| 1. |
- Adshead, Mason, et al.
(författare)
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Erbium implantation in thin film Lithium Niobate
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Lithium niobate on insulator (LNOI), thanks to its electro-optic properties and second order nonlinearity, is one of the most promising photonic materials for on-chip implementation of a complex photonic integrated circuit (PIC) [1]. Integration of rare earth ion emitters (RIE), characterized by high coherent transitions in both optical and microwave domains, into LNOI is a very attractive perspective to fully exploit the potential of this material in quantum optics applications and for on chip light generation and amplification. By choosing Erbium ions these functionalities can be implemented at telecom wavelengths (~1550 nm). Erbium integration in LNOI can be achieved using the smart cut technique [2]. However, this approach implies heating the material up to ~1100 ºC, approaching the Curie temperature of lithium niobate (~1200 ºC). Ion implantation also permits the incorporation of RIE into the lithium niobate (LN) crystal structure, operating at lower temperature with high spatial precision of the doped region in a complex PIC.
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| 2. |
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| 3. |
- Fergestad, Halvor, et al.
(författare)
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Engineered dispersion measurements in LiNbO3 nanophotonic wires
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Dispersion engineering of waveguides in photonic integrated circuits (PIC) is a crucial design tool for tailoring nonlinear functionalities in the rapidly emerging thin film LiNbO3 (TFLN) platform, exemplified by frequency comb generation, soliton formation and broadband frequency conversion [1]. Experimentally, the dispersion of PIC structures is typically measured in terms of free-spectral range (FSR) variation in ring cavity configurations or propagation time delays in long waveguides under short pulse excitation [2], methods with their own limitations when it comes to measurements in straight and relatively short (< cm) waveguides, such as TFLN ones.
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| 4. |
- Fu, Daiheng, et al.
(författare)
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Polarization coupling in thin film lithium niobate waveguide
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Polarization control in photonic integrated circuit (PIC) waveguides is receiving broad attention for application in quantum systems and telecommunication [1]. Thin film lithium niobate (TFLN) is an ideal platform for polarization control applications due to its birefringence and electro-optic properties [2]. We observe polarization coupling between fundamental TE and TM modes in TFLN waveguides.
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| 5. |
- Gallo, Katia, Professor, 1972-, et al.
(författare)
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Spectral engineering of LNOI waveguide : from ultranarrow to broadband
- 2021
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Ingår i: The 11th International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 2021. - : META Conference. ; , s. 784-
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Konferensbidrag (refereegranskat)abstract
- The development of advanced nano-structuring capabilities on LNOI is paving the way towards low-footprint photonic circuits leveraging appealing functionalities of LiNbO3 for ultrafast signal processing and wavelength conversion. In the talk we shall present ultra-narrow bandpass and multiresonance filters, implemented with phase-shifted Bragg gratings in LNOI photonic wires. We shall also discuss designs of dispersion engineered waveguides for broadband second harmonic generation, appealing for wavelength multicasting, ultrashort pulse frequency doubling and enhanced quadratic cascading in the telecom band.
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| 6. |
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| 7. |
- Li, Tiantong, et al.
(författare)
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Tailoring guided-wave Fano resonances in LiNbO3 nanophotonic wires
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Fano resonances in nanophotonic structures are attracting significant attention for the engineering possibilities they may offer in applications such as lasers, sensing and optical signal processing [1]. Most widely explored device architectures in the quest for fully integrated implementation scenarios involve the side-coupling of different waveguide-cavity systems providing the narrowband and broad resonances (discrete and continuum states, respectively) whose interference gives rise to the signature asymmetric Fano lineshapes. Here we present a brand-new approach to achieve Fano resonances in ultracompact 1D waveguide formats through a polarization diversity scheme, exploiting the longitudinal field components of guided modes in high confinement photonic wires in combination with integrated Bragg-resonant structures achieved by sidewall modulation of the same.
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| 8. |
- Passoni, Matteo, et al.
(författare)
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Energetic ions at moderate laser intensities using foam-based multi-layered targets
- 2014
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 56:4, s. 045001-
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Tidskriftsartikel (refereegranskat)abstract
- The experimental feasibility of the laser-driven ion acceleration concept with multi-layered,foam-based targets has been investigated. Targets with the required features have beenproduced and characterized, exploiting the potential of the pulsed laser deposition technique.In the intensity range 1016–1017 Wcm−2, they allow us to obtain maximum proton energies2–3 times higher compared to bare solid targets, able to reach and surpass the MeV range withboth low and ultrahigh contrast pulses. The results of two-dimensional particle-in-cellsimulations, supporting the interpretation of the experimental results, and directions to exploitthe concept also at ultrahigh intensities, are presented.
