- School of Physics and Astronomy, Cardiff University, Cardiff, Wales, United Kingdom
Institute for Compound Semiconductors, Cardiff University, Cardiff, Wales, United Kingdom
Nicolás Abadía
Cardiff University, School of Physics and Astronomy, Faculty Member
- CEA-Leti, CMOS Labs, Graduate StudentGhent University, Information Technology, Undergraduate, and 5 moreadd
- Silicon Photonics, Optics, Optical Fiber Communications, Optical Interconnects, Polarizing Beam Splitters, Semiconducting Indium Phosphide, and 66 moreSilicon, Semiconductors, III-V Semiconductors, Fiber Optics, Optoelectronics, Optical Modulators, Mach–Zehnder Interferometer, Optical Splitter, Physics, Electrical Engineering, Electronics and Telecommunication Engineering, Hardware, Energy Efficient Data Centers, Power Consumption, Applied Optics, Telecommunications Engineering, Condensed Matter Physics, Electro-optic modulators, Integrated optical waveguide modulators, Electro-Absorption Modulators, Optical Interconnects in Data Centers, Optical interconnects for high performance computing, Surface Plasmon-Polaritons, Plasmonics, Plasmonics and Nanophotonics, Quantum Plasmonics, Optical Waveguides, Plasmons, CMOS Technology, Integrated Circuits, Directional Couplers, Polarizers, Passive Devices, Bragg Gratings, Silicon on Insulator, Magnetic Recording, Hard Disk Drives - Magnetic Recording, Micromagnetics, HAMR( Heat Assisted Magnetic Recording), Near Field Transducer, Light-Matter Interactions, Optical Communications, Group III-V Semiconductors, Germanium, InAs/InP, Gallium nitride, Indium-Phosphide (InP) based Alloys, Pulse Amplitude Modulation (PAM), Extinction Coefficients, Molecular beam epitaxy, Quantum Wells, Quantum Dots, Orthogonal Frequency Division Multiplexing (OFDM), Microring Resonators, Amplitude shift keying, Physical Optics, Applied Physics, Optical Systems (Advanced Optical Modulation and Multiplexing Techniques, Optical Design, Nonlinear Optics, Comsol Multi Physics, Fundamental Physics, Photonic devices - Nonlinear optics, Quantum Electronics, Photonics, and Nanophotonicsedit
- Nicolás Abadía received a Telecommunications Engineering degree from the Technical University of Madrid and the Royal... moreNicolás Abadía received a Telecommunications Engineering degree from the Technical University of Madrid and the Royal Institute of Technology. Afterward, Nicolás obtained a joint M.Sc. in Photonics at Ghent University, the Royal Institute of Technology, and the Free University of Brussels. Dr. Abadía pursued his Ph.D. degree at the University of Paris-Sud, working in collaboration with CEA-Leti. Nicolás was a joint postdoctoral fellow at Trinity College Dublin and McGill University, working on III-V and silicon photonics devices and systems in partnership with Ciena, Lumentum, and Western Digital.
Dr. Abadía is currently an assistant professor at Cardiff University and the Institute for Compound Semiconductors with research interests including integrated photonic devices and systems in III-V, silicon, and silicon nitride platforms for aerospace and data/telecom.
Nicolás is currently a work package leader on the EPSRC Future Compound Semiconductor Manufacturing Hub, working closely with Airbus, IQE, Sheffield University, and University College London.
Dr. Abadía has received several international recognitions, including the 2016 OSA Outstanding Reviewer Recognition, the SPIE Optics and Photonics Education Scholarship, and the Erasmus Mundus Scholarship; as well as national recognitions such as the Dr. César Milstein Grant and the best thesis award by the Official College of Telecommunication Engineers and the Spanish Association of Telecommunication Engineers.edit
The quantum-confined Stark effect in InAs/In(Ga)As quantum dots (QDs) using non-intentionally doped and p-doped QD barriers was investigated to compare their performance for use in optical modulators. The measurements indicate that the... more
The quantum-confined Stark effect in InAs/In(Ga)As quantum dots (QDs) using non-intentionally doped and p-doped QD barriers was investigated to compare their performance for use in optical modulators. The measurements indicate that the doped QD barriers lead to a better figure of merit (FoM), defined as the ratio of the change in absorption ∆α for a reverse bias voltage swing to the loss at 1 V α(1 V), FoM=∆α/α (1 V). The improved performance is due to the absence of the ground-state absorption peak and an additional component to the Stark shift. Measurements indicate that p-doping the QD barriers can lead to more than a 3x increase in FoM modulator performance between temperatures of −73°C to 100°C when compared with the stack with NID QD barriers.
