Showing papers on "Optical communication published in 1972"
Patent•
30 Mar 1972TL;DR: A light coupler for transferring optical wave energy to or from light transmitting means including at least one optical waveguide is described in as discussed by the authors, where the coupler consists of a tapered core of transparent material of refractive index n 1 and a layer of transparent cladding material of as discussed by the authors.
Abstract: A light coupler for transferring optical wave energy to or from light transmitting means including at least one optical waveguide. The coupler comprises a tapered core of transparent material of refractive index n1 and a layer of transparent cladding material of refractive index n2 disposed upon the surface of the tapered core, n1 being greater than n2. The tapered core has a large diameter end which is aligned with an end of the light transmitting means and a small diameter end which is disposed adjacent to electro-optic energy conversion means such as a light emitting diode, a light detector or the like. When used at the transmitting end of an optical communication system, the small diameter end of the tapered core receives light from a source, and the coupler functions to collimate those light rays which enter the small diameter end and which reflect from the core-cladding interface thereof.
72 citations
01 Jan 1972
TL;DR: An introduction is provided to the important ideas involved in the design and the evaluation of optical communication systems which transmit digital or analog data.
Abstract: An introduction is provided to the important ideas involved in the design and the evaluation of optical communication systems which transmit digital or analog data. Field representations are discussed together with background noise, a detector statistical model, quantum receivers, and turbulent and scatter channels. Free-space channels are considered, taking into account heterodyne systems, preamplifier and homodyne systems, direct-detection systems, and optimum quantum systems.
41 citations
NEC1
TL;DR: A wide-band optical communication system that modulates the envelope of the carrier of a high-speed optical pulse having no relation to the PCM signals, was developed.
Abstract: A wide-band optical communication system that modulates the envelope of the carrier of a high-speed optical pulse having no relation to the PCM signals, was developed. This optical pulse is supplied from a He-Ne gas laser oscillator that is controlled to generate a single transversal mode. The transmission bit rate of this optical communication system is 123 Mbits/s, and this system has a transmission capacity of three monochrome video signals, three program signals, and one channel of 48-kHz high-speed facsimile signal or one National Television System Commission (NTSC) color TV signal and one program signal. When this optical communication system is used to propagate through the atmosphere for a distance of 2-3 km, reliability is expected to be 99 percent.
21 citations
TL;DR: Lower bounds are given on the attainable mean-square performance in causally tracking the phase and frequency of a subcarrier that modulates an optical carrier in a direct-detection opticalcommunication system.
Abstract: Lower bounds are given on the attainable mean-square performance in causally tracking the phase and frequency of a subcarrier that modulates an optical carrier in a direct-detection opticalcommunication system.
9 citations
TL;DR: The Poisson statistics of photoelectron emissions are used to find simple, easily evaluated, but tight upper bounds on error probability for these two problems of detecting the presence of a pulsed optical signal in background light.
Abstract: Two different receiver strategies for use with photoelectron emitting optical detectors are evaluated. Upper bounds on error probability are derived both for optical communication with pulse position modulation and for the general problem of detecting the presence of a pulsed optical signal in background light. The Poisson statistics of photoelectron emissions are used to find simple, easily evaluated, but tight upper bounds on error probability for these two problems. These receiver performance bounds illustrate several basic principles in optical communication and signal detection. These basic principles are then discussed in detail.
8 citations
TL;DR: In this paper, a carbon dioxide laser oscillating at 28.4 THz has been modulated simultaneously by three commercial television signals with carriers at 54, 66, and 82 MHz.
Abstract: Experiments are described in which a carbon dioxide laser oscillating at 28.4 THz has been modulated simultaneously by three commercial television signals with carriers at 54, 66, and 82 MHz. Signal-to-noise degradation in the system was measured to be less than 1 dB, corresponding to modulator drive power of 1 W. This combination of wide bandwidth and low power consumption was made possible by the application of coupling modulation. This technique employs an intracavity electrooptic crystal to which the modulating fields are applied. Despite the fact that the crystal is positioned inside the laser cavity, the maximum bandwidth attainable is independent of both the cavity Q and the laser transition linewidth, and is limited only by modulator characteristics and optical transit time. Rigrod's (1965) method has been adapted to obtain an expression for the power coupled out of the laser. Modulator frequency response and drive power requirements are also summarized. It is seen that the noise bandwidth performance of the system would allow simultaneous modulation by 17 color television channels, or equivalently, more than a 300-megabit/sec capacity.