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| 9. |
- Prencipe, Alessandro, et al.
(författare)
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Electro- and Thermo-Optics Response of X-Cut Thin Film LiNbO3Waveguides
- 2023
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Ingår i: IEEE Journal of Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9197 .- 1558-1713. ; 59:3
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Tidskriftsartikel (refereegranskat)abstract
- Lithium niobate has been for decades the material of election for integrated nonlinear and electro-optics. Its recent availability in thin films affording subwavelength confinement of light and nanostructuring capabilities has led to ground-breaking results in numerous applications, ranging from ultrafast signal processing to efficient nonlinear optics, where electro-optic (EO) and thermo-optic (TO) functionalities can be further leveraged for enhanced tunability and reconfigurability. This work provides a consistent comparison between these two approaches in the most widely used configuration in LiNbO3 nanophotonics at telecom wavelengths. Using state of the art Bragg grating technology for high precision index measurements, we evaluate the guided-wave EO and TO tunability to be 3\× 10-5 V-1 and 3.6× 10 -3W-1 , respectively, and study further operation and design tradeoffs, cross-talk effects and long-term stability. The results provide useful insights to identify the most appropriate strategies for implementing reconfigurable integrated photonic circuits effectively leveraging the unique features of LiNbO3.
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| 10. |
- Prencipe, Alessandro, 1994-
(författare)
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Nanophotonic devices in thin film lithium niobate
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Photonic devices play a fundamental role in today’s society and are a central building blocks for numerous applications, ranging from modern internet to sensing and manufacturing, and photonics is foreseen to be the backbone of future quantum internet and quantum communication systems thanks to the long coherence time of light. At variance with electronic integrated circuits, where silicon has been the material of election for many decades, in the case of photonic integrated circuits (PICs) there are numerous options available for the material substrate. One of the most promising platforms for future PICs is thin film lithium niobate (TFLN). Lithium niobate (LN) is a ferroelectric crystal characterized by a wide transparency window and excellent electro- and nonlinear optical properties. Additionally the thin film format allows the implementation of submicrometric devices, characterized by a footprint similar to the one realized on silicon and silicon nitride but with improved capabilities in terms of coherent electrical control of light and more efficient on-chip photon-photon interactions. This thesis demonstrates a few novel nanophotonic devices and contributes to the quickly developing TFLN technology platform, encompassing also hybrid integration processes. In term of monolithic TFLN nanowaveguide components, nanostructuring capabilities for ultrasmall footprint photonic devices have been developed and utilized to implement high quality factor resonators based on waveguide integrated phase shifted Bragg gratings (PSBG). The response of these devices, operating at telecom wavelength and characterized by a transmission bandwidth as narrow as 8.8 pm (corresponding to a quality factor Q in excess of 1.7×105) and by a footprint smaller than 500 μm2, was analyzed with the help of a model based on coupled mode theory (CMT) showing excellent agreement with the experimental data. This model provides insights on fabricated device losses and useful guidelines for the design of optimized PSBG. While spanning the full parameter space for device fabrication and optimization, deviations from such a model were also experimentally observed. Upon further investigation, these effects were explained as the results of a Fano resonance occurring in the PSBG structure involving the interaction of TE00 and TM01 modes in the supporting waveguide. The effect results in a narrowband and asymmetric response which can be tuned upon changing the waveguide design, as confirmed by experiments and simulations. The excellent sensitivity to refractive index changes of PSBG devices was leveraged to develop a comprehensive study of the electro- and the thermo- optical properties of X-cut TFLN. The study highlights the advantages and the limits of both approaches to device trimming and reconfigurability. The thesis includes also experimental contributions to dispersion-engineered TFLN waveguides, whose properties were characterized for fundamental TE and TM modes as function of the waveguide geometry in the telecom band by means of dual comb spectroscopy. This thesis addresses also hybrid photonic devices for on-chip light detection and emission, specifically demonstrating the integration of superconducting nanowire single-photon detectors (SNSPDs) and erbium emitters in TFLN. SNSPDs based on niobium-titanium-nitride (NbTiN) were integrated onto single mode TFLN nanowaveguides and their spectral sensitivity was leveraged to implement on-chip wavelength meters working in the telecom C- and L- bands, achieving photon counting and spectral sensitivity on a single waveguide- integrated device. Furthermore, a process for the effective incorporation of Er ions in TFLN was successfully developed in collaboration with researches at the university of Manchester. Structural and optical characterization of the Er:TFLN samples indicates essentially no disruption to the intrinsic properties of the LN crystal. The photoluminescence from the implanted films, emitting in the C-band, was studied as a function of temperature. The results hold promise for the implementation of a complete platform for on-chip quantum photonic circuits in the 1550 nm band, capable of operating at cryogenic temperature comprising on-demand single photon sources, electro-optic photon routing and manipulation as well as detection in TFLN circuits.