Research Interests:
Two twelve-channel arrays based on surface-etched slot gratings, one with nonuniformly spaced slots and another with uniformly spaced slots are presented for laser operation in the O-band. A wavelength tuning range greater than 40 nm,... more
Two twelve-channel arrays based on surface-etched slot gratings, one with nonuniformly spaced slots and another with uniformly spaced slots are presented for laser operation in the O-band. A wavelength tuning range greater than 40 nm, with a side-mode suppression ratio (SMSR) > 40 dB over much of this range and output power greater than 20 mW, was obtained for the array with non-uniform slots over a temperature range of 15°C-60°C. The introduction of multiple slot periods, chosen such that there is minimal overlap among the side reflection peaks, is employed to suppress modes lasing one free spectral range (FSR) from the intended wavelength. The tuning range of the array with uniformly spaced slots, on the other hand, was found to be discontinuous due to mode-hopping to modes one FSR away from the intended lasing mode which are not adequately suppressed. Spectral linewidth was found to vary across devices with the lowest measured linewidths in the range of 2 MHz to 4 MHz.
Research Interests: Electrical Engineering, Physics, Optics, Optical Fiber Communications, Fiber Optics, and 15 moreLaser Physics, Nanophotonics, III-V Semiconductors, Semiconductors, Optoelectronics, Lasers, Hardware, Semiconductor Lasers, Optical Interconnects, Photonics,Multiple Quantum Wells, Optical Devices etc, Low Power Consumption, Electronics and Telecommunication Engineering, Semiconductors and Nanotechnology, Semiconducting Indium Phosphide, and Electrical and Electronics Engineering
A complementary-metal-oxide semiconductor (CMOS) compatible all-silicon TM-pass polarizer using plasmonic bends is proposed. To simplify the fabrication and be compatible with the CMOS process, we employ only two materials: silicon and... more
A complementary-metal-oxide semiconductor (CMOS) compatible all-silicon TM-pass polarizer using plasmonic bends is proposed. To simplify the fabrication and be compatible with the CMOS process, we employ only two materials: silicon and silicon dioxide. Highly doped silicon is used to support the plasmons. We obtain an extinction ratio and an insertion loss of 45.4 and 1.7 dB, respectively, at 1550 nm and a maximum extinction ratio of 58 dB. This is the highest reported extinction ratio for a TM-pass polarizer to the best of our knowledge. Furthermore, we achieved >20 dB of extinction ratio and <2 dB of insertion loss over 72 nm bandwidth for a device footprint <8.8 × 5.4 μm 2. To achieve this, we exploit the properties of tight bends in plasmonic waveguides. Another advantage of the device is that it is robust against fabrication variations.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Optics, Optical Fiber Communications, and 14 moreFiber Optics, Nanophotonics, Electronics, Semiconductors, Plasmonics, Silicon, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Optical Interconnects, Low Power Consumption, Applied Optics, and Polarizing Beam Splitters
We investigate the energy conversion process and subsequent thermal and bit-writing performance of a plasmonic near-field transducer (NFT) under steady-state operation within heat-assisted magnetic recording (HAMR) devices. The NFT is... more
We investigate the energy conversion process and subsequent thermal and bit-writing performance of a plasmonic near-field transducer (NFT) under steady-state operation within heat-assisted magnetic recording (HAMR) devices. The NFT is composed of metal-insulator-metal (MIM) layers that are designed to localize heating and produce optimal thermal gradients in order to relieve parasitic heating effects in the NFT. The thin-film MIM structure confines the electromagnetic energy in the down-track direction while cross-track confinement is achieved by tapering the insulator feature of the MIM. A comparative analysis using Gold and a number of novel Au alloys is undertaken. Modeled performance shows excellent thermal spot confinement (50 × 50 nm2) of temperatures above 650 K at an input laser power of 830 nm of less than 5 milliwatts. In addition, micromagnetic simulations using a stochastic Landau-Lifshitz-Bloch equation yield excellent signal to noise ratio with minimum jitter of under 2 nm when recording.
