Photoluminescence and Photocurrent from InGaN/GaN Diodes with Quantum Wells of Different Widths and Polarities.

We compare the optical properties of four diode samples differing by built-in field direction and width of the InGaN quantum well in the active layer: two diodes with standard layer sequences and 2.6 and 15 nm well widths and two diodes with inverted layer ordering (due to the tunnel junction grown before the structure) also with 2.6 and 15 nm widths.

Using both faces of polar semiconductor wafers for functional devices.

Unlike non-polar semiconductors such as silicon, the broken inversion symmetry of the wide-bandgap semiconductor gallium nitride (GaN) leads to a large electronic polarization along a unique crystal axis. This makes the two surfaces of the semiconductor wafer perpendicular to the polar axis substantially different in their physical and chemical properties. In the past three decades, the cation (gallium) face of GaN has been used for photonic devices such as light-emitting diodes (LEDs) and lasers.

Digital holographic content manipulation for wide-angle holographic near-eye displays.

In recent years, the development of holographic near-eye displays (HNED) has surpassed the progress of digital hologram recording systems, especially in terms of wide-angle viewing capabilities. Thus, there is capture-display parameters incompatibility, which makes it impossible to reconstruct recorded objects in wide-angle display. This paper presents a complete imaging chain extending the available content for wide-angle HNED of pupil and non-pupil configuration with narrow-angle digital holograms of real objects.

Harnessing III-Nitride Built-In Field in Multi-Quantum Well LEDs.

III-nitrides possess several unique qualities, which allow them to make the world brighter, but their uniqueness is not always beneficial. The uniaxial nature of the wurtzite crystal leads to strikingly large electric polarization fields, which along with the high acceptor ionization energy cause low injection efficiency and uneven carrier distribution for multiple quantum well (QW) light emitting devices. In this work, we explore the carrier distribution in Ga-polar LED in two configurations: standard "p-up" and "p-down", which is accomplished by utilizing a bottom-tunnel junction.

Bidirectional light-emitting diode as a visible light source driven by alternating current.

Gallium nitride-based light-emitting diodes have revolutionized the lighting market by becoming the most energy-efficient light sources. However, the power grid, in example electricity delivery system, is built based on alternating current, which raises problems for directly driving light emitting diodes that require direct current to operate effectively. In this paper, we demonstrate a proof-of-concept device that addresses this fundamental issue - a gallium nitride-based bidirectional light-emitting diode.

Eyebox expansion with accurate hologram generation for wide-angle holographic near-eye display.

Small eyebox in wide-angle holographic near-eye display is a severe limitation for 3D visual immersion of the device. In this paper, an opto-numerical solution for extending the eyebox size in these types of devices is presented. The hardware part of our solution expands the eyebox by inserting a grating of frequency fg within a non-pupil forming display configuration.

LED near-eye holographic display with a large non-paraxial hologram generation.

In this paper, two solutions are proposed to improve the quality of a large image that is reconstructed in front of the observer in a near-eye holographic display. One of the proposed techniques, to the best of our knowledge, is the first wide-angle solution that successfully uses a non-coherent LED source. It is shown that the resulting image when employing these types of sources has less speckle noise but a resolution comparable to that obtained with coherent light.

Negative Magnetoresistivity in Highly Doped n-Type GaN.

This paper presents low-temperature measurements of magnetoresistivity in heavily doped n-type GaN grown by basic GaN growth technologies: molecular beam epitaxy, metal-organic vapor phase epitaxy, halide vapor phase epitaxy and ammonothermal. Additionally, GaN crystallized by High Nitrogen Pressure Solution method was also examined. It was found that all the samples under study exhibited negative magnetoresistivity at a low temperature (10 K < T < 50 K) and for some samples this effect was observed up to 100 K.

Role of Metallic Adlayer in Limiting Ge Incorporation into GaN.

Atomically thin metal adlayers are used as surfactants in semiconductor crystal growth. The role of the adlayer in the incorporation of dopants in GaN is completely unexplored, probably because n-type doping of GaN with Si is relatively straightforward and can be scaled up with available Si atomic flux in a wide range of dopant concentrations. However, a surprisingly different behavior of the Ge dopant is observed, and the presence of atomically thin gallium or an indium layer dramatically affects Ge incorporation, hindering the fabrication of GaN:Ge structures with abrupt doping profiles.

Dependence of InGaN Quantum Well Thickness on the Nature of Optical Transitions in LEDs.

The design of the active region is one of the most crucial problems to address in light emitting devices (LEDs) based on III-nitride, due to the spatial separation of carriers by the built-in polarization. Here, we studied radiative transitions in InGaN-based LEDs with various quantum well (QW) thicknesses-2.6, 6.

Wide angle holographic video projection display.

Holographic projection displays provide high diffraction efficiency. However, they have a limited projection angle. This work proposes a holographic projection display with a wide angle, which gives an image of size 306×161 at 700 mm and reduced speckle noise.

