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Berlin, Germany

Plumhof J.D.,IBM | Plumhof J.D.,u2t Photonics AG | Stoferle T.,IBM | Mai L.,IBM | And 2 more authors.
Nature Materials | Year: 2014

A Bose-Einstein condensate (BEC) is a state of matter in which extensive collective coherence leads to intriguing macroscopic quantum phenomena. In crystalline semiconductor microcavities, bosonic quasiparticles, known as exciton-polaritons, can be created through strong coupling between bound electron-hole pairs and the photon field. Recently, a non-equilibrium BEC (ref.) and superfluidity have been demonstrated in such structures. With organic crystals grown inside dielectric microcavities, signatures of polariton lasing have been observed. However, owing to the deleterious effects of disorder and material imperfection on the condensed phase, only crystalline materials of the highest quality have been used until now. Here we demonstrate non-equilibrium BEC of exciton-polaritons in a polymer-filled microcavity at room temperature. We observe thermalization of polaritons and, above a critical excitation density, clear evidence of condensation at zero in-plane momentum, namely nonlinear behaviour, blueshifted emission and long-range coherence. The key signatures distinguishing the behaviour from conventional photon lasing are presented. As no crystal growth is involved, our approach radically reduces the complexity of experiments to investigate BEC physics and paves the way for a new generation of opto-electronic devices, taking advantage of the processability and flexibility of polymers. © 2014 Macmillan Publishers Limited.

Perez-Galacho D.,University of Malaga | Zhang R.,Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut | Ortega-Monux A.,University of Malaga | Halir R.,University of Malaga | And 7 more authors.
Journal of Lightwave Technology | Year: 2014

Monolithically integrated polarization management is a key objective for the next generation of high speed optical coherent receivers, and will enable transmission rates up to 400 Gbps. In this work we present a polarization beam splitter (PBS) based on an asymmetrical Mach-Zehnder interferometer (MZI) monolithically integrated with a coherent receiver. Thermal tuning is incorporated on the MZI arms to partially compensate fabrication errors. We propose a complete model that predicts that thermal tuning can furthermore be used to adjust the wavelength response of the PBS. Measurements on a fully integrated receiver validate this model. We show full tunability of the PBS response within the C-band, with a polarization extinction ratio in excess of 16 dB for devices with an estimated width error up to 75 nm. © 2013 IEEE.

Debnath K.,University of St. Andrews | O'Faolain L.,University of St. Andrews | O'Faolain L.,Stanford University | Gardes F.Y.,University of Southampton | And 3 more authors.
Optics Express | Year: 2012

Integration density, channel scalability, low switching energy and low insertion loss are the major prerequisites for on-chip WDM systems. A number of device geometries have already been demonstrated that fulfill these criteria, at least in part, but combining all of the requirements is still a difficult challenge. Here, we propose and demonstrate a novel architecture consisting of an array of photonic crystal modulators connected by a dielectric bus waveguide. The device architecture features very high scalability and the modulators operate with an AC energy consumption of less than 1fJ/bit. Furthermore, we demonstrate cascadeability and multichannel operation by using a comb laser as the source that simultaneously drives 5 channels. © 2012 Optical Society of America.

u2t Photonics AG | Date: 2013-09-12

An embodiment of the invention relates to an optical component (

u2t Photonics AG | Date: 2012-09-27

The invention inter alia relates to a method of receiving an optical-duo-binary, ODB, signal (S), which has a predefined ODB-transmission bit-rate (B), using a photoreceiver, said method comprising the step of filtering the ODB signal using a filter (

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