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Your search keyword '"Micheletti, Paolo"' showing total 46 results
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46 results on '"Micheletti, Paolo"'

1. Broadband surface-emitting THz laser frequency combs with inverse-designed integrated reflectors

Author

Senica, Urban, Gloor, Sebastian, Micheletti, Paolo, Stark, David, Beck, Mattias, Faist, Jérôme, and Scalari, Giacomo

Subjects
Physics - Optics
Abstract

THz quantum cascade lasers (QCLs) based on double metal waveguides feature broadband and high-temperature devices for use in spectroscopy and sensing. However, their extreme field confinement produces poor output coupling efficiencies and divergent far-fields. Here, we present a planarized THz QCL with an inverse-designed end facet reflector coupled to a surface-emitting patch array antenna. All the components have been optimized for octave-spanning spectral bandwidths between 2-4 THz and monolithically integrated on the same photonic chip. We demonstrate this experimentally on broadband THz QCL frequency combs, with measured devices showing a seven-fold improvement in slope efficiency compared to devices with a cleaved facet. They feature peak powers of up to 13.5 mW with surface emission into a narrow beam with a divergence of (17.0{\deg}x 18.5{\deg}), while broadband fundamental and harmonic comb states spanning up to 800 GHz are observed., Comment: 6 pages, 5 figures

Published
2023
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2. THz optical solitons from dispersion-compensated antenna-coupled planarized ring quantum cascade lasers

Author

Micheletti, Paolo, Senica, Urban, Forrer, Andres, Cibella, Sara, Torrioli, Guido, Frankié, Martin, Faist, Jérôme, Beck, Mattias, and Scalari, Giacomo

Subjects
Physics - Optics
Abstract

Quantum Cascade Lasers (QCL) constitute an intriguing opportunity for the production of on-chip optical Dissipative Kerr Solitons (DKS): self-organized optical waves which can travel while preserving their shape thanks to the interplay between Kerr effect and dispersion. Originally demonstrated in passive microresonators, DKS were recently observed in mid-IR ring QCL paving the way for their achievement even at longer wavelengths. To this end we realized defect-less THz ring QCLs featuring anomalous dispersion leveraging on a technological platform based on waveguide planarization. A concentric coupled-waveguide approach is implemented for dispersion compensation whilst a passive broadband bullseye antenna improves the device power extraction and far field. In these devices, comb spectra featuring sech$^2$ envelopes are presented for free-running operation. This first hint of the presence of solitons is further supported by the observation of highly hysteretic behaviour and by phase-sensitive measurements which show the presence of self-starting 12 ps-long pulses in the reconstructed time profile of the emission intensity. These observations are in very good agreement with our numeric simulations based on a Complex Ginzburg-Landau equation time-domain solver. Such devices constitute a new experimental platform for the study of soliton phenomena in the THz range, allowing as well on-chip, passive ultrashort THz pulse generation appealing for a variety of applications.

Published
2022

3. Planarized THz quantum cascade lasers for broadband coherent photonics

Author

Senica, Urban, Forrer, Andres, Olariu, Tudor, Micheletti, Paolo, Cibella, Sara, Torrioli, Guido, Beck, Mattias, Faist, Jérôme, and Scalari, Giacomo

Subjects
Physics - Optics, Physics - Applied Physics
Abstract

Recently, there has been a growing interest in integrated THz photonics for various applications in communications, spectroscopy and sensing. We present a new integrated photonic platform based on active and passive elements integrated in a double-metal, high confinement waveguide layout planarized with a low-loss polymer. An extended top metallization results in low waveguide losses and improved dispersion, thermal and RF properties, as it enables to decouple the design of THz and microwave cavities. Free-running on-chip quantum cascade laser combs spanning 800 GHz, harmonic states over 1.1 THz and RF-injected broadband incoherent states spanning over nearly 1.6 THz are observed. With a strong external RF drive, actively mode-locked pulses as short as 4.4 ps can be produced, as measured by SWIFTS. We demonstrate as well passive waveguides with low insertion loss, enabling the tuning of the laser cavity boundary conditions and the co-integration of active and passive components on the same THz photonic chip., Comment: 27 pages, 5 figures

Published
2022
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4. Regenerative Terahertz Quantum Detectors

Author

Micheletti, Paolo, Faist, Jerome, Olariu, Tudor, Senica, Urban, Beck, Mattias, and Scalari, Giacomo

Subjects
Physics - Optics, Physics - Instrumentation and Detectors
Abstract

Because of the ultrafast and photon-driven nature of the transport in their active region, we demonstrate that quantum cascade lasers can be operated as resonantly amplified terahertz detectors. Tunable responsivities up to 50 V/W and noise equivalent powers down to 100 pW/sqrt(Hz) are demonstrated at 4.7 THz. Constant peak responsivities with respect to the detector temperature are observed up to 80K. Thanks to the sub-ps intersubband lifetime electrical bandwidths larger than 20 GHz can be obtained, allowing the detection of optical beatnotes from quantum cascade THz frequency combs.

