arXiv subjects

Tobias Kippenberg

Publications and source records attributed to Tobias Kippenberg.

10 recordsLinked to original sources

arXiv2026

A fully integrated dispersion-managed femtosecond mode-locked laser

Femtosecond lasers underpin applications ranging from material processing to corneal surgery, while their regular pulse trains form optical frequency combs that have revolutionized timekeeping, spectroscopy, and metrology. On-chip optical frequency combs, such as Kerr microcombs, have enabled high-repetition-rate applications in optical communications and microwave photonics. However, integrated chip-scale sources operating at low repetition rates (100 MHz to 1 GHz), crucial for high peak intensities, remain elusive, as existing devices typically operate well beyond 10 GHz. Here, we demonstrate a self-starting, photonic integrated mode-locked laser based on a dispersion-managed architecture that accesses this regime. The laser combines erbium-implanted silicon nitride gain waveguides, integrated chirped Bragg gratings, and a semiconductor saturable absorber mirror to generate optical pulses with repetition rates from 0.5 to 1.2 GHz, pulse durations as short as 300 fs, and mode-locking thresholds down to 27.3 mW. The output forms a passively stable optical frequency comb with a comb-line drift below 1% of the repetition rate, surpassing the stability of commercial fiber lasers by two orders of magnitude. Leveraging this ultra-low threshold, we achieve complete hybrid integration by co-packaging the laser with a telecom-grade 980-nm III-V pump diode chip inside a compact photonic module. The resulting electrical-in/optical-out module delivers turnkey, stable mode-locked pulses, providing a compact, low-power, and vibration-insensitive foundry-compatible platform for field-deployable optical metrology and precision sensing.

physics.optics↗

arXiv2025

Integrated Telecom Wavelength Heralded Single-Photon Source based on GHz gated detectors

We introduce a simple and flexible concept for a heralded -- spectrally pure -- single photon source. The scheme uses a probabilistic photon pair source pumped with a CW laser, whereby a rapid gating InGaAs/InP single photon avalanche diode provides a synchronous clock and temporally resolves, and hence spectrally filters, the heralded photons. We demonstrate the concept by combining this with a narrow-band integrated silicon nitride photon-pair source. This simple architecture is capable of heralding photons with high spectral purity in the telecom band, but could be adapted to other wavelengths and bandwidth regimes.

quant-ph↗

arXiv2024

Ultrabroadband thin-film lithium tantalate modulator for high-speed communications

The continuous growth of global data traffic over the past three decades, along with advances in disaggregated computing architectures, presents significant challenges for optical transceivers in communication networks and high-performance computing systems. Specifically, there is a growing need to significantly increase data rates while reducing energy consumption and cost. High-performance optical modulators based on materials such as InP, thin-film lithium niobate (LiNbO3), or plasmonics have been developed, with LiNbO3 excelling in high-speed and low-voltage modulation. Nonetheless, the widespread industrial adoption of thin film LiNbO3 remains compounded by the rather high cost of the underlying 'on insulator' substrates -- in sharp contrast to silicon photonics, which can benefit from strong synergies with high-volume applications in conventional microelectronics. Here, we demonstrate an integrated 110 GHz modulator using thin-film lithium tantalate (LiTaO3) -- a material platform that is already commercially used for millimeter-wave filters and that can hence build upon technological and economic synergies with existing high-volume applications to offer scalable low-cost manufacturing. We show that the LiTaO3 photonic integrated circuit based modulator can support 176 GBd PAM8 transmission at net data rates exceeding 400 Gbit/s. Moreover, we show that using silver electrodes can reduce microwave losses compared to previously employed gold electrodes. Our demonstration positions LiTaO3 modulator as a novel and highly promising integration platform for next-generation high-speed, energy-efficient, and cost-effective transceivers.

physics.optics↗

arXiv2024

Large-scale photonic chip based pulse interleaver for low-noise microwave generation

