Composite laser gain medium

Abstract

A composite laser gain medium is comprised of a first rare-earth element doped core; and a second rare-earth element doped cladding, at least partially, adjacent to the core. A portion of the lasing by the cladding at one wavelength within the composite laser gain medium is absorbed by the core so as to cause lasing of the core at a different wavelength. At least two distinct rare earth element pairs may be used in embodiments: (1) thulium (Tm) as a cladding rare-earth dopant and holmium (Ho) as the core rare-earth dopant; and (2) ytterbium (Yb) as a cladding rare-earth dopant and erbium (Er) as the core rare-earth dopant. Other rare earth element pairs are also believed possible. The laser composite gain medium may be configured to have a slab, or a cylindrical geometry.

Description

GOVERNMENT INTEREST[0001]Governmental Interest—The invention described herein may be manufactured, used and licensed by or for the U.S. Government.FI ELD[0002]This application generally relates to lasers, and more particularly, to a composite laser gain medium.BACKGROUND[0003]Laser gain media are used in lasers. For example, both thulium-doped and holmium0doped lasers are important laser sources because they are considered “eyesafe,” i.e., in the 2 μm spectral region, and have applications in remote sensing, and medical and military technology. Thulium has several favorable properties with respect to laser diode pumping, such as a strong absorption band at a diode emission wavelength around 785 nm and an efficient cross-relaxation process yielding two ions in the upper laser level per absorbed pump photon.[0004]Some Tm-Ho lasers are comprised of two separate laser systems combined in series. However, the cost, bulk and complexity of such systems are relatively high, and flexibility ...

AI Technical Summary

Benefits of technology

[0008]At least two distinct rare earth element pairs may be used in embodiments: (1) thulium (Tm) as a cladding rare-earth dopant and holmium (Ho) as the core rare-earth dopant; and (2) ytterbium (Yb) as a cladding rare-earth dopant and erbium (Er) as the core rare-earth dopant. Other rare earth element pairs though are also believed possible. The core may have a refractive index smaller, equal or larger than that of the cladding depending of the application. Also, the composite laser gain medium may include at least one optical coating formed on an end surface of the composite laser gain medium which is orientated perpendicular to the core and cladding. Additionally or alternatively, the composite laser gain medium may further include at least one optical coating formed on a side surface the composite laser gain medium which is orientated parallel to the core and cladding.

Problems solved by technology

However, the cost, bulk and complexity of such systems are relatively high, and flexibility of design options to tailor for different applications is limited.

However, it has been a challenge to obtain laser radiation of both good beam quality and high power.

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