Optically mutual-injected terahertz quantum cascade lasers for self-mixing velocity measurements

Area of Science:

• Optoelectronics
• Quantum Cascade Lasers
• Sensor Technology

Background:

• Terahertz quantum cascade lasers (THz QCLs) offer unique properties for sensing applications.
• Self-mixing interferometry is a technique that utilizes the laser's own output for measurement.
• Mutual injection coupling in laser arrays can enhance stability and functionality.

Purpose of the Study:

• To theoretically investigate a self-mixing velocity sensor utilizing a mutual-injected two-element THz QCL array.
• To analyze the impact of frequency detuning and feedback strength on sensor performance.
• To explore the potential for simultaneous measurement of multiple targets.

Main Methods:

• Theoretical modeling of a mutual-injected two-element THz QCL array.
• Simulation of sensor characteristics under varying frequency detuning and feedback conditions.
• Analysis of phase-locking dynamics and self-mixing feedback effects.

Main Results:

• The THz QCL array can achieve stable, phase-locked states for self-mixing velocity measurements within a specific detuning range.
• Even with large frequency detuning or strong feedback, self-mixing velocity measurements remain feasible.
• The array demonstrated the capability to simultaneously measure two independent moving targets.

Conclusions:

• Mutual injection coupling enables THz QCL arrays to function effectively as self-mixing velocity sensors.
• The sensor design shows robustness against variations in frequency detuning and feedback strength.
• This theoretical work supports the future development of THz QCL array-based self-mixing sensors for advanced applications.