scholarly journals Hollow Core Optical Fibers for Industrial Ultra Short Pulse Laser Beam Delivery Applications

Fibers ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 80 ◽  
Author(s):  
Sebastian Eilzer ◽  
Björn Wedel
Keyword(s):  
Laser Beam ◽  
Optical Fibers ◽  
Short Pulse ◽  
Flexible Beam ◽  
Hollow Core ◽  
Laser Interaction ◽  
Short Pulse Laser ◽  
Core Fiber ◽  
Beam Delivery ◽  
Ultra Short Pulse

Hollow core fibers were introduced many years ago but are now starting to be used regularly in more demanding applications. While first experiments mainly focused on the characterization and analysis of the fibers themselves, they are now implemented as a tool in the laser beam delivery. Owing to their different designs and implementations, different tasks can be achieved, such as flexible beam delivery, wide spectral broadening up to supercontinuum generation or intense gas-laser interaction over long distances. To achieve a constant result in these applications under varying conditions, many parameters of these fibers have to be controlled precisely during fabrication and implementation. A wide variety of hollow core fiber designs have been analyzed and implemented into a high-power industrial beam delivery and their performance has been measured.

scholarly journals Small fluence photosensitivity of high germanium doped core optical fibers from 266nm UV irradiation

2020 ◽  
Author(s):  
Rex Xiao Tan
Keyword(s):  
Optical Fibers ◽  
Short Pulse ◽  
Bragg Gratings ◽  
Phase Mask ◽  
Refractive Index Modulation ◽  
Uv Laser ◽  
Center Wavelength ◽  
Germanium Content ◽  
Short Pulse Laser ◽  
Ultra Short Pulse

The photosensitivity of high germanium content optical fiber was investigated with reference to UV laser of 266nm center wavelength. Bragg gratings were inscribed into the fiber using scanning phase mask method with a 266nm ultra short pulse laser and refractive index modulation due to irradiation was calculated from the parameters of the resulting fiber Bragg gratings. At small fluence, the high germanium content optical fibers seemingly experience competing photosensitivity mechanisms, dissimilar to the characteristics of common photosensitive optical fibers.

Thermal Ablation of Mouse Skin Tissue Using Ultra-Short Pulse 1552 nm Laser

2008 ◽  
Author(s):  
Amir Yousef Sajjadi ◽  
Ogugua Onyejekwe ◽  
Shreya Raje ◽  
Kunal Mitra ◽  
Michael Grace
Keyword(s):  
Laser Beam ◽  
Short Pulse ◽  
Mouse Skin ◽  
Ablation Depth ◽  
Tissue Ablation ◽  
Tissue Samples ◽  
Histological Studies ◽  
Short Pulse Laser ◽  
Ultra Short Pulse ◽  
Ultra Short Pulse Laser

Analysis of biological tissue ablation by an ultra-short pulse laser and the corresponding mathematical modeling of ablation are of fundamental importance to the understanding of laser-tissue interaction for advancing surgical application of lasers. The objective of this paper is to analyze the thermal ablated damage zones during irradiation of freshly excised mouse skin tissue samples by a novel approach of using a focused laser beam from an ultra-short pulse laser source. Experiments are performed using Raydiance Desktop Laser having a wavelength of 1552 nm and a pulse width of 1.3 ps. Mouse tissue samples are translated in a direction perpendicular to the laser beam using three-axis automated motion-controlled stages. Scanning of the tissue sample ensures a fresh region of the tissue is irradiated each time. The surface temperature distribution is measured using a thermal imaging camera. It is observed that use of focused beam results in minimal radial heat spread to the surrounding tissue regions. The ablation phenomenon is analytically modeled by the use of two-phase transient heat conduction model. After completion of tissue irradiation experiments, histological studies are performed using frozen sectioning technique to observe morphological changes in tissue samples in response to laser irradiation. The ablation depth measurements obtained using histological studies are compared with the modeling results. A parametric study of various laser parameters such as time-average power, pulse repetition rate, and pulse energy, and as well as irradiation time and scanning velocity is performed to determine the necessary ablation threshold. Analytical modeling results are in very good agreement with experimentally measured ablation depth. The goal of this research is to develop a tool for selection of appropriate laser parameters for precise clean tissue ablation.

Ablation of Subsurface Tumors Using 1552 nm Ultra-Short Pulse Laser

2008 ◽  
Author(s):  
Shreya Raje ◽  
Amir Sajjadi ◽  
Kunal Mitra ◽  
Michael S. Grace
Keyword(s):  
Laser Beam ◽  
Pulse Laser ◽  
Continuous Wave ◽  
Short Pulse ◽  
Laser Source ◽  
Short Pulse Laser ◽  
Fiber Optic Probes ◽  
Laser Immunotherapy ◽  
Ultra Short Pulse ◽  
Long Pulse

Over last two decades lasers have been used for the treatment of subsurface tumors. Various techniques such as Laser-induced Hyperthermia, Laser Interstitial Thermal Therapy (LITT), and Laser Immunotherapy have been developed for the successful ablation of subsurface tumors by different researchers. All these techniques use photo-thermal mechanism for tumor ablation by delivering thermal energy at the tumor site. In all these existing techniques, either continuous wave (CW) or long pulse laser source has been used, which often produces larger heat affected zone as compared to that produced by short pulse laser. Moreover, the delivery of laser beam at the target site is achieved through fiber optic probes which often require perforation of the skin. These drawbacks can be eliminated if a converging laser beam from a short pulse laser source is directly focused at the subsurface location to ablate the tumor.

Silicon Thinning using Ultra-Short Pulse Laser Ablation

2004 ◽  
Author(s):  
F. Beaudoin ◽  
P. Perdu ◽  
C. DeNardi ◽  
R. Desplats ◽  
J. Lopez ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Sample Preparation ◽  
Pulse Laser ◽  
Pulse Laser Ablation ◽  
Short Pulse ◽  
Special Care ◽  
Short Pulse Laser ◽  
Ultra Short Pulse ◽  
Ultra Short Pulse Laser

Abstract Ultra-short pulse laser ablation is applied to IC backside sample preparation. It is contact-less, non-thermal, precise and can ablate the various types of material present in IC packages. This study concerns the optimization of ultra-short pulse laser ablation for silicon thinning. Uncontrolled silicon roughness and poor uniformity of the laser thinned cavity needed to be tackled. Special care is taken to minimize the silicon RMS roughness to less than 1µm. Application to sample preparation of 256Mbit devices is presented.

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