The nonlinearities in silicon are diverse. This Review covers the wealth of nonlinear effects in silicon and highlights the important applications and technological solutions in nonlinear silicon ...photonics.
Plasmonic Electro-Optic Modulators - A Review Smajic, J.; Leuthold, J.
IEEE journal of selected topics in quantum electronics,
07/2024, Volume:
30, Issue:
4: Adv. Mod. and Int. beyond Si and InP-based Plt.
Journal Article
Peer reviewed
Open access
Electro-optical modulators are key components in photonic communications, and they are decisively important for the quality and data transmission rates. They encode information by modulating the ...amplitude, phase, frequency or polarization of an optical wave in response to an electrical field. This paper offers a detailed review on plasmonic modulators, their structure, variations, capabilities, and figures of merit.
Optical modulators encode electrical signals to the optical domain and thus constitute a key element in high-capacity communication links. Ideally, they should feature operation at the highest speed ...with the least power consumption on the smallest footprint, and at low cost. Unfortunately, current technologies fall short of these criteria. Recently, plasmonics has emerged as a solution offering compact and fast devices. Yet, practical implementations have turned out to be rather elusive. Here, we introduce a 70 GHz all-plasmonic Mach-Zehnder modulator that fits into a silicon waveguide of 10 μm length. This dramatic reduction in size by more than two orders of magnitude compared with photonic Mach-Zehnder modulators results in a low energy consumption of 25 fJ per bit up to the highest speeds. The technology suggests a cheap co-integration with electronics.
Photonic integration requires a versatile packaging technology that enables low-loss interconnects between photonic chips in three-dimensional configurations. In this paper we introduce the concept ...of photonic wire bonding, where polymer waveguides with three-dimensional freeform geometries are used to bridge the gap between nanophotonic circuits located on different chips. In a proof-of-principle experiment, we demonstrate the fabrication of single-mode photonic wire bonds (PWB) by direct-write two-photon lithography. First-generation prototypes allow for efficient broadband coupling with average insertion losses of only 1.6 dB in the C-band and can carry wavelength-division multiplexing signals with multi-Tbit/s data rates. Photonic wire bonding is well suited for automated mass production, and we expect the technology to enable optical multi-chip systems with enhanced performance and flexibility.
In communications, the frequency range 0.1-30 THz is essentially terra incognita. Recently, research has focused on this terahertz gap, because the high carrier frequencies promise unprecedented ...channel capacities. Indeed, data rates of 100 Gbit s-1 were predicted for 2015. Here, we present, for the first time, a single-input and single-output wireless communication system at 237.5 GHz for transmitting data over 20 m at a data rate of 100 Gbit s-1 . This breakthrough results from combining terahertz photonics and electronics, whereby a narrow-band terahertz carrier is photonically generated by mixing comb lines of a mode-locked laser in a uni-travelling-carrier photodiode. The uni-travelling-carrier photodiode output is then radiated over a beam-focusing antenna. The signal is received by a millimetre-wave monolithic integrated circuit comprising novel terahertz mixers and amplifiers. We believe that this approach provides a path to scale wireless communications to Tbit s-1 rates over distances of >1 km.
Along with temperature, pressure and melt chemistry, magmatic oxygen fugacity (
f
O
2
) has an important influence on liquid and solid differentiation trends and melt structure. To explore the effect ...of redox conditions on mineral stability and mineral-melt partitioning in basaltic systems we performed equilibrium, one-atmosphere experiments on a picrite at 1200–1110 °C with
f
O
2
ranging from NNO-4 log units to air. Clinopyroxene crystallizes from 1180 °C to near-solidus, along with plagioclase, olivine and spinel. Olivine Mg# increases with increasing
f
O
2
, eventually reacting to pigeonite. Spinel is absent under strongly reducing conditions. Mineral-melt partition coefficients (
D
) of redox-sensitive elements (Cr, Eu, V, Fe) vary systematically with
f
O
2
and, in some cases, temperature (e.g.
