Highly compact and easy-to-use optical chip interferometer with picometric performances.

In this paper, we present a compact, inexpensive, and easy-to-use optical chip interferometer based on the telecom integrated waveguide technology. The measurement evaluation is focused on the resolution and the noise level of the sensor. The power spectral density of 100 fm Hz-1/2 @ 10 kHz is reached in static conditions. The same level is obtained with the standard Allan deviation for both short and long term measurements. Dynamic performances are also evaluated with sub-nanometer measurements made with piezoelectric systems. The potential bandwidth of the sensor is very high and is currently only limited by electronics (250 kHz).

Compact and accurate concept of laser wavemeters based on ellipsometry.

Common laser wavemeters are based on a scanning Michelson interferometer. Displacements of the moving mirror as long as tens of centimeters are needed to reach a relative accuracy of 1 × 10(-6) (1σ) on the unknown laser wavelengths. Such a long displacement range makes the system very sensitive to mechanical vibrations and to misalignments of the laser beams. The purpose of this paper is to demonstrate a new concept of laser wavemeter based on the measurements of the ellipsometric parameters ψ and Δ of the laser beams. Experimental results show that a 10(-6) (1σ) accuracy level could be reach with a displacement range of only 4 µm. Implementations of the device are described. Comparisons between our polarimetric wavemeter and a calibrated wavemeter are presented for two lasers, an extended cavity laser diode at 656 nm and a 532 nm green line Nd:YAG laser.

Note: Multiscale scanning probe microscopy.

Combining the nanoscopic and macroscopic worlds is a serious challenge common to numerous scientific fields, from physics to biology. In this paper, we demonstrate nanometric resolution over a millimeter range by means of atomic-force microscopy using metrological stage. Nanometric repeatability and millimeter range open up the possibility of probing components and materials combining multiscale properties i.e., engineered nanomaterials. Multiscale probing is not limited to atomic-force microscopy and can be extended to any type of scanning probe technique in nanotechnology, including piezoforce microscopy, electrostatic-force microscopy, and scanning near-field optical microscopy.

Polarimetric interferometer for nanoscale positioning applications.

We propose and demonstrate a displacement control method at the subnanometric scale based on a Michelson interferometer combined with a polarimeter and a phase-locked loop electronic board. Step by step displacements with a step value of 5 nm are presented. A repeatability of 0.47 nm is obtained from back and forth displacements over 1 mum range. We show that a residual ellipticity of less than 10 degrees on the polarization state leads to a positioning error of less than 1 nm. Such system could be used over millimeter range displacements in a controlled surrounding environment leading to numerous applications in nanometrology.

Enlarged atomic force microscopy scanning scope: novel sample-holder device with millimeter range.

We propose a homemade sample-holder unit used for nanopositionning in two dimensions with a millimeter traveling range. For each displacement axis, the system includes a long range traveling stage and a piezoelectric actuator for accurate positioning. Specific electronics is integrated according to metrological considerations, enhancing the repeatability performances. The aim of this work is to demonstrate that near-field microscopy at the scale of a chip is possible. For this we chose to characterize highly integrated optical structures. For this purpose, the sample holder was integrated into an atomic force microscope. A millimeter scale topographical image demonstrates the overall performances of the combined system.

Implementation of the beam reversal technique on compact cesium clocks: towards an improvement in accuracy.

We report the evaluation of the residual phase difference deltaphi in a short (18 cm) Ramsey cavity by implementing the beam reversal technique to an optically pumped cesium beam clock. Deltaphi is measured to be 21 +/- 1.5 microrad, allowing a more accurate evaluation of the frequency performances of this small cesium clock. Finally, the clock accuracy is equal to 1.1 x 10(-13).

Controlling the microwave amplitude in optically pumped cesium beam frequency standards.

Assuming square wave frequency modulation, the response, versus the amplitude of the microwave field, of an optically pumped cesium beam tube is considered. The properties of the first maximum of this response are analyzed. The effect of the neighboring lines is taken into consideration, and a model of the profile of the microwave field in each interaction region is validated. A symmetry property of the response considered is pointed out. It enables us to implement a feedback control of the microwave amplitude with a large depth of the amplitude modulation. Residual frequency offsets that may occur as a consequence of a spurious amplitude modulation correlated with the frequency modulation are assessed. And, with a cavity designed such that sigma=pi between the two oscillatory fields, it also is possible to measure the microwave amplitude at the first maximum of the sole contribution of the reference atomic line.

Transient response following frequency or amplitude switching in a cesium beam tube.

The transient responses of an optically pumped cesium beam tube to square wave frequency and amplitude modulation is considered. The frequency transient is computed assuming a phase difference phi of either 0 or pi between the two oscillatory fields. We present theoretical and experimental data showing that, contrary to the frequency transient, the amplitude transient depends on the direction of switching. The knowledge of this property is useful for the design of the servo-loop controlling the amplitude of the microwave signal applied to the atomic resonator. A justification of this asymmetrical behavior is given. Experimental results confirm the theoretical predictions in the case phi=pi.