— We report improved stabilization results for and progress toward a more accurate frequency measurement of the 532 nm iodine-stabilized system based on a frequency-doubled Nd : YAG ring laser. We confirm the CCL-adopted frequency well within its stated uncertainty (640 kHz).
A technique is presented for generating optical frequency combs centered at arbitrary wavelengths by use of cross-phase modulation (XPM) between a femtosecond pulse train and a cw laser beam by copropagating these signals through an optical fiber. We report results from use of this method to place a 90-MHz frequency comb on an iodine-stabilized Nd:YAG laser… (More)
A simple external-cavity quantum cascade laser utilizing optical feedback from a partial reflector is reported. Using a ~9.6μm QCL and off-the-shelf optics we demonstrate single-mode continuous tuning of 2.46cm<sup>-1</sup> with ~40mW power and ~2.5MHz linewidth.
Utilizing a broadly-tunable external cavity quantum cascade laser for scattering-type scanning near-field optical microscopy (s-SNOM), we measure infrared spectra of particles of explosives by probing characteristic nitro-group resonances in the 7.1-7.9 µm wavelength range. Measurements are presented with spectral resolution of 0.25 cm(-1), spatial… (More)
A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D 2 O and HDO at a rate of 40 Hz (25-ms measurement time). The chemical mixtures were generated by evaporating D 2 O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H 2 O to produce… (More)
We present a tunable diode laser absorption spectrometer (TDLAS) sensor for hydrogen fluoride (HF) detection at ambient pressure operating around the fundamental R(1) transition at 2.476 μm. We achieve 38 ppt sensitivity for 1-s integration time.
The small size, high power, promise of access to any wavelength between 3.5 and 16 microns, substantial tuning range about a chosen center wavelength, and general robustness of quantum cascade (QC) lasers provide opportunities for new approaches to ultra-sensitive chemical detection and other applications in the mid-wave infrared. PNNL is developing novel… (More)