Numerical Investigation on Transient Conjugate Optical-Thermal Fields in Thin Films Irradiated by Moving Sources for Front Treatments

2010 ◽  
Vol 297-301 ◽  
pp. 1439-1444
Author(s):  
Nicola Bianco ◽  
Oronzio Manca ◽  
Daniele Ricci
Keyword(s):  
Thin Film ◽  
Maxwell Equations ◽  
Film Structure ◽  
Laser Source ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Temperature Dependent ◽  
Motion Direction ◽  
One Dimensional ◽  
Thermal Fields

In this paper a numerical analysis on two-dimensional transient of the combined optical-thermal fields caused by a moving Gaussian laser source in a multilayer thin film structure on a glass substrate is carried out. The workpiece is considered semi-infinite along the motion direction and its optical and thermophysical properties are assumed temperature dependent. The COMSOL Multiphysics 3.4 code has been used to solve the combined thermal and electromagnetic problem. In this way, the optical field is considered locally one-dimensional and Maxwell equations are solved in order to evaluate the absorption in thin film. Results, in terms of transient temperature profiles and fields, are presented for different Peclet numbers and thin film thicknesses.

Numerical Model for Multilayer Thin Films Irradiated by a Moving Laser Source

2009 ◽  
Vol 283-286 ◽  
pp. 352-357 ◽  
Author(s):  
Nicola Bianco ◽  
Oronzio Manca ◽  
Daniele Ricci
Keyword(s):  
Thin Film ◽  
Maxwell Equations ◽  
Film Structure ◽  
Laser Source ◽  
Transient Temperature ◽  
Temperature Dependent ◽  
Motion Direction ◽  
One Dimensional ◽  
Thermal Fields ◽  
Starting Point

A two-dimensional transient analysis of the conjugate optical-thermal fields induced in a multilayer thin film structure on a glass substrate by a moving Gaussian laser source is carried out numerically. The workpiece is considered semi-infinite along the motion direction and its optical and thermophysical properties are assumed temperature dependent. The COMSOL Multiphysics 3.3 code has been used to solve the combined thermal and electromagnetic problem. The optical field is considered locally one dimensional and Maxwell equations are solved in order to evaluate the absorption in thin film. Results, in terms of transient temperature profiles and fields, are presented for different Peclet numbers and starting point of the heat source with respect to the workpiece boundary along the motion direction.

Transient Heat Conduction in Solids Irradiated by a Moving Heat Source

2009 ◽  
Vol 283-286 ◽  
pp. 358-363 ◽  
Author(s):  
Nicola Bianco ◽  
Oronzio Manca ◽  
Sergio Nardini ◽  
Salvatore Tamburino
Keyword(s):  
Three Dimensional ◽  
Transient Heat Conduction ◽  
Laser Source ◽  
Comsol Multiphysics ◽  
Work Piece ◽  
Temperature Profiles ◽  
Moving Heat Source ◽  
Gaussian Laser Beam ◽  
Motion Direction ◽  
Thermal Fields

Transient three-dimensional temperature distribution in a solid irradiated by a moving Gaussian laser beam was investigated numerically by means of COMSOL Multiphysics 3.3. The investigated work-piece are simply brick-type solids. A laser source is considered moving with constant velocity along the motion direction. The solid dimension along the motion direction is assumed as semi-infinite while width and thickness are considered finite. Several different grid distributions are tested to ensure that the calculated results are grid independent. Typical parameters involved in the processes for any particular application should be evaluated, in order to optimize the material processing and forecast the solid behavior. The results are presented in terms of temperature profiles and thermal fields are given for some Biot and Peclet numbers.

Microscale Radiation Effects in Multilayer Thin-Film Structures During Rapid Thermal Processing

1993 ◽  
Vol 303 ◽  
Author(s):  
Peter Y. Wong ◽  
Christopher K. Hess ◽  
Ioannis N. Miaoulis
Keyword(s):  
Thin Film ◽  
Numerical Model ◽  
Thermal Processing ◽  
Radiation Effects ◽  
Rapid Thermal Processing ◽  
Chemical Vapor ◽  
Film Structure ◽  
Transient Temperature ◽  
Multilayered Structures ◽  
Temperature Distributions

ABSTRACTThe individual film thicknesses of multilayered structures processed by rapid thermal processing are of the same order as the wavelengths of the incident radiation. This induces optical interference effects which are responsible for the strong dependency of surface reflectivity, emissivity, and temperature distributions on the geometry of the layering structures, presence of patterns, and thickness of the films. A two-dimensional, finitedifference numerical model has been developed to investigate this microscale radiation phenomena and identify the critical processing parameters which affect rapid thermal processing of multilayer thin films. The uniformity of temperature distributions throughout the wafer during rapid thermal processing is directly affected by incident heater configurations, ramping conditions, wafer-edge effects, and thin-film layering structure. Results from the numerical model for various film structures are presented for chemical vapor deposition of polycrystalline silicon over oxide films on substrate. A novel technique using an edge-enhanced wafer which has a different film structure near its edge is presented as a control over the transient temperature distribution.

