Single-stage MHz mid-IR OPA using LiGaS₂and a fiber laser pump source

Area of Science:

• Optics and Photonics
• Laser Physics
• Spectroscopy

Background:

• Mid-infrared (mid-IR) radiation is crucial for molecular spectroscopy.
• Generating tunable, high-repetition-rate mid-IR pulses efficiently remains a challenge.

Purpose of the Study:

• To design and characterize a novel, single-stage optical parametric amplifier (OPA) for tunable mid-IR generation.
• To provide a convenient source for high-throughput ultrafast infrared spectroscopy.

Main Methods:

• Utilized a 1 MHz, 1033 nm fiber laser as the pump source.
• Employed collinear, Type I amplification in lithium gallium sulfide (LGS).
• Seeded the OPA with a super-continuum generated in yttrium aluminum garnet (YAG).

Main Results:

• Achieved tunable mid-IR output from 3-7.5 μm.
• Generated pulses with >10 nJ energy, 85-165 cm⁻¹ bandwidth, and 140-540 fs duration.
• Isolated the mid-IR idler beam as the output.

Conclusions:

• The single-stage OPA is a simple and effective source of tunable mid-IR radiation.
• The system is well-suited for high-repetition-rate, ultrafast infrared spectroscopy applications.
• Demonstrated a practical approach for generating versatile mid-IR laser sources.