The extension of supercontinuum (SC) sources into the mid-infrared, via the use of uoride and chalcogenide optical fibers, potentially offers the high radiance of a laser combined with spectral coverage far exceeding that of typical tunable lasers and comparable to traditional black-body emitters. Together with advances in mid-IR imaging detectors and novel tunable filter designs, such supercontinua hold considerable potential as sources of illumination for spectrally-resolved microscopy targeting applications such as rapid histological screening. The ability to rapidly and arbitrarily select particular wavelengths of interest from a broad emission spectrum, covering a wide range of biologically relevant targets, lends itself to image acquisition only at key relevant wavelengths leading to more manageable datasets. However, in addition to offering new imaging modalities, SC sources also present a range of challenges to successful integration with typical spectral microscopy instrumentation, including appropriate utilisation of their high spatial coherence. In this paper the application of SC sources to spectrally-resolved microscopy in the mid-IR is discussed and systems-integration considerations specific to these sources highlighted. Preliminary results in the 3-5μm region, obtained within the European FP7 project MINERVA, are also presented here.

We report on an experimental demonstration of mid-infrared cascaded supercontinuum generation in commercial silica, fluoride, and chalcogenide fibers as a potentially cheap and practical alternative to direct pumping schemes. A pump continuum up to 4.4 μm was generated in cascaded silica and fluoride fibers by an amplified 1.55 μm nanosecond diode laser. By pumping a commercial Ge10As22Se68 single-material photonic crystal fiber with 135.7 mW of the pump continuum from 3.5- 4.4 μm, we obtained a continuum up to 7.2 μm with a total output power after the collimating lens of 54.5 mW, and 3.7 mW above 4.5 μm.

We are establishing a new paradigm in mid-infrared molecular sensing, mapping and imaging to open up the midinfrared spectral region for in vivo (i.e. in person) medical diagnostics and surgery. Thus, we are working towards the mid-infrared optical biopsy (‘opsy’ look at, bio the biology) in situ in the body for real-time diagnosis. This new paradigm will be enabled through focused development of devices and systems which are robust, functionally designed, safe, compact and cost effective and are based on active and passive mid-infrared optical fibers. In particular, this will enable early diagnosis of external cancers, mid-infrared detection of cancer-margins during external surgery for precise removal of diseased tissue, in one go during the surgery, and mid-infrared endoscopy for early diagnosis of internal cancers and their precision removal. The mid-infrared spectral region has previously lacked portable, bright sources. We set a record in demonstrating extreme broad-band supercontinuum generated light 1.4 to 13.3 microns in a specially engineered, high numerical aperture mid-infrared optical fiber. The active mid-infrared fiber broadband supercontinuum for the first time offers the possibility of a bright mid-infrared wideband source in a portable package as a first step for medical fiber-based systems operating in the mid-infrared. Moreover, mid-infrared molecular mapping and imaging is potentially a disruptive technology to give improved monitoring of the environment, energy efficiency, security, agriculture and in manufacturing and chemical processing. This work is in part supported by the European Commission: Framework Seven (FP7) Large-Scale Integrated Project MINERVA: MId-to-NEaR- infrared spectroscopy for improVed medical diAgnostics (317803; www.minerva-project.eu).

Supercontinuum generation in chalcogenide fibers is a promising technology for broadband spatially coherent sources in the mid-infrared, but it suffers from discouraging commercial prospects, mainly due to a lack of suitable pump lasers.Here, a promising approach is experimentally demonstrated using an amplified 1.55 μm diode laser to generate a pump continuum up to 4.4 μm in cascaded silica and fluoride fibers.We present experimental evidence and numerical simulations confirming that the spectral-temporal composition of the pump continuum is critical for continued broadening in a chalcogenide fiber.The fundamental physical question is concerned with the long-wavelength components of the pump spectrum, which may consist of either solitons or dispersive waves.In demonstrating this we present a commercially viable fiber-cascading configuration to generate a mid-infrared supercontinuum up to 7 μm in commercial chalcogenide fibers.

