Abstract
In this paper, we report the existence of Eckhaus instability in laser cavities with harmonically swept filters, of which Fourier Domain Mode Locked (FDML) laser is an important example. We show that such laser cavities can be modeled by a real Ginzburg Landau equation with a frequency shifting term arisen from the cavity dispersion. We analytically derived a solution of the governing equation and analyzed its stability. We found that the cavity dispersion introduces a continuous frequency shift to the laser signal such that it will be eventually pushed outside the stable region and trigger the Eckhaus instability. We show that the repeated triggering of the Eckhaus instability in the laser cavities is the dominant effect that leads to the high frequency fluctuations in FDML laser output, which is the unique feature of such laser cavities and intrinsically limits the signal quality of the FDML lasers with nonzero cavity dispersion.
Original language | English |
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Pages (from-to) | 6531 - 6538 |
Number of pages | 8 |
Journal | IEEE Journal of Lightwave Technology |
Volume | 39 |
Issue number | 20 |
Early online date | 11 Aug 2021 |
DOIs | |
Publication status | Published - 15 Oct 2021 |
Bibliographical note
This work was supported in part by National Key R&D Program of China (2019YFB1803904), in part by Science, Technology and Innovation Commission of Shenzhen Municipality (SGDX2019081623060558), in part by Research Grants Council, University Grants Committee of Hong Kong SAR (PolyU152241/18E), and in part by Guangdong Basic and Applied Basic Research Foundation (2021A1515012544) (Corresponding author: Dongmei Huang).Keywords
- Eckhaus instability
- Real Ginzburg Landau equation
- Swept laser
- Fourier domain mode locking