Effect of Impinging Jet on Heat Conduction in Workpieces Irradiated by a Moving Heat Source

2011 ◽  
Vol 312-315 ◽  
pp. 924-928 ◽  
Author(s):  
N. Bianco ◽  
Oronzio Manca ◽  
Sergio Nardini ◽  
Salvatore Tamburrino
Keyword(s):  
Radiative Heat ◽  
Three Dimensional ◽  
Impinging Jet ◽  
Laser Source ◽  
Comsol Multiphysics ◽  
Finite Width ◽  
Moving Heat Source ◽  
Temperature Dependent ◽  
Motion Direction ◽  
Biot Numbers

A three dimensional conductive field is analyzed and solved by means of the COMSOL Multiphysics code. The investigated work-pieces are made up of a simple brick-type solid. A laser source with combined donut-Gaussian distributions is considered moving with a constant velocity along motion direction. The solid dimension along the motion direction is assumed to be infinite or semi-infinite, while finite width (2ly) and thickness (s) are considered. Thermal properties are considered temperature dependent and the materials are considered isotropic. Surface heat losses toward the ambient are taken into account. Several convective heat flux values on the upper surface, with corresponding Biot numbers, and Peclet numbers are considered with negligible radiative heat losses.Results are presented in terms of profile temperatures to evaluate the effect of impinging jet.

Effect of Solid Thickness on Transient Heat Conduction in Workpieces Irradiated by a Moving Heat Source

2010 ◽  
Vol 297-301 ◽  
pp. 1445-1450 ◽  
Author(s):  
Nicola Bianco ◽  
Oronzio Manca ◽  
Sergio Nardini ◽  
Salvatore Tamburrino
Keyword(s):  
Three Dimensional ◽  
Transient Heat Conduction ◽  
Surface Heat ◽  
Laser Source ◽  
Comsol Multiphysics ◽  
Finite Width ◽  
Moving Heat Source ◽  
Temperature Dependent ◽  
Motion Direction ◽  
Gaussian Distributions

In this paper a three dimensional conductive field is analyzed and solved by means of the COMSOL Multiphysics code. The investigated work-pieces are made up of a simple brick-type solid. A laser source with combined donut-Gaussian distributions is considered moving with a constant velocity along motion direction. The solid dimension along the motion direction is assumed to be infinite or semi-infinite, while finite width (2ly) and thickness (s) are considered. Thermal properties are considered temperature dependent and the materials are considered isotropic. Surface heat losses toward the ambient are taken into account. Results are presented in terms of profile temperature to evaluate the effect of solid thickness.

Effects of High Reynolds Number Impinging Jet on the Heat Conduction in Work-Pieces Irradiated by a Moving Heat Source

2014 ◽  
Vol 354 ◽  
pp. 189-194
Author(s):  
Oronzio Manca ◽  
Sergio Nardini ◽  
D. Ricci ◽  
S. Tamburrino
Keyword(s):  
Three Dimensional ◽  
Impinging Jet ◽  
Reynolds Numbers ◽  
Heat Losses ◽  
Laser Source ◽  
Finite Width ◽  
Temperature Dependent ◽  
Motion Direction ◽  
Commercial Code ◽  
High Reynolds

A three dimensional conductive field is analyzed and solved numerically by means of a commercial code. The investigated work-pieces are made up of a simple brick-type solid. A laser source with combined donut-Gaussian distributions is considered moving with a constant velocity along motion direction. The solid dimension along the motion direction is assumed to be infinite or semi-infinite, while finite width (2ly) and thickness (s) are considered. Thermal properties are considered temperature dependent and the materials are considered isotropic. Surface heat losses toward the ambient are taken into account. Several Reynolds numbers of the impinging jet, Biot and Peclet numbers are considered with negligible radiative heat losses. Results are presented in terms of temperatures field and profile to evaluate the effect of impinging jet.

