Cosimo Lacava

Cosimo Lacava
University of Pavia | UNIPV · Department of Electrical, Computer and Biomedical Engineering

PhD

About

108
Publications
20,793
Reads
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1,407
Citations
Citations since 2017
80 Research Items
1317 Citations
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2017201820192020202120222023050100150200250300
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Introduction
Main research: Design and experimental characterization of linear and non-linear Silicon Photonics devices such as Fiber to Chip coupling devices (1D and 2D grating couplers, Inverse taper coupling), active components bonded on silicon chip, highly non-linear silicon devices (SLOT waveguides, amorphous silicon devices and High Q Silicon Micro ring resonator with enhanced nonlinear response).
Additional affiliations
July 2012 - January 2013
University of Glasgow
Position
  • Visiting Researcher
March 2011 - November 2014
University of Pavia
Position
  • PostDoc Position

Publications

Publications (108)
Article
Full-text available
We numerically investigated the use of graphene nanoribbons placed on top of silicon-on-insulator (SOI) strip waveguides for light polarization control in silicon photonic-integrated waveguides. We found that two factors mainly affected the polarization control: the graphene chemical potential and the geometrical parameters of the waveguide, such a...
Article
Full-text available
We propose and numerically demonstrate a versatile strategy that allows designing highly efficient dual-level grating couplers in different silicon nitride-based photonic platforms. The proposed technique, which can generally be applied to an arbitrary silicon nitride film thickness, is based on the simultaneous optimization of two grating coupler...
Article
Full-text available
In this work, we show the design of a silicon photonic-based polarization converting device based on the integration of semiconduction InP nanowires on the silicon photonic platform. We present a comprehensive numerical analysis showing that full polarization conversion (from quasi-TE modes to quasi-TM modes, and vice versa) can be achieved in devi...
Article
Full-text available
Multimode devices and components have attracted considerable attention in the last years, and different research topics and themes have emerged very recently. The multimodality can be seen as an additional degree of freedom in designing devices, thus allowing for the development of more complex and sophisticated components. The propagation of diffe...
Article
Full-text available
In this review we present some of the recent advances in the field of silicon nitride photonic integrated circuits. The review focuses on the material deposition techniques currently available, illustrating the capabilities of each technique. The review then expands on the functionalisation of the platform to achieve nonlinear processing, optical m...
Conference Paper
We report an experimental study on p-n junction equipped silicon waveguides, presenting the optimized parameters to achieve effective nonlinear operation. A conversion efficiency of -6.8 dB with electrical power consumption of 340 mW is demonstrated.
Article
Alternate-mark-inversion (AMI) has been used in the past to improve the transmission performance of binary intensity modulation formats. In this work, we improved the tolerance of O-band 4-level pulse amplitude modulation (PAM4) transmission to channel impairments through the adoption of an AMI scheme. Improvements in receiver sensitivity were show...
Article
In this paper we discuss two strategies to achieve wideband light generation through intermodal nonlinear parametric processes in multimode integrated waveguides. We outline how the interplay among intermodal interactions and high dispersion may lead to the generation of light characterized by substantial power spectral density if compared to super...
Article
We characterize the spectral broadening performance in silica clad and unclad Tantalum pentoxide (Ta<sub>2</sub>O<sub>5</sub>) waveguides as a function of the input pulse central wavelength and polarization, sweeping over a wavelength range from 900 nm to 1500 nm, with an average incident power of 110 mW. The waveguides are 0.7 µm high and between...
Article
We report >100-Gb/s direct-detection (DD) transmission using an integrated silicon optical receiver, which comprised a fully-differential 28-nm complementary metal-oxide-semiconductor (CMOS) transimpedance amplifier (TIA) wire-bonded to a Silicon-Germanium (SiGe) balanced photodiode (PD). The fully-differential TIA architecture enabled significant...
Article
Silicon core fibers represent a versatile platform for all-fiber integrated nonlinear optical applications. This paper describes the state of the art in four-wave mixing-based parametric amplification and wavelength conversion in silicon fibers that have been tapered to improve the material quality and engineer the dispersion profile. Fibers with s...
Conference Paper
Complex modulation format deployed within IMDD links pose the sensitivity and linearity challenges to the optical receiver design. Benefit from the proposed differential topology, this work cope with complex modulation format (e.g., PAM-4) up to 64Gb/s (OMA=-8.2dBm) under 1.0V power supply.
Article
Full-text available
In this work, we review the proposition and development history of intensity modulation and direct detection optical orthogonal frequency division multiplexing (OOFDM), as well as of its evolved versions, the layered asymmetrically clipped OOFDM (LACO-OFDM) scheme. We conceive and characterize the first experimental demonstration of a LACO-OFDM lin...
