We study exciton (EX) dynamics in single-walled carbon nanotubes (SWNTs) included in polymethylmethacrylate by two-color pump-probe experiments with unprecedented temporal resolution. In the semiconducting SWNTs, we resolve the intersubband energy relaxation from the EX2 to the EX1 transition and find time constants of about 40 fs. The observation of a photoinduced absorption band strictly correlated to the photobleaching of the EX1 transition supports the excitonic model for primary excitations in SWNTs. We also detect in the time domain coherent oscillations due to the radial breathing modes at $\approx 250{\mathrm{cm}}^{-1}$.

We report on a mid-IR frequency comb source of unprecedented tunability covering the entire 3–10 μm molecular fingerprint region. The system is based on difference frequency generation in a GaSe crystal pumped by a 151 MHz Yb:fiber frequency comb. The process was seeded with Raman-shifted solitons generated in a highly nonlinear suspended-core fiber with the same source. Average powers up to 1.5 mW were achieved at the 4.7 μm wavelength.

By means of a difference-frequency-generation (DFG) process driven by a two-branch Er-doped fiber laser at a stabilized $100\mathrm{MHz}$ repetition rate, broadly tunable pulses from $5\text{to}12\mu \mathrm{m}$ are generated with an unprecedented power level of around $100\mu \text{W}$. The mid-IR pulse train is expected to exhibit an harmonic comb structure as a result of the cancellation of the carrier-envelope offset frequency resulting from the DFG process.

A highly simplified architecture for stimulated-Raman-scattering microscopy is demonstrated, where multiple tunable narrowband picosecond pulses are generated by spectral compression of femtosecond pulses emitted by a single compact Er-fiber oscillator. The system provides high sensitivity $\left(2\times {10}^{-7}\right)$ and spectral resolution $\left(\text{sub-}15{\text{cm}}^{-1}\right)$, and it offers an unprecedented flexibility for multicolor imaging.

We report on the generation of mid-infrared (mid-IR) pulses with a maximum average optical power of 4 mW and wide tunability in the 8–14 μm range via difference frequency generation (DFG) in GaSe from an Er:fiber laser oscillator. The DFG process is seeded with self-frequency shifted Raman solitons that are shown to be phase coherent within the whole tuning range, from 1.76 to 1.93 μm. Interference measurements between adjacent pulses at the idler wavelengths attest coherence transfer to the mid-IR.