27,407 research outputs found
An equivalent circuit model of the traveling wave electrode for carrier-depletion-based silicon optical modulators
We propose an equivalent circuit model for the coplanar waveguide (CPW) which serves as the traveling wave electrode to drive carrier-depletion-based silicon modulators. Conformal mapping and partial capacitance techniques are employed to calculate each element of the circuit. The validity of the model is confirmed by the comparison with both finite-element simulation and experimental result. With the model, we calculate the modulation bandwidth for different CPW dimensions and termination impedances. A 3 dB modulation bandwidth of 15 GHz is demonstrated with a traveling wave electrode of 3 mm. The calculation indicates that, by utilizing a traveling wave electrode of 2 mm, we can obtain a 3 dB modulation bandwidth of 28 GHz
A verified equivalent-circuit model for slotwaveguide modulators
We formulate and experimentally validate an equivalent-circuit model based on
distributed elements to describe the electric and electro-optic (EO) properties
of travellingwave silicon-organic hybrid (SOH) slot-waveguide modulators. The
model allows to reliably predict the small-signal EO frequency response of the
modulators exploiting purely electrical measurements of the frequency-dependent
RF transmission characteristics. We experimentally verify the validity of our
model, and we formulate design guidelines for an optimum trade-off between
optical loss due to free-carrier absorption (FCA), electro-optic bandwidth, and
{\pi}-voltage of SOH slot-waveguide modulators
Phonon routing in integrated optomechanical cavity-waveguide systems
The mechanical properties of light have found widespread use in the
manipulation of gas-phase atoms and ions, helping create new states of matter
and realize complex quantum interactions. The field of cavity-optomechanics
strives to scale this interaction to much larger, even human-sized mechanical
objects. Going beyond the canonical Fabry-Perot cavity with a movable mirror,
here we explore a new paradigm in which multiple cavity-optomechanical elements
are wired together to form optomechanical circuits. Using a pair of
optomechanical cavities coupled together via a phonon waveguide we demonstrate
a tunable delay and filter for microwave-over-optical signal processing. In
addition, we realize a tight-binding form of mechanical coupling between
distant optomechanical cavities, leading to direct phonon exchange without
dissipation in the waveguide. These measurements indicate the feasibility of
phonon-routing based information processing in optomechanical crystal
circuitry, and further, to the possibility of realizing topological phases of
photons and phonons in optomechanical cavity lattices.Comment: 16 pages, 7 figure
Controlling phonons and photons at the wavelength-scale: silicon photonics meets silicon phononics
Radio-frequency communication systems have long used bulk- and
surface-acoustic-wave devices supporting ultrasonic mechanical waves to
manipulate and sense signals. These devices have greatly improved our ability
to process microwaves by interfacing them to orders-of-magnitude slower and
lower loss mechanical fields. In parallel, long-distance communications have
been dominated by low-loss infrared optical photons. As electrical signal
processing and transmission approaches physical limits imposed by energy
dissipation, optical links are now being actively considered for mobile and
cloud technologies. Thus there is a strong driver for wavelength-scale
mechanical wave or "phononic" circuitry fabricated by scalable semiconductor
processes. With the advent of these circuits, new micro- and nanostructures
that combine electrical, optical and mechanical elements have emerged. In these
devices, such as optomechanical waveguides and resonators, optical photons and
gigahertz phonons are ideally matched to one another as both have wavelengths
on the order of micrometers. The development of phononic circuits has thus
emerged as a vibrant field of research pursued for optical signal processing
and sensing applications as well as emerging quantum technologies. In this
review, we discuss the key physics and figures of merit underpinning this
field. We also summarize the state of the art in nanoscale electro- and
optomechanical systems with a focus on scalable platforms such as silicon.
Finally, we give perspectives on what these new systems may bring and what
challenges they face in the coming years. In particular, we believe hybrid
electro- and optomechanical devices incorporating highly coherent and compact
mechanical elements on a chip have significant untapped potential for
electro-optic modulation, quantum microwave-to-optical photon conversion,
sensing and microwave signal processing.Comment: 26 pages, 5 figure
Silicon-organic hybrid electro-optical devices
Organic materials combined with strongly guiding silicon waveguides open the route to highly efficient electro-optical devices. Modulators based on the so-called silicon-organic hybrid (SOH) platform have only recently shown frequency responses up to 100 GHz, high-speed operation beyond 112 Gbit/s with fJ/bit power consumption. In this paper, we review the SOH platform and discuss important devices such as Mach-Zehnder and IQ-modulators based on the linear electro-optic effect. We further show liquid-crystal phase-shifters with a voltage-length product as low as V pi L = 0.06 V.mm and sub-mu W power consumption as required for slow optical switching or tuning optical filters and devices
Evanescent light-matter Interactions in Atomic Cladding Wave Guides
Alkali vapors, and in particular rubidium, are being used extensively in
several important fields of research such as slow and stored light non-linear
optics3 and quantum computation. Additionally, the technology of alkali vapors
plays a major role in realizing myriad industrial applications including for
example atomic clocks magentometers8 and optical frequency stabilization.
Lately, there is a growing effort towards miniaturizing traditional
centimeter-size alkali vapor cells. Owing to the significant reduction in
device dimensions, light matter interactions are greatly enhanced, enabling new
functionalities due to the low power threshold needed for non-linear
interactions. Here, taking advantage of the mature Complimentary
Metal-Oxide-Semiconductor (CMOS) compatible platform of silicon photonics, we
construct an efficient and flexible platform for tailored light vapor
interactions on a chip. Specifically, we demonstrate light matter interactions
in an atomic cladding wave guide (ACWG), consisting of CMOS compatible silicon
nitride nano wave-guide core with a Rubidium (Rb) vapor cladding. We observe
the highly efficient interaction of the electromagnetic guided mode with the
thermal Rb cladding. The nature of such interactions is explained by a model
which predicts the transmission spectrum of the system taking into account
Doppler and transit time broadening. We show, that due to the high confinement
of the optical mode (with a mode area of 0.3{\lambda}2), the Rb absorption
saturates at powers in the nW regime.Comment: 10 Pages 4 Figures. 1 Supplementar
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