Research Interests: Physics, Condensed Matter Physics, Materials Science, Optics, Nanophotonics, and 15 moreElectronics & Telecommunication Engineering, Semiconductors, Heat Transfer, Plasmonics, Nanoscale heat transfer, Silicon Photonics, Optoelectronics, Hardware, Low Power Consumption, Applied Optics, Hard Disk Drives - Magnetic Recording, Semiconductors and Nanotechnology, HAMR( Heat Assisted Magnetic Recording), Heat Assisted Magnetic Recording, and Near Field Transducer
Four level pulse amplitude modulation (PAM-4) has become the modulation format of choice to replace on-off keying (OOK) for the 400 Gb/s short reach optical communications systems. In this paper, we investigate the possible modifications... more
Four level pulse amplitude modulation (PAM-4) has become the modulation format of choice to replace on-off keying (OOK) for the 400 Gb/s short reach optical communications systems. In this paper, we investigate the possible modifications to conventional Mach-Zehnder modulator structures to improve the system performance. We present three different silicon photonic Mach-Zehnder modulator architectures for generating PAM-4 in the optical domain using OOK electrical driving signals. We investigate the transfer function and linearity of each modulator and experimentally compare their PAM-4 generation and transmission performance with and without use of digital signal processing (DSP). We achieve the highest reported PAM-4 generation and transmission without the use of DSP. The power consumption of each modulator is presented, and we experimentally show that multielectrode Mach-Zehnder modulators provide a clear advantage at higher symbol rates compared to conventional Mach-Zehnder modulators.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Optics, Optical Fiber Communications, and 15 moreFiber Optics, Semiconductors, Silicon, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Power Consumption, Optical Interconnects, Optical physics, Electronics and Telecommunication Engineering, Mach-zehnder Interferometer, Optical Modulators, Electrical And Electronic Engineering, and PAM-4
The device is based on an integrated hybrid plasmonic waveguide (HPW) with a segmented metal design. The segmented metal will avoid the propagation of the TM mode, confined in the slot of the HPW, while the TE fundamental mode will pass.... more
The device is based on an integrated hybrid plasmonic waveguide (HPW) with a segmented metal design. The segmented metal will avoid the propagation of the TM mode, confined in the slot of the HPW, while the TE fundamental mode will pass. The TE mode is not affected by the metal segmentation since it is confined in the core of the HPW. The concept of the segmented metal can be exploited in a plasmonic circuit with HPWs as the connecting waveguides between parts of the circuit and in a silicon photonics circuit with strip or slab waveguides connecting the different parts of the circuit. Using 3D FDTD simulations, it is shown that for a length of 5.5 μm the polarization extinction ratios are better than 20 dB and the insertion losses are less than 1.7 dB over all the optical communication bands. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Research Interests: Electrical Engineering, Physics, Optics, Optical Fiber Communications, Fiber Optics, and 15 moreNanophotonics, Electronics, Electronics & Telecommunication Engineering, Semiconductors, Plasmonics, Silicon, Optical Communication, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Optical Splitter, Applied Optics, Polarizers, and Polarizing Beam Splitters
We propose and analyze via simulation a novel approach to implement a complementary metal-oxide-semiconductor compatible and high extinction ratio transverse magnetic pass polarizer on the silicon-on-insulator platform with a 340 nm thick... more
We propose and analyze via simulation a novel approach to implement a complementary metal-oxide-semiconductor compatible and high extinction ratio transverse magnetic pass polarizer on the silicon-on-insulator platform with a 340 nm thick silicon core. The TM-pass polarizer utilizes a highly doped p-silicon waveguide as the transverse hybrid plasmonic waveguide. We observed an extinction ratio of 30.11 dB and an insertion loss of 3.08 dB for a device length of 15 µm. The fabrication process of the proposed TM-pass polarizer is simpler compared to the state-of-the-art since it only uses silicon waveguides and does not require any special material or feature size.
Research Interests: Physics, Condensed Matter Physics, Materials Science, Optics, Nanophotonics, and 15 moreSemiconductors, Plasmonics, Silicon, Silicon Photonics, Optoelectronics, Hardware, Silicon Waveguide, Power Consumption, Optical Interconnects, Cmos, Telecommunication Engineering, Electronics and Telecommunication Engineering, Optical Modulators, CMOS Technology, and Electrical And Electronic Engineering
To achieve a feasible heat-assisted magnetic recording (HAMR) system, a near-field transducer (NFT) is necessary to strongly focus the optical field to a lateral region measuring tens of nanometres in size. An NFT must deliver sufficient... more
To achieve a feasible heat-assisted magnetic recording (HAMR) system, a near-field transducer (NFT) is necessary to strongly focus the optical field to a lateral region measuring tens of nanometres in size. An NFT must deliver sufficient power to the recording medium as well as maintain its structural integrity. The self-heating problem in the NFT causes materials failure that leads to the degradation of the hard disk drive performance. The literature reports NFT structures with physical sizes well below 1 micron which were found to be thermo-mechanically unstable at an elevated temperature. In this paper, we demonstrate an adiabatic NFT to address the central challenge of thermal engineering for a HAMR system. The NFT is formed by an isosceles triangular gold taper plasmonic waveguide with a length of 6 µm and a height of 50 nm. Our study shows that in the full optically and thermally optimized system, the NFT efficiently extracts the incident light from the waveguide core and can improve the shape of the heating source profile for data recording. The most important insight of the thermal performance is that the recording medium can be heated up to 866 K with an input power of 8.5 mW which is above the Curie temperature of the FePt film while maintaining the temperature in the NFT at 390 K without a heat spreader. A very good thermal efficiency of 5.91 is achieved also. The proposed structure is easily fabricated and can potentially reduce the NFT deformation at a high recording temperature making it suitable for practical HAMR application.
