Prof. Johan H. Stiens Profile

Prof. Johan H. Stiens

ETRO-LAMI Professor at Vrije Univ Brussel

SPIE Involvement:

Author

Publications (28)

Proceedings Article | 13 March 2024 Presentation + Paper

Evaluation of the impact of LED viewing angle and optical window choice on photoplethysmography signal quality

Dib Rizk, Angel Solé Morillo, Joan Lambert Cause, Bruno Da Silva, Johan Stiens

Proceedings Volume 12835, 128350Q (2024) https://doi.org/10.1117/12.3001707

KEYWORDS: Light emitting diodes, Windows, Glasses, Reflection, Skin, Infrared radiation, Signal detection, Coating thickness, Biomedical applications

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Proceedings Article | 28 April 2012 Paper

Wafer-scale nondestructive metrology on subwavelength diffraction gratings by means of Wood's anomaly

C. De Tandt, J. Stiens, G. Shkerdin, W. Ranson, W. Vandermeiren, R. Vounckx

Proceedings Volume 8430, 84300F (2012) https://doi.org/10.1117/12.922517

KEYWORDS: Diffraction gratings, Diffraction, Metrology, Semiconducting wafers, Nondestructive evaluation, Carbon dioxide lasers, Scatterometry, Neodymium, Reflectivity, Infrared spectroscopy

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Proceedings Article | 13 May 2010 Paper

Quasi-optical technique for sensing bond quality of silicon wafers

I. Huynen, R. Vounckx, A. Elhawil, C. Roda Neve, B. Olbrechts, J. Stiens, J.-P. Raskin

Proceedings Volume 7716, 77161R (2010) https://doi.org/10.1117/12.853667

KEYWORDS: Semiconducting wafers, Silicon, Wafer bonding, Silica, Infrared imaging, Infrared radiation, Plasma, Microwave radiation, Interfaces, Photography

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Proceedings Article | 29 April 2010 Paper

An experimental study of the effects of various parameters on the resonant and efficiency of circular split-ring resonators

J. Stiens, A. Elhawil, R. Vounckx, C. De Tandt, W. Ranson

Proceedings Volume 7711, 77111X (2010) https://doi.org/10.1117/12.847130

KEYWORDS: Refractive index, Silicon, Split ring resonators, Metals, Quartz, Capacitance, Skin, Resonators, Sensors, Aluminum

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Proceedings Article | 29 April 2010 Paper

A sensitivity analysis of frequency selective surface based metamaterial at THz frequency

S. Islam, J. Stiens, R. Vounckx

Proceedings Volume 7711, 77110L (2010) https://doi.org/10.1117/12.854062

KEYWORDS: Terahertz radiation, Tolerancing, Metamaterials, Dielectrics, FSS based metamaterials, Split ring resonators, Resonators, Scattering, Copper, Metals

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Proceedings Article | 26 February 2010 Paper

Evanescent wave modulator for medium infrared wavelengths (8-12 µm)

C. De Tandt, J. Stiens, V. Kotov, W. Vandermeiren, R. Vounckx, G. Shkerdin, W. Ranson, G. Borghs

Proceedings Volume 7597, 759711 (2010) https://doi.org/10.1117/12.841657

KEYWORDS: Modulation, Quantum wells, Absorption, Diffraction, Diffraction gratings, Modulators, Electrons, Doping, Amplitude modulation, Dielectrics

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Proceedings Article | 26 February 2010 Paper

Thermal crosstalk reduction in IR thermo-electric photodetectors by lock-in method: 4D numerical simulations and experimental verification

R. Vounckx, C. De Tandt, V. Kotov, G. Shkerdin, G. Borghs, P. Muys, J. Stiens, W. Vandermeiren

Proceedings Volume 7597, 75970Y (2010) https://doi.org/10.1117/12.841556

KEYWORDS: Sensors, Gallium arsenide, Absorption, Finite element methods, Diffusion, Carbon dioxide lasers, Thermography, Thermal modeling, Temperature metrology, Numerical simulations

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Proceedings Article | 25 April 2008 Paper

Grounded frequency selective surface array as millimeter wave beam splitter

Roger Vounckx, I. Jaeger, J. Stiens, S. Islam

Proceedings Volume 6994, 69940A (2008) https://doi.org/10.1117/12.778847

KEYWORDS: Beam splitters, Antennas, Sensors, Extremely high frequency, FSS based metamaterials, Free space, Reflection, Speckle, Composites, Phase measurement

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Proceedings Article | 8 October 2007 Paper

Multidimensional illumination and image processing techniques in the W-band for recognition of concealed objects

