Laser Physics Laboratory

Integrated photonics is an emerging technology for many existing and future telecommunication and data communication applications. One platform of particular interest is silicon nitride (SiN), thanks to—among others—its very low-loss waveguides. However, it lacks active devices, such as lasers, amplifiers, and photodiodes. For this, hybrid or heterogeneous integration is needed. Here, we bring high-speed uni-traveling-carrier photodiodes to a low-loss SiN-platform by means of micro-transfer-printing. This versatile technology for heterogeneous integration not only allows very dense and material-efficient III–V integration but also eases the fabrication, yielding high-performance detectors. The waveguide-coupled photodiodes feature a responsivity of 0.3 A/W at 1550 nm, a dark current of 10 nA, and a bandwidth of 155 GHz at a low bias. At zero bias, a record bandwidth of 135 GHz is achieved. We further demonstrate that this integrated detector can be used for direct photomixing at terahertz frequencies. A back-to-back communication link with a carrier frequency of around 300 GHz is set up, and data rates up to 160 Gbit/s with a low error vector magnitude are shown, showcasing a near-identical performance at zero bias.

The propagation properties of a circular cosh-Gaussian beam (CiChGB) in a fractional Fourier transform (FRFT) optical system are investigated theoretically. The analytical expressions for a CiChGB propagating through apertured and unapertured FRFT systems are derived based on the Collins formula and the expansion of the hard-aperture function into a finite sum of Gaussian functions. From the obtained expressions, the evolution of the intensity distribution at the output plane is analysed with illustrative numerical examples. It is shown that the intensity distribution of the CiChGB propagating in FRFT is closely dependent on the decentred beam parameter and the aperture size besides the fractional order of the FRFT system. The results obtained may be beneficial to applications in laser beam shaping, optical trapping, and micro-particle manipulation.

In this work, the authors report the design and fabrication of photonic crystals of indium tin oxide (ITO) in the visible range. The structures have been obtained using e-beam lithography combined with inductively coupled plasma reactive ion etching in boron trichloride and chlore plasma. They have particularly studied the effect of the process parameters on the hole features. The triangular lattice configuration consisting of air holes radii of 110 nm with a lattice spacing of 290 nm was successfully transferred through the 300-nm-thick hydrogen silsesquioxane resist mask to the 150 nm-thick ITO layer, achieving smooth and vertical sidewalls. The optical characterization, using an end-fire coupling technique, confirmed the existence of a photonic bandgap over 600–800 nm, which is of a great interest to develop new functionalities based on ITO thin films for laser applications in the visible range.

Control of cell death/survival balance is an important feature to maintain tissue homeostasis. Dependence receptors are able to induce either survival or cell death in presence or absence of their ligand, respectively. However, their precise mechanism of action and their physiological importance are still elusive for most of them including the MET receptor. We evidence that pro-apoptotic fragment generated by caspase cleavage of MET localizes to the mitochondria-associated membrane region. This fragment triggers a calcium transfer from endoplasmic reticulum to mitochondria, which is instrumental for the apoptotic action of the receptor. Knock-in mice bearing a mutation of MET caspase cleavage site highlighted that p40MET production is important for FAS-driven hepatocyte apoptosis, and demonstrate that MET acts as a dependence receptor in vivo. Our data shed light on new signaling mechanisms for dependence receptors’ control of cell survival/death balance, which may offer new clues for the pathophysiology of epithelial structures.

We present the experimental realization of a long-lived superfluid flow of a quantum gas rotating in an anharmonic potential, sustained by its own angular momentum. The gas is set into motion by rotating an elliptical deformation of the trap. An evaporation selective in angular momentum yields an acceleration of rotation until the density vanishes at the trap center, resulting in a dynamical ring with ≃350ℏ angular momentum per particle. The density profile of the ring corresponds to the one of a quasi two-dimensional superfluid, with a linear velocity reaching Mach 18 and a rotation lasting more than a minute.

The proteins β1,4GalNAcT II, β1,4-GalT1, FucT I, FucT VI and ST3Gal IV are noted B4GALNT2, B4GALT1, FUT1, FUT6 and ST3GAL4, whereas the corresponding human genes are noted B4GALNT2, B4GALT1, FUT1, FUT6 and ST3GAL4 according to the HUGO nomenclature.

The achievement of single‐channel 100 Gbit/s transmission, using linear unitravelling carrier photodiodes and QAM‐16 modulation format is reported. The wireless link has been done in the indoor case, considering the recent frequency standardised 300 GHz bands.