A conceptually simple, effective scheme for reliable, high-power pumping of neodymium:yttrium aluminum garnet (Nd:YAG) lasers (and perhaps also other solid-state lasers) has been devised. Heretofore, it has been common practice to pump a Nd:YAG crystal by use of a single diode laser. However, diode lasers are not reliable enough to support long-life, high-power operation. If multiple diode lasers could be used to pump a single Nd:YAG crystal, then laser operation would be less degraded by the deterioration or failure of a single diode laser.

Light From Multiple Pump Lasers is coupled through optical fibers into a ferrule, wherein the individual pump beams are combined.

One alternative scheme for coupling light from multiple laser-diode pumps into a single Nd:YAG crystal would involve the integration of multiple laser diodes, along with relatively complicated optics, onto a single chip. In such an arrangement, it would not be possible to change the number of pumps. Moreover, the pumps would not be isolated from each other, so that failure of one could adversely affect the operation of the others.

In contrast, the present scheme affords optical isolation of the pump lasers from each other, is amenable to addition or removal of pump lasers, and involves relatively simple optics. The output ends of the fibers of multiple independent fiber-coupled laser diodes are bundled together in a ferrule (see figure). A gradient-index-of-refraction (GRIN) lens in the ferrule combines the multiple pump beams into a single beam aimed into the Nd:YAG crystal. The failure of one laser diode does not affect the operation of the others, and the light from the others continues to pump the Nd:YAG crystal.

This work was done by Serge Dubovitsky, Jerry Mulder, and Duncan Liu of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Electronic Components and Systems category.

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to

Intellectual Assets Office
JPL
Mail Stop 202-233
4800 Oak Grove Drive
Pasadena, CA 91109
(818) 354-2240
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Refer to NPO-30353, volume and number of this NASA Tech Briefs issue, and the page number.

Topics:
Fiber optics Imaging and visualization Lasers Optics Photonics Research and development
This Brief includes a Technical Support Package (TSP).
Document cover
Multiple-Pump Lasers

(reference NPO-30353) is currently available for download from the TSP library.

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    Photonics Tech Briefs Magazine

    This article first appeared in the September, 2002 issue of Photonics Tech Briefs Magazine (Vol. 26 No. 9).

    Read more articles from the archives here.

    Overview

    The document outlines a technical support package related to the development of multiple-pump lasers, specifically focusing on enhancing the reliability and performance of Nd:YAG lasers. Traditionally, Nd:YAG lasers utilize a single diode laser pump, which has been found to be unreliable for long-term, high-power operation due to the tendency of diode lasers to lose power over time. This issue has been corroborated by both laboratory experiences and industry feedback.

    To address this reliability concern, the authors propose a novel approach that involves using multiple fiber-coupled diode lasers to pump the laser crystal. Each diode laser's output is coupled into individual fibers, which are then bundled together to form a fiber bundle. This innovative design allows for independent operation of each diode laser, meaning that if one diode fails, it does not affect the performance of the others. This level of isolation is a significant advantage over traditional methods that use a diode laser array, which are more complex and less robust.

    The document also discusses the advantages of this new method, including its simplicity and the ability to easily adjust the number of diode pumps used. The authors emphasize that their approach not only improves reliability but also simplifies the optical design, making it easier to manage and maintain.

    Additionally, the document includes a technical disclosure section that outlines the motivation behind the development of this technology, the problems it aims to solve, and a detailed description of the solution. The authors highlight that their method is a significant improvement over existing technologies, providing a more robust and efficient way to pump Nd:YAG lasers.

    Overall, this technical support package serves as a comprehensive overview of the advancements in multiple-pump laser technology, showcasing the potential for improved performance and longevity in laser applications. The work was conducted under the auspices of the Jet Propulsion Laboratory and sponsored by NASA, indicating its relevance and potential impact in aerospace and other high-tech fields.