Johan Stiens, Amna Elhawil, Peter Schelkens, Gaetan Koers, Lixiao Zhang, Irina Jaeger, Hichem Sahli

Proceedings Volume 6696, 66960R (2007) https://doi.org/10.1117/12.738487

KEYWORDS: Principal component analysis, Metals, Image processing, Firearms, Polarization, Image quality, Sensors, Mirrors, Signal detection, Nonmetals

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Proceedings Article | 18 June 2007 Paper

W-band speckle contrast images for inspection of concealed objects

Johan Stiens, Hichem Sahli, Irina Jaeger, Roger Vounckx, Lixiao Zhang, Gaetan Koers

Proceedings Volume 6616, 66160Y (2007) https://doi.org/10.1117/12.726146

KEYWORDS: Speckle, Inspection, Diffusers, Metals, Speckle pattern, Extremely high frequency, Visible radiation, Surface roughness, Reflection, Spatial resolution

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Proceedings Article | 15 September 2006 Paper

W-band speckle contrast measurements with a Hadamard diffuser

Johan Stiens, Irina Jaeger, Roger Vounckx, Saiful Islam, Gaetan Koers

Proceedings Volume 6341, 634103 (2006) https://doi.org/10.1117/12.695253

KEYWORDS: Speckle, Diffusers, Reflection, Photomasks, Speckle pattern, Extremely high frequency, Surface roughness, Gaussian beams, Opacity, Millimeter wave imaging

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Proceedings Article | 22 April 2006 Paper

Seebeck infrared photodetectors: an ultra wide dynamic range of design possibilities

Cathleen De Tandt, Werner Vandermeiren, Roger Vounckx, Johan Stiens, Gennady Shkerdin, Vladimir Kotov, Gustaaf Borghs

Proceedings Volume 6189, 61890Y (2006) https://doi.org/10.1117/12.662483

KEYWORDS: Absorption, Sensors, Doping, Pulsed laser operation, Semiconductors, Gas lasers, Gallium arsenide, Tellurium, Temperature metrology, Thermoelectric materials

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Proceedings Article | 19 April 2006 Paper

Speckle reduction in THz imaging systems with multiple phase patterns

Gaetan Koers, Gert Poesen, Irina Jaeger, Johan Stiens, Roger Vounckx

Proceedings Volume 6194, 61940B (2006) https://doi.org/10.1117/12.662512

KEYWORDS: Speckle, Speckle pattern, Terahertz radiation, Imaging systems, Diffusers, Surface roughness, Reflection, Sensors, Photomasks, Free space optics

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Proceedings Article | 19 April 2006 Paper

Characterization of speckle/despeckling in active millimeter wave imaging systems using a first order 1.5D model

R. Vounckx, J. Stiens, F. Olyslager, L. Meert, I. Jager, G. Koers, J. Fostier, B. Nauwelaers, I. Ocket

Proceedings Volume 6194, 619409 (2006) https://doi.org/10.1117/12.661689

KEYWORDS: Sensors, Speckle, Imaging systems, Diffusers, Lenses, Millimeter wave imaging, Gaussian beams, Systems modeling, Detector arrays, Point spread functions

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Proceedings Article | 1 September 2004 Paper

Optoelectronic control of coplanar transmission lines up to 110 GHz

Walter De Raedt, Gert Poesen, Pascal Simon, Johan Stiens, Gaetan Koers, Isabelle Huynen, Roger Vounckx, Jean-Pierre Raskin

Proceedings Volume 5466, (2004) https://doi.org/10.1117/12.548949

KEYWORDS: 3D modeling, Circuit switching, Capacitors, Metals, Radio propagation, Silicon, Optoelectronics, Modulation, Wave propagation, Dielectrics

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Proceedings Article | 29 May 2002 Paper

Investigation of optical nonlinearities in n-GaAs based on multivalley distributed hot electronics

Vladimir Kotov, Gennady Shkerdin, Roger Vounckx, Johan Stiens, Gustaaf Borghs

Proceedings Volume 4748, (2002) https://doi.org/10.1117/12.468955

KEYWORDS: Electrons, Reflectivity, Doping, Nonlinear optics, Gallium arsenide, Absorption, Carbon dioxide lasers, Metals, Information operations, Beam splitters

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Proceedings Article | 1 April 2002 Paper

Cascade acousto-optic diffraction for optical communication systems

Gennady Shkerdin, Vladimir Kotov, Johan Stiens, Roger Vounckx

Proceedings Volume 4750, (2002) https://doi.org/10.1117/12.464494

KEYWORDS: Diffraction, Acousto-optics, Crystals, Adaptive optics, Acoustics, Mirrors, Geometrical optics, Polarization, Laser crystals, Wave propagation

