B. Couillaud

Laser frequency stabilization by polarization spectroscopy of a reflecting reference cavity

Abstract We propose a new scheme for locking the frequency of a laser to a resonant reference cavity. A linear polarizer or Brewster plate is placed inside the reference cavity, so that the reflected light acquires a frequency-dependent elliptical polarization. A simple polarization analyzer detects dispersion shaped resonances which can provide the error signal for electronic frequency stabilization without any need for modulation techniques.

Saturation spectroscopy of ultraviolet transitions in mercury with a frequency-doubled cw ring dye laser☆

Abstract Doppler-free saturated absorption spectroscopy has been used to study the ultraviolet HgI transitions 6 3 P 0 -6 3 D 1 at 296.73 nm and 6 3 P 0 -6 1 D 2 at 296.76 nm. The required tunable ultraviolet radiation was produced by a ring cavity cw dye laser with intracavity ADA frequency doubler. The isotope shifts of the 6 3 P 0 -6 3 D 1 line for naturally abundant mercury have been measured to within a few MHz.

A hollow cathode for doppler‐free spectroscopy

We report the design criteria and performance characteristics of a hollow cathode discharge tube developed especially for high‐resolution Doppler‐free laser spectroscopy. The cathode has a large bore diameter (2.7 cm) and operates at a relatively low pressure (0.5 Torr of Ar). Very narrow homogeneous linewidths of refractory element transitions have been observed using this device. It is simple to construct, is easily demountable, and requires a small amount of sample material.

Generation of continuous-wave ultraviolet radiation by sum-frequency mixing in an external ring cavity

We have generated several milliwatts of single-frequency cw UV radiation near 265 nm by mixing the outputs of a rhodamine 6G ring dye laser and a 488-nm argon-ion laser in a crystal of ammonium dihydrogen phosphate. The dye-laser intensity inside the crystal was enhanced by a frequency-locked passive ring cavity, yielding at least a tenfold improvement in UV power over earlier mixing schemes. An envisioned extension to wavelengths near 243 nm is of particular interest for high-resolution two-photon spectroscopy of atomic hydrogen.

High power CW sum-frequency generation near 243 nm using two intersecting enhancement cavities

Abstract We have generated up to 4 mW of single frequency cw ultraviolet (UV) radiation between 243 and 247 nm by mixing the output of an ultraviolet argon-ion laser at 363.8 nm and a red LD 700 dye laser in a 90° phase matched ammonium dihydrogen phosphate crystal. Both the dye laser intensity and the UV laser intensity within the crystal have been enhanced by using two intersecting actively locked passive ring cavities. Wavelengths near 243.1 nm are of particular interest for high resolution spectroscopy of atomic hydrogen.

CW ultraviolet saturation spectroscopy of the 6p 3P0-9s 3S1 transition in mercury at 246.5 nm

Abstract We have measured the even isotope structure of the 6p 3 P 0 -9s 3 S 1 transition in mercury at 246.5 nm using saturated absorption spectroscopy with radiation produced as the sum frequency of a 363.8 nm argon ion laser and an LD700 ring dye laser in ADP. This is the first use of cw sum-frequency mixing in nonlinear laser spectroscopy in the ultraviolet. No previous cw Doppler-free measurements have been reported at wavelenghts below 294.5 nm

High resolution laser spectroscopy of atomic hydrogen

As the simplest of the stable atoms, hydrogen permits unique confrontations between theory and experiment. Precision spectroscopy of hydrogen can be a powerful tool to determine better values of fundamental constants and to probe the limits of basic physics laws. Interest in high resolution laser spectroscopy of atomic hydrogen has been growing during the past two years, as documented by this and several following papers. At least four accurate new measurements of the Rydberg constant have been completed in 1986 [1–4]. Dramatic further improvements in spectral resolution and measurement accuracy should be achievable in the future.

The Hydrogen Atom in a New Light

It is well known that lasers and coherent light techniques have revolutionized high resolution spectroscopy. Today we have at our disposal a powerful arsenal of techniques which can overcome the Doppler broadening of spectral lines, achieving ever higher spectral resolution.1 At Stanford, we have long been fascinated by the prospects of applying such tools to atomic hydrogen.2 As the simplest of the stable atoms, hydrogen permits unique confrontations between experiment and quantum electrodynamic theory. After briefly reviewing past spectroscopic studies of hydrogen, we will report on some recent experimental advances which have opened the door to dramatic future improvements in resolution, creating unprecedented opportunities for precision measurements of fundamental constants and for stringent tests of basic physics laws.

CW Two-Photon Spectroscopy of Hydrogen 1s-2s and New Precision Measurements of Fundamental Constants

The 1s–2s transition of atomic hydrogen has an extremely narrow natural width which can give a resolution of 5 parts in 1016. In this paper we report on the first experiment using continuous wave ultraviolet radiation at 243 nm to excite this transition by Doppler-free two-photon spectroscopy. The resolution of 5 parts in 109 is an order of magnitude better than achieved in any previous measurements, and the continuous wave (cw) excitation opens the way for large improvements in the future: In all experiments until now, the resolution has been limited by the bandwidth of the pulsed lasers which were used to generate the intense tunable ultraviolet (uv) radiation.