W.A. Stallard

Integrated optic devices for coherent transmission

The components required for coherent optical-fiber systems are discussed and those devices that can be implemented using electrooptic waveguide technology are identified. The current usage of integrated optic components in coherent optical-fiber systems is indicated and the system performance that has been obtained when these components are employed summarized. The design and performance of LiNbO 3 electrooptic waveguide modulators, optical combiners, frequency translators, and polarization controllers are reviewed and the benefits to be gained by employing optical-integrated circuits in coherent optical-fiber systems considered. Finally, a novel low-voltage LiNbO 3 optical-integrated circuit for use in coherent detection is presented and the various design compromises discussed.

Optical multiplexing techniques for future Gbit/s transmission systems

Optical multiplexing is considered for gigabit-per-second (Gb/s) long distance transmission networks with emphasis on applications for which optical techniques can offer remote signal processing using passive components. Experimental transmission systems, operating at multi-Gb/s line rates and using both optical-time-division multiplexing and wavelength-division multiplexing are described. Particular attention is given to demonstrating realistic practical systems, emphasizing control and the use of commercially available components.<<ETX>>

Electro-optic frequency translators and their applications in coherent optical fibre systems

The operating principles and performance of waveguide Mach-Zehnder frequency translators suitable for use in coherent optical fibre systems are described. The performance of a coherent optical fibre system transmitting analogue colour video signals and employing a Mach-Zehnder electro-optic waveguide device as a double sideband suppressed carrier frequency modulator is reported. It is shown that the receiver sensitivity of such a system may be as much as 21 dB greater than that for an equivalent direct detection system. The use of electro-optic frequency translators in coherent optical networks to assemble a frequency multiplex of wideband signals is described. Particular attention is given to the linearity of devices, in systems employing up to four channels, and it is shown that unwanted products can be suppressed to 30 dB below the signal level. The use of this type of device as a frequency control element in optical multichannel networks is also considered.

Application of semiconductor optical amplifiers to submarine systems

The principal technical considerations in the application of semiconductor laser amplifiers to submarine cable systems are discussed. Measurements of the characteristics of laser amplifiers and system transmission experiments on cascaded amplifiers indicate the feasibility of using optical amplifiers with simple control and supervisory schemes. Long span systems experiments designed to simulate a submarine cable over distances of between 200 and 420 km are reported. It is concluded that semiconductor optical amplifiers offer the promise of upgradable and flexible submarine transmission systems.<<ETX>>

Analogue video transmission using Optical Frequency Modulation with Heterodyne Detection

The design and receiver sensitivity of a novel heterodyne detection system is examined for the transmission at baseband of a single analogue colour video signal. By using optical frequency modulation a receiver sensitivity of -70.3dBm is achieved after transmission over 30km of cabled monomode fibre at a wavelength of 1.523μm. This is 21.1dB better than direct detection using the same photodetector, and is within 1.6dB of shot noise limited detection.

Lithium Niobate Electro-Optic Frequency Translators For Coherent Optical Fibre Systems

Lithium niobate electro-optic waveguide frequency translators suitable for use in coherent optical fibre systems are reviewed. The design of double sideband Mach-Zehnder interferometric Y junction frequency translators is discussed and the fabrication and operational tolerances of these devices considered. The continuous generation of frequency translated optical signals with frequency translations upto 6.5 GHz at a wavelength of 1.52 μm are reported and the experimental results compared with theoretical predictions.

LiNbO3 Optical Frequency Translators for Coherent Optical Fibre Systems

Mach-Zehnder interferometric frequency translators operating continuously at 1.5 μm are reported for the first time and their use in coherent optical fibre systems considered.