Manufacturing has begun in the new facility, which was designed specifically to produce high-power gain modules beginning with the JHPSSL Phase 3 program. Altogether, there will be 32 gain modules in the company's 100 kW JHPSSL Phase 3 demonstrator.
"This means that Northrop Grumman has designed a 100 kW solid-state laser system that can be efficiently manufactured," said Alexis Livanos, corporate vice president and president of Northrop Grumman's Space Technology sector. "We are gratified by the great confidence shown in our design and analysis for this powerful laser system."
The first gain module demonstrated under the program produced a power level of more than 3.9 kW, operated for 500 seconds at 20.6 percent efficiency, according to Mike McVey, vice president of Directed Energy Systems for Northrop Grumman's Space Technology sector.
"Our design for the JHPSSL Phase 3 laser includes design features needed for future systems," noted McVey. "We are making major improvements in size, weight and power in the Phase 3 laser compared with the system we demonstrated in the last phase."
Note: the 20.6% efficiency would mean that you need to supply 5 times the power to the lasers to get a particular amount of laser energy.
I have had several articles on using arrays of solid state lasers to launch vehicles into space and to accelerate vehicles that are already in space.
Laser arrays for space launch can be like the modular components of the internet infrastructure. Highly utilized tiered system that can be built modularly and incrementally.
Laser and magnetic launch
Putting the breaks on laser mirrors and all photonic propulsion
Using 67KW solid state lasers to send a vehicle to Mars in 10 days
BTW something that I will submit for the next carnival of space which I think is some of my best ideas on space yet.
What I think is a workable system to get space based solar power scaled up, cheaper, and identifying the best niches to supply power and grow space infrastructure
Laser focus world report from 2004 on the details of the technical details for the solid state laser
Northrop Grumman's slab laser uses a single master oscillator to pump parallel power-amplifier stages. Each power amplifier includes four diode-pumped neodymium-doped slabs in a series and is designed to generate 12.5 kW. [the new system has 32 modules] Beams from the amplifiers are tiled on the output aperture where adaptive optics adjust the wavefront to achieve high power. Scaling is by adding parallel amplifier chains.
Adaptive optics sense the output wavefront, then adjust the phase of the master oscillator output for each chain to keep the outputs of all chains in phase. As of May, Northrop has demonstrated that one of the diode-driven slab stages can produce 4.5 kW, well above the minimum needed. Scaling to 100 kW would require adding six parallel chains and combining their outputs.
A 2002 discussion of solid state laser costs. The key is getting cost down for diodes.
McKearn predicts the cost will go down from current  levels of $70 to $100 per watt down to $5 per watt during the next several years. [In 1997], he said, “a single 100 kw laser would have used three times the world’s yearly production of diodes.”
Page 21 of this pdf on the laser industry indicates that in 2006 the price of solid state laser diodes is $30/watt So the diodes for the 100KW laser are about $3 million.
So if price trends continue, then $10-15/watt in 2010 for high power laser diodes.
Laser focus world article surveying the diode laser market
More on the laser marketplace from Laser focus world
Definition: differential power efficiency of a laser
An important property of an optically pumped laser is its slope efficiency (or differential efficiency), defined as the slope of the curve obtained by plotting the laser output versus the pump power. Usually, this curve is close to linear, so that the specification of the slope efficiency as a single number makes sense. However, quite nonlinear curves can occur under various circumstances, e.g. as a consequence of three-level characteristics of the gain medium or thermal effects.
Ceramic Laser Boasts 82 Percent Slope Efficiency Diode-pumped Yb:Y2O3 laser believed to be most efficient ever.
Lasers with Nonlinear Input-Output Characteristics
The slope efficiency of a laser is an often used quantity, but there are actually plenty of cases where such a specification makes no sense – simply because there is no linear relation between pump power and output power