Lasers for Mid-IR Generation

DFG process for generation of mid-infrared light

  • Vibrational mid-IR spectroscopy
  • CEO-free frequency comb
  • High harmonic generation
  • Difference frequency generation (DFG)
  • Optical parametric oscillation (OPO)
  • DFG generating 3 - 15 µm
  • OPO generating 1.45 - 4+ µm

The spectral region between optics and electronics lying in the mid-Infrared is difficult to access. Nevertheless it is of great spectroscopic interest because it hosts the majority of molecular finger prints: This important vibrational modes with energies in the spectral range of 670 cm-1 to 4500 cm-1 can be accessed by exciting the sample at wavelengths of 2.2 µm to 15 µm.

TOPTICA's broadband offer

TOPTICA’s ultrafast fiber laser FemtoFiber dichro midIR generates powerful radiation tunable between 3 µm – 15 µm that is ideally suited for spectroscopy and (nearfield) microscopy applications. Based on difference frequency generation (DFG) of two optically synchronized laser pulses at tunable wavelengths of 1 – 2 µm a highly stable broadband emission of approximately 400 cm-1 is generated. Here, the powerful fundamental output at 1560 nm of an Erbium doped ultrafast fiber laser is superimposed with the long or short wavelength part of a supercontinuum which is efficiently generated in a highly non-linear optical materials.

A welcomed side effect of the DFG approach is the elimination of the carrier envelope offset (CEO) of the mode-locked laser: The CEO-free mid-IR laser pulses are therefore applied to attosecond spectroscopy where the extreme UV pulses consist of only a few optical cycles. The conversion of mid-IR radiation to extreme UV is accomplished by high harmonic generation. First, the mid-IR pulses are amplified by several orders of magnitude with optical parametric chirped amplification (OPCPA). Then, the intense laser fields are launched into an atomic beam or a gas-filled hollow core fibre to generate extreme UV attosecond laser pulses via high harmonics

TOPTICA’s high-resolution offer

TOPTICA’s continuous wave TOPO generates powerful radiation tunable between 1.45 - 4+ µm with very narrow spectral width and extremely fine tuning, rendering it the ideal tool for spectroscopy of gas-phase molecules. The TOPO is a continuous wave optical parametric oscillator (OPO). As in DFG, a pump source and signal photons are mixed in a nonlinear crystal to perform downconversion, but in the TOPO the signal is self-generated by the efficient OPO process.
The TOPO is frequently used for gas-phase molecular spectroscopy, as well as mid-IR quantum optics and characterization of mid-IR integrated photonic devices. Additionally, in an exciting new experiment, TOPTICA and collaborators used the TOPO to frequency convert a near-IR dual optical frequency comb source to the mid-IR. Efficient frequency conversion by the TOPO enabled record power per tooth of the optical comb. This high power allowed for extremely fast spectral acquisition time, down to 20 ns, also a world record.