Abstract

Amplified spontaneous emission (ASE) has been observed at the Balmer α wavelength from two-photon excited 3S and 3D hydrogen atoms. ASE has several advantages for atom diagnostic measurements in reacting flows compared to resonance enhanced multiphoton ionization or laser-induced fluorescence (LIF). The ASE signal is collimated along the excitation laser beam, which simplifies optical alignment, reduces the necessary optical access, and increases the spectral brightness. These can be significant advantages in reacting flows and material processing plasmas where ion collection probes can alter the process and LIF measurement precision and detectivity is often limited by background optical emission. Simultaneous ASE and LIF measurements in a variety of collisional environments are discussed, which demonstrate the influence of gas collisions on the ASE signal. Bandwidth measurements of the ASE are demonstrated for single laser pulses.

© 1991 Optical Society of America