Published
2021
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5. Small footprint optoelectrodes for simultaneous readout and passive light localization by the use of ring resonators

Author

Lanzio, Vittorino, Telian, Gregory, Koshelev, Alexander, Micheletti, Paolo, Presti, Gianni, D`Arpa, Elisa, De Martino, Paolo, Lorenzon, Monica, Denes, Peter, West, Melanie, Sassolini, Simone, Dhuey, Scott, Adesnik, Hillel, and Cabrini, Stefano

Subjects
Physics - Biological Physics, Physics - Applied Physics
Abstract

Neural probes are in vivo invasive devices that combine electrophysiology and optogenetics to gain insight into how the brain operates, down to the single neuron and its network activity. Their integration of stimulation sites and sensors allows for recording and manipulating neurons` activity with a high spatiotemporal resolution. State of the art probes are limited by tradeoffs between their lateral dimension, the number of sensors, and the ability to selectively access independent stimulation sites. Here, we realize a highly scalable probe that features a three-dimensional integration of small footprint arrays of sensors and nanophotonic circuits and scales the density of sensors per cross-section by one order of magnitude with respect to state of the art devices. For the first time, we overcome the spatial limit of the nanophotonic circuit by coupling only one waveguide to numerous optical ring resonators as passive nanophotonic switches. With our strategy, we achieve accurate on-demand light localization while avoiding spatial demanding bundles of waveguides and demonstrate the feasibility of a proof of concept device and its additional scalability, towards high resolution and low damaging neural optoelectrodes., Comment: 29 pages, 8 figures Submitted to 'Nature Microsystems and nanoengineering'

Published
2020

7. Small footprint optoelectrodes using ring resonators for passive light localization

Author

Lanzio, Vittorino, Telian, Gregory, Koshelev, Alexander, Micheletti, Paolo, Presti, Gianni, D’Arpa, Elisa, De Martino, Paolo, Lorenzon, Monica, Denes, Peter, West, Melanie, Sassolini, Simone, Dhuey, Scott, Adesnik, Hillel, and Cabrini, Stefano

Subjects
Engineering, Nanotechnology, Neurosciences, Bioengineering, 1.1 Normal biological development and functioning, Underpinning research, Neurological, Nanobiotechnology, Optics and photonics
Abstract

The combination of electrophysiology and optogenetics enables the exploration of how the brain operates down to a single neuron and its network activity. Neural probes are in vivo invasive devices that integrate sensors and stimulation sites to record and manipulate neuronal activity with high spatiotemporal resolution. State-of-the-art probes are limited by tradeoffs involving their lateral dimension, number of sensors, and ability to access independent stimulation sites. Here, we realize a highly scalable probe that features three-dimensional integration of small-footprint arrays of sensors and nanophotonic circuits to scale the density of sensors per cross-section by one order of magnitude with respect to state-of-the-art devices. For the first time, we overcome the spatial limit of the nanophotonic circuit by coupling only one waveguide to numerous optical ring resonators as passive nanophotonic switches. With this strategy, we achieve accurate on-demand light localization while avoiding spatially demanding bundles of waveguides and demonstrate the feasibility with a proof-of-concept device and its scalability towards high-resolution and low-damage neural optoelectrodes.

Published
2021

9. High-density electrical and optical probes for neural readout and light focusing in deep brain tissue

Author

Lanzio, Vittorino, West, Melanie, Koshelev, Alexander, Telian, Gregory, Micheletti, Paolo, Lambert, Raquel, Dhuey, Scott, Adesnik, Hillel, Sassolini, Simone, and Cabrini, Stefano

Subjects
Engineering, Nanotechnology, Biomedical Engineering, Neurosciences, Bioengineering, Underpinning research, 1.1 Normal biological development and functioning, Neurological, neural probes, high density, light focusing, integration, Optical Physics, Electrical and Electronic Engineering, Nanoscience & Nanotechnology, Electronics, sensors and digital hardware
Abstract

To advance neuroscience in vivo experiments, it is necessary to probe a high density of neurons in neural networks with single-cell resolution and be able to simultaneously use different techniques, such as electrophysiological recordings and optogenetic intervention, while minimizing brain tissue damage. We first fabricate electrical neural probes with a high density of electrodes and small tip profile (cross section of shank: 47-μm width × 16-μm thickness). Then, with similar substrate and fabrication techniques, we separately fabricate optical neural probes. We finally indicate a fabrication method that may allow integrating the two functionalities into the same device. High-density electrical probes have been fabricated with 64 pads. Interconnections to deliver the signal are 120-nm wide, and the pads are 5 × 25 μm. Separate optical probes with similar shank dimensions with silicon dioxide and silicon nitride ridge single-mode waveguides have also been fabricated. The waveguide core cross section is 250 nm × 160 nm. Light is focused above the waveguide plane in 2.35-μm diameter spots. The actual probes present two output focusing gratings on the shank.

