Spaceborne laser filamentation for atmospheric remote sensing

Abstract

A proof-of-concept of space-borne laser filamentation for atmospheric remote sensing is presented. The remote generation of laser filaments from an Earth-orbiting satellite is shown by numerical simulations to be theoretically possible for a large range of laser parameters. The model includes a realistic representation of the stratified atmosphere and accounts for multi-species ionization and the dependence of air density upon the molecule type and altitude profile. The remote generation of a white light continuum extending from 350 nm to 1.1 μm within the filament is demonstrated, and hereby proposed as an atmospheric in-situ light source for monitoring greenhouse gases and pollutants on a global scale by light detection and ranging (lidar) techniques. Scaling laws are also derived for estimating the filament altitude as a function of peak pulse power (3 GW-3 TW), beam radii (10-200 cm) and for three different curvatures (300, 390, 500 km) for femtosecond infrared (800 nm) pulses. We find that operating conditions for remote supercontinuum generation are already available with current ground-based mobile laser technology and within reach of future space laser systems.

Determination of molecular contributions to the nonlinear refractive index of air for mid-infrared femtosecond laser-pulse excitation

“…The most important effects are linear diffraction and dispersion, which spread the frequency components in space and time, respectively, non-linear self-focusing due to the third-order polarization, and ionization contributions [1]. The applications using precise control of filaments are numerous, and include atmospheric measurements [2,3], channeling of high power beams [4], and lightning protection [2,5]. With the recent development of high-power mid-infrared (MIR) laser sources [6,7], there is tremendous interest in harnessing filamentation in this wavelength regime, where many applications in strong-field physics could benefit greatly from the favorable wavelength scaling [8].…”

“…where χ (3) denotes the total (electronic and molecular) third-order susceptibility, and f R denotes the Raman-Kerr (molecular) fraction. The molecular response R(t) is modeled as a damped harmonic oscillator [13] and takes the form of…”

Light self-focusing in the atmosphere: thin window model

“…We would like to stress that there are many challenges in this field related to technological implementations as well as atmospheric propagation that have been discussed in more detail e.g. in 19 20 . Our work should be considered in this general context and as a contribution to possible future solutions of this global problem.…”

Nonlinear rovibrational polarization response of water vapor to ultrashort long-wave infrared pulses

“…This phenomenon has possible applications in longrange free-space optical communication, remote sensing [4,5], synthesis of ultrashort pulses by higher harmonics generation [6,7], and lightning guiding [8][9][10], to name but a few. The atmospheric transparency windows in the mid-wave infrared (MWIR) (3-5 μm) [11,12] and long-wave infrared (LWIR) (8-12 μm) [13,14] regimes are of particular interest.…”