219 research outputs found
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
resonator and 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.Comment: 10 pages, 4 figure
Detuning-dependent Properties and Dispersion-induced Instabilities of Temporal Dissipative Kerr Solitons in Optical Microresonators
Temporal-dissipative Kerr solitons are self-localized light pulses sustained
in driven nonlinear optical resonators. Their realization in microresonators
has enabled compact sources of coherent optical frequency combs as well as the
study of dissipative solitons. A key parameter of their dynamics is the
effective-detuning of the pump laser to the thermally- and Kerr-shifted cavity
resonance. Together with the free spectral range and dispersion, it governs the
soliton-pulse duration, as predicted by an approximate analytical solution of
the Lugiato-Lefever equation. Yet, a precise experimental verification of this
relation was lacking so far. Here, by measuring and controlling the
effective-detuning, we establish a new way of stabilizing solitons in
microresonators and demonstrate that the measured relation linking soliton
width and detuning deviates by less than 1 % from the approximate expression,
validating its excellent predictive power. Furthermore, a detuning-dependent
enhancement of specific comb lines is revealed, due to linear couplings between
mode-families. They cause deviations from the predicted comb power evolution,
and induce a detuning-dependent soliton recoil that modifies the pulse
repetition-rate, explaining its unexpected dependence on laser-detuning.
Finally, we observe that detuning-dependent mode-crossings can destabilize the
soliton, leading to an unpredicted soliton breathing regime (oscillations of
the pulse) that occurs in a normally-stable regime. Our results test the
approximate analytical solutions with an unprecedented degree of accuracy and
provide new insights into dissipative-soliton dynamics.Comment: Updated funding acknowledgement
Dual chirped micro-comb based parallel ranging at megapixel-line rates
Laser based ranging (LiDAR) - already ubiquitously used in industrial
monitoring, atmospheric dynamics, or geodesy - is key sensor technology.
Coherent laser ranging, in contrast to time-of-flight approaches, is immune to
ambient light, operates continuous wave allowing higher average powers, and
yields simultaneous velocity and distance information. State-of-the-art
coherent single laser-detector architectures reach hundreds of kilopixel per
second rates. While emerging applications such as autonomous driving, robotics,
and augmented reality mandate megapixel per second point sampling to support
real-time video-rate imaging. Yet, such rates of coherent LiDAR have not been
demonstrated. Here we report a swept dual-soliton microcomb technique enabling
coherent ranging and velocimetry at megapixel per second line scan measurement
rates with up to 64 spectrally dispersed optical channels. It is based on
recent advances in photonic chip-based microcombs that offer a solution to
reduce complexity both on the transmitter and receiver sides.
Multi-heterodyning two synchronously frequency-modulated microcombs yields
distance and velocity information of all individual ranging channels on a
single receiver alleviating the need for individual separation, detection, and
digitization. The reported LiDAR implementation is hardware-efficient,
compatible with photonic integration, and demonstrates the significant
advantages of acquisition speed afforded by the convergence of optical
telecommunication and metrology technologies. We anticipate our research will
motivate further investigation of frequency swept microresonator dual-comb
approach in the neighboring fields of linear and nonlinear spectroscopy,
optical coherence tomography
Relativity Laws for the Variation of Rates of Clocks Moving in Free Space and GPS Positioning Errors Caused by Space-Weather Events
Nanophotonic soliton-based microwave synthesizers
Microwave photonic technologies, which upshift the carrier into the optical
domain to facilitate the generation and processing of ultrawide-band electronic
signals at vastly reduced fractional bandwidths, have the potential to achieve
superior performance compared to conventional electronics for targeted
functions. For microwave photonic applications such as filters, coherent
radars, subnoise detection, optical communications and low-noise microwave
generation, frequency combs are key building blocks. By virtue of soliton
microcombs, frequency combs can now be built using CMOS compatible photonic
integrated circuits, operated with low power and noise, and have already been
employed in system-level demonstrations. Yet, currently developed photonic
integrated microcombs all operate with repetition rates significantly beyond
those that conventional electronics can detect and process, compounding their
use in microwave photonics. Here we demonstrate integrated soliton microcombs
operating in two widely employed microwave bands, X- and K-band. These devices
can produce more than 300 comb lines within the 3-dB-bandwidth, and generate
microwave signals featuring phase noise levels below 105 dBc/Hz (140 dBc/Hz) at
10 kHz (1 MHz) offset frequency, comparable to modern electronic microwave
synthesizers. In addition, the soliton pulse stream can be injection-locked to
a microwave signal, enabling actuator-free repetition rate stabilization,
tuning and microwave spectral purification, at power levels compatible with
silicon-based lasers (<150 mW). Our results establish photonic integrated
soliton microcombs as viable integrated low-noise microwave synthesizers.
