Tunable, low-phase-noise microwave signals from an optically injected semiconductor laser with opto-electronic...

Area of Science:

• Photonics and Laser Technology
• Microwave Engineering
• Semiconductor Device Physics

Background:

• High-performance microwave signal generation is crucial for advanced communication and sensing systems.
• Semiconductor lasers offer compact and tunable sources but often suffer from broad linewidths.
• Achieving narrow linewidths typically requires complex filtering or amplification, limiting practical applications.

Purpose of the Study:

• To experimentally demonstrate a novel method for generating ultra-narrow linewidth microwave signals from a semiconductor laser.
• To investigate the effectiveness of optical injection and opto-electronic feedback in linewidth reduction.
• To achieve a significant reduction in microwave linewidth without using microwave spectral filters or amplifiers.

Main Methods:

• Utilizing a semiconductor laser subjected to optical injection.
• Implementing an opto-electronic feedback loop without microwave spectral filters or amplifiers.
• Performing single-sideband phase measurements at specific microwave frequencies (25.4 and 45.9 GHz).
• Investigating asymmetric mutual injection for enhanced long-term stability.

Main Results:

• Generation of microwave signals with linewidths below 3 Hz.
• Achieved a tuning range exceeding 35 GHz.
• Demonstrated a reduction in microwave linewidth of six orders of magnitude.
• Obtained single-sideband phase noise measurements of -105 dBc/Hz at 10 kHz offset for 25.4 GHz and -95 dBc/Hz for 45.9 GHz.
• Showcased improved long-term stability through asymmetric mutual injection.

Conclusions:

• Optical injection and opto-electronic feedback provide an effective means to generate ultra-narrow linewidth microwave signals from semiconductor lasers.
• The demonstrated technique offers a simplified approach to linewidth reduction, avoiding the need for microwave spectral filters and amplifiers.
• The method shows promise for applications requiring highly stable and tunable microwave sources.