Enhancement of spectral purity of injection-seeded titanium:sapphire laser by cavity locking and stimulated Brillouin scattering.
We report improvements to and better characterization of the spectral purity of a diode laser injection-seeded, cavity-locked titanium sapphire laser that serves as the source for a previously reported rubidium vapor spectrally filtered Thomson scattering apparatus at 780.24 nm. In a detailed set of measurements the spectral purity P of the laser, defined as the ratio ofthe narrowband component of the laser output to the total output, has been studied as a function of frequency mismatch between the seed laser frequency and the central frequency of the unseeded cavity. It is found that spectral purity exceeding 0.999 can be obtained for a seed-cavity mismatch as high as +/- 0.25 nm, corresponding to approximately 950 cavity longitudinal-mode spacings and as high as approximately 0.9999 for a cavity-seed mismatch in the range +/- 0.10 nm (380 mode spacings). It is also shown that the addition of an external-cavity stimulated Brillouin-scattering phase-conjugate mirror increases both the spectral purity, to a minimum of 0.99999, and the cavity-seed mismatch range, to +/- 0.25 nm, for which this maximum effective purity is obtained.
Lee
Wonchul
W
Department of Mechanical Engineering, Ohio State University, 206 West 18th Avenue, Columbus, Ohio 43210-1337, USA.
Lempert
Walter R
WR