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David Thomson  - - - 
Top co-authors See all
G. T. Reed

97 shared publications

Optoelectronics Research Centre, University of Southampton, Southampton SO17 1JB, UK

Milos Nedeljkovic

88 shared publications

Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK

Wanjun Wang

23 shared publications

Silicon Technologies Centre of Excellence, Nanyang Technological University, Singapore 639798, Singapore

Callum George Littlejohns

21 shared publications

Optoelectronics Research Centre, University of Southampton, University Road, Southampton, Hampshire SO17 1BJ, UK

Zecen Zhang

16 shared publications

Nanyang Technological Univ. (Singapore)

Publication Record
Distribution of Articles published per year 
(2007 - 2018)
Total number of journals
published in
Publications See all
Article 0 Reads 0 Citations Experimental quantification of the free-carrier effect in silicon waveguides at extended wavelengths David E. Hagan, Milos Nedeljkovic, Wei Cao, David J. Thomson... Published: 03 January 2019
Optics Express, doi: 10.1364/oe.27.000166
DOI See at publisher website ABS Show/hide abstract
We examine the electro-optic effect at wavelengths ranging from 1.31 to 2.02 μm for: (1) an Electronic Variable Optical Attenuator (EVOA); and (2) a Micro-Ring Resonator (MRR). For the EVOA, simulations were performed to ascertain the relationship between free-carrier concentration and optical attenuation, and are in agreement with our observation of an increase in attenuation with increasing wavelength. MRRs were fabricated for use around wavelengths of 2 μm to explore the sensitivity of operation to bus-to-ring coupling gap and p-n junction offset. Trends observed in the experiment are replicated by simulation, calibrated using the observations of the EVOA operation. The previously proposed efficiency increase of operation around 2 μm compared to more traditional wavelengths is demonstrated. Future development of devices for these wavelengths, supported by amplification using Thulium Doped Fiber Amplifier (TDFA) technology, is a promising route to aid in the alleviation of increasing demands on communication networks.
Article 0 Reads 0 Citations Silicon slot fin waveguide on bonded double-SOI for a low-power accumulation modulator fabricated by an anisotropic wet ... James Byers, Kapil Debnath, Hideo Arimoto, M. Khaled Husain,... Published: 05 December 2018
Optics Express, doi: 10.1364/oe.26.033180
DOI See at publisher website ABS Show/hide abstract
We propose a new low VπL, fully-crystalline, accumulation modulator design based on a thin horizontal gate oxide slot fin waveguide, on bonded double Silicon-on-Insulator (SOI). A combination of anisotropic wet etching and the mirrored crystal alignment of the top and bottom SOI layers allows us for the first time to selectively pattern the bottom layer from above. Simulations presented herein show a VπL = 0.17Vcm. Fin-waveguides and passive Mach-Zehnder Interferometer (MZI) devices with fin-waveguide phase shifters have been fabricated, with the fin-waveguides having a transmission loss of 5.8dB/mm and a 13.5nm thick internal gate oxide slot.
PROCEEDINGS-ARTICLE 0 Reads 0 Citations Germanium implanted photonic devices for post-fabrication trimming and programmable circuits Xia Chen, Milan M. Milosevic, Xingshi Yu, Antoine F. J. Rung... Published: 25 October 2018
Nanophotonics and Micro/Nano Optics IV, doi: 10.1117/12.2503224
DOI See at publisher website
Article 0 Reads 1 Citation Real-time monitoring and gradient feedback enable accurate trimming of ion-implanted silicon photonic devices Bigeng Chen, Xingshi Yu, Xia Chen, Milan M. Milosevic, David... Published: 10 September 2018
Optics Express, doi: 10.1364/oe.26.024953
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Fabrication errors pose significant challenges on silicon photonics, promoting post-fabrication trimming technologies to ensure device performance. Conventional approaches involve multiple trimming and characterization steps, impacting overall fabrication complexity. Here we demonstrate a highly accurate trimming method combining laser annealing of germanium implanted silicon waveguide and real-time monitoring of device performance. Direct feedback of the trimming process is facilitated by a differential spectroscopic technique based on photomodulation. The resonant wavelength trimming accuracy is better than 0.15 nm for ring resonators with 20-µm radius. We also realize operating point trimming of Mach-Zehnder interferometers with germanium implanted arms. A phase shift of 1.2π is achieved by annealing a 7-μm implanted segment.
Article 0 Reads 0 Citations De-multiplexing free on-chip low-loss multimode switch enabling reconfigurable inter-mode and inter-path routing Chunlei Sun, Wenhao Wu, Yu Yu, Guanyu Chen, Xinliang Zhang, ... Published: 28 August 2018
Nanophotonics, doi: 10.1515/nanoph-2018-0053
DOI See at publisher website ABS Show/hide abstract
Switching and routing are critical functionalities for a reconfigurable bandwidth-dense optical network, and great efforts had been made to accommodate mode-division multiplexing technology. Although the reconfigurable routing for spatial-mode groups between different optical paths was realized recently, a demultiplexing-switching-multiplexing process is necessary. Here we present a simplified and compact on-chip 2×2 multimode switch that can be easily upgradable to a larger scale. Fully and reconfigurable routing between not only optical paths but also spatial modes is achieved. To obtain a low loss multimode processing, a novel structure free from demultiplexing and re-multiplexing operations is adopted. The switch enables minimum and maximum insertion losses of 0.3 and 1.2 dB, with a compact footprint of 433 μm×433 μm and low crosstalk of <−16.6 dB for all channels. It is further extended to two types of 4×4 switch fabrics with cross-bar and ring-bus architectures, as demonstrations of high-level integration. System characterization with 32 Gb/s high-speed modulated signals is also carried out, reaching up to 256 Gb/s aggregate throughput. These results verify a general solution of 2×2 multimode switch for reconfigurable inter-mode and inter-path routing applicable in large-scale and high-density multimode optical network.
Article 0 Reads 2 Citations High-speed silicon modulators for the 2 μm wavelength band Wei Cao, David Hagan, David J. Thomson, Milos Nedeljkovic, C... Published: 28 August 2018
Optica, doi: 10.1364/optica.5.001055
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The 2 μm wavelength band has become a promising candidate to be the next communication window. We demonstrate high-speed modulators based on a 220 nm silicon-on-insulator platform working at a wavelength of 1950 nm, using the free carrier plasma dispersion effect in silicon. A Mach–Zehnder interferometer modulator and a microring modulator have been characterized. At 1950 nm, the carrier-depletion modulator operates at a data rate of 20 Gbit/s with an extinction ratio of 5.8 dB and insertion loss of 13 dB. The modulation efficiency (Vπ·Lπ) is 2.68 V·cm at 4 V reverse bias. The device operation is broadband, and we also characterize its performance at 1550 nm. At 1550 nm, an open eye is obtained at 30 Gbit/s. The difference in bandwidth is caused by the bandwidth limit of the 2 μm measurement setup. We also show a ring modulator paired with a low power integrated driver working in hybrid carrier depletion and injection mode at a data rate of 3 Gbit/s with power consumption of 2.38 pJ/bit in the 2 μm wavelength range. This work is a proof of principle demonstration and paves a route toward a full silicon-based transceiver in the 2 μm window.