Research Interests: Physics, Condensed Matter Physics, Nanophotonics, Electronics & Telecommunication Engineering, Semiconductors, and 15 moreHeat Transfer, Plasmonics, Silicon, Nanoscale heat transfer, Silicon Photonics, Optoelectronics, Power Consumption, Data storage, Low Power Consumption, Optical physics, Hard Disk Drives - Magnetic Recording, Magnetics, HAMR( Heat Assisted Magnetic Recording), Electrical And Electronic Engineering, and Heat Assisted Magnetic Recording
Lately, the integration of two-dimensional materials into semiconductor devices has allowed the modification of their effective index by simply applying a modest voltage (between 0 and 3 volts). In this work, we present a device composed... more
Lately, the integration of two-dimensional materials into semiconductor devices has allowed the modification of their effective index by simply applying a modest voltage (between 0 and 3 volts). In this work, we present a device composed of two evanescently coupled silicon microring resonators where both rings have a graphene layer on top. This design is aimed to produce frequency combs with transmission characteristics controlled upon voltage application to the graphene layer. We numerically analyze the device response as a function of the incident wavelength and applied voltage. The results showed a low input intensity (0.6 GW/cm2) needed and a rapid response time (0.1 μs), in comparison to devices controlled by heat injection.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Materials Science, Optics, and 15 moreIII-V Semiconductors, Semiconductors, Silicon, Graphene, Medicine, Silicon Photonics, Optoelectronics, Hardware, Optical Interconnects, Optical physics, Micro Ring Resonators, Electronics and Telecommunication Engineering, Optical Modulators, Electrical And Electronic Engineering, and Ring Resonators
A novel integrated transversely coupled Fabry–Perot resonator using loop mirrors as the end reflectors are demonstrated via simulations and experiments on the silicon-on-insulator (SOI) platform. The resonator is formed by connecting two... more
A novel integrated transversely coupled Fabry–Perot resonator using loop mirrors as the end reflectors are demonstrated via simulations and experiments on the silicon-on-insulator (SOI) platform. The resonator is formed by connecting two loop mirrors to the two output ports of a directional coupler to form the resonant cavity and utilizing the other two ports as the input and the output. Depending on which two ports of the directional coupler are mirrored, two configurations of the resonator can be achieved. The impacts of varying the cavity length and the coupling coefficient of the directional coupler on the output characteristics of the resonators are analyzed. A Q-factor of 28086 and an extinction ratio of 10.04 dB with an insertion loss of 1.9 dB is achieved experimentally for a cavity length and an extinction ratio of 18.14 dB and a Q-factor of 5120 with an insertion loss of 2.12 dB is obtained for a cavity length of . The reported resonator offers additional freedom to tune the spectral characteristics.
Research Interests: Physics, Condensed Matter Physics, Optics, Optical Fiber Communications, Semiconductors, and 15 moreSilicon, Resonators, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Microring Resonators, Power Consumption, Optical Interconnects, Optical physics, Electronics and Telecommunication Engineering, Fabry Perot, Optical Modulators, Electrical And Electronic Engineering, and Light Coupling
We demonstrate a polarization-independent mode-evolution-based coupler for the silicon-on-insulator platform. The measured coupler has negligible insertion loss over a bandwidth of about 100 nm, i.e., from 1500 to 1600 nm. The measured... more
We demonstrate a polarization-independent mode-evolution-based coupler for the silicon-on-insulator platform. The measured coupler has negligible insertion loss over a bandwidth of about 100 nm, i.e., from 1500 to 1600 nm. The measured maximum power imbalances for the polarization-independent coupler are 1.2 and 0.2 dB for the fundamental transverse electric (TE 00) mode and the fundamental transverse magnetic (TM 00) mode, respectively. Our coupler also has a compact design footprint with mode-evolution region not more than 75−μm long.
Research Interests:
We investigate a tapered, hybrid plasmonic waveguide which has previously been proposed as an optically efficient near-field transducer (NFT), or component thereof, in several devices which aim to exploit nanofocused light. We numerically... more
We investigate a tapered, hybrid plasmonic waveguide which has previously been proposed as an optically efficient near-field transducer (NFT), or component thereof, in several devices which aim to exploit nanofocused light. We numerically analyze how light is transported through the waveguide and ultimately focused via effective-mode coupling and taper optimization. Crucial dimensional parameters in this optimization process are identified that are not only necessary to achieve maximum optical throughput, but also optimum thermal performance with specific application towards heat-assisted magnetic recording (HAMR). It is shown that existing devices constructed on similar waveguides may benefit from a heat spreader to avoid deformation of the plasmonic element which we achieve with no cost to the optical efficiency. For HAMR, our design is able to surpass many industry requirements in regard to both optical and thermal efficiency using pertinent figure of merits like 8.5% optical efficiency.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Magnetic Recording, Nanophotonics, and 15 moreElectronics & Telecommunication Engineering, Semiconductors, Heat Transfer, Plasmonics, Silicon, Nanoscale heat transfer, Energy Efficient Data Centers, Hardware, Power Consumption, Low Power Consumption, Applied Optics, Hard Disk Drives - Magnetic Recording, Magnetics, Plasmonics and Nanophotonics, and HAMR( Heat Assisted Magnetic Recording)
We design and demonstrate Fabry-Perot resonators with transverse coupling using Bragg gratings as reflectors on the silicon-on-insulator (SOI) platform. The effects of tailoring the cavity length and the coupling coefficient of the... more
We design and demonstrate Fabry-Perot resonators with transverse coupling using Bragg gratings as reflectors on the silicon-on-insulator (SOI) platform. The effects of tailoring the cavity length and the coupling coefficient of the directional coupler on the spectral characteristics of the device are studied. The fabricated resonators achieved an extinction ratio (ER) of 37.28 dB and a Q-factor of 3356 with an effective cavity length of 110 μm, and an ER of 8.69 dB and a Q-factor of 23642 with a 943 μm effective cavity length. The resonator structure presented here has the highest reported ER on SOI and provides additional degrees of freedom compared to an all-pass ring resonator to tune the spectral characteristics.
