A. L. Schawlow

Cooling of gases by laser radiation

It is shown that a low-density gas can be cooled by illuminating it with intense, quasi-monochromatic light confined to the lower-frequency half of a resonance lines Doppler width. Translational kinetic energy can be transferred from the gas to the scattered light, until the atomic velocity is reduced by the ratio of the Doppler width to the natural line width.

Saturation spectroscopy in molecular iodine by intermodulated fluorescence

Abstract The hyperfine structures of the P(13)R(15) (43−0) lines (5145A) in molecular iodine were observed at very low pressures using a new saturated fluorescence technique. Two oppositely-directed beams from the same laser are chopped at different frequencies and the modulation of the fluorescence is monitored at the sum frequency.

Absolute measurement of very low sodium-vapor densities using laser resonance fluorescence*

By use of a cw dye laser, the resonance-fluorescence method is used to make absolute density measurements of sodium vapor from 102 atoms/cm3 at −28 °C to 1011 atoms/cm3 at 144 °C. The results are compared with other measurements at higher temperature by a thermodynamic analysis. A new vapor-pressure curve is derived, which is slightly different from previous curves based on the higher-temperature measurements. The application of laser resonance fluorescence to other species is also discussed. In particular, a scheme for detecting sodium-quark atoms, if they exist, with a sensitivity of nq/nB ~ 10−15, is proposed.

Two-photon spectroscopy of Na 3s-4d without Doppler broadening using a cw dye laser

Abstract We have observed the optically forbidden 3s-4d transition in sodium vapor, using two-photon excitation with a cw dye laser and monitoring the 4d population via fluorescence cascades. High resolution spectra without Doppler broadening and line widths of less than 30 MHz were obtained with two counter-propagating laser beams, whose Doppler shifts cancel. We have measured the 4d fine structure splitting to be 1035 ± 10 MHz.

Composite Rod Optical Masers

A new optical maser structure is described which reduces the threshold pumping power and increases the available output. It consists of a composite rod, which has a core of maser material (e.g., ruby) covered by a coaxial sheath of transparent refractive material (e.g., sapphire). Refraction of pumping light by the sheath is shown to increase the intensity at the active core. The structure also facilitates cooling by providing an increased surface area.

Digital wavemeter of cw lasers

The ratio of an unknown laser wavelength to that of a standard is quickly determined by a two-beam interferometer with a corner-cube reflector moving on an air track. Standard and unknown wavelength beams travel identical paths in opposite directions, so refractive index corrections are minimized. Accuracy is about six parts in 10/sup 8/. Absolute measurements of some iodine hyperfine component wavelengths are reported.

An improved wavemeter for cw lasers

We report on a modified version of our previous moving mirror wavelength measuring interferometer. Its accuracy has been experimentally confirmed to one part in 108. The device is simple and seems ideally suited for cw lasers.

Three-photon-excited fluorescence detection of atomic hydrogen in an atmospheric-pressure flame

By using three-photon excitation at 291.7 nm of the n = 4 hydrogen level and observing Balmer-beta radiation at 486.1 nm, hydrogen atoms in an atmospheric C(2)H(2)/O(2) flame have been detected. Other schemes for hydrogen detection were also tried, and the results are discussed.

IMAGE AMPLIFICATION BY DYE LASERS

Wide‐angle high‐gain image amplification has been achieved with several organic dye solution lasers. Rhodamine 6G, rhodamine B, or fluorescein disodium salt in ethanol, side pumped by a nitrogen laser, were used. With excitation pulses of 10−4 J and an active volume of about 1.3×0.1×0.1 mm3, a single‐pass gain of 23 dB/mm and a diffraction‐limited resolution of more than 104 distinguishable spots have been observed.

Scanning pulsed-polarization spectrometer applied to Na 2

We report on a computer-controlled system for pulsed-polarization-labeling spectroscopy using a Fizeau-wedge wavemeter and a scanned narrow-band probe. Constants for n=3-7 Σ1g+ states in Na2 are presented.