In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The m...In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The mission aims at determining the equation of state of matter at supra-nuclear density, measuring effects of QED, and understanding the dynamics of matter in strong-field gravity. In addition to investigating fundamental physics, eXTP will be a very powerful observatory for astrophysics that will provide observations of unprecedented quality on a variety of galactic and extragalactic objects. In particular, its wide field monitoring capabilities will be highly instrumental to detect the electro-magnetic counterparts of gravitational wave sources.The paper provides a detailed description of:(1) the technological and technical aspects, and the expected performance of the instruments of the scientific payload;(2) the elements and functions of the mission, from the spacecraft to the ground segment.展开更多
Electro-optic modulation at frequencies of 100 GHz and beyond is important for photonic-electronic signal processing at the highest speeds.To date,however,only a small number of devices exist that can operate up to th...Electro-optic modulation at frequencies of 100 GHz and beyond is important for photonic-electronic signal processing at the highest speeds.To date,however,only a small number of devices exist that can operate up to this frequency.In this study,we demonstrate that this frequency range can be addressed by nanophotonic,silicon-based modulators.We exploit the ultrafast Pockels effect by using the silicon–organic hybrid(SOH)platform,which combines highly nonlinear organic molecules with silicon waveguides.Until now,the bandwidth of these devices was limited by the losses of the radiofrequency(RF)signal and the RC(resistor-capacitor)time constant of the silicon structure.The RF losses are overcome by using a device as short as 500 μm,and the RC time constant is decreased by using a highly conductive electron accumulation layer and an improved gate insulator.Using this method,we demonstrate for the first time an integrated silicon modulator with a 3dB bandwidth at an operating frequency beyond 100 GHz.Our results clearly indicate that the RC time constant is not a fundamental speed limitation of SOH devices at these frequencies.Our device has a voltage–length product of only V_(π)L=11 V mm,which compares favorably with the best silicon-photonic modulators available today.Using cladding materials with stronger nonlinearities,the voltage–length product is expected to improve by more than an order of magnitude.展开更多
基金support of the Chinese Academy of Sciences through the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA15020100)support by ASI, under the dedicated eXTP agreements and agreement ASI-INAF (Grant No. 2017-14-H.O.)+3 种基金by INAF and INFN under project REDSOXsupport from the Deutsche Zentrum für Luft- und Raumfahrt, the German Aerospce Center (DLR)support of Science Centre (Grant No. 2013/10/M/ST9/00729)support from MINECO (Grant No. ESP2017-82674-R) and FEDER funds
文摘In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The mission aims at determining the equation of state of matter at supra-nuclear density, measuring effects of QED, and understanding the dynamics of matter in strong-field gravity. In addition to investigating fundamental physics, eXTP will be a very powerful observatory for astrophysics that will provide observations of unprecedented quality on a variety of galactic and extragalactic objects. In particular, its wide field monitoring capabilities will be highly instrumental to detect the electro-magnetic counterparts of gravitational wave sources.The paper provides a detailed description of:(1) the technological and technical aspects, and the expected performance of the instruments of the scientific payload;(2) the elements and functions of the mission, from the spacecraft to the ground segment.
基金We acknowledge support by the DFG Center for Functional Nanostructuresthe Helmholtz International Research School of Teratronics+3 种基金the Karlsruhe School of Optics and Photonicsthe EU-FP7 projects SOFI(grant 248609)and EURO-FOS(grant 224402)the BMBF joint project MISTRAL,which is funded by the German Ministry of Education and Research under grant 01BL0804and the European Research Council(ERC Starting Grant‘EnTeraPIC’,number 280145).
文摘Electro-optic modulation at frequencies of 100 GHz and beyond is important for photonic-electronic signal processing at the highest speeds.To date,however,only a small number of devices exist that can operate up to this frequency.In this study,we demonstrate that this frequency range can be addressed by nanophotonic,silicon-based modulators.We exploit the ultrafast Pockels effect by using the silicon–organic hybrid(SOH)platform,which combines highly nonlinear organic molecules with silicon waveguides.Until now,the bandwidth of these devices was limited by the losses of the radiofrequency(RF)signal and the RC(resistor-capacitor)time constant of the silicon structure.The RF losses are overcome by using a device as short as 500 μm,and the RC time constant is decreased by using a highly conductive electron accumulation layer and an improved gate insulator.Using this method,we demonstrate for the first time an integrated silicon modulator with a 3dB bandwidth at an operating frequency beyond 100 GHz.Our results clearly indicate that the RC time constant is not a fundamental speed limitation of SOH devices at these frequencies.Our device has a voltage–length product of only V_(π)L=11 V mm,which compares favorably with the best silicon-photonic modulators available today.Using cladding materials with stronger nonlinearities,the voltage–length product is expected to improve by more than an order of magnitude.
