Selective Optical Addressing of Nuclear Spins through Superhyperfine Interaction in Rare-Earth Doped Solids.

In Er^{3+}:Y_{2}SiO_{5}, we demonstrate the selective optical addressing of the ^{89}Y^{3+} nuclear spins through their superhyperfine coupling with the Er^{3+} electronic spins possessing large Landé g factors. We experimentally probe the electron-nuclear spin mixing with photon echo techniques and validate our model. The site-selective optical addressing of the Y^{3+} nuclear spins is designed by adjusting the magnetic field strength and orientation.

Large efficiency at telecom wavelength for optical quantum memories.

We implement the ROSE protocol in an erbium-doped solid, compatible with the telecom range. The ROSE scheme is an adaptation of the standard two-pulse photon echo to make it suitable for a quantum memory. We observe a retrieval efficiency of 40% for a weak laser pulse in the forward direction by using specific orientations of the light polarizations, magnetic field, and crystal axes.

Time reversal of optically carried radiofrequency signals in the microsecond range.

The time-reversal (TR) protocol we implement in an erbium-doped YSO crystal is based on photon echoes but avoids the storage of the signal to be processed. Unlike other approaches implying digitizing or highly dispersive optical fibers, the proposed scheme reaches the μs range and potentially offers high bandwidth, both required for RADAR applications. In this Letter, we demonstrate faithful reversal of arbitrary pulse sequences with 6 μs duration and 10 MHz bandwidth.

Emission of photon echoes in a strongly scattering medium.

We observe the two- and three-pulse photon echo emission from a scattering powder, obtained by grinding a Pr3+:Y2SiO5 rare earth doped single crystal. We show that the collective emission is coherently constructed over several grains. A well defined atomic coherence can therefore be created between randomly placed particles.

Diode laser extended cavity for broad-range fast ramping.

A novel design for an extended-cavity diode laser is presented. The cavity contains an electro-optic prism for synchronous tuning of the cavity length and the grating's incident angle. A simple analysis of the cavity is presented.

Measuring time-domain optical response functions with an optimized sampling rate.

We propose a time-domain interferometry method that circumvents the usual sampling rate condition. It was devised for the retrieval of fast optical response functions in low-repetition-rate experiments. Its potential temporal dynamic range matches the spectral resolution and bandwidth requirements of the arbitrarily shaped spectral filters that are engraved in amorphous spectral hole-burning materials.

Time-to-frequency Fourier transformation with photon echoes.

We propose to use photon echoes in rare-earth-doped crystals to implement the Fourier-transform chirp algorithm. The process is considered for application to spectral analysis of fast radio-frequency signals. Compared with surface acoustic wave devices, the proposed scheme gives access to the larger bandwidths of rare-earth-doped crystals and greater flexibility.

Demonstration of a radio-frequency spectrum analyzer based on spectral hole burning.

Spectral hole-burning (SHB) technology is considered for >10-GHz instantaneous bandwidth signal-processing applications. In this context we report on what is believed to be the first demonstration of a SHB microwave spectrometer. A set of gratings engraved in a SHB crystal is used to filter one sideband of the optically carried microwave signal.

Active stabilization of a rapidly chirped laser by an optoelectronic digital servo-loop control.

We propose and demonstrate a novel active stabilization scheme for wide and fast frequency chirps. The system measures the laser instantaneous frequency deviation from a perfectly linear chirp, thanks to a digital phase detection process, and provides an error signal that is used to servo-loop control the chirped laser. This way, the frequency errors affecting a laser scan over 10 GHz on the millisecond timescale are drastically reduced below 100 kHz.

Wideband and high-resolution coherent optical transients with a frequency-agile laser oscillator.

We report what is believed to be the first experimental demonstration of a wideband spectral coherent process driven by a frequency-agile laser in a rare-earth-ion-doped crystal. The very demanding chirp-transform algorithm is studied in detail and is applied to radio-frequency spectral analysis. A time-bandwidth product of 24,000 is demonstrated.

Photon echoes in an amplifying rare-earth-ion-doped crystal.

We report what we believe is the first experimental demonstration of photon echoes in an amplifying rare-earth-ion-doped crystal. Population inversion is achieved by optical pumping, which yields high-power photon echoes, with an energy gain of as much as a factor of 5. Effects of the pump on the photon echo process highlight the advantages of an amplifying crystal.

Wideband versatile radio-frequency spectrum analyzer.

Operation of a wideband, versatile optical spectrum analyzer for radio-frequency (RF) signals is demonstrated. The device is based on spectral hole burning (SHB). The demonstration features 2.

Time domain investigation on vibrational dephasing and spectral diffusion in CO-doped solid N2.

Infrared picosecond accumulated photon echo experiments have been performed for the first time, using the Orsay Free Electron Laser, on the v = 0-->v = 1 transition of CO in solid nitrogen. The vibrational dephasing time is found to be exceptionally long ( T2>/=120 ns) at low temperature. The analysis of the observed spectral diffusion leads one to assume different energy transfer mechanisms depending on the CO concentration.