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Jijun He

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Related publications (42)

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Monolithic piezoelectric control of soliton microcombs

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Erwan Guillaume Albert Lucas, Wenle Weng, Jijun He, Arslan Sajid Raja, Miles Henry Anderson, Tianyi Liu

High-speed actuation of laser frequency(1)is critical in applications using lasers and frequency combs(2,3), and is a prerequisite for phase locking, frequency stabilization and stability transfer among optical carriers. For example, high-bandwidth feedbac ...

NATURE PUBLISHING GROUP2020

Compact, spatial-mode-interaction-free, ultralow-loss, nonlinear photonic integrated circuits

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Johann Emmeram Riemensberger, Jijun He, Zheru Qiu, Xinru Ji

Multi-mode waveguides are ubiquitously used in integrated photonics. Although interaction among different spatial waveguide eigenmodes can induce novel nonlinear phenomena, spatial mode interaction is typically undesired. Adiabatic bends, such as Euler ben ...

NATURE PORTFOLIO2022

Magnetic-free silicon nitride integrated optical isolator

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Jijun He, Anat Siddharth, Terence Albert Emile Blésin

Integrated photonics enables signal synthesis, modulation and conversion using photonic integrated circuits (PICs). Many materials have been developed, among which silicon nitride (Si3N4) has emerged as a leading platform particularly for nonlinear photoni ...

Nature Publishing Group2021

Cascaded all-optical quantization employing step-size MMI and shape-optimized power splitter

Jijun He

As a key unit of future high-throughput communications, optical analog to digital converter (OADC) with all-optical quantizer element that simultaneously possesses high resolution, large bandwidth and compact size is highly promising. A pending issue of co ...

ELSEVIER SCI LTD2023

Chip-based soliton microcomb module using a hybrid semiconductor laser

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Erwan Guillaume Albert Lucas, Jijun He, Arslan Sajid Raja, Nicolas Volet

Photonic chip-based soliton microcombs have shown rapid progress and have already been used in many system-level applications. There has been substantial progress in realizing soliton microcombs that rely on compact laser sources, culminating in devices th ...

2020

Discrete metal nanoparticles with plasmonic chirality

Jijun He

From a geometrical perspective, a chiral object does not have mirror planes or inversion symmetry. It exhibits the same physical properties as its mirror image (enantiomer), except for the chiroptical activity, which is often the opposite. Recent advanceme ...

Royal Society of Chemistry2021

A photonic integrated circuit-based erbium-doped amplifier

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Johann Emmeram Riemensberger, Jijun He, Anton Lukashchuk, Zheru Qiu, Xinru Ji

Erbium-doped fiber amplifiers revolutionized long-haul optical communications and laser technology. Erbium ions could provide a basis for efficient optical amplification in photonic integrated circuits but their use remains impractical as a result of insuf ...

American Association for the Advancement of Science2022

High-yield, wafer-scale fabrication of ultralow-loss, dispersion-engineered silicon nitride photonic circuits

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Jijun He, Arslan Sajid Raja, Guanhao Huang, Nils Johan Engelsen, Tianyi Liu

Low-loss photonic integrated circuits and microresonators have enabled a wide range of applications, such as narrow-linewidth lasers and chip-scale frequency combs. To translate these into a widespread technology, attaining ultralow optical losses with est ...

Nature Research2021

Integrated turnkey soliton microcombs

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Jijun He, Tianyi Liu

Optical frequency combs have a wide range of applications in science and technology(1). An important development for miniature and integrated comb systems is the formation of dissipative Kerr solitons in coherently pumped high-quality-factor optical micror ...

NATURE RESEARCH2020

Advanced Progress on chi((3)) Nonlinearity in Chip-Scale Photonic Platforms

Jijun He, Feng Li

chi((3)) nonlinearity enables ultrafast femtosecond scale light-to-light coupling and manipulation of intensity, phase, and frequency. chi((3)) nonlinear functionality in micro- and nanoscale photonic waveguides can potentially replace bulky fiber platform ...

The Electromagnetic Academy2021

Gain-switched semiconductor laser driven soliton microcombs

Tobias Kippenberg, Junqiu Liu, Erwan Guillaume Albert Lucas, Wenle Weng, Jijun He

Dissipative Kerr soliton generation using self-injection-locked III-V lasers has enabled fully integrated hybrid microcombs that operate in turnkey mode and can access microwave repetition rates. Yet, continuous-wave-driven soliton microcombs exhibit low e ...

