About

Amy Foster is an associate professor of electrical and computer engineering at Johns Hopkins University. Her expertise lies in the nanoscale design and control of silicon-based photonic devices for optical interactions. Foster's research involves utilizing CMOS-compatible fabrication techniques to develop integrated photonic devices aimed at next-generation communication systems, both on-chip and off-chip. Her work has applications in optical communications, sensing, imaging, spectroscopy, high-speed processing, precision measurement, and security. Foster's research has been funded by notable agencies including IARPA, NSF, APL, and DARPA. She serves as an associate editor of the OSA journal Optics Express and chairs the OSA Frontiers in Optics Photonic Integrated Devices for Computing, Sensing, and Other Applications Committee. Additionally, she is involved with the IEEE Photonics Conference Optical Interconnects Committee and has served as a guest editor for the IEEE Journal of Selected Topics in Quantum Electronics. Foster has co-authored over 45 journal publications in silicon photonics, with her work recognized through awards such as the 2016 Johns Hopkins Catalyst Award and the 2012 DARPA Young Faculty Award. She holds a BS in electrical engineering from the University at Buffalo and an MS and PhD in electrical and computer engineering from Cornell University. Prior to her appointment at Johns Hopkins in 2010, she was a postdoctoral researcher at Cornell.

Research topics

• Computer Science
• Computer Security
• Physics
• Materials science
• Algorithm
• Computer architecture
• Software engineering
• Computer engineering
• Engineering
• Optics
• Electronic engineering
• Optoelectronics
• Metallurgy

Selected publications

• Escalator Interconnects for Massively Multi-Layer Integrated Photonic Systems

  2024-04-15

  articleSenior author

  We demonstrate the fabrication of four-layer escalator interconnects using sputtered metal oxide alloys for the purpose of multi-layer routing of optical power. Broad bandwidth interlayer couplers with losses as low as 1 dB/transition are reported.

  PublisherDOI

• Machine Learning Resistant Amorphous Silicon Physically Unclonable Functions (PUFs)

  arXiv (Cornell University) · 2024-02-05

  preprintOpen access

  We investigate usage of nonlinear wave chaotic amorphous silicon (a-Si) cavities as physically unclonable functions (PUF). Machine learning attacks on integrated electronic PUFs have been demonstrated to be very effective at modeling PUF behavior. Such attacks on integrated a-Si photonic PUFs are investigated through application of algorithms including linear regression, k-nearest neighbor, decision tree ensembles (random forests and gradient boosted trees), and deep neural networks (DNNs). We found that DNNs performed the best among all the algorithms studied but still failed to completely break the a-Si PUF security which we quantify through a private information metric. Furthermore, machine learning resistance of a-Si PUFs were found to be directly related to the strength of their nonlinear response.

  PublisherOA PDFDOI

• Sputtered metal-oxide waveguides for visible-wavelength integrated photonics

  2024-03-13

  article1st authorCorresponding

  Applications such as quantum and biological sensing require visible wavelengths of operation. While incumbent integrated photonic platforms such as silicon nitride enable low-loss light propagation at these wavelengths, the autofluorescence suffered in silicon nitride causes unwanted signals that will significantly reduce performance in sensing applications. Sputtered metal oxides have recently emerged as a promising alternative platform for integrated photonics from visible to NIR, with the added advantage of a drastic reduction in autofluorescence in the visible regime. Here, I present our recent results in propagation loss and autofluorescence characterization of our sputtered metal oxide platforms in the visible light regime.

  PublisherDOI

• Comparative autofluorescence analysis of silicon nitride and tantalum pentoxide waveguides at 532 nm

  Optics Express · 2024-12-09 · 3 citations

  articleOpen accessSenior author

  In this paper, we quantitatively compare the autofluorescence of stoichiometric low pressure chemical vapor deposition (LPCVD) silicon nitride and sputtered tantalum pentoxide waveguides at a pump wavelength of 532 nm. Through a direct quantitative characterization of comparable waveguides formed from the two films, we find no observable autofluorescence for tantalum pentoxide waveguides. Our experimental sensitivity is limited by Raman scattering of the pump into our detection band and our measurements indicate that the autofluorescence of the tantalum pentoxide waveguides is more than 600 × smaller than that of silicon nitride waveguides. This finding holds promise for visible technologies such as biosensors and quantum devices that require strong optical pumping and minimal background noise.