scholarly journals Characterization of Absorption Losses and Transient Thermo-Optic Effects in a High-Power Laser System

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 94
Author(s):  
Lukasz Gorajek ◽  
Przemyslaw Gontar ◽  
Jan Jabczynski ◽  
Jozef Firak ◽  
Marek Stefaniak ◽  
...  
Keyword(s):  
High Power ◽  
Continuous Wave ◽  
Beam Quality ◽  
Laser System ◽  
Infrared Camera ◽  
High Energy ◽  
Laser Source ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Beam Diameter

(1) Background: The modeling, characterization, and mitigation of transient lasers, thermal stress, and thermo-optic effects (TOEs) occurring inside high energy lasers have become hot research topics in laser physics over the past few decades. The physical sources of TOEs are the un-avoidable residual absorption and scattering in the volume and on the surface of passive and active laser elements. Therefore, it is necessary to characterize and mitigate these effects in real laser systems under high-power operations. (2) Methods: The laboratory setup comprised a 10-kW continuous wave laser source with a changeable beam diameter, and dynamic registration of the transient temperature profiles was applied using an infrared camera. Modeling using COMSOL Multiphysics enabled matching of the surface and volume absorption coefficients to the experimental data of the temperature profiles. The beam quality was estimated from the known optical path differences (OPDs) occurring within the examined sample. (3) Results: The absorption loss coefficients of dielectric coatings were determined for the evaluation of several coating technologies. Additionally, OPDs for typical transmissive and reflective elements were determined. (4) Conclusions: The idea of dynamic self-compensation of transient TOEs using a tailored design of the considered transmissive and reflecting elements is proposed.

Quasi-Steady State Numerical Model for a Multilayer Thin Film Irradiated by a Moving Laser Source at High Peclet Numbers

2003 ◽  
Author(s):  
Nicola Bianco ◽  
Oronzio Manca ◽  
Vincenzo Naso ◽  
Giuseppe Rotondo
Keyword(s):  
Thin Film ◽  
Steady State ◽  
Film Thickness ◽  
Numerical Technique ◽  
Laser Source ◽  
Maximum Temperature ◽  
Temperature Profiles ◽  
Quasi Steady State ◽  
Thin Film Thickness ◽  
Absorption Function

A numerical analysis of the conjugate optical-thermal fields in an amorphous silicon thin film deposited on a glass substrate and irradiated by a moving Gaussian laser source is carried out. The velocity of the laser is assumed constant and quasi-steady state conditions are considered. Optical and thermophysical properties of materials are assumed temperature dependent. The conjugate optical and thermal models are solved by means of a finite volume numerical technique and the heat conduction along the direction of motion has been neglected. The optical field is considered locally one-dimensional and it has been solved by means of the matrix method. Results are given in terms of radiative coefficients, absorption function distribution and temperature profiles and fields. The effect of the relative velocity and of the thin film depth are analyzed. For the considered model, radiative coefficients profiles show that for the largest thin film thickness, reflectance values do not depend very much on the Peclet number and on the x coordinate. Temperature profiles point out that the maximum temperature values are attained for an intermediate thin film thickness among the three considered values. This is due to the interference effects within the thin film that cause the maximum energy absorption for this thickness.

The effect of an aluminum heat-sink layer on the laser-induced amorphization of SiOx/TeGeSn/SiOx phase-change recording films

1989 ◽  
Vol 47 ◽  
pp. 574-575
Author(s):  
Matthew R. Libera ◽  
Martin Chen
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Heat Sink ◽  
Multilayer Film ◽  
Glassy Phase ◽  
Film Structure ◽  
Glass Forming ◽  
Active Storage ◽  
Dielectric Layers ◽  
Amorphous States

Phase-change erasable optical storage is based on the ability to switch a micron-sized region of a thin film between the crystalline and amorphous states using a diffraction-limited laser as a heat source. A bit of information can be represented as an amorphous spot on a crystalline background, and the two states can be optically identified by their different reflectivities. In a typical multilayer thin-film structure the active (storage) layer is sandwiched between one or more dielectric layers. The dielectric layers provide physical containment and act as a heat sink. A viable phase-change medium must be able to quench to the glassy phase after melting, and this requires proper tailoring of the thermal properties of the multilayer film. The present research studies one particular multilayer structure and shows the effect of an additional aluminum layer on the glass-forming ability.

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