Further, the low repetition rates are critical for future dense WDM channel
generation schemes, and can significantly reduce the system complexity of
photonic integrated frequency synthesizers and atomic clocks
Massively parallel coherent laser ranging using soliton microcombs
Coherent ranging, also known as frequency-modulated continuous-wave (FMCW)
laser based ranging (LIDAR) is currently developed for long range 3D distance
and velocimetry in autonomous driving. Its principle is based on mapping
distance to frequency, and to simultaneously measure the Doppler shift of
reflected light using frequency chirped signals, similar to Sonar or Radar.
Yet, despite these advantages, coherent ranging exhibits lower acquisition
speed and requires precisely chirped and highly-coherent laser sources,
hindering their widespread use and impeding Parallelization, compared to modern
time-of-flight (TOF) ranging that use arrays of individual lasers. Here we
demonstrate a novel massively parallel coherent LIDAR scheme using a photonic
chip-based microcomb. By fast chirping the pump laser in the soliton existence
range of a microcomb with amplitudes up to several GHz and sweep rate up to 10
MHz, the soliton pulse stream acquires a rapid change in the underlying carrier
waveform, while retaining its pulse-to-pulse repetition rate. As a result, the
chirp from a single narrow-linewidth pump laser is simultaneously transferred
to all spectral comb teeth of the soliton at once, and allows for true
parallelism in FMCW LIDAR. We demonstrate this approach by generating 30
distinct channels, demonstrating both parallel distance and velocity
measurements at an equivalent rate of 3 Mpixel/s, with potential to improve
sampling rates beyond 150 Mpixel/s and increase the image refresh rate of FMCW
LIDAR up to two orders of magnitude without deterioration of eye safety. The
present approach, when combined with photonic phase arrays based on
nanophotonic gratings, provides a technological basis for compact, massively
parallel and ultra-high frame rate coherent LIDAR systems.Comment: 18 pages, 12 Figure
Dynamics of soliton crystals in optical microresonators
Dissipative Kerr solitons in optical microresonators provide a unifying
framework for nonlinear optical physics with photonic-integrated technologies
and have recently been employed in a wide range of applications from coherent
communications to astrophysical spectrometer calibration. Dissipative Kerr
solitons can form a rich variety of stable states, ranging from breathers to
multiple-soliton formations, among which, the recently discovered soliton
crystals stand out. They represent temporally-ordered ensembles of soliton
pulses, which can be regularly arranged by a modulation of the continuous-wave
intracavity driving field. To date, however, the dynamics of soliton crystals
remains mainly unexplored. Moreover, the vast majority of the reported crystals
contained defects - missing or shifted pulses, breaking the symmetry of these
states, and no procedure to avoid such defects was suggested. Here we explore
the dynamical properties of soliton crystals and discover that often-neglected
chaotic operating regimes of the driven optical microresonator are the key to
their understanding. In contrast to prior work, we prove the viability of
deterministic generation of soliton crystal states, which
correspond to a stable, defect-free lattice of optical pulses inside the
cavity. We discover the existence of critical pump power, below which the
stochastic process of soliton excitation suddenly becomes deterministic
enabling faultless, device-independent access to perfect soliton crystals.
Furthermore, we demonstrate the switching of soliton crystal states and prove
that it is also tightly linked to the pump power and is only possible in the
regime of transient chaos. Finally, we report a number of other dynamical
phenomena experimentally observed in soliton crystals including the formation
of breathers, transitions between soliton crystals, their melting, and
recrystallization
Ultrafast optical ranging using microresonator soliton frequency combs
Light detection and ranging (LIDAR) is critical to many fields in science and
industry. Over the last decade, optical frequency combs were shown to offer
unique advantages in optical ranging, in particular when it comes to fast
distance acquisition with high accuracy. However, current comb-based concepts
are not suited for emerging high-volume applications such as drone navigation
or autonomous driving. These applications critically rely on LIDAR systems that
are not only accurate and fast, but also compact, robust, and amenable to
cost-efficient mass-production. Here we show that integrated dissipative
Kerr-soliton (DKS) comb sources provide a route to chip-scale LIDAR systems
that combine sub-wavelength accuracy and unprecedented acquisition speed with
the opportunity to exploit advanced photonic integration concepts for
wafer-scale mass production. In our experiments, we use a pair of free-running
DKS combs, each providing more than 100 carriers for massively parallel
synthetic-wavelength interferometry. We demonstrate dual-comb distance
measurements with record-low Allan deviations down to 12 nm at averaging times
of 14 s as well as ultrafast ranging at unprecedented measurement rates of
up to 100 MHz. We prove the viability of our technique by sampling the
naturally scattering surface of air-gun projectiles flying at 150 m/s (Mach
0.47). Combining integrated dual-comb LIDAR engines with chip-scale
nanophotonic phased arrays, the approach could allow widespread use of compact
ultrafast ranging systems in emerging mass applications.Comment: 9 pages, 3 figures, Supplementary information is attached in
'Ancillary files
- …