39 research outputs found
Radiation Hardness of High-Q Silicon Nitride Microresonators for Space Compatible Integrated Optics
Integrated optics has distinct advantages for applications in space because
it integrates many elements onto a monolithic, robust chip. As the development
of different building blocks for integrated optics advances, it is of interest
to answer the important question of their resistance with respect to ionizing
radiation. Here we investigate effects of proton radiation on high-Q silicon
nitride microresonators formed by a waveguide ring. We show that the
irradiation with high-energy protons has no lasting effect on the linear
optical losses of the microresonators
Photonic chip based optical frequency comb using soliton induced Cherenkov radiation
By continuous wave pumping of a dispersion engineered, planar silicon nitride
microresonator, continuously circulating, sub-30fs short temporal dissipative
solitons are generated, that correspond to pulses of 6 optical cycles and
constitute a coherent optical frequency comb in the spectral domain. Emission
of soliton induced Cherenkov radiation caused by higher order dispersion
broadens the spectral bandwidth to 2/3 of an octave, sufficient for self
referencing, in excellent agreement with recent theoretical predictions and the
broadest coherent microresonator frequency comb generated to date. In a further
step, this frequency comb is fully phase stabilized. The ability to preserve
coherence over a broad spectral bandwidth using soliton induced Cherenkov
radiation marks a critical milestone in the development of planar optical
frequency combs, enabling on one hand application in e.g. coherent
communications, broadband dual comb spectroscopy and Raman spectral imaging,
while on the other hand significantly relaxing dispersion requirements for
broadband microresonator frequency combs and providing a path for their
generation in the visible and UV. Our results underscore the utility and
effectiveness of planar microresonator frequency comb technology, that offers
the potential to make frequency metrology accessible beyond specialized
laboratories.Comment: Changes: - Added data (new Fig.4) on the first full phase
stabilization of a dissipative Kerr soliton (or dissipative cavity soliton)
in a microresonator - Extended Fig. 8 in the SI - Introduced nomenclature of
dissipative Kerr solitons - Minor other change
Microresonator solitons for massively parallel coherent optical communications
Optical solitons are waveforms that preserve their shape while propagating,
relying on a balance of dispersion and nonlinearity. Soliton-based data
transmission schemes were investigated in the 1980s, promising to overcome the
limitations imposed by dispersion of optical fibers. These approaches, however,
were eventually abandoned in favor of wavelength-division multiplexing (WDM)
schemes that are easier to implement and offer improved scalability to higher
data rates. Here, we show that solitons may experience a comeback in optical
communications, this time not as a competitor, but as a key element of
massively parallel WDM. Instead of encoding data on the soliton itself, we
exploit continuously circulating dissipative Kerr solitons (DKS) in a
microresonator. DKS are generated in an integrated silicon nitride
microresonator by four-photon interactions mediated by Kerr nonlinearity,
leading to low-noise, spectrally smooth and broadband optical frequency combs.
In our experiments, we use two interleaved soliton Kerr combs to transmit a
data stream of more than 50Tbit/s on a total of 179 individual optical carriers
that span the entire telecommunication C and L bands. Equally important, we
demonstrate coherent detection of a WDM data stream by using a pair of
microresonator Kerr soliton combs - one as a multi-wavelength light source at
the transmitter, and another one as a corresponding local oscillator (LO) at
the receiver. This approach exploits the scalability advantages of
microresonator soliton comb sources for massively parallel optical
communications both at the transmitter and receiver side. Taken together, the
results prove the significant potential of these sources to replace arrays of
continuous-wave lasers in high-speed communications.Comment: 10 pages, 3 figure
Frequency comb up- and down-conversion in a synchronously-driven optical microresonator
Optical frequency combs are key to optical precision measurements. While most
frequency combs operate in the near-infrared regime, many applications require
combs at mid-infrared, visible or even ultra-violet wavelengths. Frequency
combs can be transferred to other wavelengths via nonlinear optical processes,
however, this becomes exceedingly challenging for high-repetition rate
frequency combs. Here, it is demonstrated that a synchronously driven high-Q
microresonator with a second-order optical nonlinearity can efficiently convert
high-repetition rate near-infrared frequency combs to visible, ultra-violet and
mid-infrared wavelengths providing new opportunities for microresonator and
electro-optic combs in applications including molecular sensing, astronomy, and
quantum optics
Coherent terabit communications with microresonator Kerr frequency combs
Optical frequency combs enable coherent data transmission on hundreds of
wavelength channels and have the potential to revolutionize terabit
communications. Generation of Kerr combs in nonlinear integrated microcavities
represents a particularly promising option enabling line spacings of tens of
GHz, compliant with wavelength-division multiplexing (WDM) grids. However, Kerr
combs may exhibit strong phase noise and multiplet spectral lines, and this has
made high-speed data transmission impossible up to now. Recent work has shown
that systematic adjustment of pump conditions enables low phase-noise Kerr
combs with singlet spectral lines. Here we demonstrate that Kerr combs are
suited for coherent data transmission with advanced modulation formats that
pose stringent requirements on the spectral purity of the optical source. In a
first experiment, we encode a data stream of 392 Gbit/s on subsequent lines of
a Kerr comb using quadrature phase shift keying (QPSK) and 16-state quadrature
amplitude modulation (16QAM). A second experiment shows feedback-stabilization
of a Kerr comb and transmission of a 1.44 Tbit/s data stream over a distance of
up to 300 km. The results demonstrate that Kerr combs can meet the highly
demanding requirements of multi-terabit/s coherent communications and thus
offer a solution towards chip-scale terabit/s transceivers
Ultraviolet astronomical spectrograph calibration with laser frequency combs from nanophotonic waveguides
Astronomical precision spectroscopy underpins searches for life beyond Earth,
direct observation of the expanding Universe and constraining the potential
variability of physical constants across cosmological scales. Laser frequency
combs can provide the critically required accurate and precise calibration to
the astronomical spectrographs. For cosmological studies, extending the
calibration with such astrocombs to the ultraviolet spectral range is highly
desirable, however, strong material dispersion and large spectral separation
from the established infrared laser oscillators have made this exceedingly
challenging. Here, we demonstrate for the first time astronomical spectrograph
calibrations with an astrocomb in the ultraviolet spectral range below 400 nm.
This is accomplished via chip-integrated highly nonlinear photonics in
periodically-poled, nano-fabricated lithium niobate waveguides in conjunction
with a robust infrared electro-optic comb generator, as well as a
chip-integrated microresonator comb. These results demonstrate a viable route
towards astronomical precision spectroscopy in the ultraviolet and may
contribute to unlocking the full potential of next generation ground- and
future space-based astronomical instruments