Theory of microscopic semiconductor lasers with external optical feedback.

Area of Science:

• Optics and Photonics
• Semiconductor Device Physics

Background:

• Microscopic semiconductor lasers are crucial for modern optoelectronics.
• External optical feedback can significantly impact laser performance and stability.
• Understanding feedback effects is vital for designing reliable laser systems.

Purpose of the Study:

• To theoretically analyze the properties of microscopic semiconductor lasers under external optical feedback.
• To clarify the size-dependence of critical feedback levels for laser instability.
• To evaluate the influence of spontaneous emission and operation damping on laser phase sensitivity and stability.

Main Methods:

• Theoretical analysis of semiconductor laser properties.
• Investigation of size-dependent critical feedback levels.
• Evaluation of spontaneous emission factor (β-factor) and damping effects.

Main Results:

• Laser gain is identified as the dominant factor for feedback stability, independent of laser size.
• Increased spontaneous emission and over-damped operation diminish phase sensitivity in microscopic lasers.
• A trade-off exists between modulation bandwidth and feedback stability.

Conclusions:

• Laser gain is a universal indicator of feedback stability for microscopic semiconductor lasers.
• Microscopic lasers exhibit reduced phase sensitivity with higher spontaneous emission and damping.
• Optimizing laser performance requires balancing modulation bandwidth and feedback stability.