I report work on mid-infrared super-continuum generation in chalcogenide fibers and waveguides pumped by 320fsec pulses at 21MHz in the 3-4.6µm range. Average powers of ≈20mW were produced with spectral coverage from <2µm to >11µm.

A more than two-octave mid-infrared supercontinuum with an average output power of 15.6 mW covering 1.7-7.5 μm (1,333-5,900 cm-1) is generated in a low-loss As38Se62 suspended core fiber with core diameter of 4.5 μm.

A low-loss suspended core As 38 Se 62 fiber with core diameter of 4.5 μm and a zero-dispersion wavelength of 3.5 μm was used for mid-infrared supercontinuum generation.The dispersion of the fiber was measured from 2.9 to 4.2 μm and was in good correspondence with the calculated dispersion.An optical parametric amplifier delivering 320 fs pulses with a peak power of 14.8 kW at a repetition rate of 21 MHz was used to pump 18 cm of suspended core fiber at different wavelengths from 3.3 to 4.7 μm.By pumping at 4.4 μm with a peak power of 5.2 kW coupled to the fiber a supercontinuum spanning from 1.7 to 7.5 μm with an average output power of 15.6 mW and an average power >5.0 μm of 4.7 mW was obtained.

We propose an all-optical switch constructed from a two-mode optical resonator containing a strongly coupled, three-level system [1]. The coupling allows a weak, continuous wave laser drive to incoherently control the transmission of a much stronger, continuous wave signal laser into and through the resonator. The switch operates at low energies, and such optical devices provide an interesting alternative to silicon logic. We also consider an approach to measure the parity of two qubits located in separate cavities, and we demonstrate how coherent feedback can be used to conditionally decrease the total photon loss and decoherence during the measurement [2]. the a Transient absorption reveal on a Using scattering the dynamics of studied. This study We study a possible gene silencing assay with miRNA coated gold nanoparticles. The loading of the miRNA is characterizedin vitro according to nanoparticle size, as is the controlled laser-induced release due to localized heating. In cells, the laser induced heating also allows us to control the release of the gold nanoparticles and miRNA from the endosomes into the cytoplasm. A luciferase reporter plasmid will allows us to verify the intact miRNA in the cytoplasm. We present a comprehensive analysis of salt transport in microchannels during concentration polarization. We have carried out full numerical simulations of the coupled Poisson–Nernst–Planck–Stokes problem governing the transport and rationalized the behaviour of the system. A surprising discovery is that bulk advection relies heavily on the surface currents, even when these surface currents do not contribute much to the overlimiting current themselves. The numerical simulations are supplemented by analytical results valid in the long channel limit as well as in the limit of negligible surface charge. Notably, by including the effects of diffusion and advection in the diffuse double layers we extend a recently published analytical model of overlimiting current due to surface conduction. A Spin-Echo Modulated Small Angle Neutron Scattering (SEMSANS) instrument in a time-of-flight (TOF) mode has been investigated by comparing experimental data from a TOF SEMSANS set-up, where a spatial beam modulation of a white beam is obtained using triangular field coils, with Monte Carlo ray tracing simulations.Our experiments and simulations in accordance demonstrate that a good contrast can be achieved, using a constant field in the triangular coils. In our set-up only neutrons with certain wavelengths rotate by a Larmor precession angle that spatially modulates their polarisation to be coinciding with the period of a grating installed at the detector position. This is shown by measuring with a broad wavelength range while scanning the echo condition.The demonstrated SEMSANS technique can e.g. be used for investigating structures in the nano- to micrometer range without having to worry about depolarisation caused by sample and/or sample environment, and will be able to excel at pulsed neutron sources such as the European Spallation Source (ESS) currently under construction. Integration of nanostructures in organic solar cells (OSCs) has been investigated intensively in the past few years as an alternative way for enhancing the power conversion efficiency of the devices. Incorporating structured electrodes in the solar cell architecture holds potential for light absorption improvement in the active layer of the devices. A prospective, cheap and large-scale compatible method for structuring the electrodes in OSCs arises by the use of anodic aluminum oxide (AAO) membranes.In the present work, aluminum films of high purity and low roughness are formed via e-beam evaporation of a few nanometers of aluminum followed by a micrometer layer of aluminum formed via sputter deposition. The samples are then anodized to form nano-scale pores of controlled sizes. The anodization of the prepared samples occurs in an electrochemical cell in H2SO4, H2C2O4 and H3PO4 solutions. Electrolyte solution variation and anodization parameters (sample temperature, voltage) control, allows for AAO pore diameter and interpore distance tuning. The fabricated AAO is selectively etched in H2CrO4/H3PO4 mixtures, in order to reveal the underlying aluminum nanoscale dimples, which are present at the bottom of the pores.For the characterization of their light-trapping properties, the dimples are covered with