Research Interests: Physics, Condensed Matter Physics, Materials Science, Optics, Quantum Physics, and 15 moreOptical Fiber Communications, Fiber Optics, Semiconductors, Silicon, Medicine, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Optical Interconnects, Applied Optics, Optical physics, Micro Ring Resonators, Electronics and Telecommunication Engineering, and Electrical And Electronic Engineering
We present a dual-polarization O-band silicon photonic (SiP) transmitter for intradatacenter optical interconnects. The transmitter is built using two identical O-band traveling wave Mach-Zehnder modulators with an average V π L and a... more
We present a dual-polarization O-band silicon photonic (SiP) transmitter for intradatacenter optical interconnects. The transmitter is built using two identical O-band traveling wave Mach-Zehnder modulators with an average V π L and a bandwidth at 1.5 V bias voltage of 2.88 V.cm and 24.5 GHz, respectively. We experimentally demonstrate the transmitter in a Stokes vector direct-detection (SV-DD) system for dual-polarization intensity modulated signals with 2-level and 4-level pulse amplitude modulation (DP-PAM2 and DP-PAM4) formats. The direct-detection Stokes vector receiver (DD-SVR) followed by offline digital signal processing (DSP) is implemented for SOP de-rotation. We characterize the performance of the SV-DD system versus number of taps, received signal power, state of polarization (SOP), reach, and bit rate. Results reveal that 112 Gb/s DP-PAM2 can be transmitted over 10 km of single mode fiber (SMF) at a bit error rate (BER) below 10 −5 at −1 dBm received signal power irrespective of the SOP. Moreover, a 168 Gb/s (42 Gbaud) DP-PAM4 signal can be transmitted over 2 km and 10 km at a BER below the 7% hard-decision forward error correction (HD-FEC) threshold (i.e., 3.8 × 10 −3) at 0 dBm and 2 dBm, respectively. Furthermore, 224 Gb/s and 200 Gb/s DP-PAM4 are successfully received at a BER below the HD-FEC in the back-to-back and 2 km cases, respectively. Finally, we compare the performance of the 6 × 2 multiple-input multiple-output (MIMO) equalization to a simpler 4 × 2 MIMO equalization and explain the superior performance of the 6 × 2 in the presence of SVR imperfections.
Research Interests:
We present an experimental study and analysis of a travelling wave series push-pull silicon photonic multi-electrode Mach-Zehnder modulator (ME-MZM) and compare its performance with a single-electrode travelling wave Mach-Zehnder... more
We present an experimental study and analysis of a travelling wave series push-pull silicon photonic multi-electrode Mach-Zehnder modulator (ME-MZM) and compare its performance with a single-electrode travelling wave Mach-Zehnder modulator (TWMZM). Utilizing the functionality of the ME-MZM structure plus digital-signal-processing, we report: 1) the C-band transmission of 84 Gb/s OOK modulated data below the KP4 forward error correction threshold with 2 Vpp drive voltage over a distance of 2 km; 2) the transmission of a 128 Gb/s optical 4-level pulse amplitude modulated signal over 1 km of fiber; and 3) the generation of a 168 Gb/s PAM-4 signal using two electrical OOK signals. By comparing the transmission system performance measurements for the ME-MZM with measurements performed using a similar series push-pull TWMZM, we show that the ME-MZM provides a clear advantage in achieving higher baud PAM-4 generation and transmission compared to a TWMZM.
Research Interests: Electrical Engineering, Telecommunications Engineering, Physics, Optics, Optical Fiber Communications, and 15 moreFiber Optics, Semiconductors, Silicon, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Power Consumption, Optical Interconnects, Applied Optics, Optical physics, Electronics and Telecommunication Engineering, Mach-zehnder Interferometer, Optical Modulators, and Electrical And Electronic Engineering
We experimentally and via simulations demonstrate ultracompact single-stage and cascaded optical add-drop multiplexers using misaligned sidewall Bragg grating in a Mach-Zehnder interferometer for the silicon-on-insulator platform. The... more
We experimentally and via simulations demonstrate ultracompact single-stage and cascaded optical add-drop multiplexers using misaligned sidewall Bragg grating in a Mach-Zehnder interferometer for the silicon-on-insulator platform. The single-stage configuration has a device footprint of 400 μm × 90 μm, and the cascaded configuration has a footprint of 400 μm × 125 μm. The proposed designs have 3-dB bandwidths of 6 nm and extinction ratios of 25 dB and 51 dB, respectively, and have been fabricated for the transverse electric mode. A minimum lithographic feature size of 80 nm is used in our design, which is within the limitation of 193 nm deep ultraviolet lithography.
