Path to a 100 kHz 2D IR spectrometer based on a tunable Er fiber front end

Area of Science:

• Physical Chemistry
• Spectroscopy
• Nonlinear Optics

Background:

• Two-dimensional infrared (2D IR) spectroscopy reveals chemical structure and dynamics.
• High-repetition-rate (100 kHz) systems offer improved signal-to-noise and faster data acquisition over lower-rate systems (1 kHz).
• This enables more demanding experiments like 2D IR microscopy.

Purpose of the Study:

• To present a tunable, 100 kHz mid-infrared (mid-IR) light source for 2D IR spectroscopy.
• To demonstrate its utility for advanced spectroscopic investigations.

Main Methods:

• Utilized an Er fiber laser system as the front end.
• Employed a three-stage periodically poled lithium niobate (PPLN) optical parametric chirped pulse amplifier (OPCPA).
• Incorporated Raman shifting in photonic crystal fiber (PCF) for tuning the seed laser.
• Used difference frequency generation (DFG) in a zinc germanium phosphate (ZGP) crystal for mid-IR generation.

Main Results:

• Generated a tunable 100 kHz mid-IR source.
• Achieved tunability of the PPLN seed from 1660 nm to 1760 nm.
• Produced mid-IR outputs tunable from 4 µm to 6.5 µm.
• Supported pulse durations of 42-65 fs.

Conclusions:

• The developed system provides a versatile and efficient source for high-repetition-rate 2D IR spectroscopy.
• It enables faster and more sensitive measurements of chemical dynamics.
• This technology advances the capabilities for studying complex molecular systems.