Observation of Algebraic Time Order for Two-Dimensional Dipolar Excitons

Emergence of algebraic quasi-long-range order is a key feature of superfluid phase transitions at two dimensions. For this reduced dimensionality interactions prevent Bose-Einstein condensation with true long range order, at any finite temperature. Here, we report the occurence of algebraic order in a strongly interacting quantum liquid formed by dipolar excitons confined in a bilayer semiconductor heterostructure. We observe a transition from exponential to algebraic decay of the excitons temporal coherence, accompanied by a universal scaling behaviour of the equation of state. Our results provide strong evidence for a Berezinskii-Kosterlitz-Thouless (BKT) transition in a multi-component boson-like system governed by strong dipolar interactions

Ultra-Strong Light-Matter Coupling in Deeply Subwavelength THz LC Resonators

International audienceThe ultra-strong light-matter coupling regime has been demonstrated in a novel three-dimensional inductor-capacitor (LC) circuit resonator, embedding a semiconductor two-dimensional electron gas in the capacitive part. The fundamental resonance of the LC circuit interacts with the intersubband plasmon excitation of the electron gas at ω c = 3.3 THz with a normalized coupling strength 2Ω R /ω c = 0.27. Light matter interaction is driven by the quasi-static electric field in the capacitors, and takes place in a highly subwavelength effective volume V eff = 10 −6 λ 3 0. This enables the observation of the ultra-strong light-matter coupling with 2.4 × 10 3 electrons only. Notably, our fabrication protocol can be applied to the integration of a semiconductor region into arbitrary nano-engineered three dimensional meta-atoms. This circuit architecture can be considered the building block of metamaterials for ultra-low dark current detectors

Mixing Properties of Room Temperature Patch‐Antenna Receivers in a Mid‐Infrared (λ ≈ 9 µm) Heterodyne System

A room‐temperature mid‐infrared (λ = 9 µm) heterodyne system based on high‐performance unipolar optoelectronic devices is presented. The local oscillator (LO) is a quantum cascade laser (QCL), while the receiver is an antenna coupled quantum well infrared photodetector optimized to operate in a microcavity configuration. Measurements of the saturation intensity show that these receivers have a linear response up to very high optical power, an essential feature for heterodyne detection. By providing an accurate passive stabilization of the LO, the heterodyne system reaches at room temperature the record value of noise equivalent power (NEP) of 30 pW at 9 µm and in the GHz frequency range. Finally, it is demonstrated that the injection of microwave signal into the receivers shifts the heterodyne beating over the large bandwidth of the devices. This mixing property is a unique valuable function of these devices for signal treatment in compact QCL‐based systems

THz detectors based on electromechanical meta-atoms

International audienc

Polarization- and diffraction-controlled second-harmonic generation from semiconductor metasurfaces

International audienc

Harmonic generation with multi-layer dielectric metasurfaces

Metasurfaces have recently gained extensive interest because of their extraordinary optical behavior as artificial material interfaces with ultrahigh compactness. In this framework, dielectric platforms have newly become very promising for nonlinear nanophotonics, providing opportunities, especially for ultrafast optical switching, and high harmonic generation, opening the research field of nonlinear metaoptics. Up to now, nonlinear metaoptics have been mostly explored using single metasurfaces. However, in a long-term vision, the stacking of optical metasurfaces, very challenging in terms of fabrication, is one key goal of this research field. Here, we demonstrate a three-layer metasurface in the AlGaAs-on-insulator platform, which improves the second harmonic generation efficiency by more than one order of magnitude with respect to its one-layer counterpart. Our achievement paves the way toward phase-shaping multilayer and multifunctional all-dielectric metasurfaces

High temperature metamaterial terahertz quantum detector

We demonstrate a high-temperature performance quantum detector of Terahertz (THz) radiation based on three-dimensional metamaterial. The metamaterial unit cell consists of an inductor-capacitor (LC) resonator laterally coupled with antenna elements. The absorbing region, consisting of semiconductor quantum wells, is contained in the strongly ultra-subwavelength capacitors of the LC structure. The high radiation loss of the antenna allows strongly increased collection efficiency for the incident THz radiation, while the small effective volume of the LC resonator allows intense light-matter coupling with a reduced electrical area. As a result, our detectors operate at much higher temperatures than conventional quantum well detectors demonstrated so far. This work was supported by the French National Research Agency under Contract No. ANR-16-CE24-0020, the regional DIM-SIRTEQ project, “CIEL,” Project Qombs (FET Flagship on Quantum Technologies Grant No. 820419) and the Engineering and Physical Sciences Research Council (UK) under Grant No. EP/P021859/1. EHL acknowledges the support of the Royal Society and Wolfson Foundation

Mixing properties of room temperature patch-antenna receivers in a mid-infrared (λ\lambda ∼\sim 9μ\mum) heterodyne system

A room-temperature mid-infrared (9 um) heterodyne system based on high-performance unipolar optoelectronic devices is presented. The local oscillator (LO) is a quantum cascade laser, while the receiver is an antenna coupled quantum well infrared photodetector optimized to operate in a microcavity configuration. Measurements of the saturation intensity show that these receivers have a linear response up to very high optical power, an essential feature for heterodyne detection. By an accurate passive stabilization of the local oscillator and minimizing the optical feed-back the system reaches, at room temperature, a record value of noise equivalent power of 30 pW at 9um. Finally, it is demonstrated that the injection of microwave signal into our receivers shifts the heterodyne beating over the bandwidth of the devices. This mixing property is a unique valuable function of these devices for signal treatment

Mixing properties of room temperature patch-antenna receivers in a mid-infrared (λ\lambda ∼\sim 9μ\mum) heterodyne system

A room-temperature mid-infrared (9 um) heterodyne system based on high-performance unipolar optoelectronic devices is presented. The local oscillator (LO) is a quantum cascade laser, while the receiver is an antenna coupled quantum well infrared photodetector optimized to operate in a microcavity configuration. Measurements of the saturation intensity show that these receivers have a linear response up to very high optical power, an essential feature for heterodyne detection. By an accurate passive stabilization of the local oscillator and minimizing the optical feed-back the system reaches, at room temperature, a record value of noise equivalent power of 30 pW at 9um. Finally, it is demonstrated that the injection of microwave signal into our receivers shifts the heterodyne beating over the bandwidth of the devices. This mixing property is a unique valuable function of these devices for signal treatment