Ofer M - Academia.edu (original) (raw)

Papers by Ofer M

We demonstrate experimentally that disorder enhances transport of waves in Penrose-type photonic ... more We demonstrate experimentally that disorder enhances transport of waves in Penrose-type photonic quasicrystals. Increasing disorder gives rise to a transition from "bumpy ride" to diffusive transport.

Conference on Lasers and Electro-Optics, May 4, 2008

ABSTRACT

Nonlinear Guided Waves and Their Applications, 2005

... Vladimir Shandarov State University of Control Systems and Radioelectronics, 40 Lenin Ave., 6... more ... Vladimir Shandarov State University of Control Systems and Radioelectronics, 40 Lenin Ave., 634050 Tomsk, Russia ... Using the symmetry n(z) = n(z +Λ), we apply the Floquet-Bloch theorem and look for solutions A(z) = U(z) exp(iKz z), where Kz is the transverse wave number ...

Optics & Photonics News, Dec 1, 2011

We have learned how to construct ordered index-of-refraction-modulated structures that allow us t... more We have learned how to construct ordered index-of-refraction-modulated structures that allow us to control the propagation of light. Initially, researchers were simply interested in fabrication; now they are exploring limitations in the structures.

Nonlinear Guided Waves and Their Applications, 2005

... Vladimir Shandarov State University of Control Systems and Radioelectronics, 40 Lenin Ave., 6... more ... Vladimir Shandarov State University of Control Systems and Radioelectronics, 40 Lenin Ave., 634050 Tomsk, Russia ... Using the symmetry n(z) = n(z +Λ), we apply the Floquet-Bloch theorem and look for solutions A(z) = U(z) exp(iKz z), where Kz is the transverse wave number ...

2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science, 2008

We demonstrate, theoretically and experimentally, resonance effects associated with modulation in... more We demonstrate, theoretically and experimentally, resonance effects associated with modulation instability of incoherent light. The resonance is exemplified in a sharp transition of the spatial-frequency of maximum-gain, and in the absence of threshold.

Nonlinear Guided Waves and Their Applications, 2005

We identify nondiffracting beams in two-dimensional periodic systems, exhibiting symmetry propert... more We identify nondiffracting beams in two-dimensional periodic systems, exhibiting symmetry properties and phase structure characteristic of the band(s) they are associated with.

Optics Express, 2007

We propose diffractive optical elements with a spatially-varying nonlinear refractive index. Such... more We propose diffractive optical elements with a spatially-varying nonlinear refractive index. Such a component acts as a diffractive optical element whose properties depend on the intensity of the incoming beam. We present a method for designing such elements, and as specific examples we study three types of nonlinear diffractive optical elements: Nonlinear Fresnel Zone Plates, Two-foci Nonlinear Fresnel Zone Plates, and Fresnel Zone Plate to Grating interpolator.

Journal of The Optical Society of America B-optical Physics, Jul 1, 2005

We describe experimental and theoretical results of research on a new type of waveguide, the so-c... more We describe experimental and theoretical results of research on a new type of waveguide, the so-called gratingmediated waveguide (GMW) recently reported by our group. This waveguide structure relies on Bragg diffractions from a 1D grating giving rise to wave guiding in the direction normal to the grating wave vector. The structure consists of a shallow 1D grating having a bell-or trough-shaped amplitude in the confinement direction. We provide the theoretical analysis of the underlying wave-guiding mechanism along with experimental evidence for both the bell-and the trough-shaped waveguides. We investigate the robustness of gratingmediated wave guiding and suggest more elaborate, 2D structures, such as a GMW superlattice and a gratingmediated ring waveguide. Finally we discuss the relation between grating-mediated wave guiding and holographic solitons, which are the beams that are self-trapped solely by virtue of their jointly induced grating.

Optics Express, 2005

We investigate, experimentally and theoretically, light propagation in one-dimensional waveguide ... more We investigate, experimentally and theoretically, light propagation in one-dimensional waveguide arrays exhibiting a saturable self-defocusing nonlinearity. We demonstrate low-intensity "discrete diffraction", and the high-intensity formation of spatial gap solitons arising from the first band of the transmission spectrum. The waveguide arrays are fabricated by titanium in-diffusion in a photorefractive copper-doped lithium niobate crystal, and the optical nonlinearity arises from the bulk photovoltaic effect.

We report what is to our knowledge the first experimental observation of gap random-phase lattice... more We report what is to our knowledge the first experimental observation of gap random-phase lattice solitons: self-trapped spatially incoherent entities whose modal constituents lie within a photonic bandgap.

