Mode splitting and the coherent instability in high-gain lasers

Journal Article · Tue Jan 01 04:00:00 EST 1985 · J. Opt. Soc. Am. B: Opt. Phys.; (United States)

DOI:https://doi.org/10.1364/JOSAB.2.000120· OSTI ID:5811604

Minden, M L; Casperson, L W

A high-gain continuous-wave laser may exhibit an output instability in the form of a periodic pulse train or chaotic signal. In the time domain, the instability is interpreted as resulting from the inability of the medium's polarization to respond quickly enough to perturbations in the optical field of the cavity. In the frequency domain, it can be interpreted as arising from the splitting of a single longitudinal mode into several oscillating lines, each of which satisfies the same cavity resonance condition as the original mode. We show that the mode-splitting interpretation of the instability yields a new understanding of the complex behavior reported in xenon, helium--xenon, and helium--neon lasers. The fundamental frequencies of the instability and the possibility of chaotic output are shown to be consistent with unequally spaced resonant modes that arise close to the laser threshold. With saturation, nonresonant harmonics of the fundamental frequencies appear in the laser output. These harmonics have fixed phases relative to the resonant modes and lead to the complex asymmetries of the pulse shapes. Interaction between the resonant and nonresonant modes can trigger period doubling in the pulse train.

• Research Organization: Hughes Research Laboratories, 3011 Malibu Canyon Road, Malibu, California 90265
• OSTI ID: 5811604
• Journal Information: J. Opt. Soc. Am. B: Opt. Phys.; (United States), Journal Name: J. Opt. Soc. Am. B: Opt. Phys.; (United States) Vol. 2:1; ISSN JOBPD
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420300* -- Engineering-- Lasers-- (-1989)
AMPLIFICATION
GAIN
HARMONICS
INSTABILITY
LASERS
OSCILLATION MODES
OSCILLATIONS