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An optical enhancement method applied to a diode laser photoacoustic trace gas detector is presented. In order to improve the detection sensitivity, the light intensity inside the acoustic resonator is amplified using a Fabry-Perot cavity. A feedback signal stabilizes the laser frequency to the optical cavity length, in order to maintain the light amplification constant during the probe frequency scan. The usefulness of the optical amplifier is demonstrated by showing two ethylene spectra obtained at 1.624μm with and without the optical enhancement. Tens to hundreds ppb (part per billion) sensibility for molecules absorbing in the region between 1.5–1.7μm can be obtained.

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We present the coherent control of the temporal shape of laser pulses obtained by exploiting the propagation dynamics of electromagnetically induced transparency. Temporal compression, as a special case of pulse tailoring, is discussed. We envisage applications in nonlinear optics processes and control of pulse shapes in the vacuum ultraviolet spectral region