Conference on Lasers and Electro-Optics, May 4, 2008

We study the extended modes of a nonlinear quasi-periodic system and show that the nonlinear spec... more We study the extended modes of a nonlinear quasi-periodic system and show that the nonlinear spectra are deformed versions of the Hofstadter butterfly. An optical realization of the Hofstadter butterfly is proposed.

Optics & Photonics News, Dec 1, 2004

arXiv (Cornell University), Mar 14, 2023

Transferring the absolute depth prediction capabilities of an estimator to a new domain is a task... more Transferring the absolute depth prediction capabilities of an estimator to a new domain is a task with significant real-world applications. This task is specifically challenging when images from the new domain are collected without ground-truth depth measurements, and possibly with sensors of different intrinsics. To overcome such limitations, a recent zero-shot solution was trained on an extensive training dataset and encoded the various camera intrinsics. Other solutions generated synthetic data with depth labels that matched the intrinsics of the new target data to enable depth-scale transfer between the domains. In this work we present an alternative solution that can utilize any existing synthetic or real dataset, that has a small number of images annotated with ground truth depth labels. Specifically, we show that self-supervised depth estimators result in up-to-scale predictions that are linearly correlated to their absolute depth values across the domain, a property that we model in this work using a single scalar. In addition, aligning the field-of-view of two datasets prior to training, results in a common linear relationship for both domains. We use this observed property to transfer the depth-scale from source datasets that have absolute depth labels to new target datasets that lack these measurements, enabling absolute depth predictions in the target domain. The suggested method was successfully demonstrated on the KITTI, DDAD and nuScenes datasets, while using other existing real or synthetic source datasets, that have a different field-of-view, other image style or structural content, achieving comparable or better accuracy than other existing methods that do not use target ground-truth depths. (c) Mixed-supervision Source RGBs Self-supervision on source & target images Full-supervision with source GT depth (c) Mixed-supervision Source RGBs Self-supervision on source & target images Full-supervision with source GT depth Inference stage Training stage Loss Depth scaling module (e) Depth-scale transfer using source GT depth (ours) Source RGBs Self-supervision on source & target images Target RGBs Depth scaling with source GT depth

2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science, 2008

We study the extended modes of a nonlinear quasi-periodic system and show that the nonlinear spec... more We study the extended modes of a nonlinear quasi-periodic system and show that the nonlinear spectra are deformed versions of the Hofstadter butterfly. An optical realization of the Hofstadter butterfly is proposed.

2006 IEEE LEOS Annual Meeting Conference Proceedings, 2006

ABSTRACT We provide an overview of recent theoretical and experimental results in the area of sur... more ABSTRACT We provide an overview of recent theoretical and experimental results in the area of surface lattice solitons. The observation of these waves in Kerr and quadratic nonlinear periodic structures is discussed

SPIE Proceedings, 2011

Modern electro-optical systems contain several components such as thermal imager, laser designato... more Modern electro-optical systems contain several components such as thermal imager, laser designator, laser range finder, etc. The demand for compact systems with low power consumption and low cost can be addressed by incorporating some of the traditional system abilities into the IR detector. We present SNIR, a new type of detector, which consists of a Read Out Integrated Circuit (ROIC) with advanced on-chip signal processing. The ROIC is flip chip-bonded to a 640×512 InSb detector array of 15µm pitch. SNIR digital ROIC can be operated in either one of the following four different modes of operation. The first operation mode is standard thermal imaging, which has typical functionalities and performance of MWIR detector. The second operation mode is a dual-function mode that includes both standard thermal imaging and information on Asynchronous Laser Pulse Detection (ALPD) for each pixel. The detection probability of a laser pulse is significantly increased by integrating a dedicated in-pixel circuit for identifying a fast signal temporal profile. Since each pixel has internal processing to identify laser pulses, it is possible also to measure the elapsed time between a trigger and the detection of a laser pulse. This yields a third mode of operation in which the detector is synchronized to a laser and becomes a Two-dimensional Laser Range Finder (TLRF). The forth operation mode is dedicated to Low Noise Imaging (LNIM) for the SWIR band, where the IR radiation signal is low. It can be used in both passive or active imaging. We review some of the predicted and measured results for the different modes of operation, both at the detector level and at the system level.

Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides, 2007

We show that MI is the driving force bringing spatially-incoherent light to an equilibrium state,... more We show that MI is the driving force bringing spatially-incoherent light to an equilibrium state, while propagating through non-instantaneous nonlinearities. The equilibrium state depends only on the initial coherence, and not on the nonlinearity strength.

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

It is theoretically shown that nonlinear surface-waves are possible in optical lattices. Such sol... more It is theoretically shown that nonlinear surface-waves are possible in optical lattices. Such solitons can exist at the interface between two different semi-infinite 1D waveguide arrays and also at the boundaries of a 2D lattice.

