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We demonstrate the broadband operation and beam calibration over 70nm tuning range of an optical phased array (OPA) fabricated in a generic InP photonic integration platform, which enables multi-wavelength OPA operation. The broadband performance was demonstrated on an 8-channel OPA, whose calibration and phase modulator characterization were executed through near-field and far-field measurements. The architecture reported here is scalable, and the results are promising for reducing the complexity of calibration and control of large-scale OPAs for their use at multiple wavelengths, for example, for spectral imaging or 2D beam steering through dispersive gratings.

The autoionising series 6pnf (J=2, 3, 4) and 6pnh (J=4, 5, 6) of barium have been studied in an atomic beam using multistep laser excitations from the 6s5d and 5d2 1G4 metastable states. Level assignments were made assuming jK coupling and using calculations of electric quadrupole splittings resulting from the long-range electrostatic interaction as well as calculated oscillator strengths. Effects of the interactions between the 6p1/2nf, h and 6p3/2 nf,h series as well as between the 6pnf and 6pnp configurations could be observed.

Recent, partly unpublished results obtained with CW high resolution laser-atomic-beam spectroscopy on the 1snp bound Rydberg series of 3,4He and on autoionising 5dnf series of Ba, excited field free as well as in the presence of an electric field, will be reviewed. In the He 1snp series isotope shift, hyperfine structure and linear Stark effect were investigated. Ba 5dnf series show extremely narrow linewidths enabling the first observation of hyperfine structure, isotope shift and resolved angular momentum manifolds in autoionising series.

Accurate values for the energies and linewidths of the 5dnf J=5, 4 (n=4-50) autoionising Rydberg series of neutral barium have been collected using either a single-mode CW ring dye laser or a Nd:YAG pumped pulsed dye laser and a beam of neutral atoms in the metastable 5d2 1G4 and 5d2 3F states. The interactions between series within the configuration converging to the 5d3/2 and 5d5/2 ionisation limits as well as the continuum interactions (for J=5) have been analysed using multichannel quantum defect theory (MQDT) in the 'phaseshifted reaction matrix' formalism. Good agreement between experiment and MQDT calculations is obtained; however, not all interaction parameters could be determined from the available data.

We report the first observation of hyperfine structure and isotope shift in autoionizing states. This structure was investigated in the 5d32nf J=4,5 (n=36-40) barium Rydberg series, excited from the recently localized metastable 5d2G41 level. An isotope-selective detection method was used in a cw laser spectroscopic experiment on a collimated atomic beam. The experimental data provide valuable additional information for the analyses of these doubly excited series. © 1988 The American Physical Society.

The 5 dnd and 5 dngJ=2, 3 and 4 as well as the 5 dnsJ=2 autoionising series of barium have been studied with two-step pulsed laser excitations in an atomic beam. Dipole moments and the interactions with the 6 s∈l continua were fitted starting from existing Multi-channel Quantum Defect Theory (MQDT) analyses. The interactions of the 5 dndJ=4 and 2, and 5 dnsJ=2 series with 6 sεgJ=4 and 6 sεdJ=2 continua could be analysed succesfully. © 1989 Springer-Verlag.