| 1. |
- Lei, Fuchuan, 1987, et al.
(författare)
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Hyperparametric Oscillation via Bound States in the Continuum
- 2023
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 130:9
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Tidskriftsartikel (refereegranskat)abstract
- Optical hyperparametric oscillation based on the third-order nonlinearity is one of the most significant mechanisms to generate coherent electromagnetic radiation and produce quantum states of light. Advances in dispersion-engineered high-Q microresonators allow for generating signal waves far from the pump and decrease the oscillation power threshold to submilliwatt levels. However, the pump-to-signal conversion efficiency and absolute signal power are low, fundamentally limited by parasitic mode competition and attainable cavity intrinsic Q to coupling Q ratio, i.e., Qi/Qc. Here, we use Friedrich-Wintgen bound states in the continuum (BICs) to overcome the physical challenges in an integrated microresonator-waveguide system. As a result, on-chip coherent hyperparametric oscillation is generated in BICs with unprecedented conversion efficiency and absolute signal power. This work not only opens a path to generate high-power and efficient continuous-wave electromagnetic radiation in Kerr nonlinear media but also enhances the understanding of a microresonator-waveguide system - an elementary unit of modern photonics.
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| 2. |
- Lei, Fuchuan, 1987, et al.
(författare)
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Power-efficient hyperparametric oscillation via bound states in the continuum
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023.
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Konferensbidrag (refereegranskat)abstract
- Optical hyperparametric oscillation (h-OPO) emerges in a driven Kerr cavity because of modulation instability. Two pump photons are converted into a pair of two correlated photons at new wavelengths. For many realistic applications, efficient operation of h-OPO is required, especially at high-power regime. Currently, the pump-to-signal conversion efficiency is fundamentally limited mainly by two factors: parasitic mode competition [1] and attainable cavity intrinsic Q (Qi) to coupling Q (Qc) ratio [2].
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| 3. |
- Ye, Zhichao, 1991, et al.
(författare)
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Overcoming the quantum limit of optical amplification in monolithic waveguides
- 2021
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Ingår i: Science advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:38
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Tidskriftsartikel (refereegranskat)abstract
- Optical amplifiers are essential in numerous photonic applications. Parametric amplifiers, relying on a nonlinear material to create amplification, are uniquely promising as they can amplify without generating excess noise. Here, we demonstrate amplification based on the third-order nonlinearity in a single chip while, in addition, reporting a noise figure significantly below the conventional quantum limit when operated in phase-sensitive mode. Our results show the potential of nanophotonics for realizing continuous-wave parametric amplification that can enable applications in optical communications, signal processing, and quantum optics across a wide range of frequencies.
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| 4. |
- Ye, Zhichao, 1991, et al.
(författare)
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Ultralow-loss meter-long dispersion-engineered silicon nitride waveguides
- 2021
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. - 9781943580910
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Konferensbidrag (refereegranskat)abstract
- We demonstrate dispersion-engineered meter-long silicon nitride waveguides with record-low loss of 1.4 dB/m. Based on these, we demonstrate continuous-wave-pumped optical parametric amplification for the first time in an integrated Kerr nonlinear waveguide.
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| 5. |
- Helgason, Òskar Bjarki, 1989, et al.
(författare)
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Dark-pulse Kerr combs in linearly coupled microring structures
- 2020
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Ingår i: Optics InfoBase Conference Papers. - 2162-2701. - 9781943580767 ; Part F183-CLEO-SI 2020
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Konferensbidrag (refereegranskat)abstract
- The generation of dissipative Kerr solitons in microresonators became a milestone in the quest towards a chip-scale frequency comb source. Although successful demonstrations in diverse fields have been made, one outstanding issue with dissipative Kerr solitons is their poor power conversion efficiency. This has a fundamental origin in the need to operate the soliton microcomb at a large frequency detuning. The limited conversion efficiency is a crucial aspect when considering co-integration with chip-scale laser sources or applications that demand higher power per line, such as optical communications.
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| 6. |
- Helgason, Òskar Bjarki, 1989, et al.
(författare)
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Dissipative solitons in photonic molecules
- 2021
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Ingår i: Nature Photonics. - : Springer Science and Business Media LLC. - 1749-4885 .- 1749-4893. ; 15:4, s. 305-310
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Tidskriftsartikel (refereegranskat)abstract
- Many physical systems display quantized energy states. In optics, interacting resonant cavities show a transmission spectrum with split eigenfrequencies, similar to the split energy levels that result from interacting states in bonded multi-atomic—that is, molecular—systems. Here, we study the nonlinear dynamics of photonic diatomic molecules in linearly coupled microresonators and demonstrate that the system supports the formation of self-enforcing solitary waves when a laser is tuned across a split energy level. The output corresponds to a frequency comb (microcomb) whose characteristics in terms of power spectral distribution are unattainable in single-mode (atomic) systems. Photonic molecule microcombs are coherent, reproducible and reach high conversion efficiency and spectral flatness while operated with a laser power of a few milliwatts. These properties can favour the heterogeneous integration of microcombs with semiconductor laser technology and facilitate applications in optical communications, spectroscopy and astronomy.
