Generation of 400 μW at 17.5 μm using a two-color Yb fiber chirped pulse amplifier

High-power, high-repetition-rate tunable longwave mid-IR sources based on DFG in the OPA regime

We demonstrate high-power longwave mid-IR ultrafast sources based on a high-power Er-fiber laser system at 1.55 µm with a 32-MHz repetition rate. Compared with previous 1.03-µm-driven difference frequency generation (DFG), our current configuration allows tighter focusing in the GaSe crystal thanks to an increased damage threshold at 1.55 µm. Consequently, the 1.55-µm-driven DFG can operate in the regime of optical parametric amplification (OPA), in which the mid-IR power grows exponentially with respect to the square root of the pumping power. We experimentally demonstrate this operation regime and achieve broadband mid-IR pulses that are tunable in the 7.7-17.3 µm range with a maximum average power of 58.3 mW, which is also confirmed by our numerical simulation.

Generation of 8–20 μm Mid-Infrared Ultrashort Femtosecond Laser Pulses via Difference Frequency Generation

Mid-infrared (MIR) ultrashort laser pulses have a wide range of applications in the fields of environmental monitoring, laser medicine, food quality control, strong-field physics, attosecond science, and some other aspects. Recent years have seen great developments in MIR laser technologies. Traditional solid-state and fiber lasers focus on the research of the short-wavelength MIR region. However, due to the limitation of the gain medium, they still cannot cover the long-wavelength region from 8 to 20 µm. This paper summarizes the developments of 8–20 μm MIR ultrafast laser generation via difference frequency generation (DFG) and reviews related theoretical models. Finally, the feasibility of MIR power scaling by nonlinear-amplification DFG and methods for measuring the power of DFG-based MIR are analyzed from the author’s perspective.

Investigation of long wavelength mid-infrared generation in the tight focusing limit

An ultrafast coherent long wavelength MIR source based on difference frequency generation was demonstrated. An average power of 2.5 mW at ∼18 μm was achieved. The angular distribution of the generated MIR source under the condition of tight-focusing limit shows the onset of conical emission of the MIR beam due to on-axis phase mismatching.

Generation of 400 μW at 17.5 µm using a two-color Yb fiber chirped pulse amplifier: erratum

An Erratum is presented to correct the reported [Opt. Lett.36, 1080 (2011)OPLEDP0146-959210.1364/OL.36.001080] power of the generated long wavelength, mid-infrared power.

Milliwatt-level mid-infrared (10.5-16.5 μm) difference frequency generation with a femtosecond dual-signal-wavelength optical parametric oscillator

We demonstrate the generation of mid-infrared radiation using a femtosecond dual-signal-wavelength optical parametric oscillator and difference frequency generation in an extracavity gallium selenide or silver gallium diselenide crystal. This system generates up to 4.3 mW of average mid-infrared power. Its spectra can be tuned to between 10.5 μm and 16.5 μm wavelength (952  cm(-1)-606  cm(-1)) with more than 50  cm(-1) spectral bandwidth. We demonstrate that the power and spectra of this system are temporally very stable.

Tunable mid-infrared source from an ultrafast two-color Yb:fiber chirped-pulse amplifier

We present a tunable, ultrafast, mid-infrared source based on difference frequency between 16 μm and 20 μm from an ultrafast, two-color Yb:fiber chirped-pulse amplifier. We have recorded an average power of 1.5 mW at ∼18  μm. We have improved the output power after the pre-amplifier by one order of magnitude. We present the simulation and experimental results to the pre-amplifier.