Textron’s J-HPSSL 100 kW ThinZag® Laser Program

Abstract

A new approach (ThinZag®) for scaling Nd:YAG solid-state slab lasers to high power levels is described. Using an innovative optical configuration, thin slabs of solid-state gain material are immersed in a flowing cooling fluid, resulting in improved thermal management. Measurements at the ~1 kW level were conducted to compare Nd:YAG ceramic with Nd:YAG crystalline slabs. The ceramic slabs demonstrated comparable laser output power relative to the more standard crystalline slabs and demonstrated better optical properties, which result in improved medium uniformity. Performance results from our nominally 5 kW and 15 kW modules are also presented. The 15 kW modules represent basic building blocks for the Joint High Power Solid State 100 kW Laser (J-HPSSL) currently being designed and developed by Textron Defense Systems. Recent measurements of three nominally 15 kW modules operating as a single aperture power oscillator where outputs to 30 kW with beam quality of 3.3 XDL were measured are also included. The reported powers were for operation below maximum pump rate of the device.

Ceramic laser materials

“…Several similar thin disk lasers were combined to generate a total of >25 KW output [25]. [26] (b) end-pumped slab laser [27] and (c) thinzag slab laser [28].…”

“…Then in 2009 Northrop Grumman Corp. (NGC) demonstrated >100 KW output power [27], followed soon by Textron in 2010 [28]. The collective evolution of output power from YAG ceramics with time is shown in figure 19.…”

Numerical approach to temperature and thermal stress in direct-liquid-cooled Nd:YAG thin disk laser medium

“…A cooling fluid flows above the solid-state elements and a laser diode provides optical pump radiation into the volume of the laser chamber such that laser emission from the device passes through the gain medium and the fluid [1]. In 2010, Textron Defense Inc. presented an 100 kW output from the single aperture with six laser modules placed within the cavity, by using Nd:YAG thin slabs and the direct-liquid-cooled configuration [2]. It is one of the highest output power of solid-state lasers by so far, however, the detail of which has not been disclosed yet.…”

Novel transparent ceramics for solid-state lasers

“…In 2006, the Lawrence Livermore National Laboratory (LLNL) succeeded in achieving a world record high power of 67 kW emission from its solid-state heat capacity laser system using a large-scale transparent Nd:YAG ceramic with samarium edge cladding supplied by Konoshima Chemical [14] . Very recently, the emission of a Nd:YAG ceramic laser system with output power beyond 100 kW was further demonstrated [15][16][17] .…”