Conference Paper
This paper presents recent results on the use of silicon-rich silicon nitride waveguides for intermodal four wave mixing. Through appropriate design of the mode propagation characteristics, broadband wavelength conversion of signals is achieved.
Conference Paper
Wavelength conversion of 20 Gb/s quadrature phase shift keying (QPSK) signals is demonstrated in a tapered silicon core fiber extending across the S-, C- and L-bands. The results indicate the platform’s suitability for use in broadband all-optical communication systems.
Conference Paper
Silicon photonic technologies have undoubtedly revolutionized the optical communication and photonic industries during the last 10 years. Silicon on insulator (SOI) devices are now routinely used to build high performance transceivers and optical components, with a privileged route to the integration with electronic devices. However, in order to in...
Article
This paper presents the design and implementation of a fully differential optical receiver, which is aimed for short reach intensity modulation and direct detection (IMDD) transceiver links. A Si-Ge balanced photodetector (PD) has been co-designed and packaged with a novel differential transimpedance amplifier (TIA). The TIA design is realized with...
Conference Paper
We show the characterisation of spectral broadening in the Tantalum Pentoxide waveguide system as a function of pump wavelength, showing spectra for central pump wavelengths of 0.9 to 1.5 µm (150 fs, 80 MHz). We have achieved octave spanning spectra with approximately 5 mW of laser power coupled in the waveguide at 1 µm pumping wavelength for a lin...
Conference Paper
We demonstrate up to 173.22-Gb/s direct-detection transmission using a balanced photodetector wire-bonded to a 28-nm CMOS fully-differential gain-tunable TIA. Both 100-Gb/s PAM4 and capacity-maximized adaptively-loaded DMT are studied for up to 2-km SSMF transmission.
Conference Paper
We demonstrate PECVD based silicon nitride materials for range of applications. These applications are for non-linear functionalities in the C band, coarse wavelength division multiplexing in the O band and a 1-micron thick SiN waveguiding platform at 2 microns demonstrating filters and trimming capabilities.
Article
Full-text available
Publishers note re original article: APL Photonics 4 (10), 106109 (2019) DOI: 10.1063/1.5123547 This article was originally published online on 25 October 2019 with mislabeled figures. Figure 1 was labeled as Fig. 3, Fig. 2 was labeled as Fig. 4, Fig. 3 was labeled as Fig. 1, and Fig. 4 was labeled as Fig. 2. The figure order has been corrected in...
Conference Paper
We report on the use of fiber-integrated plasmonic metamaterial absorbers in signal processing applications in coherent information networks. Quantum states filtering, perfect nonlinear absorption, all-optical gating and encrypted signal distribution are demonstrated.
Article
In recent years, silicon nitride has drawn attention for the realisation of integrated photonic devices due to its fabrication flexibility and advantageous intrinsic properties that can be tailored to fulfill the requirements of different linear and non-linear photonic applications. This paper focuses on our progress in the demonstration of enhance...
Article
Full-text available
An out-of-plane silicon grating coupler capable of mode-order conversion at the chip–fiber interface is designed and fabricated. Optimization of the structure is performed through finite-difference time-domain simulations, and the final device is characterized through far-field profile and transmission measurements. A coupling loss of 3.1 dB to a c...
Article
A new form of interferometry combining high phase sensitivity and excellent mechanical isolation is proposed and demonstrated. These features arise from maintaining a probe and reference tone in the same medium under test at all times, their ultimate homodyne detection, as well as a novel method employing an optical programmable filter which is use...
Conference Paper
We demonstrate devices with enhanced linear and nonlinear functionalities in the near-infrared fabricated on our low temperature silicon nitride platform. The devices include polarisation insensitive MUX/DEMUX, waveguides with enhanced non-linear effects useful for wavelength conversion applications and devices for the 2 μm wavelength range.
Article
Full-text available
We show that subwavelength Si-rich nitride waveguides efficiently sustain high-speed transmissions at 2 μm. We report the transmission of a 10 Gbit/s signal over 3.5 cm with negligible power penalty. Parametric conversion in the pulsed pump regime is also demonstrated using the same waveguide structure with an efficiency as high as −18 dB.
Conference Paper
Full-text available
We show that cm-long silicon and silicon-rich silicon nitride waveguides with subwavelength transverse dimensions can efficiently sustain high-speed transmissions at 2 µm. We report the transmission of a 10 Gbit/s signal with negligible power penalty. Parametric conversion in both continuous and pulsed pump regimes is also demonstrated, as well as...
Article
Full-text available
Dispersion engineering in optical waveguides allows applications relying on the precise control of phase matching conditions to be implemented. Although extremely effective over relatively narrow band spectral regions, dispersion control becomes increasingly challenging as the bandwidth of the process of interest increases. Phase matching can also...
