RF injection locked 18 GHz regeneratively mode-locked semiconductor laser.

Area of Science:

• Optoelectronics
• Laser Physics
• Fiber Optics

Background:

• Mode-locked fiber lasers are crucial for various applications requiring precise optical pulses.
• Achieving low timing jitter and amplitude fluctuation is essential for high-performance laser systems.
• Regenerative driving and RF injection locking are advanced techniques for laser stabilization.

Purpose of the Study:

• To present a semiconductor-based fiber ring cavity mode-locked laser.
• To investigate the impact of radio frequency (RF) injection locking on laser phase noise and timing jitter.
• To optimize laser performance by analyzing the relationship between injected RF power and noise characteristics.

Main Methods:

• A semiconductor-based fiber ring cavity laser was constructed and regeneratively driven at 18 GHz.
• Radio frequency (RF) injection locking was employed using an external 18 GHz source.
• Phase noise and amplitude fluctuation were measured across different frequency ranges.
• The laser's noise response to varying injected RF power levels was systematically studied.

Main Results:

• The mode-locked laser operated with an optical spectrum centered at 1578 nm.
• Integrated timing jitter was measured as low as 10.8 fs (100 Hz to 20 MHz).
• Integrated amplitude fluctuation remained below 0.02% (100 Hz to 20 MHz).
• RF injection power significantly reduced phase noise, with optimal jitter 40 dB lower than cavity regenerated power.

Conclusions:

• The presented semiconductor fiber ring laser demonstrates excellent timing stability and low phase noise.
• RF injection locking is a highly effective method for suppressing timing jitter in mode-locked fiber lasers.
• Optimizing RF injection power is critical for achieving state-of-the-art laser performance in terms of noise reduction.