Feedback effects in optical communication systems: characteristic curve for single-mode InGaAsP lasers

Area of Science:

• Semiconductor physics
• Optoelectronics
• Laser technology

Background:

• InGaAsP injection lasers are crucial for optical communications.
• Optical feedback can significantly alter laser diode performance.
• Previous models did not fully capture feedback effects on quantum efficiency.

Purpose of the Study:

• Investigate the unexpected decrease in differential quantum efficiency in InGaAsP lasers under optical feedback.
• Develop a microscopic model to explain the laser diode's response to optical feedback.
• Analyze the nonlinear dependence of interband carrier lifetime on optical feedback levels.

Main Methods:

• Experimental analysis of InGaAsP injection lasers with optical feedback.
• Development of a microscopic model based on coupled equations.
• Inclusion of microscopic parameters characterizing material and device properties.
• Accounting for the nonlinear dependence of interband carrier lifetime.

Main Results:

• Observed an unexpected decrease in differential quantum efficiency with increasing injected current under optical feedback.
• The microscopic model accurately predicted threshold current and differential quantum efficiency.
• The model demonstrated good agreement with experimental data across varying feedback ratios.

Conclusions:

• The microscopic model provides a valid explanation for the observed behavior of InGaAsP lasers under optical feedback.
• Nonlinear carrier lifetime dependence on feedback is critical for understanding laser efficiency.
• This work offers insights into optimizing laser diode performance in feedback-sensitive applications.