We demonstrate experimentally that disorder enhances transport of waves in Penrose-type photonic ... more We demonstrate experimentally that disorder enhances transport of waves in Penrose-type photonic quasicrystals. Increasing disorder gives rise to a transition from "bumpy ride" to diffusive transport.

Conference on Lasers and Electro-Optics, May 4, 2008

ABSTRACT

Nonlinear Guided Waves and Their Applications, 2005

... Vladimir Shandarov State University of Control Systems and Radioelectronics, 40 Lenin Ave., 6... more ... Vladimir Shandarov State University of Control Systems and Radioelectronics, 40 Lenin Ave., 634050 Tomsk, Russia ... Using the symmetry n(z) = n(z +Λ), we apply the Floquet-Bloch theorem and look for solutions A(z) = U(z) exp(iKz z), where Kz is the transverse wave number ...

Optics & Photonics News, Dec 1, 2011

We have learned how to construct ordered index-of-refraction-modulated structures that allow us t... more We have learned how to construct ordered index-of-refraction-modulated structures that allow us to control the propagation of light. Initially, researchers were simply interested in fabrication; now they are exploring limitations in the structures.

Nonlinear Guided Waves and Their Applications, 2005

... Vladimir Shandarov State University of Control Systems and Radioelectronics, 40 Lenin Ave., 6... more ... Vladimir Shandarov State University of Control Systems and Radioelectronics, 40 Lenin Ave., 634050 Tomsk, Russia ... Using the symmetry n(z) = n(z +Λ), we apply the Floquet-Bloch theorem and look for solutions A(z) = U(z) exp(iKz z), where Kz is the transverse wave number ...

2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science, 2008

We demonstrate, theoretically and experimentally, resonance effects associated with modulation in... more We demonstrate, theoretically and experimentally, resonance effects associated with modulation instability of incoherent light. The resonance is exemplified in a sharp transition of the spatial-frequency of maximum-gain, and in the absence of threshold.

Nonlinear Guided Waves and Their Applications, 2005

We identify nondiffracting beams in two-dimensional periodic systems, exhibiting symmetry propert... more We identify nondiffracting beams in two-dimensional periodic systems, exhibiting symmetry properties and phase structure characteristic of the band(s) they are associated with.

Optics Express, 2007

We propose diffractive optical elements with a spatially-varying nonlinear refractive index. Such... more We propose diffractive optical elements with a spatially-varying nonlinear refractive index. Such a component acts as a diffractive optical element whose properties depend on the intensity of the incoming beam. We present a method for designing such elements, and as specific examples we study three types of nonlinear diffractive optical elements: Nonlinear Fresnel Zone Plates, Two-foci Nonlinear Fresnel Zone Plates, and Fresnel Zone Plate to Grating interpolator.

Journal of The Optical Society of America B-optical Physics, Jul 1, 2005

We describe experimental and theoretical results of research on a new type of waveguide, the so-c... more We describe experimental and theoretical results of research on a new type of waveguide, the so-called gratingmediated waveguide (GMW) recently reported by our group. This waveguide structure relies on Bragg diffractions from a 1D grating giving rise to wave guiding in the direction normal to the grating wave vector. The structure consists of a shallow 1D grating having a bell-or trough-shaped amplitude in the confinement direction. We provide the theoretical analysis of the underlying wave-guiding mechanism along with experimental evidence for both the bell-and the trough-shaped waveguides. We investigate the robustness of gratingmediated wave guiding and suggest more elaborate, 2D structures, such as a GMW superlattice and a gratingmediated ring waveguide. Finally we discuss the relation between grating-mediated wave guiding and holographic solitons, which are the beams that are self-trapped solely by virtue of their jointly induced grating.

Optics Express, 2005

We investigate, experimentally and theoretically, light propagation in one-dimensional waveguide ... more We investigate, experimentally and theoretically, light propagation in one-dimensional waveguide arrays exhibiting a saturable self-defocusing nonlinearity. We demonstrate low-intensity "discrete diffraction", and the high-intensity formation of spatial gap solitons arising from the first band of the transmission spectrum. The waveguide arrays are fabricated by titanium in-diffusion in a photorefractive copper-doped lithium niobate crystal, and the optical nonlinearity arises from the bulk photovoltaic effect.

We report what is to our knowledge the first experimental observation of gap random-phase lattice... more We report what is to our knowledge the first experimental observation of gap random-phase lattice solitons: self-trapped spatially incoherent entities whose modal constituents lie within a photonic bandgap.

Conference on Lasers and Electro-Optics, May 4, 2008

We study the extended modes of a nonlinear quasi-periodic system and show that the nonlinear spec... more We study the extended modes of a nonlinear quasi-periodic system and show that the nonlinear spectra are deformed versions of the Hofstadter butterfly. An optical realization of the Hofstadter butterfly is proposed.