4 citations
2 citations
TL;DR: This paper reviews research and developmental activities in optical communications currently under way in Japan and three major systems, using various types of lasers and newly developed optical devices and components, are reviewed.
Abstract: This paper reviews research and developmental activities in optical communications currently under way in Japan. Three major systems: 1) atmospheric optical communication systems, 2) optical-cable systems, and 3) lens-waveguide systems, using various types of lasers and newly developed optical devices and components, have been extensively studied at the Electrical Communication Laboratories of Nippon Telegraph and Telephone (NTT) and other electronic manufacturing companies in Japan.
2 citations
01 Sep 1972
TL;DR: In this article, the edge tracking operation in a binary PPM system is examined, taking into account the quantum nature of the optical transmissions, and performance analysis is made in terms of timing error and its associated statistics.
Abstract: A pulse position modulated (PPM) optical communication system using narrow pulses of light for data transmission requires accurate time synchronization between transmitter and receiver. The presence of signal energy in the form of optical pulses suggests the use of a pulse edge tracking method of maintaining the necessary timing. The edge tracking operation in a binary PPM system is examined, taking into account the quantum nature of the optical transmissions. Consideration is given first to pure synchronization using a periodic pulsed intensity, then extended to the case where position modulation is present and auxiliary bit decisioning is needed to aid the tracking operation. Performance analysis is made in terms of timing error and its associated statistics. Timing error variances are shown as a function of system signal to noise ratio.
1 citations
Proceedings Article•
01 Jan 1972TL;DR: In this paper, a model that is sufficiently general to describe the predominant statistical characteristics of the output of many real optical detectors is formulated, which is used to study the optimum receiver processing for direct-detection optical communication systems.
Abstract: A model that is sufficiently general to describe the predominant statistical characteristics of the output of many real optical detectors is formulated. This model is used to study the optimum receiver processing for direct-detection optical communication systems. In particular, the structures of detectors and estimators for filtered doubly stochastic Poisson processes (DSPP) observed in additive white Gaussian noise are considered. Representations for the posterior statistics of a vector Markov process that modulates the intensity of the DSPP are obtained.
01 Jul 1972
TL;DR: In this article, the optical technology requirements for four advanced military systems involving multiterminal data buses, heterodyne detection, tethers, and optical phase front control are described in detail.
Abstract: : Military avionics systems can be expected to benefit from the development of optical data communication systems which use fiber optics. Advantages involving size, weight and freedom from electromagnetic interference can be realized in the near future. Integrated optical circuits can increase the flexibility of such systems as well as perform independent functions in other useful optical devices. The state of the art of optical fibers and integrated optical circuits is reviewed. A strategy for the development of these technologies is recommended. The optical technology requirements for four advanced military systems involving multiterminal data buses, heterodyne detection, tethers, and optical phase front control are described in detail.
01 Jan 1972
TL;DR: In this paper, a ten-micrometer band communication system using CO2 lasers for space-to-space links is discussed, with particular emphasis on low earth orbiting earth observation satellites to geosynchronous satellites at high data rate.
Abstract: Ten-micrometer band communication systems using CO2 lasers for space to space links are discussed. Particular emphasis is on low earth orbiting earth observation satellites to geosynchronous satellites at high data rate. Four key technology areas are discussed: wideband mixers for Doppler tracking; tunable laser local oscillators; high data rate modulators; and laser transmitters.
01 Aug 1972
TL;DR: In this paper, a technique for measuring speed of response of high speed visible and IR optical detectors to mode-locked Nd:YAG laser pulses is described, and results of measurements of response times of four detectors are presented.
Abstract: A technique for measuring speed of response of high speed visible and IR optical detectors to mode-locked Nd:YAG laser pulses is described. Results of measurements of response times of four detectors are presented. Three detectors that can be used as receivers in a 500-MHz optical communication system are tested.