Graphene photodetector employing double slot structure with enhanced responsivity and large bandwidth

Silicon photonics integrated with graphene provides a promising solution to realize integrated photodetectors operating at the communication window thanks to graphene’s ultrafast response and compatibility with CMOS fabrication process.However, current hybrid graphene/silicon photodetectors suffer from low responsivity due to the weak light-graphene interaction. Plasmonic structures have been explored to enhance the responsivity, but the intrinsic metallic Ohmic absorption of the plasmonic mode limits its performance. In this work, by combining the silicon slot and the plasmonic slot waveguide, we demonstrate a novel double slot structure supporting high-performance photodetection, taking advantages of both silicon photonics and plasmonics. With the optimized structural parameters, the double slot structure significantly promotes graphene absorption while maintaining low metallic absorption within the double slot waveguide. Based on the double slot structure, the demonstrated photodetector holds a high responsivity of 603.92 m A/W and a large bandwidth of 78 GHz. The high-performance photodetector provides a competitive solution for the silicon photodetector. Moreover,the double slot structure could be beneficial to a broader range of hybrid two-dimensional material/silicon devices to achieve stronger light-matter interaction with lower metallic absorption.

Impact of Chinese Local Government-led Construction Land Supply Strategies on Urban Innovation and its Spatiotemporal Differences

This study constructs a theoretical framework to analyze the impact of local governmentled construction land supply(LGCLS)strategies on urban innovation.It uses data related to 265 cities in China from 2005 to 2019 for empirical analysis.Its conclusions are as follows.For development stage differences,the impact of LGCLS strategies on urban innovation exhibited an inverted U shape with economic growth.The inflection point occurred when the per capita GDP equaled approximately RMB23,101 in 2008.For regional diferences,the inflection point in eastern China is higher and earlier than that in central and western China;before the inflection point,the positive infuence was more obvious in the central and western regions,whereas after the inflection point,the negative influence was more obvious in the eastern region.For the eastern Yangtze River Delta urban agglomerations and the northwestern resource-based urban agglomerations with relatively high per capita GDP,the negative impact of LGCLS strategies on urban innovation occurred earlier and showed spatial agglomeration characteristics.

Broadband on-chip integrator based on silicon photonic phase-shifted Bragg grating

All-optical integrators are key devices for the realization of ultra-fast passive photonic networks, and, despite their broad applicability range(e.g., photonic bit counting, optical memory units, analogue computing, etc.), their realization in an integrated form is still a challenge. In this work, an all-optical integrator based on a silicon photonic phase-shifted Bragg grating is proposed and experimentally demonstrated, which shows a wide operation bandwidth of 750 GHz and integration time window of 9 ps. The integral operation for single pulse, inphase pulses, and π-shifted pulses with different delays has been successfully achieved.

Metasurface for highly-efficient on-chip classical and quantum all-optical modulation

Metasurface made of artificially two-dimensional structured subwavelength-scaled nanostructures gives rise to unprecedented efficient way to realize on-chip all-optical modulation,in both classical regime and quantum regime.