Two-optical-cycle pulses in the mid-infrared from an optical parametric amplifier

Area of Science:

• Optics and Photonics
• Mid-Infrared Spectroscopy
• Nonlinear Optics

Background:

• Ultrabroadband mid-infrared (IR) pulses are crucial for various spectroscopic applications.
• Generating tunable, high-energy, and ultrashort mid-IR pulses remains a significant challenge.
• Optical parametric amplifiers (OPAs) offer a versatile platform for generating light across different spectral regions.

Purpose of the Study:

• To generate ultrabroadband mid-IR pulses with high energy and broad tunability.
• To achieve pulse durations in the femtosecond regime, corresponding to a few optical cycles.
• To characterize the generated pulses for potential applications in ultrafast spectroscopy.

Main Methods:

• Utilized an 800 nm pumped optical parametric amplifier.
• Employed periodically poled stoichiometric lithium tantalate (PPSLT) as the nonlinear medium.
• Performed bulk compression using a Germanium (Ge) plate and characterized pulses with frequency-resolved optical gating (FROG).

Main Results:

• Generated ultrabroadband mid-IR pulses with energies up to 2 microJoules.
• Achieved tunability across the 2 to 5 micrometer wavelength range.
• Measured a minimum pulse duration of 25 femtoseconds, corresponding to two optical cycles at 3.6 micrometers.

Conclusions:

• Demonstrated a robust method for generating high-energy, ultrashort, tunable mid-IR pulses.
• The achieved pulse characteristics are suitable for advanced ultrafast spectroscopic investigations.
• Periodically poled stoichiometric lithium tantalate is an effective material for mid-IR OPA generation.