Sub-picosecond tunable mid-infrared light source for driving high-efficiency optical rectification

Area of Science:

• Optics and Photonics
• Nonlinear Optics
• Terahertz Science

Background:

• Optical rectification (OR) is a key method for generating coherent terahertz (THz) radiation.
• Enhancing OR efficiency is crucial for practical THz applications.
• Mid-infrared (mid-IR) light sources with specific wavelengths and pulse durations are needed for efficient OR.

Purpose of the Study:

• To develop a sub-picosecond mid-IR light source with tailored parameters to enhance OR efficiency.
• To identify optimal pump wavelength and pulse duration for OR using numerical simulations.
• To experimentally demonstrate a high-performance mid-IR light source for efficient OR.

Main Methods:

• Numerical simulations of OR in LiNbO3 with tilted pulse-front excitation.
• Development of a BaGa4Se7-based optical parametric chirped-pulse amplification (OPCPA) system.
• Utilizing a 1030-nm thin-disk laser as the pump source and broadband mid-IR seeds.

Main Results:

• Simulations showed that 4-µm, sub-picosecond pulses approximately double OR efficiency compared to 0.8-µm pulses.
• The developed OPCPA system achieved >200-µJ pulse energy and ~600-fs pulse duration.
• The light source is tunable from 3.5 to 5 µm with a 1-kHz repetition rate.

Conclusions:

• The optimized mid-IR light source significantly enhances optical rectification efficiency.
• The developed light source offers high energy scalability and tunability for efficient OR in various materials.
• This work paves the way for advanced THz generation technologies.