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| 7. |
- Odeh, Mutasem, et al.
(författare)
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Mode Sensitivity Analysis of Subwavelength Grating Slot Waveguides
- 2019
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Ingår i: IEEE Photonics Journal. - 1943-0655. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the mode sensitivity (S-mode) of subwavelength grating slot (SWGS) waveguides. S-mode is an important parameter in various waveguide-based photonic circuits such as sensors, modulators, and thermally-controlled devices. It is a measure of the sensitivity of the waveguide effective index towards the refractive index perturbations in the cladding medium. The SWGS waveguide exhibits high mode sensitivity, as it combines sensitivity enhancement features of both slot and subwavelength grating waveguides. Finite-difference time-domain simulations are performed for the analysis, design, and optimization of the hybrid structure. The SWGS waveguide is incorporated into a Mach-Zehnder interferometer and fabricated on a silicon-on-insulator platform for the experimental estimation of S-mode. The measured S-mode value of 79% is consistent with the theoretical prediction of 83%.
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| 8. |
- Rebolledo Salgado, Israel, 1992, et al.
(författare)
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Coherent supercontinuum generation in all-normal dispersion Si 3 N 4 waveguides
- 2022
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 30:6, s. 8641-8651
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Tidskriftsartikel (refereegranskat)abstract
- Spectral broadening of optical frequency combs with high repetition rate is of significant interest in optical communications, radio-frequency photonics and spectroscopy. Silicon nitride waveguides (Si3N4) in the anomalous dispersion region have shown efficient supercontinuum generation spanning an octave-bandwidth. However, the broadening mechanism in this regime is usually attained with femtosecond pulses in order to maintain the coherence. Supercontinuum generation in the normal dispersion regime is more prone to longer (ps) pulses, but the implementation in normal dispersion silicon nitride waveguides is challenging as it possesses strong requirements in propagation length and losses. Here, we experimentally demonstrate the use of a Si3N4 waveguide to perform coherent spectral broadening using pulses in the picosecond regime with high repetition rate. Moreover, our work explores the formation of optical wave breaking using a higher energy pulse which enables the generation of a coherent octave spanning spectrum. These results offer a new prospect for coherent broadening using long duration pulses and replacing bulky optical components.
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| 9. |
- Rebolledo Salgado, Israel, 1992, et al.
(författare)
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Nonlinear Broadening of Electro-Optic Frequency Combs in All-Normal Dispersion Si 3 N 4 Waveguides
- 2021
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Ingår i: 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021.
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Konferensbidrag (refereegranskat)abstract
- Dispersion-engineered silicon nitride waveguides are often used for broadening of frequency combs. Previous experiments have focused on anomalous dispersion waveguides pumped by femtosecond laser pulses, whereby coherent supercontinuum generation relies on soliton compression and dispersive wave emission (see e.g. [1] ). This regime of operation does not work well with high-repetition rate sources, such as microcombs or electro-optic (EO) combs, because the pulse duration is not sufficiently short to drive coherent broadening in anomalous dispersion media. Indeed, octave-spanning coherent broadening of high-repetition rate sources has been attained in anomalous dispersion silicon nitride waveguides, but this required using a pre-broadening stage in a normal-dispersion highly nonlinear fiber (HNLF) [2]. Implementing this stage in a silicon nitride waveguide is the topic we address in this contribution.
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| 10. |
- Twayana, Krishna Sundar, 1986
(författare)
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Advanced characterization techniques of photonic devices with frequency combs
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Integrated photonics has witnessed remarkable progress in the last decades. Measuring photonic devices in amplitude and phase provides insight into their performance. Swept wavelength interferometry is a prominent technique for the broadband characterization of the complex response. It leverages continuous advances in rapidly tunable laser sources but is prone to systematic errors associated with frequency calibration. This thesis focuses on the non-destructive measurement of ultralow-loss photonic devices using swept wavelength interferometric technique. We overcome issues associated with nonlinear tuning by calibrating the frequency of the laser on the fly with the aid of a frequency comb. We apply the concept to diverse components of relevance including microresonators and spiral waveguides. This technique enables diagnosing waveguides for the loss and potential defects and is instrumental in optimizing device fabrication ecosystems. The measured phase response of microresonators allows for untangling the coupling condition and provides insight into microresonator-waveguide systems. The later part of this thesis covers the linear (stepped and multi-heterodyne) methods for spectral and temporal characterization of frequency combs. The linear heterodyne method provides unprecedented sensitivity and bandwidth range of measurement. In addition, we provide an overview and comparative assessment of the state-of-the-art in the field.
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