The design of a continuously tunable optical delay line based on a compact graphene-based silicon Bragg grating is reported. High performance, in terms of electro-optical switching time (tswitch < 8 ...ns), delay range (Δτ = 200 ps), and figure of merit FOM = Δτ/A = 1.54x10
ps/mm
, has been achieved with an ultra-compact device footprint (A ~1.3 x 10
mm
), so improving the state-of-the-art of integrated optical delay lines. A continuous and complete tunability of the delay time can be achieved with a very low delay loss ( = 0.03 dB/ps) and a weak power consumption ( = 0.05 mW/ps). A flat bandwidth B = 1.19 GHz has been calculated by exploiting the slow-light effect in the device. This performance makes the proposed optical delay line suitable for several applications in Microwave Photonics (MWP), such as beamsteering/beamforming, for which large delay range, flat and wide bandwidth and small volume are required.
Advances in Gyroscope Technologies Armenise, Mario N; Ciminelli, Caterina; Dell'Olio, Francesco ...
2011, 2010, 20101120, 2014-07-30
eBook
This monograph collects and critically reviews the main results obtained by the scientific community in gyroscope technologies research field. It describes architectures, design techniques and ...fabrication technology of angular rate sensors proposed in literature. MEMS, MOEMS, optical and mechanical technologies are discussed together with achievable performance. The book also consideres future research trends aimed to cover special applications. The book is intended for researchers and Ph.D. students interested in modelling, design and fabrication of gyros. The book may be a useful education support in some university courses focused on gyro technologies.
Perovskite-based solar cells have observed tremendous growth in the last decade aiming at developing renewable energy sources. The enhancement of the power conversion efficiency (PCE), ...sustainability, and easing of the fabrication are the main driving forces of the ongoing research activity. In this context, graphene is particularly promising since it not only provides better charge collection but also helps to improve the sustainability and low-temperature fabrication of the perovskite cell. Here, a homojunction MaPbI 3 perovskite solar cell with graphene-TiO 2 nano-composite as the electron transport layer (ETL) has been numerically investigated. The effect of doping concentration on the p and n-doped section in the homojunction-MaPbI 3 has been studied, showing that 10 17 and 10 16 cm −3 doping on the p and n section of MaPbI 3 , respectively, provide the best band alignment with the ETL layer. The optimum thickness ratio of two doped sections (p:n) is found to be 60:40 in %. Moreover, the presence of graphene in the TiO 2 layer improves PCE thanks to enhanced fill factor and saturated current density. A combined effect of all these results in a PCE of 22.71% with a 100 nm thick ETL layer having an optimum graphene concentration of around 1%.
The design, fabrication, and optical characterization of the sensing element of a photonic InP-based gyroscope intended for applications in the field of aerospace and defense are reported in this ...paper. The sensing element is a spiral resonator coupled to a straight bus waveguide through a multimode interference coupler and exhibits a Q factor of approximately 600 000 with a footprint of approximately 10 mm 2 . The design of each component of the sensor is based on some well-established numerical methods such as the Finite Element Method, the beam propagation method, and the film mode matching method. The spiral cavity was designed using the standard transfer matrix method. The selected fabrication process, which is an enhanced version of the standard COBRA process, allows the monolithic integration of the sensing element with the other active components of the gyroscope, e.g., lasers, photodiodes, and modulators. Each component of the fabricated sensing element was optically characterized using an appropriate setup, which was also used for the optical characterization of the whole sensor. Based on the results of the characterization, the gyro performance was evaluated, and a way to improve both the resolution and the bias drift, i.e., down to 10°/h and 1°/h, respectively, was also clearly identified. The achieved results demonstrate, for the first time, the actual feasibility of a photonic gyro-on-chip through a well-established InP-based generic integration process.
A novel photonic/plasmonic cavity based on a 1-D photonic crystal cavity vertically coupled to a plasmonic gold structure is reported. The design has been optimized to achieve an ultra-high Q/V ...ratio, therefore improving the light-matter interaction and making the device suitable for optical trapping applications. Accurate 3-D finite element method (FEM) simulations have been carried out to evaluate the device behavior and performance. The device shows Q = 2:8 × 10 3 and V = 4 × 10 -4 (λ=n) 3 , which correspond to a Q=V = 7 × 10 6 (λ=n) -3 with a resonance transmission around 50% at λ R = 1589:62 nm. A strong gradient of the optical energy has been observed in the metal structure at the resonance, inducing a strong optical force and allowing a single particle trapping with a diameter less than 100 nm. The device turns out very useful for novel biomedical applications, such as proteomics and oncology.
