Photonic qubits can represent an ideal choice in quantum information science since photons travel at the speed of light and interact weakly with the environment over long distances. In this context, ...technological platforms allowing the development and implementation of chip-scale integrated photonics represent a possible solution toward scalable quantum networking schemes. However, at present, most examples of integrated quantum photonics still require the coupling of light to external photodetectors operating at very low temperatures. In this paper, we demonstrate that the GeSn/Si-in-SOI technological platform can be a good candidate to realize integrated single-photon avalanche detectors (SPADs), operating at room temperature. Thus, we report the design and simulation of waveguide-based SPADs for operation at 1550 and 2000 nm wavelengths. We calculate the breakdown voltage, the dark count rate (DCR), the single photon detection efficiency (SPDE), the noise equivalent power (NEP), the dark count, and the afterpulsing probabilities by simulating the avalanche process and the statistical features in a self-consistent way. The PIPIN SPAD performance parameters are estimated as a function of the GeSn’s threading dislocation density and of the temperature. We also demonstrate that for operation at 1550 and 2000 nm wavelengths with the 220 nm GeSn separate absorber film centered in the 250 nm high Si waveguide end, it is possible to cover a number of applications at room or near room temperature, ranging from ultrasensitive LIDAR to quantum communications, metrology, sensing, and key distribution.
In this paper we propose an optical biosensor based on two vertically stacked Silicon on Insulator (SOI) micro-ring resonators interacting with a microfluidic ring channel. This device behaves as a ...resonant optical coupler and it is very sensitive to the variation of the coupling coefficient between the two vertically stacked ring resonators. A ring microfluidic channel is proposed in the coupling region between the two vertically stacked ring resonators. The inner walls of the channel are funzionalized in order to the trap a specific biological species. Assuming a biotin-streptavidin system, the straptividin trapping gives rise to a change of the biological thickness of about 3 nm. This thickness increase of the deposited layer leads to a consequent change in the coupling strength between the two rings. These theoretical predictions have been validated by using both 3D Finite-Difference Time-Domain (FDTD) and 3D full-vectorial Finite Element Method (FEM) approaches. Moreover, by appropriately choosing the design parameters of the micro-resonant structure, we evaluate a sensitivity of the spectral response to the streptavidin adlayer variation of about 20% nm
−1
for TE polarization and 34% nm
−1
for TM polarization, which represents an important achievement to obtain selective SOI bio-sensors with ultra-high resolution.
In this paper, the detailed modeling of Raman lasers in silicon-on-insulator guided-wave racetrack resonant microcavities is developed. Modeling based on full-vectorial equations and systematic ...design rules are presented for the first time. Simulation results are compared with experimental and theoretical results in literature, demonstrating a very good agreement. Moreover, parametric investigations including waveguide sizes, pump and Stokes coupling factors, cavity shape, polarization states, and waveguide orientation are presented, and their influence on the laser features are discussed.
Electromagnetic field photonic sensors Passaro, V.M.N.; Dell’Olio, F.; De Leonardis, F.
Progress in quantum electronics,
2006, 2006-1-00, Volume:
30, Issue:
2
Journal Article
Peer reviewed
In this paper, we review the different configurations proposed for electromagnetic field optical sensing. Intrinsic and extrinsic optical fiber sensors for electric and magnetic field measurement are ...examined, including those realized jacketing the fiber by magnetostrictive, conductive, electrochromic and polymeric materials and those measuring induced strain by magnetostrictive, electrostrictive and piezoelectric transducers. Extrinsic optical fiber sensors exploiting magneto-optic, electro-optic and Joule effects are also presented.
Moreover, integrated optical electric and magnetic field sensors in which microwave signal provided by an antenna modulates the optical signal generated by an optical source are reviewed. Finally, active and coupled resonators based on electric field sensors are investigated.
The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy s=8 TeV based on a high-statistics data sample obtained with ...the β⁎=90 m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027<|t|<0.2 GeV2 with a significance greater than 7 σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t=0, and further applying the optical theorem, yields total cross-section estimates of (101.5±2.1) mb and (101.9±2.1) mb, respectively, in agreement with previous TOTEM measurements.
In this paper, a rigorous leaky mode propagation method has been used to investigate the influence of the grating period and grating index profile on the design of grating-assisted directional ...couplers (GADC's). A detailed explanation of resonance condition and radiation loss in terms of electromagnetic field contribution in the grating region as a function of the grating period and profile is given. Optimal design parameters hare been found for well-defined structures in order to achieve either minimum coupling length or maximum coupling efficiency. A very fast method to extract the resonance condition in any grating-assisted structure by using a sinusoidal profile is proposed. Numerical results are presented for both moderately and strongly asymmetric structures in terms of normalized propagation constant, mode radiation loss, coupling length and coupling efficiency. Comparisons with grating period and coupling length predictions obtained by other methods are also shown. The rectangular profile with optimized duty cycle has been demonstrated to be the best choice in order to minimize the GADC coupling length.
The TOTEM collaboration has measured the proton–proton total cross section at
s
=
13
TeV
with a luminosity-independent method. Using dedicated
β
∗
=
90
m
beam optics, the Roman Pots were inserted ...very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton–proton cross section is
σ
tot
=
(
110.6
±
3.4
) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections:
σ
el
=
(
31.0
±
1.7
)
mb
and
σ
inel
=
(
79.5
±
1.8
)
mb
.
The TOTEM experiment at the LHC has performed the first measurement at
s
=
13
TeV
of the
ρ
parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at
t
=
0
, obtaining the ...following results:
ρ
=
0.09
±
0.01
and
ρ
=
0.10
±
0.01
, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the
ρ
measurement, combined with the TOTEM total cross-section measurements in an energy range larger than
10
TeV
(from 2.76 to
13
TeV
), has implied the exclusion of all the models classified and published by COMPETE. The
ρ
results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the
t
-channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state
t
-channel exchange is not of importance for the description of elastic scattering, the
ρ
value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-|
t
| reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton–proton cross-section measurement
σ
tot
=
(
110.3
±
3.5
)
mb
, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields
σ
tot
=
(
110.5
±
2.4
)
mb
.
The TOTEM collaboration has measured the elastic proton-proton differential cross section
d
σ
/
d
t
at
s
=
13
TeV LHC energy using dedicated
β
∗
=
90
m beam optics. The Roman Pot detectors were ...inserted to 10
σ
distance from the LHC beam, which allowed the measurement of the range 0.04 GeV
2
; 4 GeV
2
in four-momentum transfer squared |
t
|. The efficient data acquisition allowed to collect about 10
9
elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-|
t
| tail. The average nuclear slope has been found to be
B
=
(
20.40
±
0
.
002
stat
±
0
.
01
syst
)
GeV
-
2
in the |
t
|-range 0.04–0.2 GeV
2
. The dip position is
|
t
dip
|
=
(
0.47
±
0
.
004
stat
±
0
.
01
syst
)
GeV
2
. The differential cross section ratio at the bump vs. at the dip
R
=
1.77
±
0
.
01
stat
has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.
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