Effect of mode nonorthogonality in distributed-feedback lasers

Area of Science:

• Quantum optics
• Laser physics
• Semiconductor device physics

Background:

• Distributed-feedback (DFB) lasers are crucial in optical communications.
• Accurate modeling of quantum noise is essential for high-performance lasers.
• Standard models often assume orthogonal laser modes, which may not be physically accurate.

Purpose of the Study:

• To develop a quantum noise analysis for DFB lasers considering nonorthogonal modes.
• To compare the results of this realistic model with the standard orthogonal mode approach.
• To investigate the impact of nonvanishing end reflectivity and complex coupling coefficients.

Main Methods:

• Utilized the Fokker-Planck equation to analyze quantum noise.
• Developed a theoretical framework incorporating nonorthogonal laser modes.
• Obtained numerical solutions for the steady-state single-mode operation.

Main Results:

• The study reveals significant differences between the standard orthogonal mode model and the realistic nonorthogonal mode model.
• Numerical results highlight discrepancies in steady-state solutions for DFB lasers.
• The model accounts for nonvanishing end reflectivity and complex coupling coefficients.

Conclusions:

• Nonorthogonality of laser modes is a critical factor in accurately modeling quantum noise in DFB lasers.
• The developed model provides a more realistic prediction of DFB laser performance.
• This work is important for the design and optimization of advanced DFB lasers.