Phase-matching-free pulse retrieval based on transient absorption in solids

Area of Science:

• Ultrafast optics
• Nonlinear optics
• Spectroscopy

Background:

• Characterizing ultrashort and ultra-broadband pulses is crucial for scientific advancement.
• Existing techniques often face limitations such as phase-matching constraints or restricted spectral ranges.

Purpose of the Study:

• To introduce a novel pulse characterization technique free of phase-matching constraints.
• To enable the characterization of low-intensity, ultra-broadband pulses across extended spectral ranges.

Main Methods:

• Utilizing transient absorption in solids as an ultrafast optical switch in a pump-probe setup.
• Employing ptychography to retrieve temporal profiles of probe pulses and the optical switch.
• Demonstrating the technique with pulses from a titanium-sapphire amplifier and an optical parametric amplifier.

Main Results:

• Successful characterization of pulses from 0.5 to 20 μm (five octaves) using zinc selenide (ZnSe).
• Measurement of ultrashort pulses with durations down to sub-two optical cycles.
• Characterization of pulses with energies as low as a few nanojoules across various wavelengths (0.77, 1.53, 1.75, 4, and 10 μm).

Conclusions:

• The developed technique offers a versatile and sensitive method for characterizing ultra-broadband pulses.
• This approach overcomes limitations of traditional methods, extending pulse characterization capabilities.
• Enables detailed analysis of ultrashort laser pulses across a wide spectral range.