Improved spectral characteristics of MQW-DFB lasers by incorporation of multiple phase-shifts

• The single-mode stability of strained-layer MQW-DFB lasers with electron-beam written gratings containing zero, one and three phase-shifts, and with a relatively large coupling strength, has been investigated theoretically and experimentally. The fabricated lasers with the multiple phase-shifted (MPS) structure exhibited a higher degree of stability than the lambda;/4-shifted lasers, and a considerably improved stability for both categories with phase-shifts compared to the nonshifted lasers was obtained. These results were in good agreement with our simulations. An investigation of the linewidths of the phase-shifted lasers is also presented. The MPS lasers had a significantly lower linewidth floor (down to 600 kHz) than those with one phase-shift. There was no degradation of the side-mode suppression-ratio correlated to the linewidth floor or rebroadening. A possible explanation for the lower linewidth floors obtained for the MPS lasers is that this structure is less sensitive to inhomogeneous carrier fluctuations. Longitudinal fluctuations in the shape of the photon density distribution will thereby be suppressed

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Telekommunikation (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Telecommunications (hsv//eng)

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Nyckelord

lambda;/4-shifted lasers;InGaAsP-InP;InGaAsP-InP laser diode;MQW-DFB lasers;electron-beam written gratings;inhomogeneous carrier fluctuations;large coupling strength;linewidth floor;linewidths;multiple phase-shifted structure;multiple phase-shifts;phase-shifted lasers;photon density distribution;rebroadening;side-mode suppression-ratio;simulation;single-mode stability;spectral characteristics;stability;strained-layer MQW-DFB lasers;III-V semiconductors;distributed feedback lasers;electron beam applications;fluctuations;gallium arsenide;gallium compounds;indium compounds;laser modes;laser stability;quantum well lasers;spectral line breadth

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