ABSTRACT
In every criminal inquiry, identification is of utmost importance. Cheiloscopy is a technique used in forensic investigation that focuses on identifying people from their lip prints. Just like fingerprints, each person's lip crease pattern is unique. Moreover, Lip prints are seen to remain consistent throughout an individual's life. Lip prints can therefore be used to confirm if a person was at the crime scene or not. Cheiloscopy is used to examine the sulci labiorum, or "lip prints," which are the wrinkling and furrows on the labial mucosa that produce a distinctive pattern. The current review article focuses on the potential of cheiloscopy as a vital role player in the process of criminal investigation by detecting and identifying individual(s).
Subject(s)
Mouth Mucosa , HumansABSTRACT
The ultrafast laser inscription technique has been used to fabricate channel waveguides in Tm3+-doped Lu2O3 ceramic gain medium for the first time to our knowledge. Laser operation has been demonstrated using a monolithic microchip cavity with a continuous-wave Ti:sapphire pump source at 796 nm. The maximum output power achieved from the Tm:Lu2O3 waveguide laser was 81 mW at 1942 nm. A maximum slope efficiency of 9.5% was measured with the laser thresholds observed to be in the range of 50-200 mW of absorbed pump power. Propagation losses for this waveguide structure are calculated to be 0.7 dBâ cm-1 ± 0.3 dBâ cm-1 at the lasing wavelength.
ABSTRACT
Flow effects on the thermal loading in different optofluidic systems (optical trap and various microfluidic channels) have been systematically explored by using dye-based ratiometric luminescence thermometry. Thermal images obtained by fluorescence microscopy demonstrate that the flow rate plays a key role in determining both the magnitude of the laser-induced temperature increment and its spatial distribution. Numerical simulations were performed in the case of the optical trap. A good agreement between the experimental results and those predicted by mathematical modelling was observed. It has also been found that the dynamics of thermal loading is strongly influenced by the presence of fluid flow.
ABSTRACT
Laser slope efficiencies close to the quantum defect limit and in excess of 78% have been obtained from an ultrafast laser inscribed buried channel waveguide fabricated in a ytterbium-doped bismuthate glass. The simultaneous achievement of low propagation losses and preservation of the fluorescence properties of ytterbium ions is the basis of the outstanding laser performance.
ABSTRACT
A novel technique was used to control the spatial overlap of the orthogonal linearly polarized waveguide modes in ultrafast laser inscribed BiB(3)O(6) waveguides. We report that the strain fields induced by the expansion of material in the laser focus can be considered independently in the design of "type II" waveguides guiding orthogonal linearly polarized light. The waveguide with the optimal mode overlap was used for type I birefringently phase-matched second-harmonic generation of a continuous wave laser source at 1047 nm.
ABSTRACT
A new (to our knowledge) ultrashort laser pulse irradiation regime that allows us to directly modify and increase the refractive index of rare earth doped YAG polycrystalline ceramics has been identified. Single-mode buried channel waveguides in both Ho:YAG and Er:YAG ceramics at the near-IR wavelengths of 1.55 µm and 1.95 µm are demonstrated by fabricating positive square step-index cores. Minimum propagation losses of 1.5 dB cm(-1) at a 1.51 µm wavelength have been preliminarily obtained. Confocal microluminescence mapping reveals that the increased refractive index regions retain the near-IR spectral properties of Er3+ ions in the YAG crystalline matrix.
ABSTRACT
We report optical guiding and laser action at around 1.9 µm in a Tm³âº-doped fluorogermanate glass waveguide fabricated using ultrafast laser inscription. A monolithic laser cavity was constructed by directly butt coupling dielectric mirrors to each facet of the 6.0 mm long Tm³âº-doped waveguide. When the waveguide was pumped by a Ti:sapphire laser tuned to 791 nm, laser oscillation was achieved at around 1.91 µm. This waveguide laser exhibited a maximum slope efficiency of 6% and a maximum output power of 32 mW when pumped with 620 mW of incident laser power.
ABSTRACT
We used ultrafast laser inscription to fabricate three-dimensional integrated optical transitions that efficiently couple light from a multimode waveguide to a two-dimensional array of single mode waveguides and back. Although the entire device has an average insertion loss of 5.7 dB at 1539 nm, only ≈0.7 dB is due to mode coupling losses. Based on an analysis which is presented in the paper, we expect that our device should convert a multimode input into an array of single modes with a loss of ≈2.0 dB, assuming the input coupling losses are zero. Such devices have applications in astrophotonics and remote sensing.
ABSTRACT
We report on the microstructuring of Nd:YAG crystals by direct proton-beam writing. Buried channel waveguides have been fabricated with full spatial control by the combined variation of crystal position and proton energy. The fluorescence images of the obtained structures have been used to evaluate the potential application of the fabricated structures for laser gain as well as to elucidate the mechanism at the basis of the refractive index increment induced at the end of the proton path. We have concluded that this increment is very likely a local enhancement in the electronic polarizability caused by nuclear collisions.
ABSTRACT
We report the successful fabrication of a low-loss near-IR waveguide in polycrystalline ZnSe using ultrafast laser inscription. The waveguide, which was inscribed using the multiscan fabrication technique, supported a well-confined mode at 1.55 µm. Propagation losses were characterized at 1.55 µm using the Fabry-Perot technique and found to be 1.07 dB · cm(-1) ± 0.03 dB · cm(-1).
