A compact broadband atmospheric gas spectrometer has been developed in the framework of the EU-H2020 FLAIR project. The system is composed of a mid-IR 2-4um broadband supercontinuum source, a temperature controlled 10- meter-long multipass-cell for light-gas interaction, a diffraction grating, and an uncooled PbSe-on-CMOS matrix detector recording absorption spectra. The detection limit has been measured at sub-ppm level on methane under laboratory conditions. We also present 2 successful field measurement campaigns aboard airborne platforms: a hot-air airship for controlled methane release experiments, and a helicopter tracking ship exhaust fumes abroad the coastline of Denmark, with special emphasis on methane detection.
We report a novel ultra-short light pulse emitters utilizing transient charge carrier behaviour in a multiple wide-quantumwell (WQW) heterostructure. The optical waveguide is implemented as a tandem-cavity laser diode with electro absorber section in the middle, surrounded by two end-firing gain sections. The ultrashort pulse production is achieved by employing the gain region with three wide GaAsP tensile strained quantum wells separated by GaInP barriers in an unintentionally doped active region of the p-i-n laser diode structure. At large negative absorber bias, lasing emission spiking starts with an unusually long delay of 7 μs. By applying the current pulses of duration smaller than 7 μs it is possible to quench entirely the lasing emission. With selection of the parameters of the electrical pump pulse and the absorber voltage it is possible to obtain ultra-short light pulse regime. This optical pulse appears at the end of the electrical pump pulse, as a single optical pulse on top of wide pedestal, due to amplified spontaneous emission. The duration of the pulse is 1.2 ps and pulse energy is 80 pJ. We attribute this behaviour to quantum confined Stark effect. Removal of the external bias field, enabling stronger overlap of carriers yields a sudden increase in the radiative recombination rate and optical gain enabling SR emission. We provide a detailed report on the pulse width and optical spectral behaviour as well as on possible nonclassical correlation in the emitted light state seen from comparison to CW lasing regime.
Imaging with non-classical photons allows to bypass the Rayleigh resolution limit and classical shot-noise level. One step towards imaging demonstration with large photon numbers is the separation of non-classical photon states from the classical photons, thus increasing dynamic range and signal to background contrast on the detector. We demonstrate the feasibility of such separation by an échelle grating at high diffraction orders. In our demonstration, a PPKTP crystal generates entangled photon pairs in type-0 SPDC. The crystal is cw pumped and produces non-collinear degenerated photon pairs at 810nm. The classical light states are produced by a VCSEL at nearly same wavelength. After diffraction on echelle grating, the spatial far-field patterns and the photon arrival times are recorded by a novel 32×32 SPAD array sensor with 160 ps timing resolution. It allows real-time monitoring of the first- and second order correlation patterns. Within the observation window, we detected correlated biphoton arrivals in the four diffraction orders corresponding to their de Broglie wavelength, which is a half of the classical wavelength. Respectively a half of these diffraction orders is prohibited for classical photons. Placing a slit mask in these orders allows us to transmit only non-classical photon state and block the classical ones. We report on a series of experiments elucidating spatial and temporal correlations at the output of such quantum –classical photon discriminator. Those results could be used for the separation of biphotons from classical photons at the same wavelength in high-intensity light sources.
We present the first steps executed to space qualify an assembly technique for miniaturized optical components that already demonstrated its maturity for the ground segment. Two different types of demonstrators have been manufactured and submitted to various tests: endurance demonstrators placed in simulated environment reproducing strong space environmental constraints that may potentially destroy the devices under test, and a functional demonstrator put in operational conditions as typically found in a satellite environment. The technology, the realized demonstrators and the results of the tests are reported.
Efficient sources of indistinguishable single photons are a key resource for various applications in fields like quantum
sensing, quantum metrology and quantum information processing. In this contribution we report on single photon
generation based on III-V semiconductor quantum dots (QDs). To increase the emission efficiency of single photons, it
is essential to tailor the radiative properties of the quantum dot emitters by engineering their photonic environment. We
present optimized single photon emitters being based on both micropillar and photonics crystal cavities, for applications
in a vertical platform and on-chip in-plane platform, respectively.
Electrically driven single photon sources with self assembled semiconductor QDs embedded into GaAs/AlAs
micropillar cavities emit on demand net rates of ~35 MHz single photons, thus being well exploitable in quantum key
distribution systems. In order to establish also a spatially deterministic fabrication platform, position controlled quantum
dots are integrated into p-i-n micropillar cavities and single photon emission of a coupled QD-micropillar diode system
is observed. Efficient broadband coupling of single photons into photonic crystal waveguides provides the basis for all
on-chip quantum information processing, and an according approach is reported.