Frequency and linewidth dependence of distributed-feedback resonators on thermal chirp

Cristine C. Kores, Nur Ismail, Dimitri Geskus, Meindert Dijkstra, Edward H. Bernhardi, Markus Pollnau

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

Abstract

We present an analysis of the spectral characteristics of distributed-feedback (DFB) laser resonators with thermally chirped distributed mirrors. Such DFB resonators have the interesting capability of producing a linewidth as narrow as a few kHz. The investigated devices are ytterbium-doped amorphous Al2O3 channel waveguides with a periodic Bragg grating inscribed into its SiO2 top cladding. The resonance in the spectral response of the resonator results from a distributed λ/4 phase-shift produced by increasing the waveguide width. Its frequency is determined by the period of the Bragg grating, whereas its linewidth is determined by the intrinsic losses and the outcoupling losses of the resonator. When such a device is optically pumped to achieve gain and eventually lasing, the grating period becomes thermally chirped, thereby influencing the spectral characteristics of the resonator. We investigate experimentally and via simulations the frequency and linewidth of the resonance in the presence of a thermally induced linear chirp on the grating profile. Experiments and simulations show good quantitative agreement.

Original languageEnglish
Title of host publicationICTON 2017 - 19th International Conference on Transparent Optical Networks
PublisherIEEE
ISBN (Electronic)9781538608586
DOIs
Publication statusPublished - 1 Sept 2017
Event19th International Conference on Transparent Optical Networks, ICTON 2017 - Girona, Spain
Duration: 2 Jul 20176 Jul 2017
Conference number: 19

Conference

Conference19th International Conference on Transparent Optical Networks, ICTON 2017
Abbreviated titleICTON
Country/TerritorySpain
CityGirona
Period2/07/176/07/17

Keywords

  • chirped gratings
  • coupled mode theory
  • distributed-feedback resonators
  • narrow linewidth

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