arXiv subjects

Benoit Boulanger

Publications and source records attributed to Benoit Boulanger.

7 recordsLinked to original sources

arXiv2026

Photon-triplets for quantum optics generated by a phase-matched third-order difference-frequency mixing in a KTiOPO4 bulk crystal pumped at 532 nm

We report implementation and modelling of an efficient photon-triplets generation experiment based on a difference-frequency-mixing of two picosecond beams at 532 nm and 1491 nm in a type II phase-matched KTP crystal. The photon-triplets flux was measured as a function of the energy of the two incident beams using a coincidence protocol. A maximal flux of 11.6 photon-triplets per second was achieved. These experimental data were satisfactorily described by a semiclassical model based on the quantum fluctuations of vacuum and the classical equations of nonlinear optics.

quant-ph↗

arXiv2025

Epitaxial growth of KTiOAsO4 by pulsed laser deposition for nonlinear frequency conversion

Twin photons and triple photons generations require pump laser intensities of several hundred Mega Watts per square centimeter. Micrometer sized crystalline waveguides allow such interactions to be achieved at relatively low energies by taking advantage of the confinement of light. The materials selected to achieve these phenomena in the present work are from the titanyl phosphate family. The chosen architecture is a micrometric layer of KTA grown on a KTP substrate forming a planar waveguide in a first step. These two isostructural materials have a low lattice parameter mismatch, making it possible to achieve high quality epitaxial growth. The refractive index of KTA being higher than that of KTP, this couple of materials could allow light to be guided in the deposited layer. To grow the KTA film, the chosen technique is pulsed laser deposition (PLD) that allows nonlinear complex oxides layer of optical quality to be grown. In this study, we show that the growth is well oriented for layers with a thickness up to 200 nm after deposition. Then, after annealing, the crystal state is improved as well as the surface. In this study we demonstrate the feasibility of KTA epitaxy over KTP by PLD with good epitaxial quality, good orientation and theoretical phase-matching conditions for a planar KTA waveguide.

physics.optics↗

arXiv2025

Crystal growth, measurement and modeling of the optical activity of $\alpha$-GeO$_2$. Comparison with $\alpha$-SiO$_2$

This work aimed first at growing high quality bulk $\alpha$-GeO$_2$ crystals in their Quartz iso-structural form ($\alpha$-SiO$_2$), using a high temperature flux method. By optimizing the flux composition and the geometry and orientation of the seeds, it has been possible to achieve growth yields up to 90 % leading for the first time to bulk single crystals up to 3.5 cm$^3$. Thanks to the optical quality and size of the obtained crystals, the second step of this study was the measurement of the optical activity of $\alpha$-GeO$_2$ between 0.3 and 2 $\mu$m. This gave access to the value of one of the independent components of the gyration tensor (g33) as a function of the wavelength. An $\alpha$-SiO$_2$ slab have been used to validate our methodology. Both crystals show a magnitude of optical activity of 3.4x10$^{-5}$ rad/$\mu$m in the near IR range and great variations where the higher values are 3.4x10$^{-3}$ rad/$\mu$m and 1.7x10$^{-3}$ rad/$\mu$m at 0.3 $\mu$m for $\alpha$-GeO$_2$ and $\alpha$-SiO$_2$, respectively. The measurements are perfectly described by an empirical model that we propose and which relies on the macroscopic first-order electrical susceptibility and on the pitch of the structural helix compared to the wavelength of light.

physics.optics↗

arXiv2024

Experimental demonstration and modeling of near-infrared nonlinear third-order triple-photon generation stimulated over one mode

Triple Photon Generation (TPG) is a third-order nonlinear optical interaction in which a photon, i.e. the pump, splits into three lower energy photons, i.e. modes 1, 2 and 3. The triplets possess different quantum signatures from those of photon pairs, with a strong interest in quantum information. In the present study, we performed the first experimental demonstration of TPG stimulated over one mode of the triplet, mode 1, the previous work on TPG concerning stimulation over two modes,2 and 3. The nonlinear medium is a KTiOPO4 crystal pumped in the picosecond regime (15 ps, 10 Hz) at a pump wavelength of 532 nm. The stimulation beam is emitted by a tunable optical parametric generator: the phase-matching was found at a stimulation wavelength of 1491 nm, the other two modes of the triplet being both at 1654 nm in orthogonal polarizations. Using superconducting nanowires single photon detectors, the measurement of the polarizations and wavelength signatures of the two generated modes are in full agreement with calculations. It has been possible to generate a total number of photons per pulse on modes 2 and 3 up to 2x10-4, which corresponds to the generation of 10-4 triplets per pulse, or 10-5 triplets per second since the repetition rate is equal to 10 Hz. We interpreted these results in the framework of a model we developed on the basis of the nonlinear momentum operator in the Heisenberg representation under the undepleted pump and stimulation approximation.

quant-ph↗

arXiv2018

Phase-Matched Second Harmonic Generation in a flux grown KTiOPO4 crystal ridge optical waveguide

Type II second-harmonic generation was performed in a 15.8-mm-long KTiOPO4 micrometric ridge waveguide with an average transversal section of 38 micrometer^2. Theoretical predictions are compared with experiments. Strong agreements are obtained for both phase-matching wavelengths and second-harmonic intensity. This work opens wide perspectives for integrated parametric optics.

physics.optics↗

arXiv2017

Nanobob: A Cubesat Mission Concept For Quantum Communication Experiments In An Uplink Configuration

We present a ground-to-space quantum key distribution (QKD) mission concept and the accompanying feasibility study for the development of the low earth orbit CubeSat payload. The quantum information is carried by single photons with the binary codes represented by polarization states of the photons. Distribution of entangled photons between the ground and the satellite can be used to certify the quantum nature of the link: a guarantee that no eavesdropping can take place. By placing the entangled photon source on the ground, the space segments contains only the less complex detection system, enabling its implementation in a compact enclosure, compatible with the 12U CubeSat standard (12 dm3). This reduces the overall cost of the project, making it an ideal choice as a pathfinder for future European quantum communication satellite missions. The space segment is also more versatile than one that contains the source since it is compatible with a multiple of QKD protocols (not restricted to entangled photon schemes) and can be used in quantum physics experiments, such as the investigation of entanglement decoherence. Other possible experiments include atmospheric transmission/turbulence characterization, dark area mapping, fine pointing and tracking, and accurate clock synchronization; all crucial for future global scale quantum communication efforts.

quant-ph↗

arXiv2015

Intrinsic ionic screening of the ferroelectric polarization of KTP

Mobile charges and lattice polarization interact in ferroelectric materials because of the Coulomb interaction between the mobile free charges and the fixed lattice dipoles. We have investigated this mutual screening in KTiOPO4, a ferroelectric/superionic single crystal in which the mobile charges are K+ ions. The ionic accumulation close to the crystal surfaces leads to orders of magnitude increase of the Second Harmonic Generation. This ionic space charge model is supported by the absence of such an effect in non-ionic conductor but ferroelectric BaTiO3, by its temperature dependence in KTiOPO4 and by its broad depletion at domain walls.

cond-mat.mtrl-sci↗