Coherent ultrafast pulse synthesis between an optical parametric oscillator and a laser

Area of Science:

• Ultrafast Optics and Photonics
• Nonlinear Optics
• Laser Physics

Background:

• Synchronously pumped femtosecond optical parametric oscillators (OPOs) are crucial for generating tunable ultrashort laser pulses.
• Maintaining phase coherence between pump and OPO output is essential for advanced applications like coherent pulse synthesis.
• Environmental noise can destabilize femtosecond laser systems, impacting pulse overlap precision.

Purpose of the Study:

• To demonstrate coherent pulse synthesis between a femtosecond OPO's second-harmonic output and its Ti:sapphire pump laser.
• To achieve high-precision temporal overlap of these ultrashort pulses.
• To enhance the stability of the synthesized pulses against environmental noise.

Main Methods:

• Utilized a single nonlinear crystal for both parametric down-conversion and second-harmonic generation.
• Employed spectral interferometry to optically verify mutual coherence between the pump and OPO pulses.
• Measured the autocorrelation of combined pulses to assess synthesis quality with and without carrier-envelope phase locking.

Main Results:

• Achieved a temporal overlap precision of 30 attoseconds (1% of the optical period) within a 20 ms observation time.
• Demonstrated maximized common-mode rejection of environmental noise by using a single nonlinear crystal.
• Verified mutual coherence and successful pulse synthesis optically.

Conclusions:

• Coherent pulse synthesis is feasible between carrier-envelope phase-locked pulses from a synchronously pumped femtosecond OPO and its Ti:sapphire pump laser.
• A single nonlinear crystal approach effectively minimizes environmental noise, leading to high-precision temporal overlap.
• The demonstrated technique offers a stable and precise method for generating synchronized ultrashort laser pulses.