Sapphire ( 0 0 0 1 ) surface modifications induced by long - pulse 1054 nm laser irradiation

نویسندگان

  • Sheng-Nian Luo
  • Pedro D. Peralta
  • Chi Ma
  • Dennis L. Paisley
  • Scott R. Greenfield
  • Eric N. Loomis
چکیده

We have investigated modifications of sapphire (0 0 0 1) surface with and without coating, induced by a single laser pulse with a 1054 nm wavelength, 2.2 ms duration, 7.75 mm spot and energy of 20–110 J. A holographic optical element was used for smoothing the drive beam spatially, but it induced small hotspots which initiated damage on the uncoated and coated surfaces. The individual damage effects of hotspots became less pronounced at high fluences. Due to high temperature and elevated non-hydrostatic stresses upon laser irradiation, damage occurred as fracture, spallation, basal and rhombohedral twinning, melting, vitrification, the formation of nanocrystalline phases, and solid–solid phase transition. The extent of damage increased with laser fluences. The formation of regular linear patterns with three-fold symmetry (h1 1 2̄ 0i directions) upon fracture was due to rhombohedral twinning. Nanocrystalline a-Al2O3 formed possibly from vapor deposition on the coated surface and manifested linear, triangular and spiral growth patterns. Glass and minor amounts of g-Al2O3 also formed from rapid quenching of the melt on this side. The ato g-Al2O3 transition was observed on the uncoated surface in some partially spalled alumina, presumably caused by shearing. The nominal threshold for laser-induced damage is about 47 J cm 2 for these laser pulses, and it is about 94 J cm 2 at the hotspots. # 2007 Elsevier B.V. All rights reserved.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

EXTENDED REPORT Application of femtosecond ultrashort pulse laser to photodynamic therapy mediated by indocyanine green

Backgrounds/aims: To evaluate treatment with high peak power pulse energy by femtosecond ultrashort pulse laser (titanium sapphire laser) delivered at an 800 nm wavelength for corneal neovascularisation using photodynamic therapy (PDT) mediated by indocyanine green (ICG). Methods: Using a gelatin solid as an in vitro corneal model, the safety of laser power was studied to determine if it degene...

متن کامل

Application of femtosecond ultrashort pulse laser to photodynamic therapy mediated by indocyanine green.

BACKGROUND/AIMS To evaluate treatment with high peak power pulse energy by femtosecond ultrashort pulse laser (titanium sapphire laser) delivered at an 800 nm wavelength for corneal neovascularisation using photodynamic therapy (PDT) mediated by indocyanine green (ICG). METHODS Using a gelatin solid as an in vitro corneal model, the safety of laser power was studied to determine if it degener...

متن کامل

STSM Report Fabrication of Bio-inspired surfaces

2.1 Fabrication of microstructures (silicon spikes) Single crystal n-type Si (1 0 0) wafers were subjected to laser irradiation in a vacuum chamber evacuated down to a residual pressure of 10 -2 mbar. A constant pressure of 500 Torr was maintained during the process through a precision micro valve system. The irradiating laser source was constituted by a regenerative amplified Ti:Sapphire (λ = ...

متن کامل

Growth mechanism of iron nanoparticles on (0 0 0 1) sapphire wafers

Laser ablation of a high purity (99.7%) iron target was used to accomplish the depositions of iron nanoparticles on the (0 0 0 1) face of single crystal sapphire wafers. The nanoparticles were characterized in situ by means of X-ray photoelectron spectroscopy (XPS). The growth mechanism was determined by applying the QUASES-Tougaard methodology to the extended part of the background intensity o...

متن کامل

Shallow implantation of Ti ions in sapphire [ a - Al 2 O 3 ( 0 0 0 1 ) ]

Sapphire single crystal [a-Al2O3(0 0 0 1)] samples were treated by irradiation with Ti‡ ions in the energy range 0.5±7.0 keV at 25°C and 750°C under UHV conditions for total doses of 10 Ti‡/cm2. These Ti treated sapphire samples were studied by ex situ X-ray photoelectron spectroscopy (XPS) depth pro®ling and by atomic force microscopy (AFM). Aluminum in the oxidation states Al0;3‡;x‡, where 0 ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2007