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Simulation studies of DFB laser longitudinal structures for narrow linewidth emission

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Details

Original languageEnglish
Article number160
Number of pages13
JournalOptical and Quantum Electronics
Volume49
Issue number4
DOIs
Publication statusPublished - 23 Mar 2017
Publication typeA1 Journal article-refereed

Abstract

The paper presents simulation studies targeting high-power narrow-linewidth emission from semiconductor distributed feedback (DFB) lasers. The studies contain analytic and numerical calculations of emission linewidth, side mode suppression ratio and output power for DFB lasers without phase shifts and with 1 × λ/ 4 and 2 × λ/ 8 phase shifts, taking into account the grating and facets reflectivities, the randomness of the spontaneous emission and the longitudinal photon and carrier density distributions in the laser cavity. Single device structural parameter optimization is generally associated with a trade-off between achieving a narrow linewidth and a high output power. Correlated optimization of multiple structural parameters enables the evaluation of achievable ranges of narrow linewidth and high power combinations. Devices with long cavities and low grating coupling coefficients, κ (keeping κL values below the levels that promote re-broadening), with AR-coated facets and with a distributed phase-shift have the flattest longitudinal photon and carrier density distributions. This flatness enables stable single-longitudinal-mode operation with high side-mode-suppression ratio up to high injection current densities, which facilitates narrow linewidths and high output powers. The results reported in the paper indicate that Master-Oscillator Power-Amplifier laser structures are needed for achieving W-level high-powers with sub-MHz linewidths because most single-cavity DFB laser structural variations that reduce the linewidth also limit the achievable output power in single-mode operation.

Keywords

  • Distributed feedback laser, High power, Narrow linewidth

Publication forum classification

Field of science, Statistics Finland

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