Multiple emitter side pumping method and apparatus for fiber lasers
AssigneeBAE Systems Information and Electronic Systems Integration Inc.
InventorsKevin J. Snell, Scott D. Setzler
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Abstract
A modified V-groove structure in a double clad laser system permits multiple emitter side pumping of a fiber laser. In one embodiment, a stack of at least five emitters have individual outputs coupled into the inner cladding, with as many sources as desired coupled to the fiber to raise the cumulative pumping power to in excess of 2-KW, thus to achieve a 1-KW fiber laser.
Claims20
Apparatus for pumping a high power fiber laser having a fiber with a doped core, comprising:
- a number of pumping sources;
- optics for focusing the light from said pumping sources to points within said fiber;
- and,
- a series of closely spaced V-grooves in the side of said fiber pointing towards respective pumping sources, said grooves spaced by less than an absorption length, each of said grooves having an alpha facet angled to reflect pumping light down said fiber in a predetermined direction, said V-grooves being positioned such that the point to which a pumping source is focused lies on an alpha facet of an associated V-groove, such that light from a number of pumping sources is reflected down said fiber around subsequent V-grooves and is combined to pump the core of said fiber.
A method of pumping a high power fiber laser made from a double clad fiber having a core, an inner cladding layer and an outer cladding layer, comprising the steps of:
- providing a number of closely spaced modified V-grooves in a surface of the inner cladding so as to define a first V-groove and subsequent downstream V-grooves, the downstream V-grooves having a beta facets which are sloped so as not to reflect light from an upstream facet so that light reflected by the beta facet impinges on the outer surface of the inner core at an angle less than the critical angle such that upstream pumping light introduced at one V-groove moves by a subsequent V-groove, whereby there is total internal reflection of pumping light introduced into the inner cladding, each V-groove having an alpha facet for reflecting pumping light in the downstream direction;
- and,
- focusing pumping light from a number of independent pumping sources onto the alpha facets of the V-grooves, whereby a number of independent pumping sources may be used to pump the core, thus to combine the pumping energy from a number of independent pumping sources sufficient to provide for a high power fiber laser output.
A high powered fiber laser, comprising:
- a double clad fiber having a core, an inner cladding for said fiber and an outer cladding for said fiber;
- a plurality of modified V-grooves closely spaced along a surface of said inner cladding, each of said modified V-grooves having an alpha facet, modified V-grooves downstream of a first modified V-groove having beta facets sloped to assure total internal reflection of pumping light reflected from an upstream alpha facet onto a downstream beta facet such that light introduced at one modified V-groove goes by a subsequent modified V-groove;
- a substantially identical plurality of pumping sources having pumping light focused on alpha facets of respective modified V-grooves;
- an HR Bragg grating in the fiber upstream of said first modified V-groove;
- and,
- an output coupler Bragg grating downstream of the last of said modified V-grooves, said pumping sources collectively providing sufficient pumping power.
Dependencies are inferred from the claim text.