the paths is combined in heterodyne detection with a local oscillator signal having a frequency shifted with respect to the carrier. The local oscillator signal is delayed prior to combination by a delay corresponding to a delay of the delay multiplexing.
22 citations
TL;DR: In this article, the authors describe gigabit single-mode fiber transmission using 1.3-μm edge-emitting LED's for broadband subscriber loops, focusing on a method of calculation for maximum transmission distance and 1.2-Gbit/s and 600-M bit/s transmission experiments.
Abstract: This paper describes gigabit single-mode fiber transmission using 1.3-μm edge-emitting LED's for broad-band subscriber loops, focusing on a method of calculation for maximum transmission distance and 1.2-Gbit/s and 600-Mbit/s transmission experiments. Gigabit single-mode fiber transmission is necessary for subscriber loops, especially in broad-band ISDN and optical CATV systems. Edgeemitting LED's are excellent light sources because of their high power launched into the fiber compared with surface-emitting LED's, and currently lower cost and higher reliability than laser diodes. The maximum transmission distance is carefully estimated by taking into account the wavelength dependence for both chromatic dispersion and loss of the single-mode fiber, and the possibility of gigabit transmission near the dispersion free wavelength 1.3 μm, is confirmed. Encouraged by the above results, we demonstrate 1.2-Gbi,t/s 10-km and 600-Mbit/s 20-km transmission experiments using a newly developed 1.3-μm edge-emitting LED and a new driver circuit with a simple response compensation circuit. These results show the proposed calculation method and the LED response compensation circuit to be powerful tools for the realization of low-cost gigabit single-mode fiber transmission using edge-emitting LED's.
10 citations
Patent•
09 Dec 1987
TL;DR: In this paper, a system for the transmission of signals along an optical carrier employs a technique to extend the effective frequency range of modulation beyond that of which a semiconductor laser is capable by combination of signals at the source to form a composite difference signal and recombination at the receiver to restore the original signal.
Abstract: A system for the transmission of signals along an optical carrier employs a technique to extend the effective frequency range of modulation beyond that of which a semiconductor laser is capable by combination of signals at the source to form a composite difference signal and recombination at the receiver to restore the original signal.
7 citations
19 Jan 1987
TL;DR: In this article, an alternative technique is reported which achieves diversity by scrambling the polarisation at the transmitter subsequent to modulating the optical carrier, and the advantages of this technique are that for wavelength multiplexed systems one scrambler per transmission fibre is all that is required.
Abstract: Practical coherent optical fibre transmission systems will have to be insensitive to the random polarisation changes introduced by the birefringent transmission medium and to date the techniques considered for achieving this are polarisation tracking receivers [1] and polarisation diversity receivers [2]. In this paper an alternative technique is reported which achieves diversity by scrambling the polarisation at the transmitter subsequent to modulating the optical carrier. The advantages of this technique are that for wavelength multiplexed systems one scrambler per transmission fibre is all that is required and because the receiver design is kept simple it is particularly suited to local network applications.
7 citations
Patent•
26 Jun 1987
TL;DR: In this paper, a broad spectrum optical carrier from a source (1) is divided over at least two paths (4), and the carrier in at least one path (4) is modulated (M1-4) in accordance with information (I 1-4).
Abstract: A broad spectrum optical carrier from a source (1) is divided over at least two paths (4), and the carrier in at least one path (4) is modulated (M1-4) in accordance with information (I1-4). The paths are recombined (6) with delay multiplexing (t1-4). At a distribution point (7), the recombined paths (6) are divided and the modulated carrier in at least one of the paths is combined in heterodyne detection (at D1-4) with a local oscillator signal (via path 5) having a frequency shifted with respect to the carrier. The local oscillator signal is delayed prior to combination by a delay (t1'-4') corresponding to a delay of the delay multiplexing.
6 citations
Patent•
09 Nov 1987
TL;DR: In this paper, a small and compact LED is used as a light source of an optical pulse to make it possible to make a measuring apparatus itself at low cost and easily perform its measurement.
Abstract: PURPOSE:To make it possible to make compact a measuring apparatus itself at low cost and easily perform its measurement, by using a small and compact LED as a light source of an optical pulse. CONSTITUTION:A sample 1 to be measured is held between electrodes 3 and 4 in such a state that a voltage is applied by a high voltage power supply 2. A high brightness LED 5 using GaAlAs, for example, is provided on the front surface of one electrode 3 through a converging lens group 6 and generates an optical pulse of a short constant width at a predetermined time by a LED driver 8 which operates on receiving a signal from a pulse generator 7. A current is detected by an optical carrier generated in the sample 1 on receiving the optical pulse as a voltage across a load resistance 9 and the voltage is amplified by an amplifier 10 and observed by an oscilloscope 11 as a wave form.