Research Interests: Telecommunications Engineering, Physics, Condensed Matter Physics, Optics, Optical Fiber Communications, and 15 moreFiber Optics, Nanophotonics, Semiconductors, Silicon, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Power Consumption, Optical Interconnects, Low Power Consumption, Applied Optics, Electronics and Telecommunication Engineering, Mach-zehnder Interferometer, and Optical Modulators
In this work, a novel highly fabrication tolerant polarization beam splitter (PBS) is presented on an InP platform. To achieve the splitting, we combine the Pockels effect and the plasma dispersion effect in a symmetric 1x2 Mach-Zehnder... more
In this work, a novel highly fabrication tolerant polarization beam splitter (PBS) is presented on an InP platform. To achieve the splitting, we combine the Pockels effect and the plasma dispersion effect in a symmetric 1x2 Mach-Zehnder interferometer (MZI). One p-in phase shifter of the MZI is driven in forward bias to exploit the plasma dispersion effect and modify the phase of both the TE and TM mode. The other arm of the MZI is driven in reverse bias to exploit the Pockels effect which affects only the TE mode. By adjusting the voltages of the two phase shifters, a different interference condition can be set for the TE and the TM modes thereby splitting them at the output of the MZI. By adjusting the voltages, the very tight fabrication tolerances known for fully passive PBS are eased. The experimental results show that an extinction ratio better than 15 dB and an on-chip loss of 3.5 dB over the full Cband (1530-1565nm) are achieved.
Research Interests: Electrical Engineering, Telecommunications Engineering, Physics, Optics, Optical Fiber Communications, and 15 moreFiber Optics, III-V Semiconductors, Semiconductors, Silicon, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Power Consumption, Optical Interconnects, Optical Splitter, Applied Optics, Mach-zehnder Interferometer, Optical Modulators, and Semiconducting Indium Phosphide
A simple experimental method for determining the number of modes in planar dielectric multi-mode waveguides, and the effective index difference of these modes, is presented. Applying a thin, dye-doped polymer cladding, the fluorescence... more
A simple experimental method for determining the number of modes in planar dielectric multi-mode waveguides, and the effective index difference of these modes, is presented. Applying a thin, dye-doped polymer cladding, the fluorescence excited by multiple modes propagating in a silicon nitride slab waveguide is imaged to extract information. Interference between the modes produces a structured intensity profile along the waveguide which is constant in time. The spatial frequencies of this intensity profile are directly linked to the propagation constants of the underlying modes. Through a discrete Fourier transform, the modes' effective index differences are found and compare well with analytically calculated values. Furthermore, the amplitudes in the Fourier transform are directly related to the power in each mode. Comparing the amplitudes of the Fourier components as a function of propagation distance, an estimate of the propagation losses of the individual modes relative to one another is made. The method discussed could be applied to analysing mode behaviour in integrated photonic devices, most notably in mode-division multiplexing.
Research Interests:
In this paper we report on a low energy consumption CMOScompatible plasmonic modulator based on Franz-Keldysh effect in germanium on silicon. We performed integrated electro-optical simulations in order to optimize the main... more
In this paper we report on a low energy consumption CMOScompatible plasmonic modulator based on Franz-Keldysh effect in germanium on silicon. We performed integrated electro-optical simulations in order to optimize the main characteristics of the modulator. A 3.3 dB extinction ratio for a 30 µm long modulator is demonstrated under 3 V bias voltage at an operation wavelength of 1647 nm. The estimated energy consumption is as low as 20 fJ/bit.
Research Interests: Physics, Condensed Matter Physics, Optical Fiber Communications, Electronics, Group IV semiconductors, and 15 moreSemiconductors, Plasmonics, Silicon, Optical Communication, CMOS Integrated Circuit Design, Silicon Photonics, Optical Communications, Energy Efficient Data Centers, Hardware, Power Consumption, Germanium, Applied Optics, Telecommunication Engineering, Optical Fibres, and Optical Modulators
The quantum confined Stark effect in InAs/InGaAs QDs using an undoped and p-modulation doped active region was investigated. Doping potentially offers more than a 3x increase in figure of merit modulator performance up to 100 °C.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Optics, Optical Fiber Communications, and 15 moreFiber Optics, III-V Semiconductors, Semiconductors, Optoelectronics, Quantum Dots, Energy Efficient Data Centers, Hardware, Power Consumption, Optical Interconnects, Applied Optics, Telecommunication Engineering, Electronics and Telecommunication Engineering, Optical Modulators, QCSE, and Quantum-Confined Stark Effect
We present the DC, small signal and large signal performance of low excess-noise waveguide coupled germanium-on-silicon avalanche photodetectors with over 400 GHz gain-bandwidth product.
