141 research outputs found
High-efficiency broad-bandwidth sub-wavelength grating based fibre-chip coupler in SOI
We report a comprehensive study on the performance of uniform and non-uniform
based subwavelength grating couplers in Silicon-on-Insulator. The two
performance metrics, coupling efficiency and bandwidth enhancement and
trade-offs is presented. We also present, design parameters to achieve
high-efficiency and broadband operation based on the detailed study of various
loss mechanisms in the grating. Based on the detailed analysis subwavelength
grating coupler designs with efficiency as high as 84 % with a 1 dB bandwidth
of 50 nm and 98 % with a 44 nm 1 dB bandwidth is presented
All-optical wavelength multicasting in quadruple resonance-split coupled Silicon microring cavity
We demonstrate an all-optical four-channel wavelength multicasting in a
coupled Silicon microring resonator system. The scheme is based on two-photon
absorption induced free carrier dispersion in Silicon. The coupled cavity
facilitates resonance splitting that is utilized as individual channels for
multicasting. Using the split resonances, we achieve an aggregate multicasted
data rate of 48 Gbps (4X12 Gbps). Moreover, we also present a detailed analysis
and performance of the multicasting architecture
3-D poling and drive mechanism for high-speed PZT-on-SOI Electro-Optic modulator using remote Pt buffered growth
In this work, we have demonstrated a novel method to increase the
electro-optic interaction in an intensity modulator at the C-band by optimizing
the growth methodology of PZT with the metal (Ti/Pt) as a base material and the
PZT poling architecture. Here, we have used a patterned Pt layer for PZT
deposition instead of a buffer layer. By optimizing the PZT growth process, we
have been able to do poling of the fabricated PZT film in an arbitrary
direction as well as have achieved an enhanced electro-optic interaction,
leading to a DC spectrum shift of 304 pm/V and a V{\pi} L{\pi} value of 0.6
V-cm on a Si-based MZI. For an electro-optic modulator, we are reporting the
best values of DC spectrum shift and V{\pi} L{\pi} using perovskite as an
active material. The high-speed measurement has yielded a tool-limited
bandwidth of > 12GHz. The extrapolated bandwidth calculated using the slope of
the modulation depth is 45 GHz. We also show via simulation an optimized gap of
4.5 {\mu}m and a PZT thickness of 1 {\mu}m that gives us a less than 1 V-dB.Comment: 7 pages, 5 figures, 1 Tabl
Highly Oriented PZT Platform for Polarization-Independent Photonic Integrated Circuit and Enhanced Efficiency Electro-Optic Modulation
We demonstrate, for the first time, sputtered PZT as a platform for the
development of Si-based photonic devices such as rings, MZI, and electro-optic
modulators. We report the optimization of PZT on MgO(002) substrate to obtain
highly oriented PZT film oriented towards the (100) plane with a surface
roughness of 2 nm. Si gratings were simulated for TE and TM mode with an
efficiency of -2.2 dB/coupler -3 dB/coupler respectively with a polarization
insensitive efficiency of 50% for both TE and TM mode. Si grating with an
efficiency of around -10 dB/coupler and a 6 dB bandwidth of 30 nm was
fabricated. DC Electro-optic characterization for MZI yielded a spectrum shift
of 71 pm/V at the c-band.Comment: 11 Pages, 9 Figures, 3 Table
DFT analysis and demonstration of enhanced clamped Electro-Optic tensor by strain engineering in PZT
We report 400\% enhancement in PZT Pockels coefficient on DFT
simulation of lattice strain due to phonon mode softening.The simulation showed
a relation between the rumpling and the Pockels coefficient divergence that
happens at -8\% and 25\% strain developed in PZT film.The simulation was
verified experimentally by RF sputter deposited PZT film on Pt/SiO/Si
layer.The strain developed in PZT varied from -0.04\% for film annealed at
530\degree C to -0.21\% for 600\degree C annealing temperature.The strain was
insensitive to RF power with a value of -0.13\% for power varying between
70-130 W. Pockels coefficient enhancement was experimentally confirmed by Si
Mach Zehnder interferometer loaded with PZT and probed with the co-planar
electrode.An enhancement of 300\% in Pockels coefficient was observed
from 2-8 pm/V with strain increasing from -0.04\% to -0.21\%. To the best of
our knowledge, this is the first time study and demonstration of strain
engineering on Pockels coefficient of PZT using DFT simulation, film
deposition, and photonic device fabrication.Comment: 9 Pages, 4 Figure
Review on Optical Waveguides
Optical devices are necessary to meet the anticipated future requirements for ultrafast and ultrahigh bandwidth communication and computing. All optical information processing can overcome optoelectronic conversions that limit both the speed and bandwidth and are also power consuming. The building block of an optical device/circuit is the optical waveguide, which enables low-loss light propagation and is thereby used to connect components and devices. This chapter reviews optical waveguides and their classification on the basis of geometry (Non-Planar (Slab/Optical Fiber)/Planar (Buried Channel, Strip-Loaded, Wire, Rib, Diffused, Slot, etc.)), refractive index (Step/Gradient Index), mode propagation (Single/Multimode), and material platform (Glass/Polymer/Semiconductor, etc.). A comparative analysis of waveguides realized in different material platforms along with the propagation loss is also presented
Compact Broadband Low-Loss Taper for Coupling to a Silicon Nitride Photonic Wire
We demonstrate an ultra-compact waveguide taper in Silicon Nitride platform.
The proposed taper provides a coupling-efficiency of 95% at a length of 19.5 um
in comparison to the standard linear taper of length 50 um that connects a 10
um wide waveguide to a 1 um wide photonic wire. The taper has a spectral
response > 75% spanning over 800 nm and resilience to fabrication variations;
>200 nm change in taper and end waveguide width varies transmission by <5%. We
experimentally demonstrate taper insertion loss of <0.1 dB/transition for a
taper as short as 19.5 um, and reduces the footprint of the photonic device by
50.8% compared to the standard adiabatic taper. To the best of our knowledge,
the proposed taper is the shortest waveguide taper ever reported in Silicon
Nitride
Generation of tunable, high repetition rate optical frequency combs using on-chip silicon modulators
We experimentally demonstrate tunable, highly-stable frequency combs with
high repetition-rates using a single, charge injection based silicon PN
modulator. In this work, we demonstrate combs in the C-band with over 8 lines
in a 20-dB bandwidth. We demonstrate continuous tuning of the center frequency
in the C-band and tuning of the repetition-rate from 7.5GHz to 12.5GHz. We also
demonstrate through simulations the potential for bandwidth scaling using an
optimized silicon PIN modulator. We find that, the time varying free carrier
absorption due to carrier injection, an undesirable effect in data modulators,
assists here in enhancing flatness in the generated combs.Comment: 10 pages, 7 figure
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