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Analysis of a dephased complex-coupled distributed-feedback laser by the power-series method
Applied Optics
|March 14, 2008
Summary
A new power-series method analyzes complex-coupled distributed-feedback (DFB) lasers. It reveals how coupling ratios and phase differences impact laser modes and gain margins, crucial for laser design.
Area of Science:
- Optics and Photonics
- Semiconductor Lasers
- Wave Propagation
Background:
- Distributed-feedback (DFB) lasers are essential in optical communications.
- Understanding mode stability and gain margins is critical for DFB laser performance.
- Complex coupling in DFB lasers introduces unique behaviors influenced by gain and index gratings.
Purpose of the Study:
- Introduce a novel power-series method to solve coupled-wave equations for DFB lasers.
- Investigate the threshold gain margins of complex-coupled DFB lasers.
- Analyze the impact of coupling parameters and facet reflectivity on laser behavior.
Main Methods:
- Developed and applied a power-series method to solve coupled-wave equations.
- Calculated threshold gain margins as a function of gain-to-index coupling ratio and phase difference.
- Examined the influence of facet reflectivity (magnitude and phase) on gain margins.
Main Results:
- Mode degeneracy observed in cleaved-facet lasers at specific gain-to-index coupling ratios.
- Antireflection-coated lasers become multimode at phase differences of pi/2 and 3pi/2.
- Gain margin is sensitive to the phase of facet reflectivity, but less so to its magnitude.
- Spatial hole burning is minimized at phase differences of n*pi and maximized at pi/2 and 3pi/2.
Conclusions:
- The power-series method provides an effective tool for analyzing complex-coupled DFB lasers.
- Gain coupling, index coupling, phase difference, and facet reflectivity significantly influence DFB laser mode characteristics and stability.
- Optimizing these parameters is key to designing high-performance DFB lasers with desired mode properties.
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