ABSTRACT
We have observed a large variation with laser polarization in the amount of laser light resonantly backscattered from the Earth's mesospheric sodium layer located at a 90-km altitude. This variation is evidence of optical pumping of mesospheric sodium atoms.
ABSTRACT
Changes in the refractive index of Ti:Al(2)O(3) induced by 10-nsec, 532-nm pump pulses from a frequency-doubled Nd:YAG laser have been measured interferometrically at 632.8 nm for signal polarizations parallel (pi) and perpendicular (sigma) to the c axis. The nonthermal portion of these changes decays on a 3-microsec time scale characteristic of the fluorescence lifetime of Ti(3+). For the sigma polarization, the nonthermal index change is equal to the concentration of excited Ti(3) ions times (4 +/- 2) x 10(-24) cm(3). The change for the pi polarization is lower by a factor of 3.7 +/- 0.6. The average change is consistent with the value estimated from a harmonic oscillator model that considers virtual transitions to a charge-transfer band.
ABSTRACT
The influence of amplified spontaneous emission on the time-dependent gain of a laser amplifier is considered by using a simple model. Experimental measurements of Ti:A1(2)O(3) amplifier gain are in excellent agreement with the model.
ABSTRACT
An I(2)-vapor cell filter and an optical multichannel analyzer were used to investigate inelastic scattering with low-frequency shifts from a Ag electrode that is surface-enhanced Raman-scattering active. We have extended inelastic scattering measurements to ~0.5 cm(-1) from the excitation frequency and have simultaneously monitored the spectral intensity from +60 to -60 cm(-). Attenuation measurements and the observation of I(2)-vapor absorption lines in the data verify that the observed signal is inelastic scattering and not the leakage of elastically scattered light.
ABSTRACT
A new optical technique, based on morphology-dependent peaks in the fluorescence spectra, is-used to determine the evaporation and condensation rates of a linear stream of ethanol droplets. The droplets are monodispersed, in close proximity to one another, and impregnated with fluorescent dye molecules. On irradiation of the droplets with a single N(2) laser pulse, the evaporation or condensation rates can be deduced from the wavelength shift (to the blue or to the red, respectively) of the spectrally narrow (<0.1-nm) structure-resonance peaks in the fluorescence spectra.
ABSTRACT
Inelastic emission characteristics from individual ethanol droplets (60-microm diameter) containing Rhodamine 6G dye and pumped by a cw laser (514.5 nm) were investigated. Laser emission was confirmed by noting the spectral, temporal, and output-versus-input intensity behavior. The liquid-air boundary of the droplets provides the optical feedback at selected wavelengths corresponding to the morphology-dependent resonances of a spherical droplet.