a thin layer of PMMA, and the impact from different dimple dimensions is investigated experimentally via laser ablation based measurements of the field enhancement, which is compared to FDTD calculations to further explain the mechanisms of light-trapping in these structures. These dimples can potentially serve as nanostructured electrodes in P3HT/PCBM bulk heterojunction organic solar cells. Measurements of laser induced Solid-Solid Phase Transitions in Cobalt Nanoparticles, usingTime-Resolved X-ray Scattering. Further, the necessary software to simulate the scattering signal forphase transitions and lattice expansions in the nanoparticles was made and used to analyze the obtained data Organic CNHP4 nanofibers showing a strong second-harmonic (SH) response have been successfully implemented as active components in a metal-organic hybrid system. Using nondestructive roll-on transfer technique nanofibers were transferred from the growing mica substrates onto electron-beam lithography-defined regular arrays of gold, titanium and silicon oxide. As shown in a femtosecond laser scanning microscopy study the fiber-substrate interplay leads (only) on gold to a significantly enhanced SH signal. We suggest that this effect is driven by the local field enhancement i.e. the excitation of surface plasmon polaritons (SPP) and lightning rod effects, since in case of Ti and SiO2 no SPPs are excited at a laser wavelength of 790 nm and the used array dimensions. Furthermore, we observe a considerably reduced fluorescence lifetime for the fibers deposited on gold arrays supporting the assumption of strong interaction between gold substrate and fibers. In summary we show that by adjusting substrate and fiber properties the SH response can be locally controlled. For silicon thin-film solar cells, the question of enhancing the photon capture within the absorption layer is crucial because thickness reduction without sacrificing too much efficiency is the trend followed for developing low-cost solar cells for the future. In the THINC project, we focus on the development of nanostructured backside reflectors (BSRs). Anodic aluminum oxidation (AAO) is used for fabricating nanostructures on aluminum surfaces for enhancing the optical absorption in thin-film silicon solar cells. In this report, three different BSR samples with various pore sizes of 320 nm, 430 nm and 700 nm are fabricated and investigated experimentally and theoretically. The results show that a 430 nm pore size with a 200 nm silicon coating is the best choice for actual cell production. The radioactive isotope 22 Na, a product of explosive hydrogen burning in novae, emits a characteristic gamma ray which carries important clues about nucleosynthesis in novae. Precise calculation of the expected gamma-ray flux requires precise knowledge of the rates of the nuclear reactions that create and destroy 22 Na. Unfortunately, one of the most important rates, namely, that of radiative proton capture on 22 Na, is uncertain by a factor of 2-3. In an attempt to reduce this uncertainty, we have measured the lifetime of a resonance in the compound nucleus, 23 Mg, that is known to dominate the rate. In my contribution I will describe the experiment and present preliminary results. We are working on investigation of novel micro-lasers with a diffraction-limited small modal volume. These laser structures consist of high-index-contrast gratings and aim for an emission to an in-plane waveguide which will be very important for future optical interconnects. For these structures, high-speed direct modulation and very low energy consumption are expected due to their small modal volume. Our group research on these laser structures involves theoretical/numerical investigation, device fabrication, and characterization. My project will cover mostly theoretical/numerical investigation part. In this part, an advanced optical simulator is developed based on Fourier modal method (FMM) which can solve Maxwell equations in 3D vectorial manner. Also rate equations are solved spatially and temporally and are integrated with the optical solver to make a comprehnsive laser simulator. Using the laser simulator, physics of the micro-lasers with a diffraction-limited optical cavity are investigated. with with stoichiometry: . The films SLG X-ray diffraction patterns show of CZTS of then phases start to and the associated to kesterite drops down in used to investigate – Cubic-phase Cu 2 SnS 3 is both a secondary phase of Cu 2 ZnSnS 4 and a potential solar cell absorber in its own right. Using pulsed laser deposition, thin films of copper tin sulfide were deposited from a targetenriched with Sn and S relative to the stoichiometry of Cu 2 SnS 3 . During deposition and annealing, Sn and S were lost from the film. Annealing with S powder resulted in films close to the desired Cu 2 SnS 3 stoichiometry, although the films remained Sn rich. X-ray diffraction showed that the final films contained both cubic-phase Cu 2 SnS 3 and orthorhombic-phase SnS. get components which could be well suited without too many optical problems such as aberrations or dispersion. Spurred by possible applications of nonclassical light in metrology, communication, microscopy, and interferometry we developed a new source of bright squeezed vacuum radiation with tunable properties in spatial and frequency domain. Using two-crystal configuration of the traveling-wave optical parametric amplifier operating at the high-gain regime we demonstrate a reduction of the number of transverse modes down to 1.1. with the distance between

