Time-interval analysis of laser-pulse-timing fluctuations.

Area of Science:

• Physics
• Optical Engineering
• Laser Technology

Background:

• Mode-locked lasers are crucial for various scientific applications.
• Accurate measurement of pulse-timing fluctuations (phase noise) is essential for laser performance.
• Existing methods may have limitations at low Fourier frequencies.

Purpose of the Study:

• To introduce and demonstrate a novel technique for measuring pulse-timing fluctuations in mode-locked lasers.
• To extend phase noise analysis to low Fourier frequencies (1 mHz–1 MHz).
• To achieve high dynamic range in phase noise measurements.

Main Methods:

• Utilizing zero-dead-time counters for precise measurement of time intervals between laser pulses.
• Referencing measurements to a stable atomic oscillator for high accuracy.
• Combining the new timing measurement with time-domain demodulation techniques.

Main Results:

• Successfully demonstrated a new technique for measuring low-frequency pulse-timing fluctuations.
• Estimated the phase-noise power spectral density of a mode-locked Cr:LiSAF laser.
• Achieved a 240-dB dynamic range in the measurements over the 1-mHz-1-MHz frequency range.

Conclusions:

• The proposed technique offers a precise and effective method for characterizing laser phase noise at low frequencies.
• This advancement can improve the performance and understanding of mode-locked lasers in demanding applications.
• The high dynamic range enables detailed analysis of noise sources affecting laser stability.