Publications by Jijun He | EPFL Graph Search

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

Xiaowei Zhang, Ye Tian, Jian Wu, 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

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

Tobias Kippenberg, Camille Sophie Brès, Junqiu Liu, Jianqi Hu, Wenle Weng, Jijun He, 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

Low-noise frequency-agile photonic integrated lasers for coherent ranging

Rui Ning Wang, Tobias Kippenberg, Junqiu Liu, Wenle Weng, Andrey Voloshin, Jijun He, Anat Siddharth, Viacheslav Snigirev, Vladimir Shadymov

Stable and tunable integrated lasers are fundamental building blocks for applications from spectroscopy to imaging and communication. Here the authors present a narrow linewidth hybrid photonic integrated laser with low frequency noise and fast linear wave ...

Nature Portfolio2022

Microresonator Dissipative Kerr Solitons Synchronized to an Optoelectronic Oscillator

Tobias Kippenberg, Wenle Weng, Jijun He

Using phase-modulation-induced potential gradient whose period is synchronized to a microwave opto-electronic oscillator, dissipative Kerr solitons generated in a crystalline optical microresonator are trapped by the soliton tweezing effect, exhibiting a s ...

American Physical Society (APS)2022

Time-continuous Travelling-Wave Optical Parametric Amplification in a Photonic Circuit

Rui Ning Wang, Tobias Kippenberg, Junqiu Liu, Jijun He, Nikolai Kuznetsov

We demonstrate a traveling wave parametric amplifier in a photonic Si3N4 integrated spiral waveguide of 2.0 m length with footprint 3x5 mm. We achieve net gain of 7 dB on-chip and 2 dB fiberto-fiber in the optical C-band. (C) 2022 The Author(s) ...

IEEE2022

A Photonic Integrated Circuit-Based Erbium-doped Waveguide Amplifier

Rui Ning Wang, Tobias Kippenberg, Junqiu Liu, Jijun He, Xinru Ji, Yang Liu, Zheru Qiu

We demonstrate an erbium-doped waveguide amplifier by erbium ion implantation in Si3N4 photonic integrated circuits, achieving 145 mW on-chip output power and more than 30 dB small-signal gain, which is on par with commercial fiber amplifiers and beyond st ...

IEEE2022

A photonic integrated continuous-travelling-wave parametric amplifier

Rui Ning Wang, Tobias Kippenberg, Junqiu Liu, Jijun He, Nikolai Kuznetsov

The ability to amplify optical signals is of pivotal importance across science and technology typically using rare-earth-doped fibres or gain media based on III-V semiconductors. A different physical process to amplify optical signals is to use the Kerr no ...

NATURE PORTFOLIO2022

A photonic integrated circuit-based erbium-doped amplifier

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

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

Compact, Spatial-mode-interaction-free, Ultralow-loss, Nonlinear photonic integrated circuits

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

We implement Euler bends to build compact high-Q Si3N4 racetrack microresonators, featuring a small footprint of only 0.21 mm(2) for 19.8 GHz FSR. We demonstrate that these multi-mode microresonators can be operated in the single-mode regime and generate a ...

IEEE2022

Platicon microcomb generation using laser self-injection locking

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

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

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

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

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

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

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

Fully self-contained turn-key soliton microcomb source

Rui Ning Wang, Tobias Kippenberg, John David Jost, Junqiu Liu, Grigorii Likhachev, Arslan Sajid Raja, Jijun He

We demonstrate a turn-key microcomb source based on 100 GHz Si3N4 ring microresonator. The device is fully optically and electronically integrated in a compact box, which runs by pushing one button. ...

IEEE2021

Magnetic-free silicon nitride integrated optical isolator

Rui Ning Wang, Tobias Kippenberg, Junqiu Liu, Jijun He, Anat Siddharth

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

Coherent terahertz-to-microwave link using electro-optic-modulated Turing rolls

Tobias Kippenberg, Miles Henry Anderson, Arslan Sajid Raja, Wenle Weng, Jijun He, Anat Siddharth

Arising from modulation instability, Turing rolls in optical Kerr microresonators have been used in the generation of optical frequency combs and the synthesis of microwave and terahertz frequencies. In this work, by applying electro-optic modulation on te ...

AMER PHYSICAL SOC2021

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

Rui Ning Wang, Tobias Kippenberg, Junqiu Liu, 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

Magnetic-free Nitride Optical Isolator on Chip

Rui Ning Wang, Tobias Kippenberg, Junqiu Liu, Jijun He, Anat Siddharth

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

IEEE2021

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

Simulating Mold Risks under Future Climate Conditions

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

This research tests the potential susceptibility of a prevalent, residential, wall assembly to the risk of sustained mold-growth in predicted future climate conditions. Here, the authors demonstrate a methodology that combines hygrothermal and mold-growth ...

IEEE2021

Gain-switched semiconductor laser driven soliton microcombs

Tobias Kippenberg, Erwan Guillaume Albert Lucas, Junqiu Liu, 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