TL;DR: A unique technique is proposed which enables rapid and accurate indication of frame synchronization together with no considerable bit error occurrence for the digital signal just after activation in a fiber-optic subscriber system in the NTT project.
Abstract: A call-by-call activation technique for fiber-optic subscriber systems has been developed to reduce electric power consumed in transmission units installed on subscriber premises. The major part of the transmission unit is supplied power call-by-call. The technique has been applied for a fiber-optic subscriber system in the INS Model System (NTT project) for which the PFM technique is used to transmit a frequency division multiplexed signal containing video, audio, and digital signals bidirectionally. This paper describes the control procedure and hardware implementation for this call-by-call activation. Discussion is made on methods of achieving optical carrier sensing. A unique technique is proposed which enables rapid and accurate indication of frame synchronization together with no considerable bit error occurrence for the digital signal just after activation. Experimental results which reveal validity of control procedure, carrier sensing, and frame synchronization methods are also shown together with the effect of power saving and assessment of build-up time required for activation.
TL;DR: In this article, a sampling technique for optical timedivision multiplexing circuit and packet switched data is proposed using a gain-switched distributed feedback semiconductor laser and lithium niobate modulators.
Abstract: A simple and novel sampling technique for optical timedivision multiplexing circuit and packet switched data is proposed using a gain-switched distributed feedback semiconductor laser and lithium niobate modulators. System error rate measurements on a two-channel system multiplexing data at 140 Mbit/s and 50 Mbit/s are given and operating penalties analysed.
01 Jan 1987
TL;DR: The network envisaged is a long-haul, packet-switched network, with optical fibre links between the nodes, for the integrated transmission of voice and data, which effectively utilizes the bandwidth of 140 Mbit/s fibre optic links.
Abstract: Digital transmission through optical fibres and 'packet-switching' are two independent technologies that have gained wide acceptance during the past decade. This paper considers the possibility of a fusion between the two technologies. The network envisaged is a long-haul, packet-switched network, with optical fibre links between the nodes, for the integrated transmission of voice and data. The advantages of implementing packet-switching on an optical fibre network are brought out. The proposed network effectively utilizes the bandwidth of 140 Mbit/s fibre optic links to transport voice and data packets in a store-and-forward manner from the source node to the destination node. The issues involved in the selection of routes for voice and data packets are discussed.
18 Sep 1987
TL;DR: In this article, the authors considered a typical mission to planet Jupiter, using CO 2, Nd:YAG and semiconductor diode lasers, and the first two systems allow the realization of coherent optical transponders which are required for a two way Doppler measurement with the optical carrier.
Abstract: The data transmission and position determination of deep space probes is today performed with microwave systems. Large antennas have to be used at ground (up to 300 m in diameter) and on board (several meters in diameter). Low data rates of the order of 100 Kbps must be transmitted. The position of the deep space probe can be determined from Doppler measurements of the microwave carrier from observations made over some days. The application of advanced optical data links allows both a reduction of antenna diameters and position determination error by orders of magnitude. For a typical mission to planet Jupiter three different optical technologies are considered, using CO 2 , Nd:YAG and semiconductor diode lasers. The first two systems allow the realization of coherent optical transponders which are required for a two way Doppler measurement with the optical carrier. For the semiconductor laser system direct detection with pulse position modulation is assumed. Consequently position determination of the spacecraft can not be made as precise as with microwave or CO 2 and Nd:YAG systems. The assumed laser diode pumped Nd:YAG laser with a modulated output power of 10 W and a tunable diode laser pumped-Nd:YAG laser local oscillator are not available at the present time. But the clear advantage of this technology for deep space missions must be taken into account for further technological developments.
01 Jan 1987
TL;DR: In this article, a 1.13 Gbps system with 8 plesiochronous in-and outputs at 140 Mbit/s was demonstrated, where all complicated signal processing functions are carried out at tributary speed.
Abstract: Gigabit/s optical transmission systems operating on single-mode fibre, which upgrade the transmission capacity of 565 Mbit/s systems now being installed, will become available in the next years. To relieve the burden on electronic circuitry operating at the highest speed the system architecture is chosen such that these circuits can be kept simple. All complicated signal processing functions are carried out at tributary speed and can be implemented with Si IC technology, while for the highest speed circuits GaAs technology may be appropriate. Excellent linearity of optical sources allows multilevel modulation of the optical signal. Feasibility of a 1.13 Gbit/s system with 8 plesiochronous in- and outputs at 140 Mbit/s, realized with todays industrially available electronics, sources and detectors, and operating over 33 km of single-mode fibre, has been demonstrated. Multigigabit/s systems are preferably operated in the 1550 nm wavelength region, taking advantage of the low fibre attenuation. Ultimately the fibre dispersion characteristic should be shaped to have low dispersion in this low attenuation region.