Person

Wei Liu

This person is no longer with EPFL

Related publications (24)

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Diffraction from deformed volume holograms: perturbation theory approach

Demetri Psaltis, Wei Liu

We derive the response of a volume grating to arbitrary small deformations, using a perturbative approach. This result is of interest for two applications: (a) when a deformation is undesirable and one seeks to minimize the diffracted field's sensitivity t ...

2005

Volume holographic grating-based continuously tunable optical filter

Demetri Psaltis, Wei Liu

We propose and demonstrate a widely tunable optical filter, realized by angle tuning a volume holographic grating. The volume holographic grating selectively drops a narrow portion of the signal bandwidth into a fiber while passing through the rest of the ...

2004

Imaging using volume holograms

Demetri Psaltis, Wei Liu

We present an overview of imaging systems that incorporate a volume hologram as one of the optical field processing elements in the system. We refer to these systems as volume holographic imaging (VHI) systems. The volume hologram is recorded just once, an ...

2004

Volume holographic hyperspectral imaging

Demetri Psaltis, Wei Liu

A volume hologram has two degenerate Bragg-phase-matching dimensions and provides the capability of volume holographic imaging. We demonstrate two volume holographic imaging architectures and investigate their imaging resolution, aberration, and sensitivit ...

2004

Folded shift multiplexing

Demetri Psaltis, Wei Liu

Shift multiplexing is a holographic recording method that uses a spherical reference wave. We extend the principle to a thin slab of holographic material that acts as a waveguide. Total internal reflection folds the reference spherical beam in one dimensio ...

2003

Real-time spectral imaging in three spatial dimensions

Demetri Psaltis, Wei Liu

We report what is to our knowledge the first volume-holographic optical imaging instrument with the capability to return three-dimensional spatial as well as spectral information about semitranslucent microscopic objects in a single measurement. The four-d ...

2002

Derivation and measurement of the M/# in spectral hole burning media

Demetri Psaltis, Wei Liu

We demonstrate 10 plane wave holograms angularly multiplexed at one frequency channel in spectral hole burning medium. We show that the M/# is still a valid system metric and the measured M/# in one frequency channel is about 0.01. ...

2001

Holographic random access memory

Demetri Psaltis, Wei Liu

We examine the primary challenges for building a practical and competitive holographic random access memory (HRAM) system, specifically for size, speed, and cost. We show that a fast HRAM system can be implemented with a compact architecture by incorporati ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2000

Optical memory for computing and information processing

Demetri Psaltis, Wei Liu

The high data transfer rate achievable in page-oriented optical memories demands for parallel interfaces to logic circuits able to process efficiently the data. The Optically Programmable Gate Array, an enhanced version of a conventional FPGA, utilizes a h ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa1999

The pixel size limit for a holographic memory system

Demetri Psaltis, Wei Liu

Compact holographic memory architecture with phase conjugate readout and diffraction suppression by internal reflection is investigated. The pixel size requirement for a competitive system is determined. The bandwidth of the holographic recording in LiNbO3 ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa1999