We report on the capability of a direct detection differential absorption lidar (DIAL) for range resolved and integrated path (IPDIAL) remote sensing of ${\mathrm{CO}}_2$ in the atmospheric boundary layer (ABL). The laser source is an amplified nested cavity optical parametric oscillator (NesCOPO) emitting approximately 8 mJ at the two measurement wavelengths selected near 2050 nm. Direct detection atmospheric measurements are taken from the ground using a 30 Hz frequency switching between emitted wavelengths. Results show that comparable precision measurements are achieved in DIAL and IPDIAL modes (not better than a few ppm) on high SNR targets such as near range ABL aerosol and clouds, respectively. Instrumental limitations are analyzed and degradation due to cloud scattering variability is discussed to explain observed DIAL and IPDIAL limitations.

We demonstrate the first emitter, based on a single optical source device, capable of addressing three species of interest (${\mathrm{CO}}_2$, ${\mathrm{CH}}_4$, and ${\mathrm{H}}_2\mathrm{O}$) for differential absorption Lidar remote sensing of atmospheric greenhouse gases from space in the 2 μm region. It is based on an amplified nested cavity optical parametric oscillator. The single frequency source shows a total conversion efficiency of 37% and covers the 2.05–2.3 μm range.

We demonstrate a nanosecond single-frequency nested cavity optical parametric oscillator (NesCOPO) based on orientation-patterned GaAs (OP-GaAs). Its low threshold energy of 10 μJ enables to pump it with a pulsed single-frequency Tm:YAP microlaser. Stable single-longitudinal-mode emission is obtained owing to Vernier spectral filtering provided by the dual-cavity doubly-resonant NesCOPO scheme. Crystal temperature tuning covers the 10.3–10.9 μm range with a quasi-phase-matching period of 72.6 μm. A first step toward the implementation of this device in a differential absorption lidar is demonstrated by carrying out short-range standoff detection of ammonia vapor around 10.4 μm. Owing to the single-frequency emission, interferences due to absorption by atmospheric water vapor can be discriminated from the analyte signal.

We report on the first microsecond doubly resonant optical parametric oscillator (OPO). It is based on a nested cavity OPO architecture allowing single longitudinal mode operation and low oscillation threshold (few microjoule). The combination with a master oscillator-power amplifier fiber pump laser provides a versatile optical source widely tunable in the 3.3–3.5 μm range with an adjustable pulse repetition rate (from 40 to 100 kHz), high duty cycle ($\cong {10}^{-2}$) and mean power (up to 25 mW in the idler beam). The potential for trace gas sensing applications is demonstrated through photoacoustic detection of atmospheric methane.

We report on infrared quantum counting of photons at optical communication wavelengths based on nondegenerate two-photon absorption in a GaAs photomultiplier tube. The detected photon energy is lower than the GaAs band gap and the energy difference is complemented by a high intensity pump field. This detection setup is simple, compact, has a broad spectral bandwidth, and benefits from the intrinsic low noise and dark counts of large band gap semiconductor junctions.