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Coherent optical fiber transmission using injection locked lasers

: Braun, R.-P.; Strebel, B.

Institution of Electrical Engineers -IEE-, London:
IEE Colloquium on Advances in Coherent Optic Devices and Technologies 1985 : London, UK, 26 March 1985
London: IEE, 1985 (Digest. Institution of Electrical Engineers 30)
Colloquium on Advances in Coherent Optic Devices and Technologies <1985, London>
Conference Paper
Fraunhofer HHI ()
cable television; frequency division multiplexing; laser beam applications; optical fibres; optical links; semiconductor junction lasers; coherent optical fibre transmission; injection locked lasers; subscriber area; optical frequency-division multiplex systems; narrow channel distances; laser spectral linewidths; external cavity; subcarrier modulation methods; injection locking; transmitter; local lasers; common frequency modulation master laser; slave lasers; optical carrier frequencies; coherent heterodyning; very narrow intermediate frequency linewidth; catv-system; central office; phase coherent pilot tone

Future coherent optical communications in the subscriber area may include optical frequency-division multiplex systems with narrow channel distances. The are several proposals to overcome the restrictions due to high laser spectral linewidths e.g. linewidths narrowing by an external cavity, subcarrier modulation methods and the injection locking of transmitter and local lasers by a common frequency modulation master laser. In the latter case a number of slave lasers (SL) can be locked to one master laser (ML) at different optical carrier frequencies. The coherent heterodyning of two injection locked SL's results in a very narrow intermediate frequency linewidth. A future CATV-system using injection locking can be operated with transmitter and local lasers in the central office. Another possibility is to allocate the transmitter SL in the central office and the local SL within the receiver. In this case the local SL has to be locked to a phase coherent pilot tone.