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Frequency Noise in Widely Tunable Lasers for Coherent Communication
KTH, School of Information and Communication Technology (ICT).
2013 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Frekvensbrus hos mycket avstämbara lasrar för koherent kommunikation (Swedish)
Abstract [en]

The objectives of this thesis are to measure the frequency noise of a widely tunable semiconductor laser, determine the main causes for the frequency uctuations and investigate the requirements for laser frequency noise for mQAM modulation formats by means of simulations. The following theoretical aspects are covered: the derivation of the frequency noise spectrum and the detuned loading effect from the rate equations; the shape and the causes of the frequency noise power spectral density; the derivation of the linewidth spectrum from white and 1/f frequency noise; the functionality of the laser and feedback loop used for the measurements. Measurements using the feedback loop showed substantial improvements in the -3 dB laser line width, but further investigation is needed in order to obtain a laser that is suitable both as a transmitter and as a local oscillator in coherent communication. Simulations outlined the dependence of linewidth, constellation diagrams and symbol error rates on frequency noise, for BPSK, QPSK, 8PSK modulation formats and their respective differential formats.

Place, publisher, year, edition, pages
2013. , 66 p.
National Category
Computer and Information Science
URN: urn:nbn:se:kth:diva-143209OAI: diva2:705929
Subject / course
Microelectronics and Applied Physics
Educational program
Master of Science - Photonics
Available from: 2014-03-18 Created: 2014-03-18 Last updated: 2015-01-09Bibliographically approved

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