Images 2017

Best image

"The correlations of a Swedish chessboard", Robert Lindberg, APhys/Laserfysik

The correlations of a Swedish chessboard: This funky looking figure shows the correlation map, generated from about 27000 consecutive pulse spectra that were recorded using a dispersive Fourier transform setup, of a mode-locked fiber laser operated in the soliton regime. This map visualizes the linear correlation between different wavelengths along the x- and y-axis, whose scales have been removed for aesthetical reasons, with stronger colors indicating a higher degree of correlation, yellow, or anti-correlation, blue, and black indicating the lack of linear correlation. The yellow parts thus correspond to wavelength regions which increase or decrease in intensity simultaneously, for example the main diagonal which corresponds to the same wavelengths along the x- and y-axis. On the contrary, blue parts indicate spectral regions that counteract each other such that if one region’s intensity increases, the other region’s decreases. Based on these simple principles, it can be seen that the middle-most checker pattern corresponds to wavelengths on the same side of the central wavelength increasing or decreasing in intensity together, whereas wavelengths on opposite sides don’t. This is indicative of a fluctuating central wavelength. Similarly, the checker patterns along the main diagonal adjacent to the middle-most one correspond to fluctuating positions of the soliton’s sidebands. The off diagonal checker patterns show how the sidebands fluctuate relative to the soliton, as well as how the sidebands fluctuate relative to each other. ( original image (jpg 479 kB) )

Prize: SuperPresentkortet worth 2500 kr

Submissions

Voting statistics: 1(10 votes), 2(0), 3(4), 4(7), 5(2), 6(6), 7(2), 8(8), 9(1), 10(14) (Thanks to Federico!)

Surprise prize: Each contestant is awarded with a mug printed with their submitted photo, worth priceless (Thanks to Miao!).

1. Bridging the gap

"Bridging the Gap", Julien Zichi, APhys/QNP

Bridging the gap: The SEM image shows a Niobium Titanium Nitride (NbTiN) superconducting nano-bridge, dry etched and released from its substrate by a Hydrofluoric acid bath and subsequent critical point drying. Should you be a one of the electrons from a Cooper pair, walking pass this bridge (without any resistance), you would be standing on an 8 nm thick, 200 nm wide and 2.5 µm long free-standing plank. But beware of any rain, as the smallest drop touching this bridge would instantly make it collapse due to capillary forces. Scientifically speaking, this structure is interesting as it visually highlights the intrinsic compressive stress present in the original NbTiN film and superconducting single photon detector, and it will be further studied to reveal the hotspot relaxation dynamics of a structure without phonon de-excitation through the substrate. The image was taken with the FEI Nova SEM of the Albanova Nanofabrication laboratory at 50 000 X magnification, 10 kV acceleration voltage, with a 45˚ tilt and through lens imaging. Mild post-processing was applied, such as brightness/contrast adjustment and noise reduction. ( original image (jpg 421 kB) )

2. Doctoral ladder in infrared

Doctoral ladder in infrared, M. Yan and friends, APhys/OFO

Doctoral ladder in infrared: Three PhD candidates at KTH imaged with an infrared camera. The color scale should be temperature ranging from 24 to 37 degrees, but here “tweaked” to represent KTH’s doctoral ladder (doktorandstegen). The readiness of a PhD student is manifested by their head colors. Indeed, the candidate on the right defends his thesis on 2017-Sept-29. Tools used include a FLIR T420 camera, and two towels soaked in cold or warm water. ( original image (jpg 362 kB) )

3. Diffaction fire

"Diffraction fire", Elena Vasileva, APhys/OFO

Diffraction fire: It is the photo of the black screen taken with the mobile phone, where you can see the diffraction of He-Ne laser beam on the tip of the transparent wood fiber. The image is original and it is not modified in any software (only cropped). The structure of TW fiber is mesoporous, so laser beam diffraction on the fiber tip creates a unique complicated interference pattern. ( original image (jpg 1.2 MB) )

