Rare earth ion doped CW cascade fiber laser
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsLeon Esterowitz, Roger E. Allen
Life of this patent
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Abstract
A continuous wave(CW) activator ion doped fiber laser is presented which lases at a normally self-terminating laser transition at a slope efficiency greater than that achieved by a self-terminating fiber laser. Two laser transitions, one corresponding to a self-terminating laser transition and the other to a transition out of the lower level of the self-terminating transition, are simultaneously stimulated in the activator ion doped fiber. Through simultaneous lasing of the two wavelengths corresponding to these transitions, the lower level of the self-terminating transition is sufficiently depopulated so that CW operation is achieved.
Claims23
A fiber laser system for producing a continuous wave (CW) fiber laser output, said fiber laser system comprising:
- a fiber host medium doped with a preselected concentration of activator ions to form a fiber;
- first and second reflective means butt-coupled to first and second opposite ends of said fiber to cooperatively form a fiber laser, said reflective means having reflectivities sufficient for producing continuous wave (CW) lasing at first and second preselected wavelengths when pumped by a pump beam;
- and
- a laser pumping means directed at said fiber for providing a continuous wave (CW) pump beam operating at a preselected pump wavelength sufficient for promoting electrons of said activator ions to the upper energy level of a self-terminating laser transition;
- said second reflective means operating as a fiber laser output coupler through which passes said CW fiber laser output at said preselected first wavelength corresponding to said self-terminating laser transition of said activator ions from said fiber at a slope efficiency greater than that achieved by a self-terminating fiber laser.
A method for producing a continuous wave (CW) fiber laser output at a slope efficiency greater than that achieved by a self-terminating fiber laser, said method comprising the steps of:
- continuously pumping an activator ion doped fiber host medium at a preselected pump wavelength sufficient to enable the activator ion doped fiber host medium to produce the continuous wave (CW) fiber laser output at a first preselected wavelength corresponding to the self-terminating laser transition;
- and
- producing the CW fiber laser output at the first preselected wavelength corresponding to the self-terminating laser transition wherein said producing step includes the steps of:
- utilizing first and second reflective means, with preselected first, second and third reflectivities, the first and second reflective means butt-coupled to first and second opposite ends of the activator ion doped fiber host medium;
- preselecting the first reflectivity of the first reflective means to allow, at least, 50-100% of incoming pump power at the preselected pump wavelength to be absorbed by the activator ion doped fiber host medium;
- preselecting the second reflectivity of the first and second reflective means sufficient for the CW fiber laser output at the first wavelength corresponding to the self-terminating transition;
- preselecting the third reflectivity of the first and second reflective means sufficient for a fiber laser output at a second wavelength, said second wavelength corresponding to a laser transition out of the lower energy level of the self-terminating laser transition of the activator ion, to an even lower energy level of the activator ion thereby increasing the slope efficiency of the fiber laser output at the first wavelength corresponding to the self-terminating laser transition and eliminating the large power loss of the fiber laser output due to self-termination and thus producing the CW fiber laser output at the first preselected wavelength;
- and
- allowing the resultant CW fiber laser output at the first wavelength to be transmitted through the second reflective means also operating as an output coupler.
Dependencies are inferred from the claim text.