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.
- Article: Attoscience goes OPCPA, Hellerer, Optik & Photonik, 2012
- Article: Eisele, M. et al. Ultrafast multi-terahertz nano-spectroscopy with sub-cycle temporal resolution. Nat. Photonics 8 (2014)
- Article: C. Erny et al., Mid-infrared difference-frequency generation of ultrashort pulses tunable between 3.2 and 4.8 µm from a compact fiber source, Optics Letters 32 (2007)
- Article: A. Gambetta et al., Mid-infrared optical combs from a compact amplified Er-doped fiber oscillator, Optics Letters 33 (2008)
- Article: O. Chales et al., Design and simulation of few-cycle optical parametric chirped pulse amplification at mid-IR wavelengths, Optics Express 16 (2008)
- Article: Liu, S., et al., Mid-infrared time-domain spectroscopy system with carrier-envelope phase stabilization, Appl. Phys. Lett. 103 (2013)
- Article: Benz, A. et al., Strong coupling in the sub-wavelength limit using metamaterial nanocavities, Nat. Commun. 4, (2013)
- Article: Amenabar, I. et al., Structural analysis and mapping of individual protein complexes by infrared nanospectroscopy, Nat. Commun. 4, (2013)
- Article: Keilmann, F., et al., Mid-infrared Frequency Comb Spanning an Octave Based on an Er Fiber Laser and Difference-Frequency Generation. J. Infrared Millim. Terahertz Waves 33 (2012)
- Online Article: Dimitri Basov, Martin Wagner et al: How to control superfast surface plasmons