538 research outputs found
Silicon-organic hybrid phase shifter based on a slot waveguide with a liquid-crystal cladding
DAC-Less amplifier-less generation and transmission of QAM signals using sub-volt silicon-organic hybrid modulators
We demonstrate generation and transmission of optical signals by directly interfacing highly efficient silicon-organic hybrid (SOH) modulators to binary output ports of a field-programmable gate array. Using an SOH Mach-Zehnder modulator (MZM) and an SOH IQ modulator we generate ON-OFF- keying and binary phase-shift keying signals as well as quadrature phase-shift keying and 16-state quadrature amplitude modulation (16QAM) formats. Peak-to-peak voltages amount to only 0.27 V-pp for driving the MZM and 0.41 V-pp for the IQ modulator. Neither digital-to-analog converters nor drive amplifiers are required, and the RF energy consumption in the modulator amounts to record-low 18 fJ/bit for 16QAM signaling
Diffusion in nanopores recorded by microscopic measuring techniques
The poster presents two measuring techniques which, by their very nature, can be focused on,
exclusively, microscopic dimensions, including the interior of the individual particles (crystallites) of
the material under study. Correspondingly, they are referred to as “microscopic measuring techniques”.
The examples presented refer, in particular, to the potentials of these techniques for investigating mass
transfer in complex systems
40 Gbit/s silicon-organic hybrid (SOH) phase modulator
A 40 Gbit/s electro-optic modulator is demonstrated. The modulator is based on a slotted silicon waveguide filled with an organic material. The silicon organic hybrid (SOH) approach allows combining highly nonlinear electro-optic organic materials with CMOS-compatible silicon photonics technology
Analysis of Kerr comb generation in silicon microresonators under the influence of two-photon absorption and free-carrier absorption
Kerr frequency comb generation relies on dedicated waveguide platforms that
are optimized towards ultralow loss while offering comparatively limited
functionality restricted to passive building blocks. In contrast to that, the
silicon-photonic platform offers a highly developed portfolio of
high-performance devices, but is deemed to be inherently unsuited for Kerr comb
generation at near-infrared (NIR) telecommunication wavelengths due to strong
two-photon absorption (TPA) and subsequent free-carrier absorption (FCA). Here
we present a theoretical investigation that quantifies the impact of TPA and
FCA on Kerr comb formation and that is based on a modified version of the
Lugiato-Lefever equation (LLE). We find that silicon microresonators may be
used for Kerr comb generation in the NIR, provided that the dwell time of the
TPA-generated free-carriers in the waveguide core is reduced by a
reverse-biased p-i-njunction and that the pump parameters are chosen
appropriately. We validate our analytical predictions with time integrations of
the LLE, and we present a specific design of a silicon microresonator that may
even support formation of dissipative Kerr soliton combs.Comment: 26 pages, 6 figures. Submitted to Physical Review
Analysis of Kerr comb generation in silicon microresonators under the influence of two-photon absorption and fast free-carrier dynamics
Kerr frequency comb generation relies on dedicated waveguide platforms that are optimized toward ultralow loss while offering comparatively limited functionality restricted to passive building blocks. In contrast to that, the silicon-photonic platform offers a highly developed portfolio of high-performance devices, but suffers from strong two-photon absorption (TPA) and subsequent free-carrier absorption (FCA) at near-infrared telecommunication wavelengths, thereby rendering Kerr comb generation a challenge. Here we present a model to investigate the impact of TPA and FCA on Kerr comb formation. Our model combines a modified version of the Lugiato-Lefever equation with a refined relation to precisely describe the fast space and time dependence of the free-carrier concentration along the circumference of the microresonator. Using this refined model, we derive conditions for modulation instability, in particular for necessary pump powers depending on TPA parameters and free-carrier lifetimes. We validate our analytical predictions by time integration and study the impact of fast free-carrier dynamics on Kerr comb formation. We find that silicon microresonators may be suitable for Kerr comb generation in the NIR, provided that the dwell time of the TPA-generated free carriers in the waveguide core is reduced by a reverse-biased p-i-n-junction and that the pump parameters are chosen appropriately
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