Subject(s)
Anaphylaxis/chemically induced , Antimalarials/adverse effects , Artemisinins/adverse effects , Drug Hypersensitivity/etiology , Malaria, Falciparum/drug therapy , Adult , Antimalarials/administration & dosage , Artemisinins/administration & dosage , Artesunate , Humans , Injections, Intravenous , MaleABSTRACT
We demonstrate laser action in diode-pumped microchip monolithic cavity channel waveguides of Yb:KGd(WO(4))(2) and Yb:KY(WO(4))(2) that were fabricated by ultrafast laser writing. The maximum output power achieved was 18.6 mW with a threshold of approximately 100 mW from an Yb:KGd(WO(4))(2) waveguide laser operating at 1023 nm. The propagation losses for this waveguide structure were measured to be 1.9 dBcm(-1).
Subject(s)
Lasers, Solid-State , Refractometry/instrumentation , Computer-Aided Design , Energy Transfer , Equipment Design , Equipment Failure Analysis , Miniaturization , Scattering, RadiationABSTRACT
We use a two-dimensional deformable mirror to shape the spatial profile of an ultrafast laser beam that is then used to inscribe structures in a soda-lime silica glass slide. By doing so we demonstrate that it is possible to control the asymmetry of the cross section of ultrafast laser inscribed optical waveguides via the curvature of the deformable mirror. When tested using 1.55 mum light, the optimum waveguide exhibited coupling losses of approximately 0.2 dB/facet to Corning SMF-28 single mode fiber and propagation losses of approximately 1.5 dB.cm(-1). This technique promises the possibility of combining rapid processing speeds with the ability to vary the waveguide cross section along its length.
Subject(s)
Lasers , Lenses , Lighting/instrumentation , Lighting/methods , Elasticity , Equipment Design , Equipment Failure AnalysisABSTRACT
We report the creation of unusual biaxial textures in Cu nanorod films, through the control of the incident vapor flux during oblique angle deposition. High-density twin boundaries were formed using a periodic azimuthal swing rotation of the substrate while the incident angle of the Cu flux was fixed at 85° with respect to the surface normal. In contrast, depositions on stationary substrates resulted in nanorod films with a much lower density of twinned crystals. From transmission electron microscopy and x-ray pole figure analysis, the nanorod axis was shown to coincide approximately with the [Formula: see text] crystallographic directions. We also observed the branching of these nanostructures into 'nanotrees'. This branching was attributed to the creation of edge dislocations during the deposition and was particularly prevalent for the case of swing rotation. The mechanisms for the development of texture, twinning, and branching in these nanostructures are discussed.
ABSTRACT
A fan-out device has been fabricated using ultrafast-laser waveguide-inscription that enables each core of a multicore optical fiber (MCF) to be addressed by a single mode fiber held in a fiber V-groove array (FVA). By utilizing the unique three-dimensional fabrication capability of this technique we demonstrate coupling between an FVA consisting of a one-dimensional array of fibers and an MCF consisting of a two-dimensional array of cores. When coupled to all cores of the MCF simultaneously, the average insertion loss per core was 5.0 dB in the 1.55 mum spectral region. Furthermore, the fan-out exhibited low cross-talk and low polarization dependent loss.
ABSTRACT
Design and fabrication of a tunable gain equalization filter for dense wavelength division multiplexed (DWDM) signals through erbium doped fiber amplifiers (EDFA) is reported. It is based on a side-polished fiber (SPF) half-coupler block loaded with a displaceable tapered multimode overlay waveguide (MMOW). A simple and accurate normal mode analysis is employed to design this filtering device for its subsequent realization. Equalization of a typical EDFA gain spectrum in the C-band within +/-0.35 dB or even less in the presence of various ITU standard C-band DWDM signal channels is demonstrated under varied operating conditions like add/drop of signals. Tunability of the filter notch is achieved through displacement of the SPF relative to the MMOW.
ABSTRACT
Frequency doubling has been achieved in femtosecond-laser-inscribed single-mode waveguides written in two periodically-poled potassium titanyl phosphate crystals. A conversion efficiency of 0.22 %W(1) was obtained for first-order quasi-phase matching at 980 nm and an efficiency of 0.02 %W(-1) for third-order quasi-phase matching at 800 nm.
ABSTRACT
A three-core tellurite glass fiber having different combinations of rare earth oxide dopants in each core has been fabricated using shaped die-extrusion. Three cores, doped with Ho(3+)-Tm(3+)-Yb(3+), Er(3+)-Ce(3+), and Tm(3+)-Yb(3+) respectively, exhibited visible upconversion (blue, green and red) and infrared emissions at 1.4 microm, 1.5 microm, 1.9 microm and 2.05 microm when pumped at a wavelength of 980 nm. The prospects for multi-band amplifiers and lasers are discussed.
Subject(s)
Metals, Rare Earth/chemistry , Optical Fibers , Tellurium/chemistry , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
We report on the fabrication of high quality embedded channel waveguides inside Bi-doped silicate glass using femtosecond waveguide inscription. Waveguides are fabricated using both single and multi-scan fabrication techniques. Refractive index modifications of up to Deltan = 4.3 x 10(-3) are observed, allowing the fabrication of waveguides nearly mode-matched to telecom fibers. When optically pumped at 980 and 810 nm broadband fluorescence emission centered at 1.3 microm with a FWHM of up to 500 nm is detected.
ABSTRACT
Understanding of cardiac rhythm requires application of physical principles governing electricity. Over a period of more than 100 years, application of the knowledge of electric current led to the gradual evolution of electrocardiogram, pacemaker, defibrillator, and ultimately electrophysiology. The discovery of electrocardiogram (ECG) by Einthoven in 1902 and that of pacing by Zoll in 1952 were two landmarks in this field.