Article
Full-text available
The ability to process optical signals without passing into the electrical domain has always attracted the attention of the research community. Processing photons by photons unfolds new scenarios, in principle allowing for unseen signal processing and computing capabilities. Optical computation can be seen as a large scientific field in which resea...
Article
Full-text available
The ability to process optical signals without passing into the electrical domain has always attracted the attention of the research community. Processing photons by photons unfolds new scenarios, in principle allowing for unseen signal processing and computing capabilities. Optical computation can be seen as a large scientific field in which resea...
Preprint
Full-text available
We show that subwavelength silicon-rich nitride waveguides efficiently sustain high-speed transmissions at 2 $\mu$m. We report the transmission of a 10 Gbit/s signal over 3.5 cm with negligible power penalty. Parametric conversion in the pulsed pump regime is also demonstrated using the same waveguide structure with an efficiency as high as -18 dB.
Conference Paper
p>A vertical silicon grating coupler that converts the propagation mode order at the waveguide-fiber interface was fabricated and characterized. Far-field intensity patterns are presented for different device configurations and the coupling efficiency is reported.</p
Conference Paper
A technique for the characterization of picosecond pulse widths is presented, based a non-linear optical fiber loop mirror and power meter measurement. Pulse-widths in the 2-10ps range are successfully recovered with a resolution of 0.25ps.
Preprint
We show that subwavelength Si-rich nitride waveguides efficiently sustain high-speed transmissions at 2 μm. We report the transmission of a 10 Gbit/s signal over 3.5 cm with negligible power penalty. Parametric conversion in the pulsed pump regime is also demonstrated using the same waveguide structure with an efficiency as high as −18 dB.
Conference Paper
We utilise the alternate mark inversion (AMI) scheme to mitigate the nonlinearity in O- band transmission. The results after transmission over 60km of SMF show that AMI outperforms the duobinary and on-off keying formats.
Conference Paper
We show the first demonstration of Bragg scattering inter-modal four-wave-mixing in silicon-rich SiN waveguides. We report wavelength conversion using two spatial modes, exhibiting a maximum efficiency of−15-dB over a flat-bandwidth in excess of 30-nm.
Article
Full-text available
All-optical encryption of information in fibre telecommunication networks offers lower complexity and far higher data rates than electronic encryption can deliver. However, existing optical layer encryption methods, that are compatible with keys of unlimited length, are based on nonlinear processes that require intense optical fields. Here, we intr...
Article
We demonstrate optical wavelength conversion in a multi-mode silicon waveguide using four wave mixing (FWM) Bragg scattering (BS) enabled by a dual-pump CW scheme. The original signal and the generated idler pair excite one spatial mode (first TE mode), while the two pumps excite a different spatial mode (second TE mode) of the same waveguide. Our...
Article
Full-text available
A method for measuring picosecond pulse width by using only fiber components and optical power meters is presented. We have shown that the output power splitting ratio of a non-linear fiber loop mirror can be used to extract the full-width half maximum of the optical pulse, assuming a known slowly varying envelope shape and internal phase structure...
Article
Full-text available
Over the last 20 years, silicon photonics has revolutionized the field of integrated optics, providing a novel and powerful platform to build mass-producible optical circuits. One of the most attractive aspects of silicon pho-tonics is its ability to provide extremely small optical components, whose typical dimensions are an order of magnitude smal...
Conference Paper
We demonstrate that in a nonlinear fibre optical network coherent interaction of light with a plasmonic metamaterial can be used for power-limiting as well as noise reduction applications.
Conference Paper
We demonstrate a new type of secure optical communication based on dissipative metamaterial logic gates that encrypt and decrypt information in an all-optical telecommunication fibre network with mutually coherent signal channels.
Conference Paper
The availability of nanometer scale fabrication techniques has inspired scientists to investigate subwavelength-structured metamaterials with engineered optical properties. Metamaterial waveguide devices are becoming established as fundamental building blocks for the next generation photonic integrated circuits. Here we present an overview of recen...
Conference Paper
We improve the tolerance of O-band PAM4 transmission to nonlinearity by adopting an alternate-mark-inversion scheme. Improvements in receiver sensitivity are shown over both semiconductor optical amplifier and bismuth doped fibre amplifier equipped links, the greatest being a 4.4dB Q-factor improvement over 60km of SMF-28e.
Conference Paper
p>We demonstrate CMOS compatible photonic components such as high speed Ge/SiGe electro-absorption modulators and a flexible BEOL SiN waveguide platform for applications such as temperature insensitive CWDM and all optical signal processing through enhanced non-linear characteristics.</p
Conference Paper
We demonstrate 3 platforms based on silicon nitride layers processed at 350°C and tailored to have different refractive indices. With these platforms, we have successfully fabricated low loss waveguides at telecom wavelengths, temperature tolerant (de)multiplexing devices, nonlinear waveguides, photonic crystal cavities and waveguides.
