Abstract-Optomechanical response with nanometer resolution in the self-mixing signal of a terahertz quantum cascade laser

Andrea Ottomaniello, James Keeley, Pierluigi Rubino, Lianhe Li, Marco Cecchini, Edmund H. Linfield, A. Giles Davies, Paul Dean, Alessandro Pitanti, Alessandro Tredicucci,

(a) Sketch of the two configurations of the SM apparatus. (b) Calculated Δ𝑁$\mathrm{\Delta }N$ (blue curve), and measured 𝑉SM$V_{\mathrm{S}\mathrm{M}}$ (red points) as a function of Δ𝐿$\mathrm{\Delta }L$ using configuration 1

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-44-23-5663

Owing to their intrinsic stability against optical feedback (OF), quantum cascade lasers (QCLs) represent a uniquely versatile source to further improve self-mixing interferometry at mid-infrared and terahertz (THz) frequencies. Here, we show the feasibility of detecting with nanometer precision, the deeply subwavelength (<𝜆/6000$<\lambda /6000$) mechanical vibrations of a suspended Si3N4${\mathrm{S}\mathrm{i}}_3{\mathrm{N}}_4$ membrane used as the external element of a THz QCL feedback interferometer. Besides representing an extension of the applicability of vibrometric characterization at THz frequencies, our system can be exploited for the realization of optomechanical applications, such as dynamical switching between different OF regimes and a still-lacking THz master-slave configuration.

Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Abstract-Black-Phosphorus Terahertz Photodetectors

Leonardo Viti, Jin Hu, Dominique Coquillat, Wojciech Knap, Alessandro Tredicucci, Antonio Politano, Miriam Serena Vitiello

https://arxiv.org/abs/1805.00735

The discovery of graphene and the related fascinating capabilities have triggered an unprecedented interest in inorganic two-dimensional (2D) materials. Despite the impressive impact in a variety of photonic applications, the absence of energy gap has hampered its broader applicability in many optoelectronic devices. The recent advance of novel 2D materials, such as transition-metal dichalcogenides or atomically thin elemental materials, (e.g. silicene, germanene and phosphorene) promises a revolutionary step-change. Here we devise the first room-temperature Terahertz (THz) frequency detector exploiting few-layer phosphorene, e.g., a 10 nm thick flake of exfoliated crystalline black phosphorus (BP), as active channel of a field-effect transistor (FET). By exploiting the direct band gap of BP to fully switch between insulating and conducting states and by engineering proper antennas for efficient light harvesting, we reach detection performance comparable with commercial detection technologies, providing the first technological demonstration of a phosphorus-based active THz device.

Abstract-Symmetry enhanced non-reciprocal polarization rotation in a terahertz metal-graphene metasurface

Andrea Ottomaniello, Simone Zanotto, Lorenzo Baldacci, Alessandro Pitanti, Federica Bianco, and Alessandro Tredicucci

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-3-3328&origin=search

In the present article we numerically investigated the magneto-optical behaviour of a sub-wavelength structure composed by a monolayer graphene and a metallic metasurface of optical resonators. Using this hybrid graphene-metal structure, a large increase of the non-reciprocal polarization rotation of graphene can be achieved over a broad range of terahertz frequencies. We demonstrate that the symmetry of the resonator geometry plays a key role for the performance of the system: in particular, increasing the symmetry of the resonator the non-reciprocal properties can be progressively enhanced. Moreover, the possibility to exploit the metallic metasurface as a voltage gate to vary the graphene Fermi energy allows the system working point to be tuned to the desired frequency range. Another peculiar result is the achievement of a structure able to operate both in transmission and reflection with almost the same performance, but in a different frequency range of operation. The described system is hence a sub-wavelength, tunable, multifunctional, effective non-reciprocal element in the terahertz region.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

CNR-Institute of Nanoscience and University of Pisa obtained new Terahertz laser

https://www.researchitaly.it/en/projects/cnr-institute-of-nanoscience-and-university-of-pisa-obtained-new-terahertz-laser/#null

An innovative laser, capable of emitting a very focused beam has been obtained thanks to the double nature of the Terahertz waves. The study, published in Light: Science & Applications, was carried out by a group of researchers from CNR NANO - the Nanoscience Institute of the National Research Council and the University of Pisa, in collaboration with SNS - Scuola Normale Superiore and the University of Cambridge.

Terahertz waves, which easily penetrate plastic, textiles and other materials, are the new frontier in radiology applied to the detection of hidden weapons or bio-agents, or defects in materials, packaging materials or artwork.

Terahertz waves are electromagnetic waves “in between” microwaves and infrared light and have a hybrid nature: they propagate with the properties of waves – like radio waves – and with those of light. That is why they can be manipulated, combining the techniques of these two fields, using both antennas and lenses or mirrors.

This is what was done in the new laser by Luca Masini, Alessandro Pitanti, Lorenzo Baldacci, Miriam Vitiello from CNR NANO, coordinated by Alessandro Tredicucci, University of Pisa, with the aim to generate a highly collimated Terahertz wave beam to overcome the limits of microlasers available today.

"The original idea" – explained Luca Masini from CNR NANO and SNS – "is to use the two natures of Terahertz radiation in one device: that of light and that of microwaves. In fact, to generate the radiation, the device treats it as if it were light, using a disk of artificial material consisting of semiconductor layers, whereas, to propagate it outwards, it manipulates it like a wave, using an embedded gold antenna. The result is a vertical and very focused emission that allows this laser to be used in devices for the spectroscopic analysis of materials and to be integrated into the new miniaturized laboratories, the so-called Labs-On-a-Chip”.

Terahertz waves, considered to be the X-rays of the future for the great potential in imaging applications (from body scanners to poison detection, to the recent water-saving applications), coupled with the low health risks, are the new frontier in photonics.

The laser was developed in the context of the European ERC SouLMan project led by Alessandro Tredicucci, University of Pisa, who said: "Generating Terahertz radiation has been a scientific challenge for many years. Now, the new challenge is to create a technology with increasingly less complex devices. Our laser, which for the first time uses a hybrid approach, goes in this direction as it allows the miniaturization of the device and a reduction of power consumption for its operation."

Publication date 06/16/2017
Source 

Abstract-Black Phosphorus Terahertz Photodetectors

• 
  

• 
  

• 
  

• 
  

• 
  

• 
  

• 
  

  
  

• http://onlinelibrary.wiley.com/doi/10.1002/adma.201502052/abstract
• The first room-temperature terahertz (THz)-frequency nanodetector exploiting a 10 nm thick flake of exfoliated crystalline black phosphorus as an active channel of a field-effect transistor, is devised. By engineering and embedding planar THz antennas for efficient light harvesting, the authors provide the first technological demonstration of a phosphorus-based active THz device.

Abstract-High performance bilayer-graphene Terahertz detectors

Davide Spirito, Dominique Coquillat, Sergio L. De Bonis, Antonio Lombardo, Matteo Bruna, Andrea C. Ferrari, Vittorio Pellegrini, Alessandro Tredicucci, Wojciech Knap, Miriam S. Vitiello

http://arxiv.org/abs/1312.3737
We report bilayer-graphene field effect transistors operating as THz broadband photodetectors based on plasma-waves excitation. By employing wide-gate geometries or buried gate configurations, we achieve a responsivity ∼1.2V/W(1.3mA/W) and a noise equivalent power ∼2×10−9W/Hz−1/2 in the 0.29-0.38 THz range, in photovoltage and photocurrent mode. The potential of this technology for scalability to higher frequencies and the development of flexible devices makes our approach competitive for a future generation of THz detection systems.