Fourier horizontal parallax only computer and digital holography of large size.

Registration and reconstruction of high-quality digital holograms with a large view angle are intensive computer tasks since they require the space-bandwidth product (SBP) of the order of tens of gigapixels or more. This massive use of SBP severely affects the storing and manipulation of digital holograms. In order to reduce the computer burden, this work focuses on the generation and reconstruction of very large horizontal parallax only digital holograms (HPO-DHs).

Photorealistic computer generated holography with global illumination and path tracing.

Computer generated holography (CGH) algorithms come in many forms, with different trade-offs in terms of visual quality and calculation speed. However, no CGH algorithm to date can accurately account for all 3D visual cues simultaneously, such as occlusion, shadows, continuous parallax, and precise focal cues, without view discretization. The aim is to create photorealistic CGH content, not only for display purposes but also to create reference data for comparing and testing CGH and compression algorithms.

Lateral carrier injection for the uniform pumping of several quantum wells in InGaN/GaN light-emitting diodes.

Most optoelectronic devices share the same basic epitaxial structure - a stack of quantum wells (QWs) sandwiched between p- and n-doped layers. In nitride semiconductors, where holes have 20-times lower mobility than electrons, the holes are able to populate only the topmost 1-2 QWs. The inability to distribute the holes in a large-enough number of QWs is a cause of high Auger recombination in nitride LEDs.

Quantum-confined Stark effect and mechanisms of its screening in InGaN/GaN light-emitting diodes with a tunnel junction.

Nitride-based light-emitting diodes (LEDs) are well known to suffer from a high built-in electric field in the quantum wells (QWs). In this paper we determined to what extent the electric field is screened by injected current. In our approach we used high pressure to study this evolution.

Suitability analysis of holographic vs light field and 2D displays for subjective quality assessment of Fourier holograms.

Measuring the impact of compression on the reconstruction quality of holograms remains a challenge. A public subjectively-annotated holographic data set that allows for testing the performance of compression techniques and quality metrics is presented, in addition to a subjective visual quality assessment methodology. Moreover, the performance of the quality assessment procedures is compared for holographic, regular 2D and light field displays.

Nitride light-emitting diodes for cryogenic temperatures.

A novel approach to fabricate efficient nitride light-emitting diodes (LEDs) grown on gallium polar surface operating at cryogenic temperatures is presented. We investigate and compare LEDs with standard construction with structures where p-n junction field is inverted through the use of bottom tunnel junction (BTJ). BTJ LEDs show improved turn on voltage, reduced parasitic recombination and increased quantum efficiency at cryogenic temperatures.

Salmonella Typhi - historical perspective of discovery and forgotten contribution of Polish anatomopathology.

Outbreaks of typhoid fever for centuries decimated armies, cities and large hosts of people. Discovery of an agent causing such a grave disease became one of the most important achievements of bacteriology - science, which had experienced rapid development in the last quarter of the 19th century and changed the course of our civilization.The article deals with the discovery of Tadeusz Browicz, Polish anatomopathologist, who in 1874 reported about rod-shaped "parasites" in viscera of typhoid fever victim.

Fourier digital holography of real scenes for 360° tabletop holographic displays.

Recently, the tabletop holographic display has been introduced to present a large 3D hologram floating over the table. When the observer looks down at the hologram, the display reconstructs upper perspectives of the object at a 45° angle. This paper presents the full imaging chain for the tabletop holographic display based on capture, processing, and reconstruction of a 360° observable hologram of the real object.

Color LED DMD holographic display with high resolution across large depth.

Holographic displays employing digital micromirror devices (DMDs) reconstruct 3D images at high diffraction orders. For LED displays, this geometry introduces large dispersion at the DMD surface, reducing image resolution and depth. This work proposes a color DMD LED holographic display with dispersion compensation utilizing an additional diffraction grating in an illumination module.

Fourier rainbow holography.

We present Fourier rainbow holographic imaging approach. It involves standard laser holographic recording and novel horizontal parallax only holographic display. In the display, the rainbow effect is introduced in an illumination module by high-frequency diffraction grating and white light LED source.

Color Fourier orthoscopic holography with laser capture and an LED display.

We present an end-to-end full color Fourier holographic imaging approach, which involves standard holographic recording with three wavelengths and an improved LED-driven display. It provides almost undistorted orthoscopic reconstruction of large objects in full color, which can be viewed with a naked eye. High quality reconstruction is preserved across large object depths, measured in meters, as shown theoretically and experimentally.

Color holographic display with white light LED source and single phase only SLM.

This work presents color holographic display, which is based on a single phase only spatial light modulator (SLM). In the display entire area of the SLM is illuminated by an on-axis white light beam generated by a single large LED. The holographic display fully utilizes SLM bandwidth and has capability of full-color, full frame rate imaging of outstanding quality.