Nature Research2021

Low-Loss Integrated Nanophotonic Circuits with Layered Semiconductor Materials

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Jijun He, Arslan Sajid Raja, Mikhail Churaev, Clément Christian Javerzac, Tianyi Liu, Philippe Andreas Rölli

Monolayer transition-metal dichalcogenides with direct bandgaps are emerging candidates for optoelectronic devices, such as photodetectors, light-emitting diodes, and electro-optic modulators. Here we report a low-loss integrated platform incorporating mol ...

AMER CHEMICAL SOC2021

Observation of Stimulated Brillouin Scattering in Silicon Nitride Integrated Waveguides

Luc Thévenaz, Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Jijun He, Arslan Sajid Raja, Flavien Gyger, Fan Yang

Silicon nitride (Si3N4) has emerged as a promising material for integrated nonlinear photonics and has been used for broadband soliton microcombs and low-pulse-energy supercontinuum generation. Therefore, understanding all nonlinear optical properties of S ...

2020

Photonic microwave generation in the X- and K-band using integrated soliton microcombs

Tobias Kippenberg, Junqiu Liu, Maxim Karpov, Rui Ning Wang, Johann Emmeram Riemensberger, Hairun Guo, Erwan Guillaume Albert Lucas, Jijun He, Arslan Sajid Raja, Romain Dany Bruno Bouchand

Microwave photonic technologies, which upshift the carrier into the optical domain, have facilitated the generation and processing of ultra-wideband electronic signals at vastly reduced fractional bandwidths. For microwave photonic applications such as rad ...

Nature Publishing Group2020

Low-noise, Frequency-agile, Hybrid Integrated Laser for LiDAR

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Johann Emmeram Riemensberger, Wenle Weng, Jijun He, Anat Siddharth, Viacheslav Snigirev

We demonstrate a hybrid photonic integrated laser with intrinsic linewidth of 40 Hz, while offering megahertz actuation bandwidth with the tuning range larger than 1 GHz, attained by a DFB laser self-injection locking to a high-Q Si3N4 microresonator with ...

IEEE2021

Platicon microcomb generation using laser self-injection locking

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Wenle Weng, Jijun He, Miles Henry Anderson

The past decade has witnessed major advances in the development and system-level applications of photonic integrated microcombs, that are coherent, broadband optical frequency combs with repetition rates in the millimeter-wave to terahertz domain. Most of ...

Nature Portfolio2022

Gain-switched semiconductor laser driven soliton microcombs

Tobias Kippenberg, Junqiu Liu, Erwan Guillaume Albert Lucas, Wenle Weng, Jijun He

Using phase-engineered coherent laser pulses produced by gain-switched semiconductor lasers, we generate low-power-threshold soliton microcombs whose repetition frequencies are in the X-band and K-band microwave ranges. (c) 2021TheAuthor(s) ...

IEEE2021

Magnetic-free Nitride Optical Isolator on Chip

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Jijun He, Anat Siddharth, Terence Albert Emile Blésin

We demonstrated a magnetic-free optical isolator for Si3N4 photonics using AlN piezoelectric actuators. Maximum of 10 dB isolation and

IEEE2021

Photo-induced cascaded harmonic and comb generation in silicon nitride microresonators

Tobias Kippenberg, Camille Sophie Brès, Junqiu Liu, Wenle Weng, Jijun He, Jianqi Hu, Edgars Nitiss, Ozan Yakar

Silicon nitride (Si3N4) is an ever-maturing integrated platform for nonlinear optics but mostly considered for third-order [chi(3)] nonlinear interactions. Recently, second-order [chi(2)] nonlinearity was introduced into Si3N4 via the photogalvanic effect, ...

2022

Monolithic piezoelectric control of integrated soliton microcombs

Tobias Kippenberg, Junqiu Liu, Rui Ning Wang, Erwan Guillaume Albert Lucas, Wenle Weng, Jijun He, Arslan Sajid Raja, Miles Henry Anderson, Tianyi Liu

We demonstrate piezoelectric actuators monolithically integrated on ultralow-loss Si3N4 waveguides. Varying the voltage applied on the actuator allows tuning the microresonator, and is used to initiate, switch, stabilize and tightly phase lock the single s ...

IEEE2020