69 research outputs found
Widely-tunable mid-IR frequency comb source based on difference frequency generation
We report on a mid-infrared frequency comb source of unprecedented tunability
covering the entire 3-10 {\mu}m 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 4.7 {\mu}m wavelength.Comment: 3 pages, 3 figure
Reduced micro-deformation attenuation in large-mode area photonic crystal fibers for visible applications
We consider large-mode area photonic crystal fibers for visible applications
where micro-deformation induced attenuation becomes a potential problem when
the effective area A_eff is sufficiently large compared to lambda^2. We argue
how a slight increase in fiber diameter D can be used in screening the
high-frequency components of the micro-deformation spectrum mechanically and we
confirm this experimentally for both 15 and 20 micron core fibers. For typical
bending-radii (R~16 cm) the operating band-width increases by ~3-400 nm to the
low-wavelength side.Comment: Accepted for Optics Letter
Absolute spectroscopy near 7.8 μm with a comb-locked extended-cavity quantum-cascade-laser
We report for the first time the frequency locking of an extended-cavity quantum-cascade-laser (EC-QCL) to a near-infrared frequency comb. The locked laser source is exploited to carry out molecular spectroscopy around 7.8 μm with a line-centre frequency combined uncertainty of ~63 kHz. The strength of the approach, in view of an accurate retrieval of line centre frequencies over a spectral range as large as 100 cm-1, is demonstrated on the P(40), P(18) and R(31) lines of the fundamental rovibrational band of N2O covering the centre and edges of the P and R branches. The spectrometer has the potential to be straightforwardly extended to other spectral ranges, till 12 μm, which is the current wavelength limit for commercial cw EC-QCLs
- …