9  μm few-cycle optical parametric chirped-pulse amplifier based on LiGaS₂

Area of Science:

• Laser Physics
• Nonlinear Optics
• Materials Science

Background:

• Ultrafast lasers operating in the long-wavelength mid-infrared (mid-IR) spectral region are crucial for various scientific applications.
• Existing technologies often face limitations in pulse energy, average power, and spectral coverage.
• Development of efficient amplification techniques for long-wavelength mid-IR pulses is an active area of research.

Purpose of the Study:

• To demonstrate a novel optical parametric chirped-pulse amplifier (OPCPA) system for generating few-cycle pulses in the long-wavelength mid-IR.
• To utilize lithium gallium sulfide (LiGaS2) crystals as the gain medium for mid-IR generation.
• To leverage a 1 µm Yb:YAG laser as the pump source for high-repetition-rate operation.

Main Methods:

• Implementation of a 1 µm Yb:YAG laser operating at a 10 kHz repetition rate as the pump source.
• Utilizing LiGaS2 crystals within an OPCPA architecture to achieve parametric amplification.
• Employing an interferometric autocorrelator for precise measurement of the generated ultrashort pulse duration.

Main Results:

• Successful generation of mid-IR pulses centered at 9 µm with a pulse energy of 1.4 µJ and an average power of 140 mW.
• Achieved an ultrashort pulse width of 142 fs, corresponding to fewer than 5 optical cycles at 9 µm.
• Demonstrated the first long-wavelength mid-IR OPCPA pumped by a 1 µm laser system.

Conclusions:

• The developed LiGaS2-based mid-IR OPCPA system represents a significant advancement in ultrafast laser technology.
• This work paves the way for energy and power scaling of ultrafast long-wavelength mid-IR lasers.
• The use of readily available 1 µm pump lasers offers a practical route for future development and application.