Optics & Photonics News, Dec 1, 2004

arXiv (Cornell University), Mar 14, 2023

Transferring the absolute depth prediction capabilities of an estimator to a new domain is a task... more Transferring the absolute depth prediction capabilities of an estimator to a new domain is a task with significant real-world applications. This task is specifically challenging when images from the new domain are collected without ground-truth depth measurements, and possibly with sensors of different intrinsics. To overcome such limitations, a recent zero-shot solution was trained on an extensive training dataset and encoded the various camera intrinsics. Other solutions generated synthetic data with depth labels that matched the intrinsics of the new target data to enable depth-scale transfer between the domains. In this work we present an alternative solution that can utilize any existing synthetic or real dataset, that has a small number of images annotated with ground truth depth labels. Specifically, we show that self-supervised depth estimators result in up-to-scale predictions that are linearly correlated to their absolute depth values across the domain, a property that we model in this work using a single scalar. In addition, aligning the field-of-view of two datasets prior to training, results in a common linear relationship for both domains. We use this observed property to transfer the depth-scale from source datasets that have absolute depth labels to new target datasets that lack these measurements, enabling absolute depth predictions in the target domain. The suggested method was successfully demonstrated on the KITTI, DDAD and nuScenes datasets, while using other existing real or synthetic source datasets, that have a different field-of-view, other image style or structural content, achieving comparable or better accuracy than other existing methods that do not use target ground-truth depths. (c) Mixed-supervision Source RGBs Self-supervision on source & target images Full-supervision with source GT depth (c) Mixed-supervision Source RGBs Self-supervision on source & target images Full-supervision with source GT depth Inference stage Training stage Loss Depth scaling module (e) Depth-scale transfer using source GT depth (ours) Source RGBs Self-supervision on source & target images Target RGBs Depth scaling with source GT depth

2008 Conference on Lasers and Electro-Optics and 2008 Conference on Quantum Electronics and Laser Science, 2008

We study the extended modes of a nonlinear quasi-periodic system and show that the nonlinear spec... more We study the extended modes of a nonlinear quasi-periodic system and show that the nonlinear spectra are deformed versions of the Hofstadter butterfly. An optical realization of the Hofstadter butterfly is proposed.

2006 IEEE LEOS Annual Meeting Conference Proceedings, 2006

ABSTRACT We provide an overview of recent theoretical and experimental results in the area of sur... more ABSTRACT We provide an overview of recent theoretical and experimental results in the area of surface lattice solitons. The observation of these waves in Kerr and quadratic nonlinear periodic structures is discussed

SPIE Proceedings, 2011

Modern electro-optical systems contain several components such as thermal imager, laser designato... more Modern electro-optical systems contain several components such as thermal imager, laser designator, laser range finder, etc. The demand for compact systems with low power consumption and low cost can be addressed by incorporating some of the traditional system abilities into the IR detector. We present SNIR, a new type of detector, which consists of a Read Out Integrated Circuit (ROIC) with advanced on-chip signal processing. The ROIC is flip chip-bonded to a 640×512 InSb detector array of 15µm pitch. SNIR digital ROIC can be operated in either one of the following four different modes of operation. The first operation mode is standard thermal imaging, which has typical functionalities and performance of MWIR detector. The second operation mode is a dual-function mode that includes both standard thermal imaging and information on Asynchronous Laser Pulse Detection (ALPD) for each pixel. The detection probability of a laser pulse is significantly increased by integrating a dedicated in-pixel circuit for identifying a fast signal temporal profile. Since each pixel has internal processing to identify laser pulses, it is possible also to measure the elapsed time between a trigger and the detection of a laser pulse. This yields a third mode of operation in which the detector is synchronized to a laser and becomes a Two-dimensional Laser Range Finder (TLRF). The forth operation mode is dedicated to Low Noise Imaging (LNIM) for the SWIR band, where the IR radiation signal is low. It can be used in both passive or active imaging. We review some of the predicted and measured results for the different modes of operation, both at the detector level and at the system level.

Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides, 2007

We show that MI is the driving force bringing spatially-incoherent light to an equilibrium state,... more We show that MI is the driving force bringing spatially-incoherent light to an equilibrium state, while propagating through non-instantaneous nonlinearities. The equilibrium state depends only on the initial coherence, and not on the nonlinearity strength.

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

It is theoretically shown that nonlinear surface-waves are possible in optical lattices. Such sol... more It is theoretically shown that nonlinear surface-waves are possible in optical lattices. Such solitons can exist at the interface between two different semi-infinite 1D waveguide arrays and also at the boundaries of a 2D lattice.