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In this paper we present a novel frequency dissemination technique which uses an all-optical interferometer to sense length fluctuations with high precision, and then utilises this information to simultaneously stabilise a transmitted optical and signal and a microwave signal.

We present a novel optical fiber-based radio-frequency distribution system that incorporates low-cost commercially available components. It has a fractional frequency stability of 7×10−17 (averaged over 104 s) for distribution of an 80-MHz signal.

Angular-momentum-dependent isotope shifts in nine high-energy Rydberg levels of xenon have been measured by sub-Doppler two-photon excitation spectroscopy, using narrowband nanosecond pulses of coherent ultraviolet light at 207–209 nm generated by nonlinear-optical conversion processes.

An optical-fibre network is being planned for distribution of optical and microwave reference frequencies in Australia. This network would connect a number of research facilities and the National Measurement Institute (NMI), allowing long-range comparison of frequency standards to high precision and providing reference signals for a wide range of applications. First results for transfer in the laboratory achieve a fractional frequency stability of 7×10−17 at an averaging time of 104 s for the distribution of an 80 MHz radio frequency signal. We present details of the technique used to cancel noise introduced by the fibre, describe the all-digital radio-frequency phasemeter used to characterise performance, and outline plans for the further development of the network.

Output pulses from a Ti:sapphire-amplified OPO are shown to be nearly Fourier-transform-limited with little additional chirp. The power is sufficient to generate narrowband vacuum-ultraviolet radiation (using nonlinear-optical methods) for precision spectroscopy.

There is a need in the context of high-resolution laser spectroscopy for pulsed, tunable, single-longitudinal-mode (SLM) coherent light sources with high peak power and narrow optical bandwidth. This holds particularly in the vacuum ultraviolet (VUV) region, where nonlinear-optical (NLO) upconversion is essential to generate required wavelengths. For instance, narrowband 120-nm VUV radiation, generated by pulsed dye amplification of a cw tunable Ti:sapphire laser and NLO upconversion, has been used [1] to measure the 2 1S ← 1 1S two-photon absorption transition of helium (He) as a test of quantum-electrodynamic theory.

A chirp-controlled nanosecond-pulsed tunable optical parametric oscillator and two-stage Ti:sapphire amplifier generate high-power coherent light at ~840 nm, with frequency stability and narrow optical bandwidth as needed for high-resolution ultraviolet spectroscopy.

We use nonlinear optical processes to generate narrowband light from an optical parametric oscillator, yielding significantly improved frequency stability compared with dye lasers where the chirp arises principally from population inversion. We measure chirp using optical heterodyne detection and minimise it by phase matching, producing a near Fourier-transform limited bandwidth.

We simulate spectro-temporal processes in a nanosecond injection-seeded optical parametric oscillator. Our simulations accurately predict the experimental behavior for the frequency chirp, optical bandwidth, and spectral purity, including effects that are not readily observed directly.

Pulsed optical parametric oscillators (OPOs) are versatile nonlinear-optical (NLO) sources of tunable coherent light for spectroscopic sensing applications. One of our most recent demonstrations of such OPO wavelength control strategies is a novel self-adaptive tunable (SAT) design, in which a photorefractive crystal serves as a phase-conjugate cavity mirror and enables SLM tuning without active variation of OPO cavity length as the TDL seed wavelength /spl lambda//sub seed/ is scanned. We now report further details of the performance of such a SAT OPO, including narrowband spectroscopic characteristics of its idler output at /spl lambda//sub idler/, via cavity ringdown absorption spectra of CO/sub 2/(g) at /spl sim/1.44 /spl mu/m, and of its seeded signal output at /spl lambda//sub signal/, by recording fluorescence-detected Doppler-free two-photon absorption (TPA) spectra of Cs(g) at /spl sim/822 nm.

A new pulsed spectroscopic technique combines optical heterodyne detection with frequency binning. Its utility is demonstrated via Doppler-free two-photon excitation in cesium using an injection-seeded pulsed optical parametric oscillator, operated close to the Fourier-transform limit.

In previous experiments we have guided excited state helium atoms through hollow optical fibres. We employ helium atoms in the metastable 2/sup 3/S/sub 1/ state, and utilise the 1083 nm transition to the 2/sup 3/P/sub 2/ state to manipulate the atomic trajectories. For these atom guiding experiments, metastable helium has the inherent advantages of near unity detection efficiency and low background counts, since metastable helium de-excites on collision with the fibre wall. We have manufactured hollow fibres with a range of dimensions, some of which support single optical mode propagation. The fibres consist of a narrow (few /spl mu/m) light guiding region around the hole, surrounded by a 20-30 /spl mu/m thick region of lower refractive index. Propagation of the lowest order mode has been observed, thereby indicating that a uniform evanescent field can be created on the inside fibre wall. In addition, excitation of the two orthogonal modes has been observed under slightly different input coupling conditions. The resulting output from the fibre yields a hollow optical beam which has the potential to funnel atoms into the fibre. The results of atom guiding experiments using these fibres are presented.

We use high resolution laser spectroscopy and nonlinear optical techniques to perform sub-Doppler resolution measurements of atmospherically important molecules in the vacuum ultraviolet (/spl lambda/

The ARC Centre of Excellence for Quantum-Atom Optics investigates the quantum nature of multiple particle states of atoms and photons. It combines pre-eminent theoretical and experimental research groups in quantum and atom optics at the Australian National University, the University of Queensland and the Swinburne University of Technology.

We use optical heterodyne and nonlinear-optical spectroscopic techniques to measure the near Fourier-transform limited output from a narrowband tunable injection-seeded, pulsed optical parametric oscillator/amplifier system that has a controllable frequency chirp of

Heterodyne technique is used to measure the optical phase characteristics of a ns-pulsed periodically poled KTiOPO/sub 4/ (PPKTP) OPO that is injection-seeded by a cw tunable diode laser (TDL). How frequency chirp in a TDL-seeded PPKTP OPO is affected by various experimental conditions is investigated.

The results of one experiment (Strecker et. al.), is numerically simulated to demonstrate that a mean-field approach is capable of describing an attractive condensate in an area of nonlinear behavior such as soliton creation, and to investigate the soliton interactions by extending the experimental parameters. In the experiment being studied, the released BEC formed a train of multiple solitons which oscillated collectively in a weak harmonic potential for many cycles, each soliton kept apart from its neighbor by the alternating phase structure of the ensemble. This result suggests the possibility of designing a series of self-focussing, phase-engineered coherent matter pulses as the basis of future experiments in non-linear atom optics. Experimentally, a quasi-1D condensate was formed in a box-like potential with significantly tighter confinement in the transverse than the axial dimension. Manipulation of a Feshbach resonance rapidly tuned the scattering length of the atoms from positive to negative, resulting in a condensate which became attractive at, or shortly after, its release. Most of the unconfined atoms were ejected in a burst, leaving behind a small proportion of remnant atoms as solitons. These were allowed to evolve as they propagated along the axial potential of a far red-detuned laser field for a short time before being imaged.

Structure in the continuum of an atomic system attributed to the coupling of a bound state by a strong laser field has been reported elsewhere (1-3). Such experiments have employed a second laser to probe the continuum from the ground state by measuring polarization rotation 0), third harmonic generation (2) or three photon ionization (3). We report here an experiment similar to reference 2 using two photon resonant, third harmonic generation in sodium, perturbed by a second laser which couples the 5s state to the continuum. Under no conditions was any laser induced continuum structure (LICS) observed in these experiments, in contrast to the results reported elsewhere (2).