D
Cr
in clinopyroxene). Clinopyroxene sector zoning is common; sectors along a- and b-axes have higher Al
IV
, Al
VI
, Cr and Ti and lower Mg than c-axis sectors. In terms of coupled substitutions, clinopyroxene CaTs (MgSi = Al
VI
Al
IV
) prevails under oxidized conditions (≥ NNO), where Fe
3+
balances the charge, but is limited under reduced conditions. Overall, Al
IV
is maximised under high temperature, oxidizing conditions and in slowly grown (a–b) sectors. High Al
IV
facilitates incorporation of REE (REEAl
IV
= CaSi), but
D
REE
(except
D
Eu
) show no systematic dependence on
f
O
2
across the experimental suite. In sector zoned clinopyroxenes enrichment in REE
3+
in Al-rich sectors is quantitatively consistent with the greater availability of suitably-charged M2 lattice sites and the electrostatic energy penalty required to insert REE
3+
onto unsuitably-charged M2 sites. By combining our experimental results with published data, we explore the potential for trace element oxybarometry. We show that olivine-melt
D
V
, clinopyroxene-melt
D
V
/
D
Sc
and plagioclase-melt
D
Eu
/
D
Sr
all have potential as oxybarometers and we present expressions for these as a function of
f
O
2
relative to NNO. The crystal chemical sensitivity of heterovalent cation incorporation into clinopyroxene and the melt compositional sensitivity of the Eu
2+
–Eu
3+
redox potential limit the use of clinopyroxene-melt and plagioclase-melt, however, olivine-melt
D
V
affords considerable precision and accuracy as an oxybarometer that is independent of temperature, and crystal and melt composition. Variation of
D
V
and
D
V
/
D
Sc
with
f
O
2
for olivine and clinopyroxene contains information on redox speciation of V in coexisting melt. By comparing the redox speciation constraints from partitioning to data from Fe-free synthetic systems and XANES spectroscopy of quenched glasses, we show that homogenous equilibria involving Fe and V species modify V speciation on quench, leading to a net overall reduction in the average vanadium valence. Mineral-melt partitioning of polyvalent species can be a useful probe of redox speciation in Fe-bearing systems that is unaffected by quench effects.
To keep pace with the demands in optical communications, electro-optic modulators should feature large bandwidths, operate across all telecommunication windows, offer a small footprint, and allow for ...CMOS-compatible fabrication to keep costs low. Here, we demonstrate a new ultra-compact plasmonic phase modulator based on the Pockels effect in a nonlinear polymer. The device has a length of only 29 µm and operates at 40 Gbit s-1 . Its modulation frequency response is flat up to 65 GHz and beyond. The modulator has been tested to work across a 120-nm-wide wavelength range centred at 1,550 nm, and is expected to work beyond this range. Its operation has been verified for temperatures up to 85 °C and it is easy to fabricate. To the best of our knowledge, this is the most compact high-speed phase modulator demonstrated to date.
We demonstrate a plasmonic Mach-Zehnder (MZ) modulator with a flat frequency response exceeding 170 GHz. The modulator comprises two phase modulators exploiting the Pockels effect of an organic ...electro-optic material in plasmonic slot waveguides. We further show modulation at 100 GBd NRZ and 60 GBd PAM-4. The electrical drive signals were generated using a 100 GSa/s digital to analog converter (DAC). The high-speed and small-scale devices are relevant for next-generation optical interconnects.
Values up to gamma=7 x 10(6)/(W km) for the nonlinear parameter are feasible if silicon-on-insulator based strip and slot waveguides are properly designed. This is more than three orders of magnitude ...larger than for state-of-the-art highly nonlinear fibers, and it enables ultrafast all-optical signal processing with nonresonant compact devices. At lambda=1.55 microm we provide universal design curves for strip and slot waveguides which are covered with different linear and nonlinear materials, and we calculate the resulting maximum gamma.
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