  PublisherDOI

• Niobium-Titanium Oxide (NbTiOx): a Novel High-Index Material for Visible and Near Infrared Integrated Photonics

  2024-01-01

  articleSenior author

  We demonstrate niobium-titanium oxide (NbTiOx), a sputtered metal oxide alloy, for visible and near-IR integrated photonics. In the near-IR, we achieve waveguide propagation losses < 1 dB/cm and a third-order nonlinearity 8 × larger than Si 3 N 4 .

  PublisherDOI

• Photon-Pair Generation in a Heterogeneous Nanophotonic Chip

  ACS Photonics · 2023-06-02 · 4 citations

  articleSenior authorCorresponding

  Integrated silicon photonics has played an important role in advancing the applications of quantum information and quantum science. However, it is challenging to integrate all components with state-of-the-art performance using only a homogeneous platform. Here, by combining high nonlinearity and low losses in a heterogeneous silicon platform, we efficiently generate high-quality photon pairs through spontaneous four-wave mixing in a hydrogenated amorphous silicon waveguide and route them off-chip through a low-loss silicon nitride waveguide. A record high coincidence-to-accidental ratio value of 1632.6 (±260.4) is achieved in this heterogeneous design with a photon pair generation rate of 1.94 MHz. We also showcase a wide range of multichannel photon sources with a coincidence-to-accidental ratio consistently around 200. Lastly, we measure heralded single-photons with the lowest gH(2)(0) of 0.1085 ± 0.0014. Our results demonstrate the heterogeneous silicon platform as an ideal platform for the efficient generation of photon pairs and off-chip routing with low losses. It also paves the way for a future hybrid photonic integrated circuit by collecting distinct features from different materials.

  PublisherDOI

• Parametric nonlinear optics in sputtered metal oxide waveguides

  2023-01-01

  articleSenior authorCorresponding

  Parametric nonlinear optical interactions including four-wave mixing-based optical parametric oscillation are demonstrated in sputtered metal oxide waveguides and resonators including Ta 2 O 5 and NbTaOx.

  PublisherDOI

• Nonlinear optics in a high-index sputtered oxide

  2023-01-01

  articleSenior authorCorresponding

  We present niobium tantalum oxide as a material for nonlinear integrated photonics. Propagation losses of 0.47 dB/cm are extracted from high-Q resonators. The nonlinear performance is demonstrated through optical parametric oscillation and super-continuum generation.

  PublisherDOI

• Direct Comparison of the Autofluorescence of Silicon Nitride and Tantalum Pentoxide Waveguides at 532 nm

  2023-01-01 · 1 citations

  articleSenior authorCorresponding

  We quantitatively compare the autofluorescence of LPCVD silicon nitride and sputtered tantalum pentoxide waveguides at 532 nm and find at least a 10, 000× reduction for tantalum pentoxide, which is promising for quantum technologies and biosensors.

  PublisherDOI

• Fully clad tantalum pentoxide on-chip optical frequency comb

  2023-01-01

  articleSenior authorCorresponding

  Here we demonstrate the first fully-clad sputtered tantalum pentoxide (Ta 2 O 5 ) on-chip optical frequency comb and validate its use as a multi-wavelength source for optical communications.

  PublisherDOI

Recent grants

• OP: Collaborative Research: Quantum Zeno Photonics on Chip

  NSF · $236k · 2015–2019

Frequent coauthors

• Mark A. Foster

  51 shared

• Ke-Yao Wang

  23 shared

• Neil MacFarlane

  22 shared

• Michael R. Kossey

  Advanced Technology Group (Czechia)

  22 shared

• A. Brinton Cooper

  15 shared

• Bryan T. Bosworth

  National Institute of Standards and Technology

  13 shared

• Hongcheng Sun

  Shanghai First People's Hospital

  12 shared

• Charbel Rizk

  Leiden University

  11 shared

Education

• Ph.D., Electrical and Computer Engineering

  Cornell University Graduate School

  2009

Awards & honors

• 2016 Johns Hopkins Catalyst Award
• 2012 DARPA Young Faculty Award
• NSF Graduate Research Fellowship
• Cornell University Fellowship
• invited lecturer at OSA’s Siegman International Summer Schoo…