Research Interests: Telecommunications Engineering, Physics, Condensed Matter Physics, Optical Fiber Communications, Fiber Optics, and 15 moreNanophotonics, Electronics, Semiconductors, Silicon, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Photodetectors, Hardware, Power Consumption, Optical Interconnects, Germanium, Low Power Consumption, Applied Optics, and Electronics and Telecommunication Engineering
In this work, the feasibility of a monolithically integrated laser and electroabsorption modulator based on the same active quantum dot epistructure is studied. The net modal gain and the absorption in the modulator were measured using... more
In this work, the feasibility of a monolithically integrated laser and electroabsorption modulator based on the same active quantum dot epistructure is studied. The net modal gain and the absorption in the modulator were measured using the segmented contact method from 25 °C to 125 °C. The maximum of the net modal gain active region of the laser decreases from 10 cm -1 at 25 °C to 3.9 cm -1 at 125 °C. The non-optimized maximum extinction ratio of the modulator, 4.1 dB·mm -1 , is almost constant until 25 °C. The wavelengths at which the net modal gain and the change in absorption are maximum shifts with temperature by 0.04 eV.
Research Interests: Computer Science, Condensed Matter Physics, Materials Science, Laser Physics, Electronics & Telecommunication Engineering, and 15 moreIII-V Semiconductors, Semiconductors, Heat Transfer, Optoelectronics, Quantum Dots, Lasers, Semiconductor Lasers, Quantum Wells, Optical Interconnects, Low Power Consumption, Applied Optics, Semiconductors and Nanotechnology, Electro-optic modulators, Optical Modulators, and Quantum Confined Stark Effect
A CMOS-compatible plasmonic multimode filter capable of working in the O, E, S, C, L, and U optical communication bands is analysed. The device consists of a hybrid plasmonic waveguide with metal segments. By properly designing the... more
A CMOS-compatible plasmonic multimode filter capable of working in the O, E, S, C, L, and U optical communication bands is analysed. The device consists of a hybrid plasmonic waveguide with metal segments. By properly designing the segments, it is possible to pass a particular mode and diffract the others. The results of the analysis show that the device has an extinction ratio over 20 dB and an insertion loss of less than 1.6 dB across the mentioned optical communication bands.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Optics, Optical Fiber Communications, and 15 moreFiber Optics, Nanophotonics, Semiconductors, Plasmonics, Silicon, Silicon Photonics, Optoelectronics, Hardware, Optical Interconnects, Optical Splitter, Applied Optics, Electronics and Telecommunication Engineering, Semiconductors and Nanotechnology, Optical Filter, and Bragg Gratings
We investigate heatsinking methods and material properties of various Au alloys to be used within thin-film plasmonic resonators to create optimal heating conditions in near-field transducers, with demonstrated application towards... more
We investigate heatsinking methods and material properties of various Au alloys to be used within thin-film plasmonic resonators to create optimal heating conditions in near-field transducers, with demonstrated application towards heat-assisted magnetic recording devices.
Research Interests:
A highly fabrication tolerant polarization beam splitter is presented. The fabrication tolerances are relaxed by adjusting two voltages. Experiments show on-chip losses of 3.5 dB and extinction ratio of 15 dB at C-band.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Materials Science, Optics, and 15 moreOptical Fiber Communications, III-V Semiconductors, Semiconductors, Optoelectronics, Energy Efficient Data Centers, Hardware, Optical Interconnects, Optical Splitter, Low Power Consumption, Applied Optics, Telecommunication Engineering, Electronics and Telecommunication Engineering, Optical Modulators, Semiconducting Indium Phosphide, and Polarizing Beam Splitter
The literature reports NFT with size below 1 micron are found to be thermo-mechanically unstable and low coupling efficiency. We demonstrate a 6 μm long adiabatic taper. A maximum coupling efficiency of 90.8% is achieved.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Materials Science, Optics, and 15 moreNanophotonics, Semiconductors, Heat Transfer, Silicon, Nanoscale heat transfer, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Power Consumption, Applied Optics, Hard Disk Drives - Magnetic Recording, Magnetics, HAMR( Heat Assisted Magnetic Recording), and Heat Assisted Magnetic Recording
In this paper, a polarization beam splitter (PBS) based on the indium phosphide (InP) platform is presented. The main advantage of the device is that the tight fabrication tolerances of fully passive devices can be overcome by adjusting... more
In this paper, a polarization beam splitter (PBS) based on the indium phosphide (InP) platform is presented. The main advantage of the device is that the tight fabrication tolerances of fully passive devices can be overcome by adjusting two voltages in an easy calibration. To produce the splitting function, the Pockels effect and the plasma dispersion effect are exploited in the phase shifters of a symmetric 1×2 Mach-Zehnder interferometer (MZI). The experimental results show that such a device operating at 1550 nm has an on-chip loss of 3.5 dB and a polarization extinction ratio better than 15 dB.
Research Interests:
We experimentally demonstrate transversely coupled Fabry-Perot resonators using sidewall Bragg gratings and loop mirrors as reflectors in silicon-on-insulator platform. The resonators have channel spacing of ~50 GHz, extinction ratio of... more
We experimentally demonstrate transversely coupled Fabry-Perot resonators using sidewall Bragg gratings and loop mirrors as reflectors in silicon-on-insulator platform. The resonators have channel spacing of ~50 GHz, extinction ratio of ~12 dB and Q-factor of ~15350.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Optics, Optical Fiber Communications, and 15 moreFiber Optics, Semiconductors, Silicon, Silicon Photonics, Integrated Optics, Optoelectronics, Energy Efficient Data Centers, Hardware, Microring Resonators, Optical Interconnects, Applied Optics, Electronics and Telecommunication Engineering, Semiconductors and Nanotechnology, Passive Devices, and Frabry-Perot
We experimentally demonstrate a compact optical add-drop multiplexer based on misaligned sidewall Bragg gratings in a MZI. We achieved 51dB transmission isolation and 5nm 3-dB bandwidth with a footprint of 400 μm × 125 μm.