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| 11. |
- Prencipe, Alessandro, et al.
(författare)
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Tunable Ultranarrowband Grating Filters in Thin-Film Lithium Niobate
- 2021
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 8:10, s. 2923-2930
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Tidskriftsartikel (refereegranskat)abstract
- Several applications in modern photonics require compact on-chip optical filters with a tailored spectral response. However, achieving subnanometric bandwidths and high extinction ratios is particularly challenging, especially in low-footprint device formats. Phase-shifted Bragg gratings implemented by the sidewall modulation of photonic nanowire waveguides are a good solution for on-chip narrowband operation with reasonable requirements in fabrication and scalability. In this work we report on their implementation and optimization in thin film lithium niobate, a photonic platform that affords reconfigurability by exploiting electrooptic effects. The phase-shifted Bragg grating filters have a footprint smaller than 1 mu m x 1 mm and operate at telecom wavelengths, featuring extinction ratios up to 25 dB. We demonstrate transmission bandwidths as narrow as 14.4 pm (Q = 1.1 x 10(5)) and 8.8 pm (Q = 1.76 x 10(5)) in critically coupled structures and multiwavelength Fabry-Perot configurations, respectively, in full agreement with theoretical predictions. Moreover, by taking advantage of the strong electro-optic effect in lithium niobate, in combination with the tight light confinement of nanophotonic wires and the ultranarrow spectral resonances of optimized grating structures, we demonstrate an electric tunability in peak wavelength and transmission of 25.1 pm/V and 2.1 dB/V, respectively, and a 10.5 dB contrast at CMOS voltages. The results pave the way for reconfigurable narrowband photonic filters with a small footprint and low consumption, to be exploited toward on-chip quantum and nonlinear optics, as well as optical sensing and microwave photonics.
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| 12. |
- Prencipe, Alessandro, et al.
(författare)
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Wavelength meter on thin film lithium niobate based on superconducting single photon detectors
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- Photonic integrated circuits (PICs) present significant benefits with respect to table-top optical systems regarding footprint, stability, and power consumption. Among the materials used to fabricate PICs, thin film lithium niobate (TFLN) is one of the most attractive ones, as its χ(2) nonlinearity and electro-optic properties allow to implement on-chip light generation and routing [1]. On-chip detection of light has also been demonstrated on TFLN, based on the waveguide integration of superconducting nanowire single photon detectors (SNSPDs) [1]. Combining efficient detectors with TFLN nanophotonic waveguides holds promises for the realization of quantum photonics experiments fully on-chip. On the other hand, the sensitivity of SNSPDs changes with the wavelength of the detected photons [2], setting a boundary to the longest detectable wavelength and limiting the use of the wide transparency window of TFLN. However, this wavelength dependency in the response of SNSPDs can be leveraged to achieve new on-chip functionalities. In this work, by performing a straightforward analysis of the light signal measured at different bias currents [2], we operate hairpin SNSPDs on TFLN as waveguide-integrated wavelength-meters in the telecom bandwidth.
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| 13. |
- Prencipe, Alessandro, et al.
(författare)
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Wavelength-Sensitive Superconducting Single-Photon Detectors on Thin Film Lithium Niobate Waveguides
- 2023
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 23:21, s. 9748-9752
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Tidskriftsartikel (refereegranskat)abstract
- Lithium niobate, because of its nonlinear and electro-optical properties, is one of the materials of choice for photonic applications. The development of nanostructuring capabilities of thin film lithium niobate (TFLN) permits fabrication of small footprint, low-loss optical circuits. With the recent implementation of on-chip single-photon detectors, this architecture is among the most promising for realizing on-chip quantum optics experiments. In this Letter, we report on the implementation of superconducting nanowire single-photon detectors (SNSPDs) based on NbTiN on 300 nm thick TFLN ridge nano-waveguides. We demonstrate a waveguide-integrated wavelength meter based on the photon energy dependence of the superconducting detectors. The device operates at the telecom C- and L-bands and has a footprint smaller than 300 × 180 μm2 and critical currents between ∼12 and ∼14 μA, which ensures operation with minimum heat dissipation. Our results hold promise for future densely packed on-chip wavelength-multiplexed quantum communication systems.
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