4. The smallest Stockholm University logo?

"The smallest Stockholm University Logo?", Adem Ergul, SU/KIKO

The smallest Stockholm University logo?: Inspired by the Andy Warhol's Marilyn Monroe series we have created the micro-meter size Stockholm University logos with varying physical properties. These test structures were fabricated by the Raith-EBL system with the dot exposure mode and using 200 nm thick layer of positive e-beam resist AR-P 6200 on silicon wafers. Main goal of these tests were the find out the limitations of various exposure modes, such as, area , line and dot exposures. We are developing Supercondcuting Nanowire detectors for Quantum Optics applications. At the left hand-side we see the Optical Microscope images of various samples with different exposure doses. While on the right hand-side we see a SEM image of the Niobium SU logo. Image is taken by the FEI-FIB system located at the KTH’s Nanofabrication lab in Albanova.This is probably the smallest Stockholm University logo ever made. ( original image (png 979 kB) )

5. Photonic finger

"Photonic finger", Dennis Visser, APhys/HMA

Photonic finger: This image is obtained using a Scanning Electron Microscope (Zeiss Ultra 55) equipped with an Inlens detector (EHT=3 kV, WD=4.4 mm and Mag=71,860x). No post-processing has been done. The image shows a hydrothermally grown zinc oxide (ZnO) flower-like structure grown from a sol-gel ZnO seedlayer, deposited on a Silicon. (Si) substrate surface. This ZnO ‘flower’ consists of ZnO nanowires (‘photonic fingers’) grown from the grains of the seedlayer and having a single crystalline hexagonal crystal structure. The (temperature depended) grain size of the seedlayer determines the diameter of the nanowires and the growth time determines its length. In the image the signature of the plane-by-plane growth of the ZnO nanowire can be observed. ZnO is a wide bandgap (~3.37 eV at RT) semiconductor of the II-VI group, which predominantly crystallizes in the Wurtzite crystal structure. Some interesting features are its high transparency in the visible-NIR spectrum and biocompatibility. Bulk ZnO has a refractive index of n≈1.9-2.2 in the NIR-visible wavelength range, which makes it a perfect candidate for anti-reflection purposes on Si-based devices. Surface reflections as low as 0-5% can be obtained in the visible-NIR spectral range, due to its light manipulation functions (anti-reflection, guiding and trapping), when structuring the ZnO seedlayer and additionally growing the ZnO flower-like structures on it. This type of structured transparent surface coating shows high potential for applications in, e.g., the field of optoelectronics. ( original image (jpg 75 kB) )

6. Finding exosomes

"Finding exosomes", Miao Zhang, APhys/Nano-Si

Finding exosomes: Exosomes are small membrane vesicles that are secreted by most cells in eukaryotic fluids, including blood, urine and cell cultures. They were not recognized until 30 years ago and are implicated in cell-cell communication and the transmission of disease states (for example, lung cancer). The size of exosomes is typically in the range of 30 – 100 nm. Here, we try to find the exosomes among many different extracellular vesicles that are obtained from a human blood sample by direct look using SEM. The specimen is cross-linked and slightly coated with carbon before SEM imaging. The image is post-colorized. ( original image (png 934 kB) )

7. KTH acronym on SiGe nanowire

"KTH acronym on SiGe nanowire", Bejan Hamawandi, APhys/Bio-X

KTH acyonym on SiGe nanowire: Acronym for our school "KTH" written on to the silicon substrate by the Ion bombardment. Sunset of the Ion-Star in the land of Silicon. Heavy ions are bombarded the sample with 15 degrees with the surface. The etch time was slightly longer than required duration in order to create a hole on the wall. An elongated shadow of the text "KTH" is created on the substrate. This phenomena similar to the creation of the elongated shadows during sunset. KTH is written on to the wall of the nanowire by ion bombardment. The thickness of the nano-bridge is 130nm while the width is 200nm. Total length of this nano-bridge is only 7 micro meter. ( original image (png 734 kB) )