Research Interests: Electrical Engineering, Physics, Condensed Matter Physics, Optics, Optical Fiber Communications, and 15 moreFiber Optics, Electronics & Telecommunication Engineering, Semiconductors, Silicon, Silicon Photonics, Optoelectronics, Energy Efficient Data Centers, Hardware, Power Consumption, Multiplexer, Optical Interconnects, Low Power Consumption, Applied Optics, Electronics and Telecommunication Engineering, and Demultiplexer
Propagation of light through planar waveguides is important for photonic integrated circuits. Experimentally imaging light intensity within multimode waveguides shows how different modes interfere. These images can be used to determine... more
Propagation of light through planar waveguides is important for photonic integrated circuits. Experimentally imaging light intensity within multimode waveguides shows how different modes interfere. These images can be used to determine waveguide properties.
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We propose an air-slot plasmonic waveguide for nano-focusing. A tapered grating is used as a dipole radiation source for surface plasmon excitation and coupling. Simulations show an effective coupling and field enhancement in our design.
Research Interests:
We present a design of an optimized CMOS-compatible germanium-on-silicon Franz-Keldysh effect plasmonic modulator. Its length is below 30 µm and the modulator operates at-3V. It features a power consumption as low as 20 fJ/bit. Summary... more
We present a design of an optimized CMOS-compatible germanium-on-silicon Franz-Keldysh effect plasmonic modulator. Its length is below 30 µm and the modulator operates at-3V. It features a power consumption as low as 20 fJ/bit. Summary Fig. 1, (a) Structure of the plasmonic modulator, (b) Intensity distribution of the plasmonic mode of the MIS waveguide and (c) static electric field distribution in the structure for V=0 V (left) and V=3 V (rigth) 63 WP12 (Contributed) 18:00-19:00
Research Interests:
We theoretically and experimentally investigate a novel modulation concept on silicon (Si) based on the combination of quantum confinement and plasmon enhancement effects. We experimentally study the suitability of Ge/SiGe quantum wells... more
We theoretically and experimentally investigate a novel modulation concept on silicon (Si) based on the combination of quantum confinement and plasmon enhancement effects. We experimentally study the suitability of Ge/SiGe quantum wells (QWs) on Si as the active material for a plasmon-enhanced optical modulator. We demonstrate that in QW structures absorption and modulation of light with transverse magnetic (TM) polarization are greatly enhanced due to favorable selection rules. Later, we theoretically study the plasmon propagation at the metal-Ge/SiGe QW interface. We design a novel Ge/SiGe QW structure that allows maximized overlap between the plasmonic mode and the underlying Ge/SiGe QWs.
Research Interests:
A semiconductor waveguide device includes a first semiconductor layer having a first surface, wherein the first surface comprises a first protrusion and a second protrusion collectively forming a first trench in the first semiconductor... more
A semiconductor waveguide device includes a first semiconductor layer having a first surface, wherein the first surface comprises a first protrusion and a second protrusion collectively forming a first trench in the first semiconductor layer, a second semiconductor layer having a second surface opposing the first surface of the first semiconductor layer, and an insulator layer disposed between and in contact with the first surface and the second surface, wherein the first semiconductor layer, the second semiconductor layer, and the insulator layer form a semiconductor waveguide region, and wherein the first trench is configured to confine a mode of light beam propagation in the semiconductor waveguide region.
Research Interests:
This work aims to design a CMOS compatible, low-electrical power consumption modulator assisted by plasmons. For compactness and reduction of the electrical power consumption, electro-absorption based on the Franz-Keldysh effect in... more
This work aims to design a CMOS compatible, low-electrical power consumption modulator assisted by plasmons. For compactness and reduction of the electrical power consumption, electro-absorption based on the Franz-Keldysh effect in Germanium was chosen for modulation. It consists in the change of the absorption coefficient of the material near the band edge under the application of a static electric field, hence producing a direct modulation of the light intensity. The use of plasmons allows enhancing the electro-optical effect due to the high field confinement. An integrated electro-optical simulation tool was developed to design and optimize the modulator. The designed plasmonic modulator has an extinction ratio of 3.3 dB with insertion losses of 13.2 dB and electrical power consumption as low as 20 fJ/bit, i.e. the lowest electrical power consumption reported for silicon photonic modulators. In- and out-coupling to a standard silicon waveguide was also engineered by the means of an optimized Si-Ge taper, reducing the coupling losses to only 1 dB per coupler. Besides, an experimental work was carried out to try to shift the Franz-Keldysh effect, which is maximum at 1650 nm, to lower wavelength close to 1.55 μm for telecommunication applications.