Pulse synthesis in the single-cycle regime from independent mode-locked lasers using attosecond-precision feedback

Area of Science:

• Ultrafast optics
• Laser physics
• Nonlinear optics

Background:

• Ultrafast optical pulse generation is crucial for scientific advancement.
• Synthesizing few-cycle pulses from independent sources presents significant challenges.
• Precise synchronization of pulse timing and phase is essential for coherent combination.

Purpose of the Study:

• To achieve stable synthesis of a nearly single-cycle ultrafast optical pulse train.
• To demonstrate the coherent combination of pulses from a Ti:sapphire laser and a fiber supercontinuum.
• To develop attosecond-precision synchronization techniques for independent laser sources.

Main Methods:

• Coherent combination of a passively mode-locked Ti:sapphire laser (6 fs pulses) and a fiber supercontinuum (8 fs pulses).
• Orthogonal, attosecond-precision synchronization of pulse envelope timing using balanced optical cross-correlation.
• Carrier envelope phase synchronization using balanced homodyne detection.
• Characterization of the synthesized pulse envelope using two-dimensional spectral shearing interferometry (2DSI).

Main Results:

• Generation of a nearly single-cycle (3.7 fs) ultrafast optical pulse train at 78 MHz.
• Successful coherent combination of pulses from independent laser sources.
• Demonstration of attosecond-precision synchronization for both timing and phase.
• Retrieval of a 1.1 optical cycle pulse envelope using 2DSI.

Conclusions:

• This work represents the first stable synthesis of few-cycle pulses from independent laser sources.
• The developed synchronization techniques enable precise control over ultrafast optical pulses.
• The synthesized pulse train has potential applications in various fields requiring high temporal resolution.