Published
2018

10. Broadband THz quantum cascade laser frequency combs with surface emission and inverse-designed facet reflectors

Author

Senica Urban, Gloor Sebastian, Micheletti Paolo, Beck Mattias, Faist Jérôme, and Scalari Giacomo

Subjects
Physics, QC1-999
Abstract

We present a planarized waveguide cavity with an integrated broadband output coupler that improves both the output power and far-field properties of THz quantum cascade laser frequency combs. The laser mirror reflectivity can be tuned by the shape of the end facet, which is obtained with an efficient inverse design algorithm, where the structure is iteratively updated to match the desired figure of merit. Surface emission is achieved with a broadband patch-array antenna, and all the components have been optimized for octave-spanning emission spectra (2-4 THz). Experimentally, we demonstrate a broadband surface-emitting THz quantum cascade laser frequency comb with optical bandwidths of up to 800 GHz, surface emission into a narrow beam with divergence below (20° x 20°) and a peak power of 13 mW.

Published
2023
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11. Surface-emitting THz quantum cascade laser frequency comb with tunable external mirror dispersion compensation

Author

Digiorgio Valerio, Senica Urban, Micheletti Paolo, Beck Mattias, Faist Jérôme, and Scalari Giacomo

Subjects
Physics, QC1-999
Abstract

We present a surface emitting THz quantum cascade laser frequency comb with an adjustable chromatic dispersion compensation via a mechanically tunable GTI cavity. Surface emission and high optical feedback into the laser cavity are achieved by a planarized ridge waveguide design with low reflectivity facets and two broadband patch array antennas for coupling to an external mirror (back side) and for power extraction (front side). We demonstrate direct and reproducible manipulation of the frequency comb state, specifically the comb stability and beatnote frequency tuning, by controlling the position of an external movable mirror.

Published
2023
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19. Field-enhancing tapered planarized waveguides for THz quantum cascade laser frequency combs

Author

Senica Urban, Forrer Andres, Olariu Tudor, Micheletti Paolo, Cibella Sara, Torrioli Guido, Beck Mattias, Faist Jérôme, and Scalari Giacomo

Subjects
Physics, QC1-999
Abstract

We present a new planarized waveguide geometry for THz quantum cascade laser frequency combs with improved waveguide losses, RF and thermal dissipation properties. Ridge devices display broadband free-running comb states, and the THz emission can be further broadened by RF injection. Tapered waveguide devices feature a strong field-enhancement effect, which results in an improved comb performance. This includes free-running comb states with strong single beatnotes up to nearly -30 dBm at 90 K, almost three orders of magnitude stronger than for ridge devices. Improved comb operation is maintained also for high operating temperatures, up to 115 K.

Published
2022
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20. THz frequency combs form dispersion-compensated antenna-coupled ring quantum cascade lasers

Author

Micheletti Paolo, Senica Urban, Forrer Andres, Cibella Sara, Torrioli Giudo, Beck Mattias, Faist Jerome, and Scalari Giacomo

Subjects
Physics, QC1-999
Abstract

We report comb operation of RF injected ring Quantum Cascade Lasers. A coupled waveguide approach is implemented for dispersion compensation while passive bullseye antenna improves the device power extraction and far field. Phase sensitive measurements are presented which hints at the presence of soliton state.

Published
2022
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27. Terahertz optical solitons from dispersioncompensated antenna-coupled planarized ring quantum cascade lasers.

Author

Micheletti, Paolo, Senica, Urban, Forrer, Andres, Cibella, Sara, Torrioli, Guido, Frankié1, Martin, Beck, Mattias, Faist, Jérôme, and Scalari, Giacomo

Subjects
*OPTICAL solitons, *QUANTUM cascade lasers, *SUBMILLIMETER waves, *QUANTUM rings, *WAVE packets, *WHISPERING gallery modes, *QUANTUM electronics, *RING lasers
Abstract

The article discusses the generation of terahertz optical solitons using dispersion-compensated antenna-coupled planarized ring Quantum Cascade Lasers (QCL). The researchers address the challenges of achieving solitons in terahertz ring QCLs, including dispersion compensation and power extraction. They propose a double waveguide structure and a planarization technique to overcome these challenges.

Published
2023
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