Publications by Zhe Zhao | EPFL Graph Search

Generation of OAM-carrying space-time wave packets with time-dependent beam radii using a coherent combination of multiple LG modes on multiple frequencies

Tobias Kippenberg, Hao Song, Maxim Karpov, Zhe Zhao, Xinzhou Su

Space-time (ST) wave packets, in which spatial and temporal characteristics are coupled, have gained attention due to their unique propagation characteristics, such as propagation invariance and tunable group velocity in addition to their potential ability ...

Optica Publishing Group2022

Experimental demonstration of dynamic spatiotemporal structured beams that simultaneously exhibit two orbital angular momenta by combining multiple frequency lines, each carrying multiple Laguerre-Gaussian modes

Tobias Kippenberg, Hao Song, Maxim Karpov, Zhe Zhao, Xinzhou Su

In general, there are different, relatively independent forms of orbital angular momenta at a given propagation distance, which might exhibit different dynamic spatial characteristics. One type involves a beam with a helical phase-front that rotates around ...

Optica Publishing Group2022

Synthesis of near-diffraction-free orbital-angular-momentum space-time wave packets having a controllable group velocity using a frequency comb

Tobias Kippenberg, Hao Song, Maxim Karpov, Zhe Zhao, Xinzhou Su

Novel forms of light beams carrying orbital angular momentum (OAM) have recently gained interest, especially due to some of their intriguing propagation features. Here, we experimentally demonstrate the generation of near-diffraction-free two-dimensional ( ...

Optica Publishing Group2022

Spark Plasma Sintering of Ceramics: From Modeling to Practice

Paul Bowen, Michael Stuer, Zhe Zhao

Summarizing the work of nearly a decade of research on spark plasma sintering (SPS), a review is given on the specificities and key factors to be considered in SPS of ceramic materials, based on the authors’ own research. Alumina is used primarily as a mod ...

2020

Synthesis and Sintering of ZnO Nanopowders

Paul Bowen, Michael Stuer, Zhe Zhao

Nanopowders are continuously under investigation as they open new perspectives in numerous fields. There are two main challenges to stimulating their development: sufficient low-cost, high throughput synthesis methods which lead to a production with well-d ...

Mdpi Ag2017

Comparison of apparent activation energies for densification of alumina powders by pulsed electric current sintering (spark plasma sintering) and conventional sintering-toward applications for transparent polycrystalline alumina

Paul Bowen, Claude Paul Carry, Michael Stuer, Zhe Zhao

In the quest for high real in-line transmittances for transparent polycrystalline alumina (PCA), we need defect free processing. One of the biggest advances in producing high density defect free ceramics over recent years has been the advent of spark plasm ...

Materials Research Society2017

Demonstration of optical multicasting using Kerr frequency comb lines

Yan Yan, Tobias Kippenberg, Martin Hubert Peter Pfeiffer, Amirhossein Mohajerin Ariaei, Arne Kordts, Long Li, Maxim Karpov, Zhe Zhao, Lin Zhang

We experimentally demonstrate optical multicasting using Kerr frequency combs generated from a Si3N4 microresonator. We obtain Kerr combs in two states with different noise properties by varying the pump wavelength in the resonator and investigate the effe ...

Optical Society of America2016

Experimental Demonstration of 7-fold Multicasting of a 20-Gbaud QPSK Signal using Kerr Frequency Combs

Yan Yan, Tobias Kippenberg, Martin Hubert Peter Pfeiffer, Amirhossein Mohajerin Ariaei, Arne Kordts, Long Li, Maxim Karpov, Zhe Zhao, Lin Zhang

We experimentally demonstrate 7-fold multicasting of 20-Gbaud QPSK signals based on Kerr frequency combs generated in a silicon nitride microresonator. The effect of high phase-noise comb state on the multicasting performance has also been studied. ...

Ieee2016

Influence of Y and La Additions on Grain Growth and the Grain-Boundary Character Distribution of Alumina

Paul Bowen, Michael Stuer, Zhe Zhao

Grain-boundary character distributions (GBCDs) were determined for spark plasma sintered Y- and La-doped aluminas prepared at temperatures between 1450 degrees C and 1600 degrees C. La doping leads to grain boundaries that adopt (0001) orientations 3.7 tim ...

Wiley-Blackwell2014

Freeze granulation: Powder processing for transparent alumina applications

Paul Bowen, Michael Stuer, Zhe Zhao

Use of freeze granulated powders is successfully used as an industrially viable alternative to loose powder sintering for transparent polycrystalline alumina (PCA). Freeze granulation with narrow granule size distribution was realized after suspension cond ...

2012

Symposium on Transparent Ceramics

Paul Bowen, Zhe Zhao

2012