Broadening of Gain and Its Bearing on the Laser Subtleties

V R Belan, V V Grigor'yants, M. L. Gurari +2 more

J. R. Boon, Evangelini Zekou, David McGloin +1 more

Inversionless gain is predicted in a Doppler-broadened $V$ scheme for which the probe laser frequency is approximately twice that of the coupling laser. A comparison is made of inversionless gain achieved via electromagnetically induced transparency in Doppler-broadened matched and mismatched wavelength systems. We show that the presence of Doppler broadening does not preclude inversionless lasing for mismatched wavelengths; importantly, this is shown to hold even for Rabi splittings significantly less than the Doppler width. Our analysis demonstrates that inversionless gain is realizable in Doppler-broadened media, at modest continuous wave laser powers, for a probe frequency well in excess of the coupling field frequency. The presented theory is related to a practical mismatched system in atomic rubidium vapor. Approximately 8% gain is predicted in a 422 nm probe field coherently driven by a 780 nm coupling field, in the presence of a modest level of incoherent excitation.

Joseph H. Simmons, Kelly S. Potter

J. Yablon, S. Tseng, M. Salit +1 more

We show how a superluminal ring laser can be realized using an inhomogeneously broadened gain medium with the addition of a dip in the gain profile, for application to enhanced precision rotation sensing and accelerometry.

P. L. Knight

Salim N. Jabr

The spectrum of the stimulated electronic Raman gain at 650 nm in Ne I, pumped by a 633-nm He-Ne cw laser in the same cavity, is derived. The question of the proper Raman-gain linewidth is addressed. It is shown that the gain has a nearly Doppler-free component whose width is measured as 30 +/- 10 MHz (FWHM) at 6 Torr. This value agrees reasonably well with the residual Doppler broadening but not with collisional broadening rates. A simple calculation is included that shows the quantum-limited frequency uncertainty of the 650-nm laser to be higher by a factor of 1.5 than the frequency uncertainty of the 633-nm laser at equal power.