Microwaves generated by optical techniques have demonstrated unprecedentedly low noise and hold significance in various applications such as communication, radar, instrumentation, and metrology. To date, the purest microwave signals are generated using optical frequency division with femtosecond mode-locked lasers. However, many femtosecond laser combs have a radio frequency (RF) repetition rate in the hundreds of megahertz range, necessitating methods to translate the generated low-noise RF signal to the microwave domain. Benchtop pulse interleavers can multiply the pulse repetition rate, avoid saturation of photodetectors, and facilitate the generation of high-power low-noise microwave signals, which have to date only been demonstrated using optical fibers or free space optics. Here, we introduce a large-scale photonic integrated circuit-based interleaver, offering size reduction and enhanced stability. The all-on-chip interleaver attains a 64-fold multiplication of the repetition rate, directly translated from 216 MHz to 14 GHz in microwave Ku-Band. By overcoming photodetector saturation, the generated microwave power was improved by 36 dB, with a phase noise floor reduced by more than 10 folds to -160 dBc/Hz on the 14 GHz carrier. The device is based on a low-loss and high-density photonic integrated circuit fabricated by the photonic Damascene process. Six cascaded stages of Mach-Zehnder interferometers with optical delay lines up to 33 centimeters long are fully integrated into a compact footprint of 8.5 mmx1.7 mm. The lithographically defined precision of the optical waveguide path length enables the scaling up of the interleaved frequency to millimeter-wave bands, which is challenging the fiber-based counterparts. This interleaver has the potential to reduce the cost and footprint of mode-locked-laser-based microwave generation, allowing for field deployment.

physics.optics↗

arXiv2021

Chaotic micro-comb based parallel ranging

The transition to chaos is ubiquitous in nonlinear systems ranging from fluid dynamics and superconducting circuits to biological organisms. Optical systems driven out of equilibrium such as lasers and supercontinuum generation exhibit chaotic states of light with fluctuations of both amplitude and phase and can give rise to Levy statistics, turbulence, and rogue waves. Spatio-temporal chaos also occurs in continuous-wave driven photonic chip based Kerr micro-resonators, where it is referred to as chaotic modulation instability. Such modulation instability states have generally been considered impractical for applications, in contrast to their coherent light state counterparts, which include soliton or dark-pulse states. Here we demonstrate that incoherent and chaotic states of light in an optical microresonator can be harnessed to implement unambiguous and interference-immune massively parallel coherent laser ranging by using the intrinsic random amplitude and phase modulation of the chaotic comb lines. We utilize 40 distinct lines of a microresonator frequency comb operated in the modulation instability regime. Each line carries more than 1 GHz noise bandwidth, which greatly surpasses the cavity linewidth, and enables to retrieve the distance of objects with cm-scale resolution. Our approach utilizes one of the most widely accessible microcomb states, and offers -- in contrast to dissipative Kerr soliton states -- high conversion efficiency, as well as flat optical spectra, and alleviates the need for complex laser initiation routines. Moreover the approach generates wideband signal modulation without requiring any electro-optical modulator or microwave synthesizer. Viewed more broadly, similar optical systems capable of chaotic dynamics could be applied to random modulation optical ranging as well as spread spectrum communication and optical cryptography systems.

physics.optics↗

arXiv2020

Parallel convolution processing using an integrated photonic tensor core

With the proliferation of ultra-high-speed mobile networks and internet-connected devices, along with the rise of artificial intelligence, the world is generating exponentially increasing amounts of data - data that needs to be processed in a fast, efficient and smart way. These developments are pushing the limits of existing computing paradigms, and highly parallelized, fast and scalable hardware concepts are becoming progressively more important. Here, we demonstrate a computational specific integrated photonic tensor core - the optical analog of an ASIC-capable of operating at Tera-Multiply-Accumulate per second (TMAC/s) speeds. The photonic core achieves parallelized photonic in-memory computing using phase-change memory arrays and photonic chip-based optical frequency combs (soliton microcombs). The computation is reduced to measuring the optical transmission of reconfigurable and non-resonant passive components and can operate at a bandwidth exceeding 14 GHz, limited only by the speed of the modulators and photodetectors. Given recent advances in hybrid integration of soliton microcombs at microwave line rates, ultra-low loss silicon nitride waveguides, and high speed on-chip detectors and modulators, our approach provides a path towards full CMOS wafer-scale integration of the photonic tensor core. While we focus on convolution processing, more generally our results indicate the major potential of integrated photonics for parallel, fast, and efficient computational hardware in demanding AI applications such as autonomous driving, live video processing, and next generation cloud computing services.

physics.optics↗

arXiv2020

Ultrafast optical circuit switching for data centers using integrated soliton microcombs