Supercontinuum generation covering an ultra-broad spectrum from 1.5-11.7μm and 1.4-13.3μm is experimentally demonstrated by pumping an 85mm chalcogenide step-index fiber with 100fs pulses at a wavelength of 4.5μm and 6.3μm, respectively.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text U. Møller, Y. Yu, C. R. Petersen, I. Kubat, L. Brilland, D. Méchin, J. Troles, B. Luther-Davies, and O. Bang, "High Average Power Mid-infrared Supercontinuum Generation in a Suspended Core Chalcogenide Fiber," in Advanced Photonics, (Optica Publishing Group, 2014), paper JM5A.54. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

(10/03/2019) Supercontinuum based mid-IR imaging spectroscopy for cancer detection The mid-infrared (IR) spectral region is of significant technical and scientific interest because most molecules display fundamental vibrational absorptions in this region, leaving distinct spectral fingerprints. To date, the limitations of mid-IR light sources, such as thermal emitters, low-power laser diodes, quantum cascade lasers and synchrotron radiation, have precluded mid-IR applications where the spatial coherence, broad bandwidth, high brightness and portability of a supercontinuum laser are all required. In an international collaboration in the EU project MINERVA [minerva-project.eu] DTU Fotonik has now demonstrated the first optical fiber based broadband so-called supercontinuum light souce, which covers 1.4-13.3 μm and thereby most of the molecular fingerprint region [1]. This ultra-fast light source is the basic component in the mid-IR camera developed in MINERVA for early cancer detection with mid-IR imaging spectroscopy.

Mid-infrared supercontinuum generation with a record-breaking spectral coverage of 1.4–13.3 µm is demonstrated by launching intense ultra-short pulses into short pieces of ultra-high numerical aperture step-index chalcogenide glass optical fibre consisting of a GaAsSe cladding and an As 2 Se 3 core.

