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Detuned grating multisection-RW-DFB lasers for high-speed optical signal processing

: Möhrle, M.; Sartorius, B.; Bornholdt, C.; Bauer, S.; Brox, O.; Sigmund, A.; Steingrüber, R.; Radziunas, H.; Wünsche, H.J.


IEEE Journal of Selected Topics in Quantum Electronics 7 (2001), No.2, pp.217-23
ISSN: 1077-260X
Journal Article
Fraunhofer HHI ()
diffraction gratings; distributed feedback lasers; laser modes; laser tuning; optical information processing; ridge waveguides; semiconductor lasers; waveguide lasers; detuned grating multisection-rw-dfb lasers; high-speed optical signal processing; high-frequency self-pulsations; integrated phase tuning section; spectrally detuned; grating periods; lasing conditions; lasing modes; phase section; external injected signal synchronisation; mutual coherence

We present a detailed description and a first theoretical study of an improved concept for high-frequency self-pulsations (SPs) in multisection (MS)-DFB lasers with an integrated phase tuning section. The DFB wavelengths of the two DFB sections are spectrally detuned by nearly the stopband width using two gratings with different grating periods. If both DFB sections are operated at lasing conditions and an appropriate phase is chosen, we obtain beating-type SP with a frequency given by the spectral distance of two lasing modes. Good agreement between theory and experiment is obtained with respect to the role of the detuning, the role of the phase section, as well as the synchronization to external injected signals. The modeling shows a strong nonlinear coupling of the two involved modes via the carrier densities. This effect is important for the mutual coherence and for the observed locking of the beating oscillations to external signals. From the results of the calculations, we draw the conclusion that even higher SP frequencies can be obtained based on the new concept.