An optimized fiber delivery system for Q-switched, Nd:YAG lasers

Technical Report · Fri Nov 01 04:00:00 EST 1996

DOI:https://doi.org/10.2172/414411· OSTI ID:414411

Setchell, R E

Interest in the transmission of high intensities through optical fibers is being motivated by an increasing number of applications. Using different laser types and fiber materials, various studies are encountering transmission limitations due to laser-induced damage processes. The authors have found that fiber transmission is often limited by a plasma-forming breakdown occurring at the fiber entrance face. System attributes that will affect breakdown and damage thresholds include laser characteristics, the design and alignment of laser-to-fiber injection optics, and fiber end-face preparation. In the present work the authors have combined insights gained in past studies in order to establish what thresholds can be achieved if all system attributes can be optimized to some degree. The multimode laser utilized past modifications that produced a relatively smooth, quasi-Gaussian profile. The laser-to-fiber injection system achieved a relatively low value for the ratio of peak-to-average fluences at the fiber entrance face, incorporated a mode scrambler to generate a broad mode power distribution within the initial segment of the fiber path, and had improved fixturing to insure that the fiber axis was collinear with the incident laser beam. Fiber end faces were prepared by a careful mechanical polishing schedule followed by surface conditioning using a CO{sub 2} laser. In combination, these factors resulted in higher thresholds for breakdown and damage than they had achieved previously in studies that utilized a simple lens injection system.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 414411
• Report Number(s): SAND--96-2795C; CONF-961070--1; ON: DE97001317
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
BEAM PROFILES
BEAM TRANSPORT
DAMAGE
EXPERIMENTAL DATA
LASER RADIATION
LIGHT TRANSMISSION
NEODYMIUM LASERS
OPTICAL FIBERS