We theoretically demonstrate a novel approach for generating Mid-InfraRed SuperContinuum (MIR SC) by using concatenated fluoride and chalcogenide glass fibers pumped with a standard pulsed Thulium (Tm) laser (T(FWHM)=3.5ps, P0=20kW, ν(R)=30MHz, and P(avg)=2W). The fluoride fiber SC is generated in 10m of ZBLAN spanning the 0.9-4.1μm SC at the -30dB level. The ZBLAN fiber SC is then coupled into 10cm of As2Se3 chalcogenide Microstructured Optical Fiber (MOF) designed to have a zero-dispersion wavelength (λ(ZDW)) significantly below the 4.1μm InfraRed (IR) edge of the ZBLAN fiber SC, here 3.55μm. This allows the MIR solitons in the ZBLAN fiber SC to couple into anomalous dispersion in the chalcogenide fiber and further redshift out to the fiber loss edge at around 9μm. The final 0.9-9μm SC covers over 3 octaves in the MIR with around 15mW of power converted into the 6-9μm range.

Supercontinuum is generated in concatenated ZBLAN and As2Se3 fibers. Initially, a 0.9-4.1mm supercontinuum is obtained by pumping the ZBLAN fiber with a Tm laser, which then continues to broaden to 0.9-9um in As2Se3 fiber.

. The advent of photonic crystal fibers (PCFs) has paved the road for commercial high-power supercontinuum light sources. The air-hole structuring in the PCF manipulates the properties of light and gives a tremendous degree of design freedom, which has enabled pushing the properties of PCFs to limits that can never be achieved with standard step index fibers. For example, one can move the zero dispersion wavelength (ZDW) into the visible [1] and make them endlessly single moded [2]. For efficient supercontinuum generation it is of great importance that the pump wavelength is close to the ZDW. We demonstrate how the spectral blue-edge can be manipulated by careful fiber design and tapering of the PCF enabling supercontinuum generation spanning all the way from 380 nm to 2.4 µ m [3]. We discuss the limiting factors of the supercontinuum bandwidth. Furthermore, we discuss how the fiber tapering influences the intensity noise of the supercontinuum source [4]. show generation in ZBLAN fibers covering 1.5-4.5 µ m [5] and supercontinuum generation in microstructured chalcogenide fibers out to 9 µ m. We discuss the prospects for extending the supercontinuum generation beyond 10 µ m and highlight useful applications such as cancer detection and food analysis. [1] J.K. Opt. Lett. 25 , 25 (2000). [2] T.A. Opt. Lett. 22 , 961 (1997). [3] U. Møller Opt. Fiber Technol. 18 , 304 (2012). [4] U. Møller et al., Opt. Express 20 , 2851 (2012). [5] P.M. Moselund et al., Proc. SPIE 8381 , 83811A (2012).

We present numerical modeling of mid-infrared (MIR) supercontinuum generation (SCG) in dispersion-optimized chalcogenide (CHALC) step-index fibres (SIFs) with exceptionally high numerical aperture (NA) around one, pumped with mode-locked praseodymium-doped (Pr(3+)) chalcogenide fibre lasers. The 4.5um laser is assumed to have a repetition rate of 4MHz with 50ps long pulses having a peak power of 4.7kW. A thorough fibre design optimisation was conducted using measured material dispersion (As-Se/Ge-As-Se) and measured fibre loss obtained in fabricated fibre of the same materials. The loss was below 2.5dB/m in the 3.3-9.4μm region. Fibres with 8 and 10μm core diameters generated an SC out to 12.5 and 10.7μm in less than 2m of fibre when pumped with 0.75 and 1kW, respectively. Larger core fibres with 20μm core diameters for potential higher power handling generated an SC out to 10.6μm for the highest NA considered but required pumping at 4.7kW as well as up to 3m of fibre to compensate for the lower nonlinearities. The amount of power converted into the 8-10μm band was 7.5 and 8.8mW for the 8 and 10μm fibres, respectively. For the 20μm core fibres up to 46mW was converted.

