ABSTRACT
We present a silicon slot microring resonator for efficient frequency conversion via four-wave mixing (FWM). The slot consists of a narrow silicon waveguide pair with a gap of 80 nm, which is filled with a nonlinear optical polymer. The group velocity dispersion for the microring is controlled by engineering the geometry of the slot structure. Because of the large buildup factor of the slot microring, an FWM conversion efficiency of -27.4 dB is achieved with an optical pump power of less than 1.0 mW. From the measured power dependence of FWM generation, a nonlinear refractive index coefficient of 1.31 × 10-17 m2 W-1 is obtained at a wavelength of 1562 nm. This work presents a hybrid silicon slot and polymer microring as a potential nonlinear device for applications in integrated photonic devices.
ABSTRACT
Efficient electro-optic (EO) modulation can be generated in the hybrid silicon modulator with EO polymer in the form of an in-plane coplanar waveguide and electrode structure. Strong confinement of the optical field in the hybrid structure is critical to performing efficient electric poling and modulation of the EO polymer. The waveguide consists of silica-based side claddings and an EO core for increasing the integral of the optical field and the overlap interaction between the optical field and the modulated electric field within the EO polymer. We discuss in detail the volume resistivity dependence of the efficiency of electric poling and modulation for various side-cladding materials. In a Mach-Zehnder interferometer modulator, the measured half-wave-voltage length product (VπL) is 1.9 V·cm at an optical communication wavelength of 1,550 nm under the TE optical mode operation. The high-speed signaling of the device is demonstrated by generating on-off-keying transmission at signal rates up to 52 Gbit/s with a Q factor of 6.1 at a drive voltage of 2.0 Vpp.
ABSTRACT
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
ABSTRACT
To reduce the ever-increasing energy consumption in datacenters, one of the effective approaches is to increase the ambient temperature, thus lowering the energy consumed in the cooling systems. However, this entails more stringent requirements for the reliability and durability of the optoelectronic components. Herein, we fabricate and demonstrate silicon-polymer hybrid modulators which support ultra-fast single-lane data rates up to 200 gigabits per second, and meanwhile feature excellent reliability with an exceptional signal fidelity retained at extremely-high ambient temperatures up to 110 °C and even after long-term exposure to high temperatures. This is achieved by taking advantage of the high electro-optic (EO) activities (in-device n3r33 = 1021 pm V-1), low dielectric constant, low propagation loss (α, 0.22 dB mm-1), and ultra-high glass transition temperature (Tg, 172 °C) of the developed side-chain EO polymers. The presented modulator simultaneously fulfils the requirements of bandwidth, EO efficiency, and thermal stability for EO modulators. It could provide ultra-fast and reliable interconnects for energy-hungry and harsh-environment applications such as datacentres, 5G/B5G, autonomous driving, and aviation systems, effectively addressing the energy consumption issue for the next-generation optical communication.
ABSTRACT
We propose a high efficiency apodized grating coupler with a bottom reflector for silicon nitride photonic integrated circuits. The reflector consists of a stack of alternate silicon nitride and silicon dioxide quarter-wave films. The design, fabrication and optical characterization of the couplers has been presented. The measured fiber to detector insertion loss was -3.5 dB which corresponds to a peak coupling efficiency of -1.75 dB. A 3 dB wavelength bandwidth of 76.34 nm was demonstrated for the grating coupler with a 20-layer reflector. The fabrication process is CMOS-compatible and requires only a single etching step.
ABSTRACT
We present the simulation, fabrication, and experimental results of a high-efficiency and wide-bandwidth segmented waveguide grating coupler on a silicon-on-insulator platform for near vertical optical coupling between the waveguide and optical fiber. The coupler comprises segmented gratings, which can increase vertical coupling to the optical fiber and reduce backward reflection. The proposed grating coupler has a 3 dB bandwidth of 71.4 nm and a coupling efficiency of 51.7% at a wavelength of 1550 nm. Compared with the standard uniform waveguide grating coupler, the coupling efficiency was improved by 25.64%.