Networks inside current data centers comprise a hierarchy of power-hungry electronic packet switches interconnected via optical fibers and transceivers. As the scaling of such electrically-switched networks approaches a plateau, a power-efficient solution is to implement a flat network with optical circuit switching (OCS), without electronic switches and a reduced number of transceivers due to direct links among servers. One of the promising ways of implementing OCS is by using tunable lasers and arrayed waveguide grating routers. Such an OCS-network can offer high bandwidth and low network latency, and the possibility of photonic integration results in an energy-efficient, compact, and scalable photonic data center network. To support dynamic data center workloads efficiently, it is critical to switch between wavelengths in sub nanoseconds (ns). Here we demonstrate ultrafast photonic circuit switching based on a microcomb. Using a photonic integrated Si3N4 microcomb in conjunction with semiconductor optical amplifiers (SOAs), sub ns (< 500 ps) switching of more than 20 carriers is achieved. Moreover, the 25-Gbps non-return to zero (NRZ) and 50-Gbps four-level pulse amplitude modulation (PAM-4) burst mode transmission systems are shown. Further, on-chip Indium phosphide (InP) based SOAs and arrayed waveguide grating (AWG) are used to show sub-ns switching along with 25-Gbps NRZ burst mode transmission providing a path toward a more scalable and energy-efficient wavelength-switched network for future data centers.

physics.app-ph↗

arXiv2020

Heteronuclear soliton molecules in optical microresonators

Optical soliton molecules are bound states of solitons that arise from the balance between attractive and repulsive effects. Having been observed in systems ranging from optical fibers to mode-locked lasers, they provide insights into the fundamental interactions between solitons and the underlying dynamics of the nonlinear systems. Here, we enter the multistability regime of a Kerr microresonator to generate superpositions of distinct soliton states that are pumped at the same optical resonance, and report the discovery of heteronuclear dissipative Kerr soliton molecules. Ultrafast electrooptical sampling reveals the tightly short-range bound nature of such soliton molecules, despite comprising dissipative Kerr solitons of dissimilar amplitudes, durations and carrier frequencies. Besides the significance they hold in resolving soliton dynamics in complex nonlinear systems, such heteronuclear soliton molecules yield coherent frequency combs whose unusual mode structure may find applications in metrology and spectroscopy.

physics.optics↗

arXiv2019

Cherenkov radiation induced symmetry breaking in counter propagating dissipative Kerr solitons

The process of soliton Cherenkov radiation (also known as dispersive wave emission) in microresonator frequency combs plays a critical role in generating broadband and coherent microcomb spectra. Here, we report the observation of symmetry breaking in the group velocity of counter-propagating dissipative Kerr solitons, induced by polychromatic soliton Cherenkov radiation. Results show that in the presence of higher-order dispersion, the temporal arrangement of a multi-soliton state affects its group velocity, an effect which originates from the interference between multiple radiative tails emitted by individual solitons. Experimentally, we bidirectionally pump a microresonator with laser fields of equal power and frequency, and observe lifting of the degeneracy between the repetition rates of the counter-propagating solitons. The observation of symmetry breaking despite symmetric pumping conditions not only shines new light on the impact of dispersive waves on dissipative Kerr soliton dynamics, but also introduces a novel approach to develop coherent dual-comb spectrometers based on microcombs.

physics.optics↗

arXiv2016

Breathing dissipative solitons in optical microresonators

Dissipative solitons are self-localized structures resulting from a double balance between dispersion and nonlinearity as well as dissipation and a driving force. They occur in a wide variety of fields ranging from optics, hydrodynamics to chemistry and biology. Recently, significant interest has focused on their temporal realization in driven optical microresonators, known as dissipative Kerr solitons. They provide access to coherent, chip-scale optical frequency combs, which have already been employed in optical metrology, data communication and spectroscopy. Such Kerr resonator systems can exhibit numerous localized intracavity patterns and provide rich insights into nonlinear dynamics. A particular class of solutions consists of breathing dissipative solitons, representing pulses with oscillating amplitude and duration, for which no comprehensive understanding has been presented to date. Here, we observe and study single and multiple breathing dissipative solitons in two different microresonator platforms: crystalline $\mathrm{MgF_2}$ resonator and $\mathrm{Si_3N_4}$ integrated microring. We report a deterministic route to access the breathing state, which allowed for a detailed exploration of the breathing dynamics. In particular, we establish the link between the breathing frequency and two system control parameters - effective pump laser detuning and pump power. Using a fast detection, we present a direct observation of the spatiotemporal dynamics of individual solitons, revealing irregular oscillations and switching. An understanding of breathing solitons is not only of fundamental interest concerning nonlinear systems close to critical transition, but also relevant for applications to prevent breather-induced instabilities in soliton-based frequency combs.

physics.optics↗