The relative intensity noise (RIN) properties at different wavelengths and power levels for picosecond supercontinuum (SC) generated by pumping a PCF in its normal dispersion regime is investigated. For low power levels the all-normal SC is generated while the generated SC extends beyond the zero dispersion wavelength (ZDW) at high power levels. The RIN measurements are compared with a red-edge matched SC generated in a highly nonlinear PCF pumped in the anomalous dispersion regime close to its ZDW.

Summary form only given. The shot-to-shot stability of a supercontiuum (SC) can be controlled both in terms of coherence and intensity stability by modulating the input pulse with a weak seed [1-3]. In the long-pulse regime, the SC generation is initiated by noise-seeded modulation instability (MI), which breaks the pump into solitons and dispersive waves. To control the spectral evolution and reduce the noise, it has been proposed to provide a seed, i.e. a weak pulse with a frequency offset relative to the pump, within the MI gain spectrum in order to ensure a deterministic rather than noise-seeded pulse break-up [1, 2]. Seeding the pulse break-up has likewise been used to control the generation of otherwise statistically rare large-amplitude rogue solitons [2-4]. In this work, we numerically investigate the influence of the MI gain spectrum on the pulse break-up and rogue wave generation. We find that the results can be clearly divided into a number of distinct dynamical regimes depending on the initial four-wave mixing process and demonstrate that seeding can be used to generate coherent and incoherent rogue waves.Figure 1 shows simulation results of seeded SC generation in a fiber with a zero-dispersion wavelength (ZDW) at 1054 nm for pump wavelengths of 1055 and 1075 nm, respectively. The MI gain spectrum depends strongly on the pump wavelength and the MI gain bandwidth decreases when the pump is moved away from the ZDW, as seen in the insets in Fig. 1. The seed causes a beating of the temporal profile, which, if chosen correctly, leads to a deterministic pulse break-up. When the pump is close to the ZDW [Fig. 1(a)], the MI gain is relatively small at the seed wavelength (1070.1 nm) and slowly increasing with wavelength. The temporal profile is therefore only slowly broken up into solitons. This means that the solitons are mainly generated from the pulse center where the peak power is highest. The solitons have time to redshift before the cascade is amplified - nd the dynamics are relatively turbulent. In contrast to this, pumping further from the ZDW [Fig. 1(b)] gives a much larger gain at the seed wavelength (1090.6 nm) that increases more rapidly with wavelength. This causes a fast breakup of the temporal pulse, where the individual temporal fringes generate fundamental solitons in a controlled fashion that almost resembles soliton fission. The most powerful solitons are still generated near the center of the pulse where the power is highest. These powerful rogue solitons only collide with the smaller solitons generated from the trailing edge of the pulse. Interestingly, a closer inspection reveals that the rogue soliton is generated incoherently when pumping close to the ZDW, but coherently when the pump is shifted away from the ZDW.At the conference we will discuss the influence of the MI gain spectrum in more detail and demonstrate that the coherent pulse break-up afforded by seeding is washed out by turbulent solitonic dynamics when the pump peak power is increased to the kW level.

Fiber-optic Cherenkov radiation (CR), also known as dispersive wave generation or non-solitonic radiation, is produced in small-core photonic crystal fibers (PCF) when a soliton perturbed by fiber higher-order dispersion co-propagates with a dispersive wave fulfilling a certain phase-matching condition. The resonant ultrafast wave conversion via the fiber-optic CR mechanism is instrumental for applications in biophotonics such as bio-imaging and microscopy. In this work, we demonstrate a highly-stable all-fiber, fully monolithic CR system based on an Yb-fiber femtosecond laser, producing electrically tunable femtosecond CR output in the visible (VIS) spectral range of 580-630 nm, with the 3 dB spectral bandwidth not exceeding 36 nm, with average power in the milliwatt range. Relative intensity noise (RIN) of this laser, affecting the sensitivity of bio-imaging and microscopy systems, is found to be as low as -103 dBc/Hz. This is 2 orders of magnitudes lower noise as compared to spectrally-sliced supercontinuum, which is the current standard of ultrafast fiber-optic generation at visible wavelength.