8. Domains

"Domains", Cristine Calil Kores, APhys/Laserfysik

Domains: Ferroelectric crystals are a group of polar, non-centrosymmetric materials that present a spontaneous electrical polarization that can be switched between stable states, and this is usually done by applying an electric field with sufficient magnitude across the material. Doing so in a controlled fashion allows the engineering of the polarization direction in the crystal, which can be explored for quasi phase-matching and thus generation of new wavelengths, representing one of many applications of these materials. Changes of temperature, the application of stress or electric field induces a charge separation in the unit cells of the crystal, which is the mechanism underlying the change in their surface polarization. The regions of the material in which several unit cells are oriented with the same dipole moment are called domains, and its shape and orientation are related to the crystallographic structure and to the switching dynamics. The converse piezoelectric effect is responsible for the appearance of mechanical strain when the domains are formed, which also leads to the appearance of birefringence in these materials. The image shows part of a Lithium niobate crystal that has undergone rapid temperature shock, and the temperature caused the formation of micro domains. The image was obtained by means of a transmission microscope with cross linear polarizers, which allowed the visualization of changes in the refractive index of the material, thus revealing the domains. ( original image (png 1.2 MB) )

9. Red-glowing nanocrystal-creature

"Red-glowing nanocrystal creature", Federico Pevere, APhys/Nano-Si

Red-glowing nanocrystal-creature: Thanks to the quantum confinement effect, silicon nanocrystals (Si-NCs) of sizes less than ~10 nm (exciton Bohr diameter) can exhibit efficient photoluminescence (PL), in contrast with bulk Si. Such nanocrystals embedded in SiO2 can be fabricated by our group using standard Si processing technology. Here you can see two PL images taken from the same sample area under UV excitation. The image on the left was taken using an electrically cooled EMCCD camera (intensity only), whereas the one on the right was acquired by a standard colored CCD camera (real colors). Many Si-NCs can be resolved in both images and form a “red-glowing nanocrystal-creature”. In addition, weak PL emission from SiO2 is visible above the NC-creature, while no emission can be seen from the thick Si below. Although not shown by PL images but movies instead, some of these NCs randomly switch between ON (bright) and OFF (dark) states over time, thus animating our little creature. Image processing included cropping, hot pixel removal and brightness/contrast adjustment. Real colors were not altered. ( original image (jpg 345 kB) )

10. The correlations of a Swedish chessboard

"The correlations of a Swedish chessboard", Robert Lindberg, APhys/Laserfysik

The correlations of a Swedish chessboard: This funky looking figure shows the correlation map, generated from about 27000 consecutive pulse spectra that were recorded using a dispersive Fourier transform setup, of a mode-locked fiber laser operated in the soliton regime. This map visualizes the linear correlation between different wavelengths along the x- and y-axis, whose scales have been removed for aesthetical reasons, with stronger colors indicating a higher degree of correlation, yellow, or anti-correlation, blue, and black indicating the lack of linear correlation. The yellow parts thus correspond to wavelength regions which increase or decrease in intensity simultaneously, for example the main diagonal which corresponds to the same wavelengths along the x- and y-axis. On the contrary, blue parts indicate spectral regions that counteract each other such that if one region’s intensity increases, the other region’s decreases. Based on these simple principles, it can be seen that the middle-most checker pattern corresponds to wavelengths on the same side of the central wavelength increasing or decreasing in intensity together, whereas wavelengths on opposite sides don’t. This is indicative of a fluctuating central wavelength. Similarly, the checker patterns along the main diagonal adjacent to the middle-most one correspond to fluctuating positions of the soliton’s sidebands. The off diagonal checker patterns show how the sidebands fluctuate relative to the soliton, as well as how the sidebands fluctuate relative to each other. ( original image (jpg 479 kB) )

Page responsible:Max Yan
Belongs to: School of Engineering Sciences (SCI)
Last changed: Oct 24, 2017