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Proceedings Article | 14 April 2000 Paper

Evanescent coupling alternatives for YAG lasers

Johan Stiens, Michele Banish, Roger Vounckx, Rodney Clark

Proceedings Volume 3929, (2000) https://doi.org/10.1117/12.382754

KEYWORDS: Diffraction gratings, Diffraction, YAG lasers, Refractive index, Crystals, Silicon, Laser crystals, Lithography, Coating, Interferometry

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Proceedings Article | 11 November 1999 Paper

Highly efficient diffraction gratings and resonant plasma layers at IR wavelengths

Galina Nemova, Johan Stiens, Roger Vounckx, Peter Muys

Proceedings Volume 3897, (1999) https://doi.org/10.1117/12.369363

KEYWORDS: Diffraction gratings, Diffraction, Refractive index, Plasma, Light wave propagation, Gallium arsenide, Germanium, Etching, Absorption, Modulation

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Proceedings Article | 9 November 1999 Paper

Optical Gunn effect in n-doped GaAs at mid- and far-IR wavelengths

Gennady Shkerdin, Filip Marest, Roger Vounckx, Johan Stiens

Proceedings Volume 3899, (1999) https://doi.org/10.1117/12.369398

KEYWORDS: Electrons, Absorption, Phonons, Gallium arsenide, Doping, Infrared radiation, Dielectrics, Electromagnetic radiation, Nonlinear optics, Semiconductors

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Proceedings Article | 24 September 1999 Paper

Acousto-optic interaction of two-color beam in isotropy media

Vladimir Kotov, Gennady Shkerdin, Johan Stiens, Roger Vounckx

Proceedings Volume 3900, (1999) https://doi.org/10.1117/12.364557

KEYWORDS: Acoustics, Acousto-optics, Diffraction, Adaptive optics, Beam splitters, Light wave propagation, Beam propagation method, Wave propagation, Glasses, Electronics

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Proceedings Article | 24 September 1999 Paper

Peculiarities of IR diffraction on rectangular-groove transmission phase grating containing a layer of a resonant plasma

Galina Nemova, Johan Stiens

Proceedings Volume 3900, (1999) https://doi.org/10.1117/12.364532

KEYWORDS: Diffraction, Plasma, Diffraction gratings, Teeth, Light wave propagation, Holography, Refractive index, Dielectrics, Gallium arsenide, Solids

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Proceedings Article | 20 September 1999 Paper

Resonant intracavity modulator for q-switching a CO2 laser in a new parameter regime

C. De Tandt, Vladimir Kotov, W. Ranson, Roger Vounckx, Peter Muys, Johan Stiens, Gustaaf Borghs

Proceedings Volume 3822, (1999) https://doi.org/10.1117/12.364223

KEYWORDS: Diffraction gratings, Q switching, Plasma, Carbon dioxide lasers, Diodes, Reflection, Modulators, Q switched lasers, Doping, Mirrors

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Proceedings Article | 15 March 1999 Paper

Coherent scattering of multicomponent optical radiation on a single acoustic wave

Johan Stiens, Roger Vounckx, Vladimir Kotov, Gennady Shkerdin

Proceedings Volume 3734, (1999) https://doi.org/10.1117/12.342355

KEYWORDS: Acoustics, Diffraction, Acousto-optics, Adaptive optics, Crystals, Wave propagation, Optical components, Polarization, Laser crystals, Beam propagation method

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Proceedings Article | 15 March 1999 Paper

Nonlinear free-carrier absorption in nonparabolic III-V semiconductors

Roger Vounckx, Johan Stiens, Gennady Shkerdin

Proceedings Volume 3734, (1999) https://doi.org/10.1117/12.342349

KEYWORDS: Absorption, Phonons, Doping, Gallium arsenide, Indium arsenide, Thermography, Semiconductors, Nonlinear optics, Scattering, Acoustics

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Proceedings Article | 10 June 1996 Paper

Nonlinear reflection of medium-infrared light from a structure containing highly doped GaAs layers

Johan Stiens, Roger Vounckx, Alexander Voronko, Gennady Shkerdin

Proceedings Volume 2801, (1996) https://doi.org/10.1117/12.242142

KEYWORDS: Absorption, Gallium arsenide, Picosecond phenomena, Semiconductors, Reflectivity, Nonlinear optics, Refractive index, Plasma, Switching, Interferometers

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