Ultra broadband microwave frequency combs generated by an optical pulse-injected semiconductor laser

Area of Science:

• Optoelectronics
• Laser Physics
• Microwave Photonics

Background:

• Semiconductor lasers are crucial for generating optical and microwave signals.
• Optical frequency combs offer precise frequency references.
• Broadband microwave signal generation is essential for advanced communication systems.

Purpose of the Study:

• To demonstrate and characterize ultra broadband microwave frequency combs.
• To investigate the impact of optical pulse injection on semiconductor laser dynamics.
• To explore potential applications in frequency conversion and signal broadcasting.

Main Methods:

• Utilizing an optical pulse-injected semiconductor laser system.
• Employing a master laser (ML) with optoelectronic feedback for pulse generation.
• Characterizing comb bandwidth, line spacing, phase noise, and timing jitter.
• Exploring frequency conversion and signal broadcasting feasibility.

Main Results:

• Achieved microwave frequency combs with >20 GHz bandwidth and tunable spacing (990 MHz–2.6 GHz).
• Measured SSB phase noise of -60 dBc/kHz at 200 kHz offset.
• Demonstrated >25 dB noise suppression and obtained 29 ps pulsewidth with 18.7 ps timing jitter.
• Observed linear conversion gain increase with signal power (0.81 dB/dBm).

Conclusions:

• Optical pulse injection is an effective method for generating ultra broadband microwave frequency combs.
• The generated combs exhibit favorable characteristics for advanced applications.
• The system shows promise for frequency conversion and signal broadcasting applications.