ABSTRACT
Electro-optic (EO) modulators are vital for efficient "electrical to optical" transitions and high-speed optical interconnects. In this work, we applied an EO polymer to demonstrate modulators on silicon-on-insulator substrates. The fabricated Mach-Zehnder interferometer (MZI) and ring resonator consist of a Si and TiO2 slot, in which the EO polymer was embedded to realize a low-driving and large bandwidth modulation. The designed optical and electrical constructions are able to provide a highly concentrated TM mode with low propagation loss and effective EO properties. The fabricated MZI modulator shows a π-voltage-length product of 0.66 V·cm and a 3-dB bandwidth of 31 GHz. The measured EO activity is advantageous to exploit the ring modulator with a resonant tunability of 0.065 nm/V and a 3-dB modulation bandwidth up to 13 GHz.
ABSTRACT
The coupling intensity modulator based on a triple-microring structure was proposed and numerically investigated for a high speed and a low bit error ratio (BER) operation. The modulator consists of a dual-microring optical cavity and a gate-microring energy feedback path. The optical cavity ensures a high energy storing efficiency, and the feedback path enables modulation with little intracavity energy decay. The bandwidth of 103 GHz and modulation depth of 6.2 dB at 2.0 Vpp were theoretically verified by the analysis of the sinusoidal modulation performance. Pulse modulation resulted in a data rate of 160 Gbps, an extinction ratio of 16.84 dB, and a BER of 1 × 10-8. The proposed modulator is applicable for compact, high-speed, and low-energy photonic integration.
ABSTRACT
A novel PbO2/graphite felt electrode was constructed by electrochemical deposition of PbO2 on graphite felt and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) analysis. The prepared electrode is a viable technology for inactivation of Escherichia coli, Enterococcus faecalis, and Artemia salina as indicator organisms in simulated ballast water treatment, which meets the International Maritime Organization (IMO) Regulation D-2. The effects of contact time and current density on inactivation were investigated. An increase in current density generally had a beneficial effect on the inactivation of the three species. E.faecalis and A.salina were more resistant to electrochemical disinfection than E. coli. The complete disinfection of E.coli was achieved in <8min at an applied current density of 253A/m(2). Complete inactivation of E. faecalis and A.salina was achieved at the same current density after 60 and 40min of contact time, respectively. A. salina inactivation follows first-order kinetics.
Subject(s)
Disinfection/methods , Graphite/chemistry , Lead/chemistry , Oxides/chemistry , Water Microbiology , Water Purification/methods , Electrodes , Enterococcus faecalis , Escherichia coli , Kinetics , WaterABSTRACT
Graphene oxide(GO)-activated carbon felt(ACF)(GO-ACF) composite was prepared by an electrophoretic deposition and subsequent thermal annealing. The structures of GO and GO-ACF were characterized by FT-IR, Raman spectra and XPS. The adsorption capacities for U(VI) from aqueous solution of ACF and GO-ACF were compared. The essential factors affected U(VI) adsorption such as initial pH, contact time and temperature were investigated. The adsorption is highly dependent on the solution pH. In addition, the adsorption isotherm and thermodynamics were investigated. The adsorptions of U(VI) from aqueous solution on GO-ACF were fitted to the Langmuir and, Freundlich adsorption isotherms. The adsorption of U(VI) could be well-described by Langmuir. The adsorption of U(VI) on ACF is remarkably improved by GO covalently bonding with ACF. The maximum sorption capacity of GO-ACF for U(VI) was evaluated to be 298 mg/g at pH 5.5, much higher than that of ACF (173 mg/g), suggesting the carboxyl functional groups of GO-ACF playing important roles in the sorption. Thermodynamic parameters further show that the sorption is an endothermic and spontaneous process. GO-ACF is a powerful promising sorbent for the efficient removal of U(VI) from aqueous solutions.
Subject(s)
Graphite/chemistry , Uranium/chemistry , Water Purification/instrumentation , AdsorptionABSTRACT
A novel reflectometer based on Michelson interference is proposed and used to measure various optical parameters of homogeneous multilayer optical waveguides. Refractive indices, thickness, insertion loss, absorbed loss, Fresnel reflectance, and diffuse reflection coefficients of optical waveguides can be measured simultaneously.