The design of a new graphene-based continuously tunable optical delay line formed by two vertically stacked microring resonators coupled to a straight waveguide is proposed. High values of delay time ...(τ g = 360 ps) and a wide tuning range (Δτ g = 230 ps) have been calculated, due to the graphene sandwiched between the stacked ring resonators, which also provides an electrooptical tuning of the delay with low energy consumption (E switch = 3.4 pJ) and fast switching time (t switch <; 2 ns). The ratio Δrg/A represents an important figure of merit (FOM) for optical delay lines. A value FOM = 1.4 × 10 -1 ps/μm 2 has been calculated, which corresponds to an enhancement of about a factor 4 compared with the state-of-the-art of the integrated optical delay lines, also providing a switching time several times faster. Such performance, together with a small device footprint (<; 1.6 × 10 3 μm 2 ), gives a significant contribution to the state-of-the-art of optical delay lines, confirming the suitability of the graphene-based resonant cavity as a high-efficient optical delay line for applications in which fast tuning and wide range of tunability are required, e.g., phased array antennas.
A hybrid titanium dioxide/silicon rich nitride ring resonator with the unique feature of being simultaneously athermal and polarization-insensitive is reported for the first time to our knowledge. ...Although its potential application domain is extremely wide, the designed integrated microphotonic cavity, having a racetrack shape, is intended for notch filtering in a microwave photonic passband filter. A careful selection of the CMOS-compatible material system and an innovative design approach have allowed a very low dependence of the filtering shape on the input beam polarization and, simultaneously, a thermal drift of the resonance wavelength <;1.5 pm/K. The numerically estimated Q-factor, free spectral range, and extinction ratio are compliant with the requirements of the selected application, being equal to 7.8 × 10 4 , 4 nm, and 30.7 dB, respectively.
Synthetic aperture radar (SAR) systems employ a Linearly Chirped Microwave Waveform Generator (LCMWG) with large time–bandwidth product (TBWP), to provide a wide range resolution. Photonics has now ...been recognized as a disruptive approach to achieve high performance at bandwidth of few tens of gigahertz, with light and compact architectures, due to the typical photonics benefits, such as electromagnetic interference immunity, small power consumption, small footprint, and high immunity to vibration/shock and radiation. In this article, we report on the photonic generation of a high-frequency LCMW, with a large TBWP (10
2
–10
3
), using a chip-scaled architecture, based on a frequency-tunable optoelectronic oscillator (OEO) and a recirculating phase modulation loop (RPML). A new configuration of the OEO employing an ultrahigh
Q
-factor resonator has been conceived to allow the oscillator working in
Ka
band at 40 GHz or even more, with very low phase noise. Key building block of the RPML is a phase modulator driven by an engineered parabolic split waveform. The ultra-large pulse compression rate (PCR) >> 10
2
, together with large signal purity, was also obtained, making the proposed architecture particularly suitable for SAR systems with large range resolution demand, such as Earth surveillance and monitoring.
A guided-wave chemical sensor for the detection of environmental pollutants or biochemical substances has been designed. The sensor is based on an asymmetric directional coupler employing slot ...optical waveguides. The use of a nanometer guiding structure where optical mode is confined in a low-index region permits a very compact sensor (device area about 1200 μm(2)) to be realized, having the minimum detectable refractive index change as low as 10(-5). Silicon-on-Insulator technology has been assumed in sensor design and a very accurate modelling procedure based on Finite Element Method and Coupled Mode Theory has been pointed out. Sensor design and optimization have allowed a very good trade-off between device length and sensitivity. Expected device sensitivity to glucose concentration change in an aqueous solution is of the order of 0.1 g/L.
Photonic ring resonators can be considered building blocks of new concept satellite payloads for implementing several functions, such as filtering and sensing. In particular, the use of a high ...Q-factor ring resonator as sensing element into a Resonant Micro Optic Gyroscope (RMOG), provides a remarkable improvement of the performance with respect to the competitive technologies. To qualify a ring resonator for Space applications, the radiation effects on it in the Space must be carefully evaluated. Here, we investigate the effects of gamma radiation on a high Q InGaAsP/InP ring resonator, for the first time, to our knowledge. The ring resonator under study has a footprint of about 530 mm
and it is based on a InGaAsP/InP rib waveguide, with a width of 2 µm and a thickness of 0.3 µm, formed on a 0.7 µm thick slab layer on an InP substrate 625 µm thick. For a total dose of about 320 krad Co60 gamma irradiation, a mean variation of about 13% and 4% was measured for Q and extinction ratio (ER), respectively, with respect to the values before irradiation (Q = 1.36 × 10
, ER = 6.24 dB). Furthermore, the resonance peak red-shifts with a linear behaviour was observed increasing the total dose of the absorbed radiation, with a maximum resonance detuning of about 810 pm. These non-significant effects of a quite high gamma radiation dose confirm the potential of high-Q InP-based ring resonators into Space systems or subsystems.
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