Article
Full-text available
Coherent interaction of two light waves on a film of subwavelength thickness provides remarkable opportunities for controlling intensity and polarization of light beams as well as all-optical image processing. Here, we show that such interactions can be used for optical dark pulse generation and basic all-optical signal processing in fully fiberize...
Article
Full-text available
Recently, coherent control of the optical response of thin films of matter in standing waves has attracted considerable attention, ranging from applications in excitation-selective spectroscopy and nonlinear optics to demonstrations of all-optical image processing. Here we show that integration of metamaterial and optical fibre technologies allows...
Article
Full-text available
We report on the generation of an optical comb of highly uniform in power frequency lines (variation less than 0.7 dB) using a silicon ring resonator modulator. A characterization involving the measurement of the complex transfer function of the ring is presented and five frequency tones with a 10-GHz spacing are produced using a dual-frequency ele...
Conference Paper
We demonstrate selective transmission and absorption of 1-ps pulses, pulse shaping and 1-ps dark pulse generation in a fiber-optic device based on a plasmonic metamaterial, providing an example of all-optical signal processing with THz bandwidth.
Conference Paper
Full-text available
We show the design and characterization of a silicon-rich silicon nitride-based all-optical wavelength converter, for phase-encoded signals. We demonstrate successful conversion of a 40 Gb/s 16-QAM signal with negligible penalty and no-signs of TPA.
Conference Paper
We discuss the latest progress on the development of all-optical signal processing devices in Si-based platform. We discuss the realization of intra and inter-modal wavelength-converters by using our internally developed si-rich-silicon nitride platform.
Article
Full-text available
We present a simple and practical strategy that allows to design high-efficiency grating couplers. The technique is based on the simultaneous apodization of two structural parameters: the grating period and the fill-factor, along with the optimization of the grating coupler etching depth. Considering a 260 nm Si-thick Silicon-on-insulator platform,...
Conference Paper
Coherent interaction of light with functional materials of substantially subwavelength thickness has given rise to the intriguing opportunity to turn any of the diverse optical functionalities that ultrathin films may provide “on” or “off” at will. Such dynamic control over the expression of thin film optical properties is possible as light-matter...
Article
Full-text available
We present the characterization of a silicon Mach-Zehnder modulator with electrical packaging and show that it exhibits a large third-order intermodulation spurious-free dynamic range (> 100 dB Hz 2/3). This characteristic renders the modulator particularly suitable for the generation of high spectral efficiency discrete multi-tone signals and we e...
Conference Paper
We demonstrate a fully functional metadevice performing coherent all-optical logical operations including NOT, AND and XOR at up to 40 Gbit/s at wavelengths between 1530 nm and 1565 nm and demonstrate that the underlying mechanism has a bandwidth of 100 THz.
Conference Paper
Nonlinear silicon photonic devices have attracted considerable attention thanks to their ability to show large third-order nonlinear effects at moderate power levels allowing for all-optical signal processing functionalities in miniaturized components. Although significant efforts have been made and many nonlinear optical functions have already bee...
Article
We have designed and fabricated a silicon photonic in-phase-quadrature (IQ) modulator based on a nested dual-drive Mach-Zehnder structure incorporating electrical packaging. We have assessed its use for generating Nyquist-shaped single sideband (SSB) signals by operating it either as an IQ Mach-Zehnder modulator (IQ-MZM) or using just a single bran...
Conference Paper
We demonstrate a back end of line compatible SiN based material with tunable refractive index enabling low optical loss, high non-linear Kerr response, low index photonic crystals, high efficiency couplers, low loss waveguides and temperature tolerant MUX for DWDM.
Conference Paper
We report the design and experimental characterization of a SOI grating coupler which shows, for the first time to our knowledge, a coupling loss below 1 dB (0.89 dB) without the use of any back-reflector.
Conference Paper
During the last decade Silicon photonics emerged as mature technology in the field of integrated optics for the fabrication of low-cost optical integrated circuits [1]. Silicon-on-insulator (SOI) represents the ideal platform for the realization of optical circuits characterized by a strong optical confinement, because of the large index contrast b...
Article
We report on the experimental characterization, in the telecom C-band, of group-velocity dispersion (D) in 100-nm high rectangular strip waveguides realized by silicon-on-insulator technology. We compare the experimental results with numerical predictions, showing that 100-nm high waveguides exhibit normal dispersion and that the absolute value of...
Conference Paper
We propose and demonstrate a flexible new scheme for measuring chromatic dispersion profiles of optical devices. This is achieved by measuring the phase difference between two mutually coherent tones that are mixed together through a modulator.